ComTouch: A Vibrotactile Mobile Communication
Device
by
Angela Chang
Bachelor of Science,
Massachusetts Institute of Technology,
Cambridge, MA
1997.
Submitted to the Program in Media arts and Sciences,
School of Architecture and Planning,
In Partial Fulfillment of the Requirements for the Degree of
Master of Science in Media Arts and Sciences
at the
Massachusetts Institute of Technology
June 2002
© Massachusetts Institute of Technology, 2002.
All rights reserved.
_____________________________________________________________
Author
Angela Chang
Program in Media Arts and Sciences
May 10, 2002
_____________________________________________________________
Certified by
Hiroshi Ishii
Associate Professor of Media Arts and Sciences
Thesis Supervisor
_____________________________________________________________
Accepted by
Andrew B. Lippman
Chairperson, Department Committee on Graduate Students
Program in Media Arts and Sciences
1
ComTouch:
A Vibrotactile Mobile Communication Device
Angela Chang
Submitted to the Program in Media Arts and Sciences,
School of Architecture and Planning, on May 10, 2002
in Partial Fulfillment of the Requirements for the Degree of
Master of Science in Media Arts and Sciences at the
Massachusetts Institute of Technology
Abstract
This thesis presents ComTouch, a new device for enhancing interpersonal
communication over distance through use of touch. The ComTouch approach
investigates how the sense of touch can be remotely represented by means of a
vibrotactile, or touch-and-vibration, interface. Touch has potential to improve existing
remote communication by allowing tactile cues to augment the audio-visual
information in real-time.
The approach of ComTouch is to use this vibrotactile mapping for conveying the
pressure exerted by each finger of the transmitter as patterns of vibration against the
corresponding finger of the receiver. The implementation is a hand-held device that
allows a user to transmit and receive patterns of vibration to and from a remote user.
A pair of prototypes was built to allow exploration of remote communication using this
vibrotactile mapping.
The hypothesis is that the vibrotactile mapping can be used in remote communication
of tactile gestures, or expressive uses of touch. User studies will be performed to gauge
the information content of the signals transmitted and received using the vibrotactile
device in remote communication. A report of the observed usages of the vibrotactile
channel will be given. This research will allow us to identify patterns of tactile
communication that may inform the design of new tactile communication devices,
languages and methods.
Thesis Supervisor:
Hiroshi Ishii
Associate Professor of Media Arts and Sciences
2
Thesis Committee
_______________________________________________________
Thesis Supervisor
Hiroshi Ishii
Associate Professor of Media Arts and Sciences
Massachusetts Institute of Technology
_______________________________________________________
Thesis Reader
Sile O’Modhrain
Principal Research Scientist, Palpable Machines
Media Lab Europe
_______________________________________________________
Thesis Reader
Robert Jacob
Associate Professor of Electrical Engineering and Computer Science
Tufts University
3
Acknowledgments
The author wishes to express sincere appreciation to Professors Hiroshi Ishii, Sile O’Modhrain
and Robert Jacob for their assistance in the preparation of this manuscript. Thank you for your
patience and willingness to see me through this undertaking.
I would like to give special thanks to Eric Gunther whose familiarity with vibrotactile actuation
was helpful during the design phase. Without the generous donation of time, equipment and
advice from Dave Franklin of Audiologic Engineering, this work would not have been possible.
The author thanks her undergraduate research assistants: Zahra Kanji, for her dedication, Flora
Chiu for her willingness to learn new tools for PCB fabrication, Matthew Malcolm for his skilled
hand in the repair of electronics, and Kenji Alt for his help in observational prototyping.
I was lucky enough to work with those whose wisdom and work ethic inspire me. Attitude is the
key of success, and Kenroy Cayetano was there to help me think through the technical issues of
the circuit design. Jennifer Yoon, whose quality videos made the presentations successful. Ian
Gouldstone, for his artistic visual guidance, critiques, timely work, and professional animations.
In addition, the members of the Tangible Media Group are acknowledged for their valuable input
and feedback. The current group members James Patten, Gian Pangaro, Dan Maynes-Aminzade,
and Brygg Ullmer contributed much camaraderie in this research.
The alumni of the Tangible Media Group were also of great help. I would like to thank Victor Su,
for his remote help in designing the system, Andrew Dahley for his evaluation and feedback, Phil
Frei, for his design advice and example, and Scott Brave for his experimental testing advice. Their
work on InTouch was inspirational. I would also like to thank Craig Wisneski, Sandia Ren, Mike
Ananny and Ali Mazalek for their engineering advice and wise viewpoints, which saved me much
time. Also, past UROP Rujira Hongladaromp’s optimism helped with the existing debugging of
inTouch.
The researchers at Media Lab Europe are thanked for their support and camaraderie.
Particularly, the folks at the Palpable machines lab, Andy Brady, Brian MacDonald, and Ian
Oakley were helpful in the understanding of the fabrication and experimental design problems I
faced.
The students of Slugfest, Fourth East, East Campus dormitory.
To my good friends Ela Ben-Ur and Arrin Katz, Rich Fletcher and Virginia Siu, Barbara Abreu
and Jackie Youngblood and my cousins, Raymond and Joyce, for visiting, emailing and calling.
To LCS/Telegraphics, specifically Robert Dezmelyk, for teaching me how to think about
technology. Howard Eglowstein, for teaching me how to design and build electronic devices to do
my bidding. John Jurewicz for imparting his thrill of technology, Sylvia Johnson-Phillips for her
systematic approach to management and Richard Poyner for showing me the importance of
technical documents and white papers.
I would like to thank Tom Hayes of the Harvard Extension School for his wisdom and hands-on
manner to working with electronics.
My parents, Matty and Enrique Chang, for allowing their daughter to go to school at such a
wonderful institution. Benjamin for his brotherly advice and encouragement.
James Edward Gouldstone, the inspiration and supporting force behind all that I do. Your
artistic ability helped me visualize ComTouch for the first time, and your guidance in the
mechanical design was the cornerstone of the work presented.
4
TABLE OF CONTENTS
ABSTRACT....................................................................................................................................2
THESIS COMMITTEE ................................................................................................................3
ACKNOWLEDGMENTS .............................................................................................................4
TABLE OF FIGURES ..................................................................................................................8
1 INTRODUCTION ......................................................................................................................9
1.1 PROBLEM DESCRIPTION ........................................................................................................10
1.2 A VIBROTACTILE MAPPING ..................................................................................................10
1.3 OUTLINE OF THIS DOCUMENT ................................................................................................11
2 RELATED RESEARCH ..........................................................................................................13
2.1 BACKGROUND AND MOTIVATION .........................................................................................13
2.1.1. Definitions and Terminology of Touch ........................................................................13
2.1.2. A Brief Overview of the Mechanics of Touch ..............................................................14
2.1.3. Psychological Aspects of Touch ..................................................................................16
2.1.4. Cognitive aspects of touch in combination with other modalities...............................17
2.1.5. Tactile illusions............................................................................................................18
2.2 RELEVANT RESEARCH ..........................................................................................................19
2.2.1. Haptic Interpersonal Communication .........................................................................20
2.2.2. Vibrotactile research ...................................................................................................22
2.2.3. Tactile languages .........................................................................................................22
2.2.4. Review of Commercial Products .................................................................................23
3 COMTOUCH DESIGN............................................................................................................25
3.1 AN ENHANCEMENT FOR VOICE COMMUNICATION .................................................................25
3.1.1. Choosing the design space for tactile communication ................................................26
3.1.2. Metaphor of Hand Gestures ........................................................................................27
3.2 DEVICE SPECIFICATIONS .......................................................................................................29
3.2.1. Vibration vs. Force Feedback......................................................................................29
3.2.2. Feedback channel ........................................................................................................30
3.2.3. Sensor and Actuator Placement...................................................................................31
3.2.4. Converting touch into vibration...................................................................................31
3.3 ERGONOMIC CONSIDERATIONS .............................................................................................33
3.3.1. Concept generation......................................................................................................33
3.3.2. Precision grip vs. strength grip ...................................................................................35
3.3.3. The nature of vibration ................................................................................................35
3.3.4. Mechanics of the hand .................................................................................................37
3.4 IMPLEMENTATIONS ...............................................................................................................37
3.4.1. Preliminary system implementation ............................................................................37
3.4.2. Ergonomic implementation..........................................................................................38
5
4 EXPERIMENTS .......................................................................................................................40
4.1 EXPERIMENT ON ONE- FINGER OF VIBROTACTILE MAPPING....................................................40
4.1.1. Introduction .................................................................................................................40
4.1.2. Preliminary user studies ..............................................................................................41
4.1.3. Experimental Procedure..............................................................................................42
4.1.4. Criteria for evaluation.................................................................................................44
4.2 RESULTS ...............................................................................................................................45
4.2.1. Results of the first experiment......................................................................................46
4.2.2. Emphasis......................................................................................................................46
4.2.3. Turn-taking ..................................................................................................................47
4.2.4. Mimicry ........................................................................................................................48
4.2.5. Encoding ......................................................................................................................48
4.3 DISCUSSION ..........................................................................................................................49
4.3.1. Ergonomics ..................................................................................................................50
4.3.2. Lack of resolution of vibration intensity......................................................................51
4.3.3. More channels please ..................................................................................................51
4.3.4. Audible Vibration.........................................................................................................51
4.3.5. Limitations ...................................................................................................................52
4.3.6. Subject familiarity........................................................................................................52
4.3.7. Data Analysis ...............................................................................................................52
4.4 SUMMARY OF FIRST EXPERIMENT .........................................................................................53
5 THE POTENTIAL OF TACTILE GESTURES… ...............................................................55
5.1 INTRODUCTION .....................................................................................................................55
5.1.1. Potential Users ............................................................................................................55
5.1.2. Adoption of potential languages ..................................................................................57
5.2 DEVELOPMENT OF A TOUCH LANGUAGE ...............................................................................58
5.2.1. Basic components of vibration communication...........................................................58
5.3 COMMUNICATING EMOTION ..................................................................................................60
5.4 TOUCH COMMUNICATION SCENARIOS ..................................................................................60
5.4.1. Messaging Application ................................................................................................61
5.4.2. Emotional aspects of tactile communication ...............................................................61
5.4.3. The use of touch in mobile communication .................................................................61
5.5 ADDITIONAL POTENTIAL OF TOUCH COMMUNICATION ..........................................................63
5.5.1. Cutaneous Illusions .....................................................................................................63
5.5.2. Coding of alphanumeric content .................................................................................64
5.5.3. Multiplexing of Tactile transmissions..........................................................................64
5.6 NO VIBROTACTILE LANGUAGE FOR COM TOUCH YET ............................................................65
6 CONCLUSION .........................................................................................................................67
6.1 THE VIBROTACTILE MAPPING ..............................................................................................67
6.2 FUTURE W ORK .....................................................................................................................68
6.3 SOME INTERESTING DESIGN IMPLEMENTATIONS ...................................................................70
6.3.1. Alternate distribution of actuators...............................................................................70
6
6.3.2. Variation of bandwidth and complexity.......................................................................70
6.3.3. Improved Ergonomics..................................................................................................70
6.4 EXPANDING THE DESIGN SPACE ............................................................................................71
6.4.1. Exploration of other modalities ...................................................................................71
6.4.2. Touch as a sensory substitution to Audio ....................................................................71
6.4.3. Touch and Smell ..........................................................................................................72
6.4.4. Touch and Vision .........................................................................................................72
6.4.5. Touch Displays ............................................................................................................73
6.4.6. Static Displays (General Haptic Displays)..................................................................73
6.4.7. Vibration Displays .......................................................................................................74
6.5 SUMMARY.............................................................................................................................74
APPENDIX A PART RESOURCES AND ELECTRICAL DIAGRAMS.............................76
APPENDIX B TESTING MATERIALS USED IN EXPERIMENT......................................79
7 REFERENCES .........................................................................................................................86
7
Table of Figures
Figure 1-1. Real-time interpersonal communication methods................................................................. 9
Figure 2-1. Cross section of the layers of hairless skin........................................................................ 14
Figure 2-2. Cell receptors .................................................................................................................. 15
Figure 2-3.The sensory homunculus diagram ..................................................................................... 16
Figure 3-1. Artistic rendering of ComTouch ........................................................................................ 25
Figure 3-2. Addition of a tactile modality to existing communication. ..................................................... 26
Figure 3-3 Design variables for tactile communication. ........................................................................ 27
Figure 3-4. Distribution of vibrotactile signals used by Gunther's Skinscape. ......................................... 28
Figure 3-5. InTouch transmits rolling touch......................................................................................... 29
Figure 3-6. ComTouch Touch to Vibration mapping. ........................................................................... 30
Figure 3-7. Sidetone definition ........................................................................................................... 30
Figure 3-8. A Force Sensing Resistor................................................................................................. 31
Figure 3-9. A V1220 Speaker actuator ............................................................................................... 32
Figure 3-10. Diagram of one transmission from finger to vibration. ....................................................... 32
Figure 3-11. Placement of actuators on the preliminary implementation ............................................... 33
Figure 3-12. Exploration of different form factors................................................................................. 34
Figure 3-13. Precision grip vs. strength grip. ....................................................................................... 35
Figure 3-14. Transmission of vibrations through ComTouch. ............................................................... 36
Figure 3-15. ComTouch Preliminary Implementation. .......................................................................... 37
Figure 3-16 A five finger ergonomic implementation ............................................................................ 38
Figure 3-17 Placement of actuators in the five finger ergonomic implementation ................................... 38
Figure 3-18. A working set of ergonomic ComTouch ........................................................................... 39
Figure 4-1. Preliminary user studies ................................................................................................... 41
Figure 4-2. Experiment setup ............................................................................................................ 42
Figure 4-3. Resulting observed tactile gestures .................................................................................. 45
Figure 4-4. Number of pairs exhibiting tactile gestures in first task ...................................................... 46
Figure 4-5. Emphasis of the audio channel......................................................................................... 47
Figure 4-6. Turn-taking ..................................................................................................................... 47
Figure 4-7. Mimicry patterns .............................................................................................................. 48
Figure 4-8. Encoding schemes. ......................................................................................................... 49
Figure 5-1. The common sense of touch. ........................................................................................... 55
Figure 5-2. Existing communication methods...................................................................................... 56
Figure 5-3. Expression increases with the number of channels. ........................................................... 59
8
1 introduction
“Communication face-t o-face is rich in social cues: we can see one another; we
know the distance between us; and we may even be able to touch. Over the
telephone, in contrast, there is little except the voice…” (p.38, Rutter)
Real-time remote communication allows peopl e to connect to each
other in real-time while being physically separated. The ability to
instantaneously exchange sound and text over great distances has
become almost commonplace. However, commercial
communication devices do not ordinarily convey a sense of touch.
With rare exceptions, communicating using touch is only possible
when people are face -to-face. Figure 1-1 shows the
communication design space we are concerned with.
Figure 1-1. Real-time
interpersonal
communication
methods.
Our specific design
space for this project
concerns remote
communication, which
will be further
discussed in
Chapter 3.
REAL-TIME Interpersonal Communication
Methods for Different Places
Remote locations
Local
Chat
Face-to-face
telephone
Gestures
email
Senses-- audio, vision,
instant messaging
smell, taste, touch
Morse code
Touch has much meaning and information in interpersonal
communication. Touch acts as an extension of the physical body.
Hand shakes between business partners signify agreement and
commitment, the supportive squeeze of your hand by a friend, or
even a quick tap of interruption from a stranger conveys a wealth
of contextual information that is rarely present in real-time remote
interpersonal communication. The promise of “reaching out to
9
touch someone” suggests that touch is a powerful and meaningful
part of interpersonal communication.
1.1 Problem Description
What is the meaning of touch in remote communication? Imagine
if you really were able to reach out and touch someone in a remote
place, and imagine if they could touch you in response. What is
the socially shared signaling system, or code? What set of shared
behaviors are possible? The answers to these questions on
communication are directly related to the interface. With
something as physical as the sense of touch, it follows that the
form defines the function. The interface will determine the nature
of the communication.
The goal of this research is to design and implement a sensory
augmentation tool that communicates the sense of touch. A
necessary step toward this goal is to explore the possible effects of
a tactile channel to verbal communication. The hypothesis is that
tactile information enhances audio remote interactions, and that if
tactile feedback is made available, there may exist a correlation
between the way tactile and audio communication channels are
used. An additional hypothesis is that tactile information can
enhance remote interaction, in a manner independent of the audio
channel.
1.2 A Vibrotactile Mapping
Tactile touch as a modality for communication has recently begun
to attract interest from researchers in the field of commercial
communication devices. Modern technological advances in
communication devices (such as reduced battery size, better data
compression, and increased bandwidth for graphics and text)
enable new modalities for mobile real-time remote communication.
What limitations exist, then, for creating a commercial remote
touch communication device?
10
Previous approaches have focused on accurately representing the
mechanics of touch. To create artificial haptic stimuli has been the
main problem with embedding communication devices with tactile
actuators. The most common method to solve this problem is to
use motors. However, motors require sophisticated motion control
algorithms, power storage and dissipation schemes, and quick
response to generate compelling tactile effects. Motors are also too
bulky for continuous use-- imagine lifting and holding a motor all
the time. The use of motors also raises issues of robustness from
timely wear-and-tear and being dropped. There are also safety
issues as motors might exert too much force or spin too quickly
for the comfort. In short, a new actuation technique is desired.
We present the use of vibration as an alternative solution to
generate tactile output for communication. This dissertation
investigates the potential of vibrotactile interfaces for remote
communication. We describe our methodology, design, and
evaluation of a new tactile communication interface.
1.3 Outline of this document
This paper describes a particular design approach to creating a
tactile communication device. The design process, research
background, and key design issues are identified.
Chapter 2 describes the background and motivation of this thesis,
as well as related work on touch, perception and communication.
Chapter 3 describes the design and prototype implementation of
the ComTouch system. An implementation of a new vibrotactile
mapping is proposed. A touch communication device using this
mapping is presented. Chapter 4 describes initial experiments on
the usage of the device in conjunction with an audio channel
present interesting results. The discussion reflects on user
reactions and the data presented. The new mapping reveals three
new uses, called tactile gestures, for the tactile information in
11
audio conversations. Users are also able to develop their own
encoding schemes, with some similarities, using the device.
Chapter 5 refle cts on the implications of the discovery of tactile
gestures on the development of a touch language. Chapter 6
summarizes conclusions on tactile gestures from this research,
and discusses future design possibilities for this research.
12
2 related research
2.1 Background and Motivation
In the beginning, we were motivated to build a tactile
communication device. We quickly found relevant information in
three main areas: the interpersonal communication work done in
the Human-Computer Interfaces (HCI) field, the work on
vibrotactile mechanisms in psychophysiology, and work on
information transmission of tactile languages used by deaf-blind
people. What follows is an overview of some terminology to
familiarize the reader with the relevant research.
2.1.1. Definitions and Terminology of Touch
Haptics is defined as anything pertaining to the sense of touch.
Haptic sensations can be subdivided further into two types:
passive and active sensations.
The first types of sensations, tactile or cutaneous sensations, are
passive and refer to the sensations applied to the skin. These
sensations are based on the stimulation of receptors in the skin.
Goldstein further subdivides tactile sensations into three types:
tactile perceptions are caused by the mechanical displacement of
the skin, temperature perceptions caused by heating or cooling of
skin and pain perception caused by stimuli that are potentially
damaging to skin. The research here is primarily concerned with
the use of these tactile sensations.
The active types of sensation are proprioceptive and kinesthetic
sensations. Proprioceptive sensation refers to the awareness of
position of your limbs. Kinesthetic sensation refers to the sense of
movement of the limbs.
13
From these sensations, the skin provides useful information to the
brain. The combination of sensations that results in
communication of information is of particular interest. In order to
realize the possibilities of how to present information via our
tactile senses, it is useful to know about the mechanics of touch.
2.1.2. A Brief Overview of the Mechanics of Touch
The composition of skin determines the sense of touch using the
three different types of sensation described earlier. These
sensations allow the skin to act in two main capacities: to
separate our insides from the environment and also to provide us
with information about the environment. Some of the functions of
skin are to warn of danger, prevent body fluids from escaping,
protect our internal organs from external irritants, exert pressure
on objects, and sense temperature.
As depicted in Figure 2-1, the skin consists of many layers. The
outermost layer is called the epidermis, composed of several layers
of dead skin cells. Under the epidermis is the dermis, an inner
layer containing nerve endings. The skin contains a vast amount
of receptors throughout the epidermis and dermis.
Figure 2-1. Cross
section of the layers of
hairless skin
showing some of the
receptors. The four
main receptors of
touch are circled.
(Adapted from
Sensation and
Perception Goldstein
p.438)
Figure 2-2 depicts the four major receptors for tactile perception
in order of closeness to the epidermis: Merkel receptor, Meissner
corpuscle, Ruffini cylinder and Pacinian corpuscle. These
14
receptors are designed to perceive different cutaneous perceptions
such as pressure, flutter, buzzing, and vibration.
Figure 2-2. Cell
receptors
The four major
receptors for tactile
reception and their
frequency range of
response
(Adapted from
Goldstein
pp.438-439.
Receptors
Frequency range
Perception
a) Merkel receptors
0.3-3Hz (slow pushin g)
Pressure
b) Meissner corpuscle
3-40 Hz
Flutter
c) Ruffini cylinder
15-400 Hz
Stretching
d) Pacinian corpuscle
10-500 Hz (very rapid vibration)
Vibration
Unlike our eyes and ears, the haptic stimuli receptors are not
encapsulated in a single organ, but rather distributed along the
body. A higher concentration of receptors in certain parts of the
body such as hands and lips results in greater sensitivity to tactile
sensations in these areas. Figure 2-3 shows the sensory
homunculus diagram representing the brain’s processing of the
distribution of touch. Notice that the area of the hand occupies
the largest cortical area. This unequal distribution shows that the
brain dedicates a large area of receptors for the fingers. Compared
to other body parts, our hands have a high density of tactile
receptors. This makes the hand an ideal site for receiving
information (Reed 1991).
15
Figure 2-3.The sensory
homunculus diagram
representing the
brain’s processing of
the distribution of
touch. Survival,
perception, cognition
are functions of touch
in everyday life. In
order to survive, we
need to move
--(From Sensation and
Perception Goldstein
p.449).
2.1.3. Psychological Aspects of Touch
Survival, cognition, emotion and perception are functions of touch
in everyday life. In order to survive, we need to move. We need to
feel around us (perception) and get these signals to our brain in
order to decide where to move (cognition).
Klatzky and Lederman proved that the haptic system is very
efficient at recognizing 3D objects. In their 1987 study, users
optimized their tactile senses using a large number of exploratory
procedures (EPs) for taking in information and manipulating
objects. Some EPs are: enclosing objects with the hands, following
contours, applying pressure, and using lateral motion. The
researchers found that people tended to use the same types of EPs
depending on the desired information needed about the object.
16
Figure 2-4 shows some typical EPs that are used for object
recognition.
Touch does more than just give us information about our
surroundings, it also helps us express emotions (e.g. patting,
squeezing, stroking). Touch has high emotional value. Ackerman
(p.71) writes, “We call our emotions feelings, and we care most
deeply when something ‘touches’ us.”
Figure 2-4. Typical
movement patterns for
EPs described by Klatzky
and Lederman.
From top left counter
clock wise: lateral motion,
static contact, enclosure,
function test, part motion
test, contour following,
unsupported holding and
pressure. –from p.346
(Klatzky 1993)
The intensity of emotion has correlations with the intensity of
physical expression. The skin is the site at which the body
releases endorphins for pain and excitement. Social and
behavioral scientists have long used the skin conductivity as an
indicator of emotion (Dawson 1990).
2.1.4. Cognitive aspects of touch in combination with other modalities
Our senses often act in unison to present a cohesive story to our
mind. Crossmodal interactions are when a combination of the
senses of touch, taste, smell, hearing, and vision jointly act. When
crossmodal interactions occur to verify one another, cognition
happens more robustly than when only one sense is acting alone.
When the senses disagree, we often experience what are called
sensory illusions, because the mind has difficulty resolving the
meaning of the stimuli. One such illusion is visual capture or the
ventriloquism effect, which often occurs in movies where a
character’s voice is perceived as coming from their mouth even
though it is really coming out of a loud speaker somewhere else
(Stein 1993, Goldstein 2002).
Our reliance on different senses can vary depending on the
situation. For example, in the dark, our sense of sight tries to
adjust to lower levels of light. Meanwhile, as one ages, the sense of
hearing and sight tend to degrade.
17
In this research, we are particularly interested in the effect of the
combination of senses. People naturally use a combination of
modalities in order to understand their environment. These
combinations affect perception in different ways. Three types of
sensory interactions are widely studied because of their powerful
effects on human perception and cognition: sensory substitution,
sensory redundancy, and synesthesia.
Sensory substitution is the process of substituting information
from one sensory modality for another in order to perceive an
object. One example of sensory substitution is when people who
are deaf rely on the lip reading, a visual sense.
Sensory redundancy or sensory augmentation is the process of
adding information from one modality to help another. When the
senses act together to verify each other, perception occurs much
strongly. An example of sensory redundancy is when you see a
rose, but you have to smell and touch it to verify whether it is real.
Although a rare condition, synesthesia is when stimulation of one
modality triggers stimulation of a different modality. For example,
a person might associate seeing different colors when hearing
certain sounds. Usually, this results in a very compelling
experience for the pe rson.
2.1.5. Tactile illusions
Brown and Stevens give an overview of two ways of stimulating the
skin using artificial stimuli (1992). Vibrotactile means to use
vibration signals delivered by one or more vibrators on the skin.
Electrotactile means to use electrical stimulation (e.g. by means of
surface electrodes) to deliver signals to the skin. It is interesting to
note that certain tactile stimulation can cause illusions on the
skin.
18
One interesting phenomenon we hope to exploit is the cutaneous
rabbit, also known as sensory saltation (Geldard 1972) . When
given a number of distinct vibrational pulses along the forearm,
people felt the vibrations were moving up their arm linearly. In
effect, their mind was interpolating the effect of phantom
vibrators. The components necessary for this effect to occur are
actuators at the desired end-points of the linear gesture, and the
correct relationships in timing and amplitude between the pulses
used to generate the illusion. The saltation effect has analogies in
vision and audition, where the person perceives more stimuli than
are actually available (Tan 2000). In Tan’s study, people who were
naïve to vibrotactile stimuli could readily distinguish patterns of
movement without any training.
There are two significant implications of sensory saltation. One
implication is that there is no learning curve for experiencing this
phenomenon. The results also imply that not as many actuators
are needed to achieve the perception of movement across the skin.
This research provokes the notion that gestures are possible with
only a few actuators. One idea is that gestural movements can be
possible by starting a motion in one direction that can be
completed mentally by the user.
2.2 Relevant Research
The following sections contain descriptions of relevant research in
three main areas: Research on interpersonal communication in
HCI provides insight on how the sense of touch is conveyed
remotely. Research in the field of psychophysiology investigates
how tactile stimuli can be used for communication. Work on
sensory communications describes touch as used by sensory
impaired people, and their use of tactile languages.
19
2.2.1. Haptic Interpersonal Communication
ComTouch was primarily influenced by prior work in the field of
haptic interpersonal communication. This work demonstrated that
technology was capable of connecting people using touch in real
time. Many previous attempts to communicate touch in real time
employed the use of mechanical linkages. In the early 80s,
Telephonic Arm Wrestling introduce d the idea of haptic remote
communication using simulation over a telephone line that
controlled levers (White 1986).
2.1.1.a Social communication
Later research focused on the interactions afforded by these
devices. Fogg’s HandJive used linked hand-held joysticks for
haptic entertainment and found that tactile interaction was
socially enjoyable (1998). Brave’s research on computer-mediated
communication provided additional evidence that the context of
the device usage can either foster cooperation or competition
(2001).
Due to the broadcast nature of audio and video, many existing
communication devices compete for our attention. The senses can
become overloaded and important information may be overlooked.
The personal communication devices of others often needlessly
interrupt our attention and compromise our privacy. One solution
is to employ the underused modality of touch. Researchers at
FXPal have focused on integrating media and modalities with
research on calm technology (Nelson 2002), in hopes to soften the
impact of interruption caused by current communication devices.
2.1.1.b Emotional connectivity
Several artistic explorations advanced the idea of haptic
interpersonal communication by using digitally augmented objects
to transmit presence information remotely, such as Dunne and
Raby’s presentation at Doors of Perception (Dunne 1994).
20
Exploratory combinations of various interface modalities and
input-output mappings evoke awareness of a remotely located
person. Feather, Scent, Shaker demonstrated how touch could be
mapped to scents, light and vibration (Strong 1996). Ishii’s
InTouch recreated a symmetric mapping of touch over distance by
preservation of the physical analog movement of rollers (Ishii
1997, Brave 1997) and described the notion of tangible
telepresence, using touch to connect remotely located people
through different mediums (Ishii 1997).
In his thesis on personal ambient displays Wisneski explores
displaying telepresence information through tactile modalities
using “thermal change (heating and cooling), movement (shifting
and vibration), and change of shape (expanding, contracting, and
deformation) (Wisneski 1999).” Wisneski further discusses the
reasons for utilizing tactile displays to keep information private,
and reducing interference with other visual and auditory activities.
Wisneski’s vision of ambient devices to transmit information in the
background of a person's perception expanded on the use of
ambient displays using expressive kinetic objects by Dahley
(Dahley1998b, Ishii 1998, Wisneski 1998).
Following Ishii’s exploration of ambient media to demonstrate
information flow (Ishii 1998), physical objects were also used by
Tollmar et al. to explore telepresence in home environments.
Tollmar represents the interaction of remotely located people with
everyday objects such as stones, chairs and portraits (Tollmar
2000). Further explorations introduced artifacts for emotional
communication, such as the Kiss Communicator by IDEO used the
active motion of a kiss to display colorful lights on remote objects
(Buchenau 2000). LumiTouch is a digitally augmented picture
frame that explored the passive communication of presence
(Chang 2000). Grimmer’s Heart2Heart vest allowed a touch to
21
convey heat, pressure, and heartbeat wirelessly to mimic a
physical embrace (Grimmer 2001).
2.2.2. Vibrotactile research
The design and implementation of ComTouch relies mainly on the
existing body of vibrotactile (touch and vibration) research.
Geldard first introduced the notion of applying vibrotactile stimuli
to the skin, and showed that people could learn an invented tactile
body language called vibratese (Geldard 1967). Tan, Reed and
Durlach proved that the hand-based reception language of
Tadoma could transmit very accurate information (Tan 1997). Tan
further investigated the use of vibrotactile interfaces to engage the
full hand (Tan 1994, 2000). Her Tactuator, a three-fingered
sensory substitution device, used a tactile interface for improving
the reception of speech (Tan 1996). Gunther’s SkinScape used
vibration devices distributed throughout the body to enhance the
audio experience by immersing audience members in musically
synchronized tactile compositions (Gunther 2001).
2.2.3. Tactile languages
The available tactile languages provide insight into the vast
amounts of information that can be achieved by use of skin. Deafblind people can use a variety of tactile communication languages.
Fingerspelling is a tactile language where the pressure and
expressive movements of one hand is received on another hand.
Tadoma is a method where the receiver places his thumbs on the
lips of the speaker, with fingers on the throat. Tadoma can be so
precise as to allow the user to detect intonation information from
the vibrotactile stimuli (Tan 1996). In comparison, Braille is a
static alphabetic re presentation coded using raised dots. “Braille
can be read at 100 words per minute, slower than the rate for
visual reading, which averages about 250 to 300 words a minute”
(Goldstein 2002, p. 406)
22
Because Braille consists of discrete patterns, it can be
computerized, and thus provide remote communication
possibilities. However, the transmission and reception of Braille is
much slower than Tadoma. Morse code, when transmitted in the
form of tactile signals, is also a form of touch communication.
Advanced users were able to efficiently use shorthand and perform
simultaneous speech encoding and decoding of Morse messages
(Tan 1996). These findings indicate that a touch-based
communication language can be a very versatile communication
tool.
A brief review of tactile communication languages demonstrates
the potential use of touch as a primary communication medium.
Deaf-blind people can use a variety of tactile communication
languages.
In an overview of existing methods, Reed mentions four common
traits of natural tactile communication that may be relevant in the
higher rates of successful information transfer (Reed 1991): The
use of the hand as the site for reception of tactual simulation, the
activation of both the cutaneous and the proprioceptive branches
of the tactual sensory system, the simultaneous presentation of
information along a number of different dimensions, and the
extensive training periods of use for a particular method.
2.2.4. Review of Commercial Products
2.2.4.a Force Feedback Devices
Assessment of the commercial products allowed us to develop an
idea of technological advances and market needs. We noted the
use of force feedback and vibration in entertainment devices to
provide more physical interaction with computer games,
enhancing the gaming experience. Some example devices are
Aura System’s Interactor Vest, Immersion’s Impulse Engine 2000
23
Joystick, BSG System’s Intensor chair, VRF’s Tactile Feedback
System, and SensAble’s PHANToM (Massie 19944).
2.2.4.b Vibrotactile Perception
Commercially available vibration devices, such as Logitech’s iFeel
mouse, serve as a redundant sensory display for visual
information by enabling users to physically feel onscreen
boundaries. Vibrating pagers and mobile phones can subtly get a
user’s attention during an important meeting.
Many tactile aids for the deaf translate audio signals into
vibration. Multimodal communication devices, such as the Tactaid
device (Verillo 1992), are often used when the information
transmitted using a particular single modality could be lost due to
the environment or the abilities of the individual. The Optacon
(Goldstein 2002, p.209) is a device that translates printed words
or pictures into patterns of vibrating pins.
2.2.4.c Hand-based Input Devices
An investigation into ways in which the hand inputs information
into the computer led to a wide array of keyboard devices. Doug
Engelbart’s 5-finger keyboard spawned many similar types of
chording keyboard devices using just one hand. One popular
input device used in wearable computing is HandyKey’s Twiddler,
a mobile, compact and wireless chording keyboard that allows for
single -handed mouse and alphanumeric input. There are even a
number of keyboards that strap to the wrist.
The existence of these devices arises mainly from a need to use the
hand more efficiently (i.e. in virtual reality situations, and mobile
computing). The devices are geared to maximize the use of the
hand as an input method. Also, most of these devices require
some time to learn before the user is proficient. This implies that
any new input device will have some learning curve.
24
3 ComTouch design
This section will discuss a range of design issues; from high-level
design principles of tactile communication, such as asynchronous
information flow, to implementation decisions for aesthetic and
usability reasons, like the number of buttons.
3.1 An enhancement for voice communication
The proposed device, called ComTouch, is designed to augment
voice communication by translating finger pressure into vibration.
The device is a cover that fits over the back of a mobile phone, as
depicted in Figure 3-1. This device enables users to augment
remote communication by transmitting touch. The pr essure under
each finger is transmitted to a remote hand. The personal nature
of touch will enhance communication by allowing users to impart
some physical, nonverbal information into their communication.
Figure 3-1. Artistic
rendering of
ComTouch
Artistic rendering of
ComTouch mobile
phone holder
concept.
–Drawing courtesy
of James Gouldstone
25
The approach of ComTouch is to use touch as the common
sensory experience that augments existing speech
communication. Our approach embodies the spirit of universal
usability by creating common sensory experiences to increase
communication. By increasing shared sensory experiences
between different groups of the user population, communication
between both the general population and users who rely on touch
may be easier. Figure 3-2 shows our proposed addition of touch to
audio communication.
Figure 3-2. Addition of a 3.1.1. Choosing the design space for tactile communication
tactile modality to existing
communication. ComTouch interactions were influenced by existing
ComTouch proposes the
addition of a new modality; communication scenarios, particularly the telephone, and face-totouch, onto an existing
interaction to increase the face communication. Like the telephone and face -to-face
shared sensory experience
in audio communication. communication, the ComTouch is bi -directional and synchronous.
Bi-directional describes the capability of each device to send and
receive signals; the information would flow in both directions.
Similarly, the device allows synchronous transmission. Thus,
signals can be sent and received simultaneously, no protocol is
needed for the users to transmit or receive information; signals
could coincide, overlap or interrupt.
Unlike the telephone, which uses audio input and output, an
asymmetric input/output mapping was chosen. Symmetric
mappings of touch-to-touch in communication interfaces have
been previously studied, such as inTouch (Brave 1997) and
HandJive (Fogg 1998). Our approach is to explore a new
asymmetric mapping using touch (e.g. touch-to-vision, or soundto-touch). The main reason for asymmetric representations was
that the signals were to be constrained to the hand, which is a
small area. The parts needed to display touch symmetrically
(touch-to-touch) would need to be small enough to be grasped by
26
the hand. Representations of touch can be effective in conveying
nonverbal information (Strong 1996).
In order to allow nonverbal expressive communication, the device
transmits time-varying (or continuous) streams of signals rather
than discrete data. In describing haptic input methods, Buxton
discusses the benefits of continuous gestures that are analogous
to physical gestures in communication (1983). Brave found that
the emotional information is best preserved using analog,
continuous signals (1998).
Figure 3-3 summarizes the design parameters of interest. We are
particularly interested in bi -directional, asynchronous
transmission of continuous information by means of an
asymmetric interface.
3.1.2. Metaphor of Hand Gestures
The concept of this handheld device was inspired by the
communication metaphor of shaking hands— a nonverbal
interaction where the information is characterized by the physical
nature of the participants (Ackerman). Although Geldard and
Figure 3-3 Design
variables for tactile
communication.
This table summarizes
the design parameters
of interest.
Variable
Range of design axis
Data direction
bi-directional
uni-directional
Data transfer
asynchronous
synchronous
I/O Mapping
asymmetric
symmetric
Data content
Continuous
discrete
Gunther both distributed vibrotactile signals over the whole body
(see figure 3-4), the hand provides a compact site on the body for
tactile input and output (Geldard 1967, Gunther 2002). The ability
to close the sensory loop at a localized member of the body means
that no extra sensory augmentation is required to both send and
27
receive signals. Fingers can function to receive and send signals
of varying degrees of intensity (Goldstein 2002).
Figure 3-4. Distribution
of vibrotactile signals
used by Gunther's
Skinscape.
–from Gunther 2002
p.45.
The choice of the hand as the interface determines the number of
actuators that can be used. In order to provide the maximum
sensory bandwidth in the hand, we chose each finger as a site of
actuation and reception. There is a higher density of touch
receptors in the fingertip, while the independent motor control of
each finger separately actuates a signal.
ComTouch uses all five fingers to maximize the sensory capacity of
the hand to give and receive. Engaging as much of the hand as
possible would allow more expression. Information theory shows
that fewer degrees of expression would cause very compact
messages that require much encoding, while an increased degree
of expressiveness corresponds to simpler coding schemes.
Because we are interested in the representation of physical
gestures, such as the nuances of squeezing and motion, a close
physical mapping between the fingers and the device inputs and
outputs will more adequately convey physical information.
28
3.2 Device Specifications
3.2.1. Vibration vs. Force Feedback
Most mechanical representations of touch, such as inTouch (in
figure 3-5), are expensive to build because motors, gears and
control systems are required for representing the analog qualities
of touch. The number of components increases the weight of the
Figure 3-5. InTouch
transmits rolling touch
by using motors gears and
sophisticated control
systems.
device and makes them more suitable for stationary than mobile
devices. Also, these mechanical components often wear out with
use. Other possible means of force display using modern hightechnology methods, such as shape memory alloys and
magnetofluid, were not pursued due to expected practical
problems with precision control of actuation, necessary operating
conditions (temperature and sealing of components) and relatively
high cost of novel technologies.
Our approach was to use vibration to represent the analog
pressure of touch. The prior research suggests that vibration is
the obvious choice of display. Vibrating objects are easier to hold
than objects that have pushing or moving components. Vibration
also was chosen because it was already implemented in many
commercial communication devices. Each finger could also serve
as a site to receive vibration signals.
A touch to vibration mapping was designed. A person would be
able to send a signal by squeezing or pressing. The pressure of
touch is then converted to intensity of vibration. This vibration
would then be transmitted and felt by a remote. Figure 3-6 depicts
the proposed interface.
29
Figure 3-6.
ComTouch Touch to
Vibration mapping.
Notice the feedback
channel and the
physical separation
of input/output
space.
–Drawing courtesy
of James Gouldstone
3.2.2. Feedback channel
Sidetone: The sound of the
speaker's own voice (and
background noise) as heard in
the speaker's telephone
receiver. Sidetone volume is
usually suppressed relative to
the transmitted volume.
Figure 3-7. Sidetone
definition
--From the 1006 Federal
Standard 103C
(Telecom Glossary)
We implemented a feedback channel for the user, so that as she
communicated by pressing on the sensors there is some indication
as to what was sent. In some devices, such as videophones and
telephones, there is a small feedback channel (see figure 3-7 on
sidetone ) to allow users to gauge how their transmission is
received. Previous research hinted that users struggled when
control of a single output was shared, perhaps due to the inability
of one user to distinguish her own contribution from that of her
partner (Fogg 1998). As a result, ComTouch affords each user
singular control over his or her output signal. Local feedback
allowed users to gauge the intensity of the signal to be
transmitted.
30
3.2.3. Sensor and Actuator Placement
The input was located on the fingertips because the flexor muscles
have dynamic physical range to control a downward pressure. The
output vibrations are located on the middle and base of the finger,
as this area gives the most contact surface on the hand.
From the related research as well as our design rationale, the
following device specifications were developed:
1. Communication using vibrotactile data. Users will be able to send
data by pressure of their fingertips and receive via vibration. The
squeeze force will be linked to the intensity of the vibration.
2. The device should be handheld. It is also important for the input
and output areas to be localized so the hand does not have to do too
much work.
3. The device should be feasible to build. The device should use
components that are cheap to build, and robust in mechanical
design against fatigue, wear and tear.
4. The device should be small enough for discreet use and mobility.
The device should be small enough to fit in the hand, and be easy
to carry.
3.2.4. Converting touch into vibration
Given the specification for a touch-to-vibration mapping, the
circuit is designed to convert pressure into vibration.
Figure 3-8. A Force
Sensing Resistor.
A finger is shown for
scale. The FSR is
made by Interlink
Electronics.
Force sensing resistors (FSRs) measure pressure. FSRs are
sensitive enough to discern a range of pressures from
approximately 0.45psi (light squeeze) to 150psi (hard squeeze).
Figure 3-8 depicts the FSR available from Interlink Electronics.
31
Vibrotactile research typically applies a maximum frequency of
250 Hz to take advantage of the fact that the Pacinian corpuscles,
the touch receptors that are sensitive to vibration, are most
Figure 3-9. A V1220
Speaker actuator
made by Audiologic
Engineering.
A finger is included
for scale.
sensitive to vibrations of about 250Hz (Bolanowski 1988). After
trying the pager motors typical of consumer devices like the iFeel
mouse, we determined that their dynamic range was too limited
for adequate expression. We found a dime -sized commercial
acoustic speaker quite suitable in range, and its response was
quick and precise enough to represent subtle changes in the
continuously varying input pressure signal. These speakers, the
V1220 model from AudioLogic Engineering, are commercially used
in the Tactaid device for the hearing impaired (Figure 3-9).
A touch-to-vibration mapping was implemented using a voltagecontrolled oscillator (VCO) circuit. When the FSR was pressed, a
voltage was input into the VCO. This signal was converted into an
oscillation, and the resulting signal was fed into an audio amplifier
circuit to drive the speakers. The VCO output was designed such
that maximum pressure corresponded to a maximum frequency of
250Hz. Figure 3-10 displays the conversion of the signal from
finger pressure to frequency of vibration through the VCO.
Figure 3-10.
Diagram of one
transmission
from finger to
vibration.
32
Note that the vibrotactile speakers were designed to have a very
narrow frequency response, the amplitude of the output vibration
signal dropped off sharply as the input frequency moved away
from 250Hz, providing an effective way to create an amplitude
envelope in response to changes in pressure on the FSR.
3.3 Ergonomic Considerations
An ergonomic form factor was necessary for this handheld device.
Much effort was spent on designing a handheld object where the
form implied the function of the fingers. A series of prototyping,
observational studies, and technical solutions were pursued.
Figure 3-11. Placement of
actuators on the
preliminary implementation
Figure 3-11 shows the layout of the input and outputs on the
finger.
3.3.1. Concept generation
The basic form was a hand-held device that allowed each finger to
squeeze independently. A series of exploratory form factors helped
to visualize possible user interfaces. The dimensions for gripping
and the elasticity of the materials were varied to gauge user
preferences. More than 7 form factors were considered in the
embodiment of the device. These prototypes explored features of
two-handed, squeezable, ergonomic, wearable, and strapped
physical interfaces. Figure 3-12 depicts some of the form factors
explored.
33
Figure 3-12.
Exploration of
different form
factors
using rough
prototypes from
clay and foam.
One key issue is that the use of the device should feel comfortable
and not obstruct the natural functions of the hand. In particular,
the device should allow communication only when intended. For
example, a user might send a squeeze signal when they are simply
trying to hold the device. One solution was to use a strap for
supporting the device in the users hand, or implement an on/off
switch so that tactile communication must be intentional.
Another solution may be to reduce the number of channels, so
that some of the fingers, particularly those with less motor control
such as the ring and pinky finger, could be devoted to holding the
device.
34
3.3.2. Precision grip vs. strength grip
Observational prototyping was employed to record people using
mobile phones in public. The types of grips used to hold mobile
phones would inform the design of the way people hold the
ComTouch. We observed that people used their index fingers to
position the mobile phone. This pose allowed them to hold the
earpiece against the ear, and point the other end toward their
mouth.
Two main different kinds of grips people use (MacLeod 2000). We
took some pictures to illustrate the two grips in Figure 3-13.
Notice that there are two types of grips, the precision grip where
the index finger is used to position an object, and the strength
grip, where all the fingers act together to tighten the hand around
an object. An overwhelming number of cellular phone users
utilized the precision grip. ComTouch was redesigned to utilize
Figure 3-13. Precision grip the precision grip.
vs. strength grip.
Precision grip uses the
index finger to position an
object (left). Strength grip 3.3.3. The nature of vibration
uses all fingers in tandem Masking and isolation of the
(right).
vibration signals is a problem due to the
compact size and localization of outputs onto a small device and contact
area with the skin. The device was designed to allow 10 independent
vibration signals to contact different areas of the hand. It would be hard to
feel the vibration of one actuator when there are nine others nearby whose
vibrations can couple either through the device or through the bones in the
hand.
35
Figure 3-14.
Transmission of
vibrations through
ComTouch.
Undesired vibrations go
through the user’s body
and the device, causing
crosstalk.
–Drawing courtesy of
James Gouldstone
Figure 3-14 displays the transmission channels for vibration on
two fingers. The desired vibrations are between the fingers and the
buttons. The diagram also shows the undesired transmissions of
vibrations through the user’s hand (via the bones) and the
structural body of the device.
Further consideration was taken to select the material properties
surrounding the actuators. Rigid materials transmit vibration
while elastic materials dampen vibration. It is important that the
material inside the structure be strong enough to position the
vibrations correctly, yet soft enough to dampen the vibration,
isolating the vibration locally under each finger. The bones inside
the fingers had the unwanted effect of transmitting the vibration
through to adjacent fingers.
After experimenting with different types of materials varying in
elasticity and thickness, it was decided that encasing the vibration
units in foam would allow desirable masking and isolation of
vibration. A structural device body would be made of rigid plastic,
so some coupling of vibrations may be unavoidable.
36
3.3.4. Mechanics of the hand
The constraint of having 3 points of contact on the device would
cause problems with users of different sized hands. Users with
small hands would have trouble applying the maximum pressure
and being able to position their hand over the reception area at
the same time. The mechanics of the finger necessitate that when
the sensor is pressed with the fingertip, the rest of the finger must
lift off the vibrating areas slightly. This lessens the ability of the
user to sense the vibrations. The most likely solution would be to
design a curved and formfitting surface. This would allow the
fingers to maintain contact with the speakers even though the
fingertip is pressing on the squeeze sensor.
Additionally, the anatomical coupling of the muscles in the ring
and the pinky finger of the hand would pose a problem, as these
two fingers lack the fine motor control of the index, thumb and
middle finger. The actuation and detection separate ring and
pinky signals may be a problem.
3.4 Implementations
Figure 3-15.
ComTouch
Preliminary
Implementation.
One-finger of
vibrotactile
communication is
conveyed between
two pads.
3.4.1. Preliminary system implementation
Because this touch-to-vibration mapping is so unusual, a test was
performed to determine whether the mapping could be used for
communication. A preliminary system implementation is depicted
in Figure 3.15. Colored areas helped users to understand the
37
touch-to-vibration mapping. The prototype allows one finger to
communicate using the touch-to-vibration mapping.
In this implementation, each hand rests on a plate. The tip of the
index finger presses down on the yellow pad to cause a vibration
in the middle of the finger (the green pad). This vibration is the
local feedback signal, and allows the user to gauge the amplitude
and frequency of her signal. The signal is also sent to the
corresponding pad, and received at the base of the finger (the blue
pad). The preliminary implementation allows two people to engage
in vibrotactile communication via their index fingers.
3.4.2. Ergonomic implementation
The final implementation of the ergonomic form factor was built to
fully realize the interaction design. Figure 3-16 depicts a
handheld device that integrates the form design with the
vibrotactile interaction. Notice that this reduces the number of
contact points for the finger. The device affords the precision grip.
Figure 3-16 A five
finger ergonomic
implementation
Figure 3-17 displays a side view of one finger in the five -finger
version. The main change made was the design of the ergonomic
shape. We decided on a shape that would need to employ the
precision grip. The shape would be small enough to grab singlehandedly. The precision grip allows each finger to press
Figure 3-17 Placement
of actuators in the
five finger ergonomic
implementation
independently.
Due to the constraint of the handheld surface, the touch-tovibration mapping was slightly altered. The original location of the
input force sensor and output displays confined three different
points of the finger to rest on the device. This is an almost
impossible fit from a human-factors standpoint. The solution was
to combine the location of the input force sensor and output of the
feedback signal. This compact design allows for the natural
curvature of the fingers.
38
.
Figure 3-18. A
working set of
ergonomic ComTouch
allowing users to use
five channels of
vibrotactile
communication
39
4 experiments
4.1 Experiment on one-finger of vibrotactile mapping
4.1.1. Introduction
Experiments were designed to observe the usage of the new
vibrotactile mapping. The experime nts described in this section
are designed to discover whether the vibrotactile mapping could
support useful information. We believed that there was a
relationship between audio and tactile channels. We wanted to
identify the information conveyed in the tactile channel.
Furthermore, we hoped to show that the additional tactile
VOICE + TOUCH
≥
VOICE
Equation 1
information enhances voice communication.
For simplicity, the experiments are performed using only a onefinger version of the vibrotactile device. In this experiment,
participants were asked to perform two tasks, each of which was
designed to discover how the tactile channel might be used. The
participant’s dependence on the tactile channel was varied in each
task. These tasks were designed to observe the usage of the tactile
channel in relationship to the audio channel, to highlight the
different ways communication by touch and voice work together or
separately.
40
4.1.2. Preliminary user studies
Figure 4-1.
Preliminary
user studies
s showing 2
pairs of
participants
using the
preliminary
ComTouch
design.
4.1.2.a Participants
A preliminary study of methods for encoding and detection of
tactile information was performed. The participants were MIT
college students. 24 participants, aged 18-27 (M=20), volunteered
in response to a general email to MIT college living groups. All of
the participants had science and engineering backgrounds. We
recruited pairs of participants who already knew each other.
Figure 4-1 shows two pairs running the experiment.
4.1.2.b Apparatus
The apparatus used for this study was the ComTouch device
described in full in chapter 3. Each pair of participants was asked
to use the one-fingered communication device (see figure 3-15) in
the two communication tasks while tactile and audio information
was recorded. Participants put their right hand on the device to
use the vibrotactile channel. Participants would send their
partner a vibration proportional to the pressure of their fingertips
by pressing on the yellow pad, and also feel their feedback
vibration on the green portions of the pad. Similarly, participants
could feel the vibrations sent by their partner on the blue pad
under their finger. Figure 4-2 shows the experiment setup.
41
Figure 4-2.
Experiment
setup
Participants wore headphones and spoke into microphones to
isolate the audio signal. The audio and tactile sessions were
recorded using MAX MSP software and a DIGI001 multiple -audio
input mixer on a Macintosh G4. Using MAX MSP, white noise was
added to the subject’s headphone outputs to allow better hearing
of the audio conversation by masking out the noises from the
device and the environment. Participants were positioned facing
away from each other such that they had no visual contact. After
the experiment, the data was reviewed using Sonic Foundry
Acid™, a program that allows simultaneous review and replay of
all four channels.
4.1.3. Experimental Procedure
The experiments use two scenarios: a general talking scenario and
a negotiation scenario. The talking scenario allowed the users to
talk freely over an audio link, with an additional tactile channel.
The negotiation scenario allowed more emphasis of the tactile
channel. In the negotiation scenario, the participants were
encouraged to use the tactile channel to agree on a ranking of 5
42
things out of a list of 15 items. The conditions were organized
within-subjects, as everyone participated in all scenarios.
The first task, a chatting task, was designed to observe whether
the participants could use the tactile channel, and to monitor how
the device would be used without specified instructions. After a
brief explanation of the device, participants were asked to chat for
5 minutes. Some preliminary topics were given as conversation
starters, but subjects were allowed to deviate from these topics.
The first task allowed participants to partially overcome the
novelty of the device by using the tactile device as a supplement to
audio. If the participants finished talking about the suggested
topics before the time limit, they would just keep talking until the
end of the duration of the task. Audio and tactile data were fed via
a DIGI001 hardware interface to a Macintosh G4 computer, which
recorded the data.
The second task, a negotiation task, was devised to get
participants to rely on the device to communicate specific
information to each other. The test used a scenario called the
Desert Survival Problem (DSP). DSP is commonly used as a
negotiation skills task (Bonito 1999). The DSP scenario gives the
users a context in which to use the device; they are stranded in
the desert and need to get to safety together.
The participants were given 5 minutes to individually rank a list of
15 survival-related items in order of importance. They were then
asked to rank a smaller set of 5 items together using mainly the
tactile channel. During the collaborative ranking task, we
monitored their audio communication channel in case they had to
resort to voice communication.
This second task gave users some incentive to use the tactile
device and avoid the voice channel. The participants were told that
43
the use of the voice channel was insecure, and could be overheard
by enemies. When the participants engaged in too much voice
conversation, they were warned using a printed sign that enemies
were in the area to further reinforce the need for using the device.
This artificial penalty for use of the voice channel was designed to
emphasize use of the tactile channel. A time limit of 10 minutes
was given to apply time pressure in order to speed up negotiation.
Again, voice and tactile data were recorded for this interval.
When the subjects were finished ranking the items, they answered
a questionnaire designed to obtain feedback about the experiment
and their communication methodology. An exit interview was
performed where subjects were asked for extra feedback on the
device and tactile interaction. All answers were recorded verbatim
and categorized on a spreadsheet. The two audio and tactile
channels were later replayed and graphed. A reviewer marked the
occurrences of interrelation between both channels.
4.1.4. Criteria for evaluation
Occurrences of interaction between the audio and tactile channels
in 12 trials (two tasks per trial) were marked. All 12 conversations
were replayed on Sonic Acid™. Reoccurring patterns were
categorized and marked. The criteria for judging occurrences of
interrelation between audio and tactile data are described as
follows:
•
Emphasis was noted when the intensity and timing of the
tactile signal coincided with the audio signal. The rise and
fall voice volume and the tactile intensity occurred at the
same time.
•
Turn-taking was identified whenever the tactile signal was
used to begin or interrupt the audio signal. In tactile turntaking, the person who spoke preceded their audio signal
44
with a tactile press. At times, the tactile press was used to
interrupt the other participant’s audio signal and the
interrupter would then interject her own audio signal.
•
Mimicry was detected when the users repeated patterns
back and forth, and the patterns did not coincide with the
information in the audio channel.
4.2 Results
Patterns in the signal data clearly indicate that subjects employed
3 meaningful tactile gestures, or representations of touch for
expression, which we call emphasis, turn-taking and mimicry. In
addition, participants developed encoding schemes for
transmitting data in the second. Figure 4-3 shows a tally of the
observed patterns.
Observed tactile gestures for each task
12
Number of conversations where tactile
gesture occurred
Figure 4-3. Resulting
observed tactile
gestures
for each experiments.
The total number of
conversations
exhibiting tactile
gestures at least once
for each task.
11
10
9
8
7
Chatting
6
Desert Survival
5
4
3
2
1
0
Emphasis Turntaking
Mimicry
Numbering
Yes-No
Tactile Gesture
45
4.2.1. Results of the first experiment.
Figure 4-4. Number
of pairs exhibiting
tactile gestures in
first task
compared to
number of pairs that
reported usage of
tactile gestures.
Task 1: Use of Tactile Gestures Observed and Reported
12
11
10
9
8
7
Observed
6
Reported
5
4
3
2
1
0
Emphasis
Turntaking
Mimicry
Tactile Gestures
In the first task, participants learned to use the device quickly,
and were able to talk freely using the device without asking for
help. Most users spent only a few seconds testing and talking
about the buzzing before moving onto other conversation topics.
Figure 4-4 displays the number of conversations where tactile
gestures were observed, in at least one occurrence, for the first
task.
4.2.2. Emphasis
Participants often synchronized their tactile pattern to their
speech, in order to emphasize their message. Only 5 out of 24
participants reported an awareness of using the tactile channel for
this purpose. Emphasis was the most frequently observed tactile
gesture, and was observed for 8 of the 12 conversation trials.
Emphasis occurred in the observed pattern when peaks in the
amplitude of the tactile signal coincided with stressed words in the
voice data. Many of the trials contained repeated use of emphasis.
Often, the speaker would press and talk at the same time to
46
highlight a phrase (Figure 4-5). The audio rhythm and tactile
signal sometimes occurred at the same time of speech, to give the
effect of the tactile information accenting certain syllables. The
redundant tactile information drew the listener’s attention to
particular spoken words or phrases.
Figure 4-5. Emphasis of
the audio channel
is shown as the user
presses to draw
attention to certain
words.
4.2.3. Turn-taking
Turn-taking cues are auxiliary information to aid in the flow of
conversation. Glances, gestures, or speech pauses are typical
turn-taking cues to pass the flow of conversation onto another
person. In 8 of 12 conversation trials, participants appeared to use
the vibrotactile signal as a turn-taking marker. A press or series of
presses was often given before the subject spoke (Figure 4-6).
These signals were sometimes used to interrupt the other speaker
to signal that the other participant intended to speak. However,
participants did not indicate such a usage in their reports.
In the trials, the tactile signal allowed users to indicate a desire to
speak by preceding comments with a buzz. Note that this use of
the tactile signal was not redundant to the audio signal.
Figure 4-6. Turn-taking
markers. Each person
takes a turn by
preceding audio with
tactile presses.
47
4.2.4. Mimicry
Participants tapped out a complex pattern and echoed it back to
one another (Figure 4-7). Rhythm, duration and intensity of the
first pattern were duplicated in the second. These patterns
sometimes happened in silence, sometimes in conjunction with an
audio signal that was independent of the tactile signal. Mimicry
was observed at least once in 7 out of 12 trials.
Four participants reported using the channel to send echoes to
one another. According to these participants, this information
served as a means of ensuring their partner’s presence and
attention. The tactile signal took the place of nodding or verbally
signifying that the other person was listening. Other participants
claimed that this behavior was an extension of physical
interactions they had, e.g. patting each other on the arms as a
form of camaraderie.
Figure 4-7.
Mimicry
patterns
are echoed
back and forth,
independent of
the audio.
4.2.5. Encoding
In the second task, the desert survival task, voice interaction was
intentionally limited. There was an observed decrease in the
number of conversations exhibiting the emphasis, turn-taking or
mimicry. Participants reported the method of their encoding
schemes. The data confirmed that subjects devised tactile
encoding schemes during the second task. Using different
durations of taps for agreement was observed in conjunction with
48
summing the occurrence of a succession of taps to represent a
number.
All 24 participants successfully completed the negotiation task. 8
out of 12 pairs of participants devised a tactile encoding system.
The use of a binary “yes-no” scheme was seen 8 of the 12 pairs.
Additionally, 5 pairs of participants devised a numbering scheme
for indicating the position of the list items. Four pairs of
participants used both schemes. Figure 4-8 shows a tactile
communication example of a numbered suggestion, with a binary
reply.
Figure 4-8.
Encoding schemes.
A numeric encoding
pattern
and an agreement
arrangement is
shown. A single
long press means
no, while three long
presses means yes.
NO
5?
10?
Y ES
4.3 Discussion
The central finding of the preliminary study is that there is a
range of correlation between the voice and tactile communication
channel. As expected, the information transmitted over the tactile
channel proved to be meaningful.
The results of the chatting task demonstrate the existence of
tactile gestures when subjects are provided with a tactile channel
in addition to voice communication. In relation to voice, the
information transmitted over the tactile channel ranged from
independent to redundant. Emphasis, for example, is a redundant
gesture. Syllables and words already stressed orally were
additionally weighted with a buzz. Mimicry, at the other extreme,
was largely independent of the voice channel. Turn-taking falls
somewhere in between the two. On the one hand, a buzz can serve
49
to highlight the beginning of a speech. On the other, a buzz
unaccompanied by audio can indicate impatience born of the
desire to interrupt.
The negotiation task demonstrates that information can be
structured and sent via the tactile channel in such a way as to
make voice communication less or not necessary. The existence of
numerous tactile communication languages supports this finding.
This is surprising because the touch-to-vibration mapping is a
new mapping, and users were not instructed as to how to use the
interface. Nevertheless, approximately 70% of the users reported
establishing their own coding schemes.
Although some participants reported being confused by the
unspecified purpose of the tactile channel, the data indicated that
almost all subjects employed at least one of the three tactile
gestures.
These results shed light upon the possible benefits of a tactile
communication device in everyday use. A touch-based device can
provide an informative and private way to augment existing
communication. For example, one might wish to remain connected
even when in a place where voice communication is inappropriate
such as inside a library. Touch based communication can allow
discreet notification of personal messages without broadcasting an
interruption to others.
Although much care was taken to design the test to be as simple
as possible, there were some improvements that participants
reported could be made on the device.
4.3.1. Ergonomics
Approximately half of the participants reported that their use of
the device was affected by the lack of ergonomics in the device.
Users with small hands reported having trouble applying the
50
maximum pressure and being able to position their hand over the
reception area at the same time. The mechanics of the finger
necessitate that when the sensor is pressed with the fingertip, the
rest of the finger must lift off the vibrating areas slightly. This
lessens the ability of the user to sense the vibrations. The most
likely solution would be to design a curved and formfitting surface,
instead of a flat plate. This would allow the fingers to maintain
contact with the speakers even though the fingertip is pressing on
the squeeze sensor.
Three participa nts were left-handed. Although it was expected
that there might be problems with left-handed users adapting to
the right-handed pad, none of these participants reported
problems in using the device.
4.3.2. Lack of resolution of vibration intensity
Although some participants were able to perceive and use the
dynamic range of the channel, approximately half reported that
the resolution of the vibration seemed to have 3 states- high, low
and off. This may be related to the aforementioned ergonomic
concerns.
4.3.3. More channels please
More than half of the participants expressed a need for more of the
fingers to communicate. Although subjects could not clearly
indicate why they would need to engage more fingers, most felt
strongly that engaging only a single finger was limiting.
4.3.4. Audible Vibration
In the test, the noise of vibration was masked by white noise in
the headphones. However, there is an audible buzzing as a result
of the vibration of the vibrating elements against the material
restraints. The audible buzzing is due to the nature of the
vibration, and could be a problem when using the device in
51
conjunction with audio. Some development will have to be to mask
the vibration from the audio signal.
4.3.5. Limitations
Some limitations of the study should be addressed. One constraint
is the need to account for the novelty effect1, as users will be
inexperienced with vibrotactile stimuli on the skin (Brave, 2001).
4.3.6. Subject familiarity
The results depended mainly on the existence of good
communication between the pairs of participants. The pre -existing
relationships between participants affect the results of the study
in two ways. First, the participants in each trial were very familiar
with one another. Thus, no claims may be made about the
potential for successful tactile communication between strangers.
Second, visual contact between participants was eliminated by the
experimental design. The availability of a visual channel may have
lessened the reliance on the tactile channel.
4.3.7. Data Analysis
The data analysis here was very conservative. The analysis merely
looked for occurrences of overlap or rhythm between the audio
and tactile channels in each trial. If at least one occurrence was
found, it was reported. The actual occurrence of the tactile
gestures was probably more prominent, as incidences of certain
gestures were repeated in many cases. However, the existence of 2
gigabytes of audio data, consisting of 96 streams allowed only
casual examination of the data. Only had one person analyzed the
data, so there was no real statistical analysis. In essence, tactile
gestures occurred far more frequently than reported.
1
The Novelty Effect is described as an effect that occurs when learners are stimulated to greater
efforts simply because of the novelty of treatment. As the treatment grows familiar, it loses its
potency (Brave 2001).
52
Also, the three identified gestures did not describe all the
vibrational gestures used. Some other gestures created were
highly reliant on implied meanings in tactile communication
channel. For example, in one incident, the user asked teasingly
“what did you do this weekend?” and then the user asked again
using a series of buzzes. The response was “nuh-uh, not that!”
Another interesting usage was the use of tactile gesture to
substitute an affective expression. A few users were observed
substituting laughing or squeezing for pressing.
4.4 Summary of first experiment
The previous section presented our findings on the observed
usages of the tactile channels. These findings confirm our
hypotheses about the value of touch communication. The data
shows that tactile information does enhance audio communication
by providing additional information. This additional tactile
information can work together or separately with audio
information, by means of the three tactile gestures described. The
significant finding is that users can detect vibrational feedback in
conjunction with, or without, verbal feedback.
We have also verified that the new vibrotactile mapping is capable
of relayi ng interesting information. Although this vibrotactile
mapping is not the most intuitive (as direct actuation), it conveys
enough information to allow expression of nonverbal cues. These
results raise the possibility of the development of communication
schemas using this particular mapping.
We began to realize that there was much future work to be done to
show how a tactile language could be developed. A series of
reoccurring questions have appeared thematically in this research
concerning the nature of tactile communication. We had to make
53
educated guesses about these issues, and we state the theories of
a tactile mobile language in the next section.
54
5 the potential of tactile gestures…
5.1 Introduction
We were initially focused on advancing the state of the art of
remote communication. Pagers and mobile telephones already
contain vibrating elements to indicate when the phone is ringing.
Extending that capability to provide more information appears to
be a sensible idea. A device that conveys more degrees of freedom
(e.g. representing the touch of each finger) might allow for more
expressive interactions.
5.1.1. Potential Users
We were interested in providing potential users with new means of
expression by employing a new modal addition to an old
communication channel. Who would be the potential users of
vibrotactile communication? To gain insight on the existing needs
of potential users, we studied users of existing tactile
communications. We found two relevant groups of people, the
sensory-impaired (particularly the deaf-blind community who rely
on touch for communication) and current remote communication
technology users (figure 5-1).
Figure 5-1. The common
sense of touch.
Touch is common
among the general
population and
sensory impaired
people.
55
We also found that there was no remote mobile communication
method for the touch-reliant population (figure 5-2). As suggested
in the background section, we found that deaf-blind people use
touch-based languages in face -to-face communication (touch
cues, gestures, sign language, fingerspelling, signed English,
signed pidgin, Braille writing and reading, Tadoma speech
reading, American sign language). We were particularly interested
in transmitting the expressive qualities of fingerspelling. However,
we found that the there is no international standard for touch
communication among this population; e.g. although Braille is the
closest “standard” it required from 6 to 9 months of training and
the percentage of the blind population that can read Braille
fluently is decreasing (Dobbs 1999). Furthermore, for remote realtime communication, the deaf-blind normally use a third party to
mediate their conversation. Existing remote communication
devices using Braille displays available to the blind are costly.
Another problem with existing communication devices is that
there is a large learning curve. We hoped that the device we build
would allow mobile technology to be more accessible for this
population.
Figure 5-2. Existing
communication methods
for different user
scenarios.
Note the lack of remote
communication methods
for the sensory impaired.
56
From interviewing of the kinds of tactile input and output
mappings that would be suitable to blind people, we found that
glove -like devices were not ideal because of the constrictive
nature. Our potential users expressed dislike of force-feedback
devices because of the difficulty in overcoming the feedback force
to communicate. There was also the concern of unintentional
injury due to the force applied by a machine; for example, if a
force-feedback glove forced the hand into an unnatural position.
As discussed in Chapter 2, Tadoma, tactile sign language (the
tactile version of American Sign Language) and fingerspelling are
existing tactile languages. Although these have all proven to be
somewhat effective for a community with the need and motivation
to learn them, there is currently no easy, established tactile
language that can be adapted for a wider user community.
While focusing on communities that relied on touch gave us
insight as to the existing tactile communication methods, we
desired mostly to enhance mobile communication in general.
Morse code was another method of communication (not a
language) that could be transmitted in any form – using flares,
lights, flags, sounds, or vibrations. The tactile version of Morse
code explored by Reed, was interesting because of its widespread
use. The established use of Morse code for transmitting messages
through telegraphs since 1901, usage by a diverse population
(from boy scouts to military servicemen) shows us of the great
potential for tactile communication.
5.1.2. Adoption of potential languages
There is currently no easy, widely adapted tactile language. We
therefore focus in this work on developing a device that would
allow a universal population of users to exchange merely a “sense”
of touch, rather than attempting to design a set protocol for
communication.
57
Many reasons exist for not adapting an existing tactile language.
First, we found that existing tactile languages were not exactly
transferable to the device we had in mind. Second, existing tactile
languages were not widely used to be a compelling fit for the
envisioned device. Third, we felt that existing tactile languages like
Braille, one-handed Braille or chording one -handed keyboards,
had too high of a learning curve to be widely adaptable. Lastly, the
recent rise of simple text messaging on cell phones provided us
with hope that the new communication schemes are possible. The
example provided by SMS, gave us reason to believe that a
vibration language may arise out of common use, developed by
users.
5.2 Development of a touch language
“The problems of control engineering and of communication engineering were
inseparable, and that they centered not around the technique of electrical
engineering but around the much more fundamental notion of the message.”—
Norbert Weiner, Cybernetics (page 8).
5.2.1. Basic components of vibration communication
A large body of psychophysics2 work exists on determining the
proprioceptive mechanics of the sense of touch and vibration. This
previous work is concerned with determining characteristics such
as the maximum frequency of skin sensitivity to vibration, as
described in the background section. From this material, it is
necessary to examine at a higher level the use of touch in
communication. Specifically, whether a language can be developed
for vibrotactile touch communication.
In his thesis entitled Skinscape: A Tactile Tool for Music
Composition, Gunther presents an overview of frequency, temporal
2
Psychophysics is the scientific study of relationships between physical stimuli and
perceptual phenomena. –MIT Encyclopedia for Cognitive Science
58
structure, dynamic range of intensity, and spatial distribution of
signals (Gunther 2001). The information content of touch is
dependent upon the bandwidth and the complexity of the
communication channel. The bandwidth of ComTouch is five
fingers. The basic component of a signal is the squeeze force
(dynamic range) and duration (temporal structure). The
combination of intensity, duration, and spatial distribution of
signals (choice of fingers) will provide the primitive tools for
construction of messages. The speed of transmission provides the
syntax (e.g. pauses, vibrations per second), while the intensity of
the vibration (from subtle to intense), combined with the use of
available fingers provides the grammar for communication. There
can be many various levels of complexity, ranging from keying
strokes, to the more multifaceted variations, like using a mix of
the different intensities, fingers, and voice contribution to the
message.
The amount of available combinations of channels is related to the
possible information that is available to be communicated. It
appears that an increase in channel capacity corresponds to an
increase in complexity. Figure 5-3 depicts the design space for
tactile communication in relation to the tactile channels in
ComTouch.
Figure 5-3. Expression
increases with the number of
channels.
Increase in expressive
bandwidth content per
channels of vibrotactile
communication.
59
5.3 Communicating emotion
A large series of questions concerned how would users
communicate ideas? Should the language being communicated be
alphabetic or conceptual? Examples of alphabetic language
devices are chording keyboards; text -based communications, and
telegraphs. Examples of conceptual languages are voice
communication, hand gestures, and body language. We believed
that the tactile language would be able to support both conceptual
and alphabetic meaning. We were more interested in conceptual
meanings, as the device was meant to focus on emotional content.
We feel that although it is quite possible to build a device like the
HandyKey Twiddler device and single-handed keyboards, to
encode what Gunther would refer to as hard information, we are
more interested in conveying the abstract qualities of touch.
Furthermore, the availability of the audio channel for voice
communication puts less reliance on the device to convey hard
information. Ideally, a touch language would convey both types of
information. However, we feel that the intended users of the device
would definitely want to use it for emotional information.
Emotional information is the desired type of message, because its
abstract qualities can map to the emotions. We leave the hard
information of facts to the more distinctly informative channels of
text and voice. We leave the graphical information to the high data
transfer rates of the Internet. In effect, emotional information
maps well to touch because of its subtle qualities.
5.4 Touch Communication Scenarios
We designed our device to allow people would use this lowbandwidth, analogous channel. How can a touch-to-vibration
channel be used to communicate this nonverbal information? The
evidence of the three tactile gestures, shows us just a hint of what
kind of information could be used. Another question is how to
60
envision the correct application to illustrate the usage of tactile
communication.
5.4.1. Messaging Application
A specially designed vibrational messaging application could
exploit this capacity for diverse types of personal content,
communicating both complex meanings and simple ideas.
Users could map different vibration patterns that identify who the
caller was, i.e. the type of vibration would indicate friend,
business, lover or family if your address book is programmed for
it. Alternatively, the phone caller could use a code when dialing to
indicate the priority of the call (urgent or not urgent, confidential,
etc.) and thus it would vibrate in a different way for each
situation. Another idea is vibration for predefined messages,
similar to SMS (Short Message Service or short text message),
where users would have a “dictionary” of available vibrations and
their meanings.
5.4.2. Emotional aspects of tactile communication
One particular vision we have is for touch to be used to remotely
communicate emotional behavior. Loved ones often want to
communicate personal messages. If the modality of touch is
available, being able to express higher-level emotions might be
desired. This idea would be similar to emoticons conveying
emotional information in text -based systems. For example, as a
lover expresses good-bye, the squeeze would emphasize the
emotional content. If the squeeze was hard, then it might signify a
strong love, if it was a light touch, it might signify a reassuring,
soft pat. In essence, the tactile channel would allow expression of
intensity of emotion.
5.4.3. The use of touch in mobile communication
Touch can act in two capacities in mobile communication. The
first is as an a sensory augmentation to the voice channel. The
61
second, when touch stands alone, is more dependent upon the
bandwidth and complexity of the touch channel.
5.4.3.a Augmentation to voice
In the experiments described in Chapter 4, touch was shown to
augment voice transmissions. The nature of touch will allow
personal content to be conveyed in a private manner. In situations
where audio communication cannot convey emotion, a touchbased device can provide a channel for this type of
communication. Touch based communication can allow discreet
transmission personal nonverbal signals under the cover of audio.
Two people could convey information privately while having an
open audio channel. One thought is that the touch channel will
act as an extension of the physical body space. In a business
setting, people could shake hands at the end of a conversation. In
a more private setting, close relationships could be signified by
meaningful squeezes, and tactile hugs. The tactile gestures of
emphasis, turn taking and mimicry would be employed.
5.4.3.b Touch Stands Alone
Where audio communication is impossible, a touch-based device
can provide a private channel for communication. For example,
one might wish to remain connected even when inside a library.
Touch based communication can allow discreet notification of
personal messages without broadcasting an interruption to others.
One possible scenario is that people might send Morse codes to
each other in lieu of audio when it is too noisy to communicate.
Two people at a concert might be able to arrange to meet by
tapping out their location because visual contact is broken.
When the deaf or hearing-impaired users are considered, then
communication can be expected to rely mainly on vision or touch.
Touch has advantage in allowing this community more privacy.
The ability to share a touch signal would allow private
62
collaboration when compared to broadcasting sign language in a
public place.
Furthermore, the mobility of touch can enable greater
communication for deaf-blind users. Among remotely located deafblind users, existing technologies limit the ability for the deafblind to communicate with one another due to the face-to-face
nature of touch. In addition, the mobile transmission of touch will
enable communication between two previously separate
populations. In a wireless touch-based communication system, a
deaf-blind person could use the common sense of touch to
communicate remotely with anyone.
5.5 Additional potential of touch communication
The following sections describe some features of touch that are of
interest in this research. When people are given the ability to
simulate touch over a vibrotactile interface in the context of
communication, some interesting properties of touch can be
studied. We hope to observe the emergence of patterns and
encoding schemes as listed below.
5.5.1. Cutaneous Illusions
The sensory Saltation phenomenon, also called the “cutaneous
rabbit” describes the illusion of movement as a result of patterns
of stimulation over an area of the skin (Geldard, 1972). The
variation of location of vibration can allow gestural information to
be displayed. The variation of duration and gaps in the signal may
be relevant to the display of tactile stimuli. The ability to stimulate
the illusion of movement across the skin using vibration,
discovered by Geldard and Sherrick (1960) may provide a means
of conveying nonverbal gestures.
Gunther’s distribution of spe akers across the body’s surface
allowed special effects of music to be displayed on the user’s skin.
63
Members of the audience at a musical performance who wore
Gunther’s devices experienced a sense of the movement of
raindrops across their arms, or motion throughout the body using
vibrotactile stimuli. In the ComTouch device, users might be able
to feel the tapping of their partner’s fingers to music, to show the
location of a rhythm (perhaps in a piece of piano music), or to
gesture —e.g. indicate the moveme nt of something across one’s
fingers.
5.5.2. Coding of alphanumeric content
The sense of touch has been proven to be effective for transmitting
hard information, such as the tactile body language invented by
Geldard (1967). The methods of transmission, reception, and
recognition of tactile patterns were detected with much training.
Numbers and alphabetic content were successfully transmitted
and received, hinting that a hand-based vibrotactile language can
also be developed.
In the ComTouch, the sensations are confined to the hand.
However, the success of one-handed devices show that learning to
code alphanumeric content is possible. Perhaps the fingers of the
hand, and the intensity of squeezing will designate keystrokes.
Another possibility is the adaptation of chording the fingers, such
as employed in Engelbart’s one -handed keyboard.
5.5.3. Multiplexing of Tactile transmissions
In places where remote communication already takes place, touch
devices can allow people to further their range of communication
by multiplexing existing communication channels. The low
attention requirement of ComTouch might allow users to have a
spoken conversation over the phone that is entirely different from
the tactile message they are sending.
The ability to sustain multiple threads of communication using
only the sense of touch, as exhibited with Morse code, may be
64
transferred to vibrotactile communication (Tan 1997). Symbolic
and alphabetic language can be combined in a language. For
example, Morse code is one example of such a combination of
methods. In one study of Morse code, users started out by
learning letters individual letters. As the time of usage increased, a
symbolic language emerged and it then became hard to
distinguish individual letters in transmission. Furthermore, users
were able to recognize whole sentences using shorthand and able
to perform simultaneous translation of speech in addition to
decoding Morse messages (Tan 1997). Perhaps simultaneous
multiple tactile conversations will one day be possible using the
ComTouch.
5.6 No vibrotactile language for ComTouch yet
At this time, we have not developed a language for the ComTouch.
However, we do not think it is appropriate to design this language.
The simple reason is consideration for the user’s freedom of
expression. The goal of the device is to communicate a sense of
touch, and we feel that the meanings encoded by the user should
be left up to the user. Another approach, however, is to develop a
standard to coordinate how people communicate. We feel the latter
approach may come later, as a result of further scientific
investigation into vibrotactile communication techniques.
We believe there is a good possibility that a language may arise
out of repeated usage of this device, similar to the way SMS and
pager codes have been developed. By allowing users to create their
own communication schemas is the best method for utilizing
touch communication. A recognized standard, akin to Morse code
would have the problems mentioned earlier—high learning curves
and standardizing usage among people who may want to use the
device for different reasons.
65
Allowing users to adopt their own approach minimizes the
learning time for that user, but the other communicating partner
may need to learn how to translate the gestures. We realize that
the lack of a benchmark standard to compare to will allow users
freedom to compose and invent their own gestures, thus enabling
a wider range of expressive techniques. The conclusion is that we
want the expression to be as personal as desired.
66
6 conclusion
The research presented in this dissertation evaluates the potential
of a proposed vibrotactile mapping as a medium for touch
communication. The strength of the ComTouch project lies in its
use of integrated modalities of touch and audio. Integration with
audio provides some insight on the use of the tactile channel.
Experiments proved that the physical representation of touch is
transmitted provide some nonverbal cues, called tactile gestures,
not available in remote audio communication.
6.1 The Vibrotactile Mapping
The scope of this study is to determine whether vibrotactile cues
can convey information that enhances remote voice
communication. This study does not aim to develop a tactile
substitute for the telephone, but rather, to examine both the
nature and amount of information a vibrotactile channel can
convey when added to an existing audio channel. Evaluating the
vibrotactile contribution is merely the first step of research in how
this information can be used in remote communication. This
investigation is interested in exploring the role of vibrotactile
information for sensory impaired communities, and creating a tool
that can be universally utilized using the common sense of touch.
Also, this research does not propose to invent a vibrotactile
communication language, but suggest how a tactile language
might be used.
Preliminary user studies provided insight into the characteristic
uses of a device that transmits tactile signals simultaneously with
audio communication. The touch signals were shown to enhance
audio conversations by providing redundant and independent
67
information in the form of tactile gestures. These gestures
presented nonverbal cues that can be lost or overlooked when
strictly audio is used.
Within moments, people new to the device were able to
communicate through the tactile channel in a non-trivial and
successful way (i.e. using mimicry, emphasis and turn taking). In
the future, a longer-term study would be needed to reveal if and to
what extent interacting with vibration affects communication.
These types of studies are much more challenging, since it is
difficult to trace the contributions from a specific person’s
gestures to the creation of a new common set of expressions.
We hope that this kind of research will contribute to enabling
mobile communication for the sensory-impaired population one
day, in addition to enhancing existing communications for the
current population of mobile device users by adding the
underused sense of touch. Understanding the nature of touch and
its role in communication may eventually inform the development
of a touch communication language.
6.2 Future Work
The design decisions of ComTouch were selected with the goal that
this research might one day inform the design of a tactile
telephone. The underlying goals of low cost, robustness to fatigue,
and small size were factors that made vibrotactile actuation a
likely candidate. The consideration of users needs led us to
design the feedback channel, and ergonomic shape of the final
device. Meanwhile, a large portion of research in existing
communications work was carried out and incremental evaluation
by peer review was performed throughout the process of
development. Much iteration of prototyping and deductive
engineering went into the successive prototypes. The reason for
so many reviews, iterations, and changes was because we were
68
doing work of interest to researchers in many fields, and at the
same time dealing with the complex problems inherent in
combining such diverse fields of thought and engineering.
A number of suggested hardware changes and alternative
mappings are presented below to guide future work on tactile
communication.
There were a number of important human factors design issues
encountered, like alternative physical spacing of input and output
actuators.
Several mechanical engineering design issues are also important,
such as isolating multiple vibrations from each other within a
small space.
The following future changes are suggested if further development
of the prototype is pursue d:
Better isolation of vibration within the body. Try different materials
to mask and isolate the vibrations better from each other.
Variations in durometer, viscoelasticity and mass of the body may
have better results. Perhaps attaching the vibrating units with
spring steel to act as a kinematic spring for isolating the
vibrations may also help.
Wireless Implementation. The devices are connected to each other
via cables. Similarly, the power source for the devices is connected
to an outlet. Future work mi ght include a wireless
implementation.
Smaller size. The circuit board for each device is outside the
handheld form factor. Re -designing the circuit board with surface mount components might allow the circuit board to fit inside the
form factor.
69
Developing a new mobile phone protocol. The cell phone
infrastructure might be developed so that the devices use the cell
phone protocols. Synchronous mobile voice and tactile
communications may be possible with some cooperation from
telecommunications providers.
6.3 Some interesting design implementations
Along with these suggestions, alternative routes of design and
construction may also be of interest.
6.3.1. Alternate distribution of actuators
There are many diverse hardware arrangements that could have
been implemented. For example, we could have settled on using a
two-handed display, a device that fit on the wrist like a watch.
Similarly, tactile displays distributed over the whole body, as used
by Gunther (2000) and Geldard (1967), may be of interest.
6.3.2. Variation of bandwidth and complexity
Another design might vary the number of actuators used. We are
curious as to the effect changes in bandwidth due to the addition
of actuators for more fingers might have and what new usages will
arise. We expect that the ability to use more fingers will better
convey nonverbal information.
Another approach is to vary the dynamic range of the actuators.
For example, decreasing the range of the actuators to exhibit 3
levels of vibration (none, middle and high) is possible.
6.3.3. Improved Ergonomics
An investigation into a decreased number of fingers employed may
also be of interest. Currently, the fingers are used to position the
device and engage the vibration mechanisms. Also, research in
ergonomics shows that the fourth and fifth fingers are
mechanically coupled. Also, reducing the number of vibrations
70
may be more comfortable, and make it easier to distinguish the
vibrations from one another.
6.4 Expanding the design space
As mentioned before, the design chosen was rather specific to the
vision of the researchers. The design space for tactile
communication is wide open, and other design alternatives are
discussed below. A brief listing of “design for the senses” is given
to help begin research in each area.
6.4.1. Exploration of other modalities
One of the ongoing themes of this project is how the information
should be presented and used by people. The ComTouch
implementation focuses on strictly vibrotactile stimuli. The use of
vibration for the low level communication has proved popular in
communication devices (e.g. pager), but there are issues of
ergonomics, robustness, ease of use and cost if the device is to
become widely used.
While the sole sense of touch in communication can be effective
(Geldard, 1967), the use of touch in combination with other
senses reinforces perception and communication. Other types of
available stimuli, such as force feedback or thermal feedback, and
their effects on remote communication can be further researched.
The following list provides a brief overview of research on tactile
stimulation in combination with other sensory modalities.
6.4.2. Touch as a sensory substitution to Audio
The current vision is to implement the addition of audio
processing into the device. Another approach is to translate the
audio channel into vibrotactile stimuli to allow users who are
comfortable with audio expression communicate with users who
rely on tactile expression. One idea is that people would be able to
talk normally to their ComTouch and the receivers would feel
vibration from their cell phones.
71
6.4.3. Touch and Smell
Experiments on smell and memory prove that there is a
connection between memory recall and smell (Aggleton 1998).
Memories involving smell are more emotional than those involving
touch (Herz 1996). Ehrlichman (1998) has used smell to recreate
moods. One study found that smells that relate to past
experiences could allow adults to recall childhood memories with
great accuracy (Aggleton 1999). Kaye (2001) gives a comprehensive
overview of applications using smell as an information displ ay.
When touch and smell are transmitted in the same
communication device, the interaction is more emotional and
memorable.
Smell is perhaps the hardest application to work with. Scratchand-Sniff technology is a fad technology that is no longer popular.
After the process of digitizing smell was discovered, companies like
DigiScents, AromaJet and France Telecom introduced devices for
broadcasting smells in a variety of contexts (for web browsing,
game playing and trade-show displays). These companies claim
that the addition of smell could combine to enhance interactions
by engaging more senses. Unfortunately, the manufacture of
smell devices is still too costly for widespread availability. Perhaps
a device that transmits the smell and touch of objects relating to
past events (such as birthday cake, childhood objects, vacation
artifacts) may make people identify and remember the past more
vividly.
6.4.4. Touch and Vision
Studies show that combined audio and visual stimulation results
in quicker timing of reflexes and better low-level perception in
children and animals (Stein 1993). Research on machine learning
showed that semantically supporting the visual presentation of an
object with a simultaneous spoken reference to an attribute of the
72
object, like its color and shape, led to faster and more accurage
word learning (Roy 1997).
Tactile information is also used to reinforce learning by recreating
experience. Flight simulators, for example, use a combination of
touch and visual displays for training pilots by simulating the
physical and visual experience of flying. Perhaps a communication
device that integrated touch and vision could combine the benefits
of both modalities. A more adaptive and immersive experience
may result. For example, such a tactile -enhancement of a
navigation system may allow people to maneuver through an
unknown area privately and without losing track of a certain
reference point, resulting in (by combining tactile and visual
direction signals).
6.4.5. Touch Displays
Currently there are two main modes for representing tactile
stimuli. One is by means of static contact pressure, and using
force feedback to display information. Tactile or pin array displays
and force-feedback displays both fall into this category. The
second means is by use of vibration signals. Furthermore, for
each display, there can be variance in the location of the display,
then number of stimuli presented on the display, as well as the
duration of the information presented.
6.4.6. Static Displays (General Haptic Displays)
Many early explorations of touch communication used direct
representation. Although vibration output is less prone to fatigue
than force displays, a central question to this research that should
be addressed is that in an ideal world, what would users prefer?
Much work in virtual reality is concerned with haptic
representation of force on the fingertips. Devices such as the
Phantom use force -feedback to simulate the reaction force of
pressure exerted from a physical object. Assistive devices, such as
73
the Braille Note use arrays of raised pins to represent Braille
letters that can be felt underneath the fingertip. In fingerspelling,
the pressure and movement of fingers from one hand on another
allows communication.
6.4.7. Vibration Displays
The displays for vibrotactile stimuli can be located anywhere on
the body. Distributed multiple stimulations over different areas
throughout the body is commonly used. For example, speakers are
embedded throughout the body (e.g. wrist, elbows, armpits and
lower back) in Gunther’s SkinScape (Gunther 2001, Geldard
1970).
In the Tadoma method (Reed 1991), the “listener” places their
hand on the speaker’s jaw and throat, sensing the vibrations that
occur during normal speech. It is possible that these vibrations
could be captured and transmitted to a device like the ComTouch
so that the listener could be separated from the speaker allowing
them to communicate remotely.
The author believes that in an ideal world, if representing touch
directly were both technologically and ergonomically feasible,
direct mapping of touch would be preferable. However, at this
point in time, technology and ergonomic designs have not
addressed how to represent the communication of touch in an
intuitive manner.
6.5 Summary
This thesis introduced ComTouch, the basis for a new class of
tactile communication interfaces. The ComTouch device has two
unique design features that have contributed to the improvement
of touch communication. The main contribution of this work is the
novel vibrotactile mapping for transmitting the sense of touch. The
74
secondary contribution is the rationale to use touch as an
augmentation to voice communication.
Unlike previous approaches to touch communication, the new
design utilizes the distinct and easily understood methods of voice
transmission to highlight the subtle and personal qualities of
touch. By examining the correlation between the touch and audio
modalities, it was much easier to discern the usage of the tactile
channel. The use of tactile information as an augmentation to
voice provides a good way to highlight the unique qualities of
communication inherent in both modalities.
The ability to correlate this new tactile channel to the more
thoroughly researched channel of audio communication allowed
better focus of the use of touch. User studies illustrated that
nonverbal qualities of tactile communication correlate in
meaningful way to the voice channel, as shown by the discovery of
the three tactile gestures: emphasis, turn-taking and mimicry. By
examining the use of touch in contrast to existing modes of
communication, we have begun discussion of the architecture of a
touch language for remote communication.
This thesis presents the use of vibrotactile transducers to enable
touch communication into handheld and small devices, thus
enabling a new type of device design in the field of mobile tactile
communication. The series of iterative design implementations
have revealed new uses of vibration actuators. This new
application for vibration transducers allows users to convey
nonverbal physical information in a more private manner, thus
enhancing audio communication. It is hoped that the research
presented in this thesis will motivate the development of a new
class of interpersonal mobile communication devices that truly do
allow us to ‘keep in touch’ with one another.
75
Appendix A Part Resources and Electrical Diagrams
Below is a brief skeleton on how to build a vibrotactile channel. I used standard components for
the schematic, so will only mention where to find vendors for unusual parts.
Electronic Parts Vendors for Nonstandard Parts
Active Electronics
http://www.future-active.com
AudioLogic Engineering (Dave Franklin)
http://www.tactilator.com/audiologicalengineering/
Interlink Electronics
http://www.interlinkelec.com
Description
Speaker Transducers
for producing vibration
low-Power audio
amplifier
Force Sensing Resistors
Part No.
V1220
Online
Audiologic engineering
Vendor
Audiologic engineering
MC34119P
Active Electronics
Motorola
FSR
Interlink Electronics
Interlink Electronics
Circuit Schematic for one touch to vibration channel
76
Schematic for 5 finger device
77
PCB layout
78
Appendix B Testing Materials used in Experiment
Experiment Materials List:
•
Experimenter’s Script
•
Informed Consent Form
•
Preliminary Questionnaire
•
Tactile Introduction Task Sheet
•
Desert Scenario Task I
•
Desert Scenario Task II
•
Exit Questionnaire
•
Payment vouchers for participants
(Total time ~ less than 1 hour)
Approximate time to spend on each material
(~7 minutes)
(~1 minutes)
(~5 minutes)
(~5 minutes)
(~5 minute)
(~15 minutes)
(~10 minutes)
(~2 minutes)
Experiment Equipment List:
•
2 ComTouch Pads with circuits
•
2 Headsets with Microphones
•
1 DIGI001 Box (hardware interface)
•
1 Macintosh G4 computer for storing data.
•
1 MAX MSP Software for data acquisition of four simultaneous signals.
Analysis Software package
•
1 Sonic Foundry Acid™ Software for analysis, or a similar program that allows simultaneous graphing and replay of
four audio signals.
B-1. Experiment setup and apparatus
79
Experimenter’s Script
Welcome and thank you for coming to participate in the study. The purpose of this study is to observe vibrotactile
communication. First please fill out the subject consent form.
•
{Give participants Subject Consent Form}
This device here {point to ComTouch} allows you to send your squeeze pressure to your partner in the form of
vibration. We will give you a few tasks and record your audio and vibrotactile exchanges. The experiment consists
of both questionnaires and using a small vibrotactile device to complete a negotiation task. Each of you will feel
small vibrations under each finger during the experiment. If at any time you feel uncomfortable or have a question,
please ask. First, please fill out this preliminary questionnaire.
•
{Give participants Preliminary Questionnaire.}
Now please put on the earphones, and place your hands on the pad. The ComTouch is a vibrotactile device that
allows tactile communication. The device translates squeeze pressure under the forefinger to vibration. When you
press down with the tip of your finger on the yellow pad, you can feel vibration related to the pressure of squeezing
on the green pad at the middle of your finger. The harder you squeeze, the harder the vibrations. The softer you
squeeze, the slower and softer the vibrations. The vibrations are also transmitted so that the squeeze can also be sent
to your partner, who can feel your squeeze under the base of the finger on the blue pad. The device is bi-directional,
and you can also feel your partner’s squeezes. Both of you can squeeze at the same time.
Now, can you both feel the vibration under each finger? Can you feel your partner’s vibration?
Now pick up the microphone, can you hear the other person?
•
{Give participants Tactile Introduction Task Sheet.}
Are there any questions? Is anyone uncomfortable with the task?
Now we move on to the experiment itself. The name of this task is called the desert survival scenario. I will first
read out the scenario and then give you 5 minutes to do the task.
•
{Give participants Desert Survival Task Sheet.}
Now, please set aside the sheet of paper with your individual rankings.
•
{Give participants Team Desert Survival Task Sheet.}
Now, please use the ComTouch in your conversation. We are recording both the audio and tactile data.
•
{Start monitoring experiment. If necessary, give them the Quiet sign.}
Now it is time for us to finish up the experiment with an exit interview. Please read and answer the following
questions.
•
{Give exit questionnaire.}
Now here is your copy of the consent form and the payment voucher.
•
{Give payment voucher.}
Thank you for participating!
80
Preliminary Questionnaire
Write your initials________
today’s date_________
Please circle the most appropriate answer:
Your age range:
Your sex: M F
Do you have any known problem with your hands, such as carpal tunnel or sore fingers? Y N
Do you describe yourself as left-handed or right- handed?
Did you know your partner before this experiment? On a scale of 1 to 5, rate how well you
know them. Circle one below:
1= best friends
2= good friends
3= friends
4= know slightly
5= stranger
How comfortable would you feel touching the other person’s hand? Circle one below:
1= very comfortable
2= comfortable
3= no opinion
4= uncomfortable
5= very uncomfortable
Tactile device introduction task
Please spend 5 minutes familiarizing with the device by using it in conversation. Talk about any of the following topics
(choose one):
Something you did last weekend
Next weekends plans
Homework
A movie you recently saw
81
INDIVIDUAL TASK – 5 minutes
Individually rank each item. Do NOT discuss the situation or problem until each member has
finished the individual ranking. Fill out the form for the individual ranking. Your task is to rank
these items according to their importance to your survival, starting with ‘1’ the most important,
to ‘15’ the least important.
Rank
large flashlight & batteries
_________
jackknife
_________
sectional air map of area
_________
large plastic raincoat
_________
magnetic compass
_________
first aid kit with gauze
_________
loaded .45 caliber pistol
_________
red & white parachute
_________
bottle (1000) salt tablets
_________
2 liters of water
_________
book: Animals of the Desert
_________
1 pair sunglasses per person
_________
2 liters 180- proof Vodka
_________
1 large coat per person
_________
a cosmetic mirror
_________
82
TEAM TASK – 15 minutes
After each person has finished the ranking, you discover that there is only one knapsack (the
other one has a huge hole) and that between the two of you, and can only carry only five things
in the knapsack. As a team, discuss which 5 things you should bring together. Once team
discussion begins, do not change your individual rankings.
As it turns out, enemy observers are in the area and can overhear your conversation. The enemy
has not yet located your position, but has the technology to locate your position based on sound.
Please be discrete about talking, and try not to talk too much. If you are in danger of being found
due to too much noise, the experimenter will notify you by presenting a card that says
“Quiet, enemy patrols in the area.”
Time is of the essence, as you only have 10 minutes before the enemy patrols find your ship.
Please make sure that you agree on the items and their rank of importance.
Rank
large flashlight & batteries
_________
jackknife
_________
sectional air map of area
_________
large plastic raincoat
_________
magnetic compass
_________
compress kit with gauze
_________
loaded .45 caliber pistol
_________
red & white parachute
_________
bottle (1000) salt tablets
_________
2 liters of water
_________
book: Animals of the Desert
_________
1 pair sunglasses per person
_________
2 liters 180- proof Vodka
_________
1 topcoat per person
_________
a cosmetic mirror
_________
83
Quiet,
enemy patrols in the area
Exit Questionnaire- 10 minutes
What was difference between your individual ordering and the team ordering?
Which items did you each end up bringing as a team?
Did you reach an agreement on which 5 items to bring?
Did you agree on an ordering?
What was the agreed-upon ordering?
How do you feel about using the device to communicate? Did it help at all?
What method did you use to communicate using the tactile channel?
Rate how difficult this task was on a scale of 1(easy) to 7(hard)?
Do you think this technology could be useful, to augment phone conversations, for example?
Do you have any feedback on the device or the experiment?
Other comments?
84
Informed Consent Form
Experiment Title:
An investigation of the information content and effect of the vibrotactile channel
Principle Investigator Angela Chang
Research Assistant * MIT Media Lab * Tangible Media Group * 1 Cambridge Center * anjchang@media.mit.edu
Subject #: _______ Date:_______
Participation in this experiment is fully voluntary and I am aware that I am free to withdraw my consent
and discontinue participation at any time without prejudice to myself. I will be paid $10 / hour and this
will be prorated for early withdrawal. The experiment lasts less an hour, and I may be asked to participate
in other experiments at later time.
Experiment overview
This series of experiments has been designed to obtain quantitative and qualitative data on the use
of a handheld vibrotactile device, using small vibrations under each finger. A series of small vibrations
will be presented under my right hand and I will be asked about the comfort level. The experimenter will
adjust different parameters until comfort is achieved. I will be asked to perform tasks and provide a
qualitative account of the experiment.
The sensations produced by the apparatus might feel “strange”, but at no point in the experiment
should these sensations cause any discomfort. The sensations are very similar to the vibration of a
speaker grille. I understand that I may withdraw from these studies at any time for any reason. I confirm
that I have passed my eighteenth birthday, the required minimum age necessary to take part in an adult
research study.
I consent to the release of scientific data resulting from my participation in this study to the
Principal Investigator for use by her for scientific purposes. The Principal Investigator assures my
anonymity. I understand that the record of this experiment becomes part of the experimental results and
is protected as a confidential document. I understand that this record will only be available to the
investigators involved with this study. Other staff may be authorized by the COUHES board to review
the record for administrative purposes or for monitoring the quality of subject care.
In the unlikely event of physic al injury resulting from participation in this research, I understand
that medical treatment will be available from the MIT Medical Department, including first aid, emergency
treatment and follow-up care as needed, and that my insurance carrier may be billed for the cost of such
treatment. However, no compensation can be provided for medical care apart from the foregoing. I
further understand that making such medical treatment available, or providing it, does not imply that such
injury is the fault of the Investigator(s). I also understand that by my participation in this study I am not
waiving any of my legal rights*.
I understand that at any point before, during, or after the experiment, I can direct any inquiries
concerning the experiment to Angela Chang (anjchang@media.mit.edu, 617-452-5618).
I understand that I may also contact the Chairman of the Committee on the Use of Humans as
Experimental Subjects (COUHES) Secretary, MIT E23-230, 253-6787, if I feel I have been treated
unfairly as a subject.
I have read and fully understand all of the above points.
Signature:__________________________________________ Date:_______________________
Witness:___________________________________________ Date:_______________________
* Further information may be obt ained by calling the Massachusetts Institute of Technology's Insurance and Legal Affairs Officer at
253-2822.
85
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