When two standing people converse with each other there is an increase in their shared postural a... more When two standing people converse with each other there is an increase in their shared postural activity, relative to conversation with different partners. We asked pairs of participants to converse with each other or with experimental confederates while standing on rigid and nonrigid surfaces. On the rigid surface, shared postural activity was greater when participants conversed with each other than when they conversed with confederates. In addition, the strength of interpersonal coupling increased across trials, but only when members of a dyad conversed with each other. On the nonrigid surface, postural sway variability increased, but we found no evidence that shared postural activity was different when participants conversed with each other, as opposed to conversing with confederates. We consider several possible interpretations of these results.
Artificial Intelligence for Engineering Design, Analysis and Manufacturing, 2015
The design community has growing familiarity with the concept of affordances and with the utility... more The design community has growing familiarity with the concept of affordances and with the utility of this concept in many areas of design. Less emphasis has been placed on natural processes by which people acquire knowledge about affordances. Consequently, little is known about how design might be optimized to enable users to detect the actions that are available in a given human–machine system. We review scientific research about what people do to obtain information about affordances. We discuss implications of this research for design.
Journal of Experimental Psychology: Human Perception and Performance, 2014
The control of standing body posture is affected by mechanical perturbations, such as motion of t... more The control of standing body posture is affected by mechanical perturbations, such as motion of the support surface. Postural activity also is responsive to subtle social factors: When 2 people interact there is spontaneous interpersonal coordination of their movements. We asked whether interpersonal postural coordination based on visual contact would be robust in the presence of mechanical perturbations that characterize sea travel. During an ocean voyage, pairs of participants stood facing together or facing apart. Interpersonal coordination of body sway was stronger when participants faced each other than when they faced apart. Furthermore, overall body movement was reduced when individuals faced together, suggesting that the sight of another person improved individuals' ability to compensate for ship motion. These findings provide the first evidence that the "soft" constraint of interpersonal visual contact can influence interpersonal postural coordination as people simultaneously adjust postural sway in response to powerful mechanical (i.e., "hard") constraints.
On land, body sway during stance becomes coupled with imposed oscillations of the illuminated env... more On land, body sway during stance becomes coupled with imposed oscillations of the illuminated environment or of the support surface. This coupling appears to have the function of stabilizing the body relative to the illuminated or inertial environment. In previous research, the stimulus has been limited to motion in a single axis. Little is known about our ability to couple postural activity with complex, multi-axis oscillations. On a ship at sea, we evaluated postural activity using measures of body movement, as such, and we separately evaluated a direct measure of coupling between body movement and ship motion. Participants were tested while facing fore-aft and athwartship. We compared postural activity between participants who had been seasick at the beginning of the voyage and those who had not. Coupling of postural activity with ship motion differed between body axes as a function of body orientation relative to the ship. In addition, coupling differed between participants who had been seasick at the beginning of the voyage and those who had not. We discuss the results in terms of implications for general theories of postural control, and for prediction of susceptibility to seasickness in individuals.
Research in developmental disabilities, Jan 12, 2015
Developmental coordination disorder (DCD) is a diagnosis for children who present with movement d... more Developmental coordination disorder (DCD) is a diagnosis for children who present with movement difficulties, but are of normal intelligence without neurological deficits. Previous studies have demonstrated that children with DCD exhibit perceptual deficits and lower cognition performance. To date, their autonomic nervous system (ANS) responses during tasks requiring cognitive and perceptual effort have not been compared to typically developing children (TDC). The present study investigated heart rate variability (HRV) as a marker for ANS response differences between DCD and TDC, and the impact of different levels of task difficulty. Participants were 60 individuals (9-10 years); 30 children at risk for DCD, and 30 TDC. Each participant performed two tasks each of which demanded enhanced cognitive effort: a visual signal detection task and a digit memory task-each task had two levels of difficulty, low (LD) and high (HD). Heart rate responses were continuously recorded during perfor...
The authors sought to evaluate the relative importance of locomotor control and postural control ... more The authors sought to evaluate the relative importance of locomotor control and postural control in the perception of affordances. While seated in a stationary wheelchair, participants made a series of judgments about the minimum lintel height under which they could roll in the wheelchair. Prior to making judgments, participants were given brief (∼2 min) experience with wheelchair locomotion. They expected that this practice would influence the accuracy of subsequent affordance judgments. During practice, participants moved under their own power (using their hands on the wheels) or with an experimenter pushing the wheelchair. Also during wheelchair locomotion the participant's head was restrained, or was not. Results revealed that head restraint during the practice session had no effect on the accuracy of subsequent judgments. By contrast, the judgments of participants who controlled locomotion during practice were significantly more accurate than the judgments of participants who had not controlled their locomotion during practice.
... To date, analyses of multi-segment control (eg, Nashner and McCollum, 1985) have concentrated... more ... To date, analyses of multi-segment control (eg, Nashner and McCollum, 1985) have concentrated on dynamical properties of the environment and the person, such as forces (torque and shear), surfaces (soft, short, etc.), and joints (ankle, hip). ...
We studied the influence of ship motion on postural activity during stance, varying stance width ... more We studied the influence of ship motion on postural activity during stance, varying stance width (the distance between the feet in side-by-side stance) and the difficulty of visual tasks. Participants (experienced crewmembers) were tested on land and then on successive ...
ABSTRACT We investigated the information that supports perception of whether an object is within ... more ABSTRACT We investigated the information that supports perception of whether an object is within reach using a locomotor task. Participants adjusted their own position relative to a fixed target by stepping or by propelling a wheelchair until they judged it to be within reach. The to-be-reached object was presented in virtual reality. The display of the target was driven in real time as a function of the observer's movement, thus depicting a stationary virtual object at a definite distance only through the relation across optical and nonoptical patterns of stimulation. We asked participants to judge the distance they could reach with their unaided hand or when holding a rod that extended their effective reach. They could see neither their body nor the rod thereby limiting available visual information about “reachability.” As expected, our results showed that despite the limited information that was available, participants' locomotor adjustments were influenced by (a) their simulated distance from the target, (b) their arm length, and (c) the presence or absence of the rod. The type of motion (stepping or wheelchair) had little influence. However, judgment accuracy was influenced by participants' initial simulated distance from the target. We compare the performance obtained in our locomotor judgment task with previous studies that have used different methods for measuring perceived reaching-ability. We discuss perceptual information that could have supported performance within the framework of the global array.
Cet article traite de la fidelite des simulateurs et des dispositifs de realite virtuelle. Un fac... more Cet article traite de la fidelite des simulateurs et des dispositifs de realite virtuelle. Un facteur classiquement utilise pour apprecier la fidelite d'une simulation est sa capacite a engendrer une sensation de presence, c'est-a-dire une experience illusoire de percevoir et/ou de controler la realite. Ce concept de presence est discute. Nous suggerons que les utilisateurs sont rarement «trompes» par la simulation et qu'une perception illusoire de la realite est extremement rare. La raison est que les co-variations energetiques emanant des situations reelles ou simulees different. La consequence est qu'une perception incorrecte de la realite pourrait en fait etre une perception correcte du realisme de la simulation. Cette distinction entre perception de la realite et perception du realisme a des implications importantes, tant au plan theorique qu'au plan des methodes utilisees pour apprecier la fidelite des simulateurs.
Behavior causes simultaneous changes in multiple forms of sensory stimulation, such as light, sou... more Behavior causes simultaneous changes in multiple forms of sensory stimulation, such as light, sound, and pressure. Research on multimodal perception has tended to focus on the integration (in the nervous system) of stimuli available to different sensory systems. However, potential sensory stimulation is not limited to patterns available to individual sensory systems. There are also patterns that extend across different forms of ambient energy. These superordinate, higher-order patterns make up the global array (Stoffregen ...
When two standing people converse with each other there is an increase in their shared postural a... more When two standing people converse with each other there is an increase in their shared postural activity, relative to conversation with different partners. We asked pairs of participants to converse with each other or with experimental confederates while standing on rigid and nonrigid surfaces. On the rigid surface, shared postural activity was greater when participants conversed with each other than when they conversed with confederates. In addition, the strength of interpersonal coupling increased across trials, but only when members of a dyad conversed with each other. On the nonrigid surface, postural sway variability increased, but we found no evidence that shared postural activity was different when participants conversed with each other, as opposed to conversing with confederates. We consider several possible interpretations of these results.
Artificial Intelligence for Engineering Design, Analysis and Manufacturing, 2015
The design community has growing familiarity with the concept of affordances and with the utility... more The design community has growing familiarity with the concept of affordances and with the utility of this concept in many areas of design. Less emphasis has been placed on natural processes by which people acquire knowledge about affordances. Consequently, little is known about how design might be optimized to enable users to detect the actions that are available in a given human–machine system. We review scientific research about what people do to obtain information about affordances. We discuss implications of this research for design.
Journal of Experimental Psychology: Human Perception and Performance, 2014
The control of standing body posture is affected by mechanical perturbations, such as motion of t... more The control of standing body posture is affected by mechanical perturbations, such as motion of the support surface. Postural activity also is responsive to subtle social factors: When 2 people interact there is spontaneous interpersonal coordination of their movements. We asked whether interpersonal postural coordination based on visual contact would be robust in the presence of mechanical perturbations that characterize sea travel. During an ocean voyage, pairs of participants stood facing together or facing apart. Interpersonal coordination of body sway was stronger when participants faced each other than when they faced apart. Furthermore, overall body movement was reduced when individuals faced together, suggesting that the sight of another person improved individuals' ability to compensate for ship motion. These findings provide the first evidence that the "soft" constraint of interpersonal visual contact can influence interpersonal postural coordination as people simultaneously adjust postural sway in response to powerful mechanical (i.e., "hard") constraints.
On land, body sway during stance becomes coupled with imposed oscillations of the illuminated env... more On land, body sway during stance becomes coupled with imposed oscillations of the illuminated environment or of the support surface. This coupling appears to have the function of stabilizing the body relative to the illuminated or inertial environment. In previous research, the stimulus has been limited to motion in a single axis. Little is known about our ability to couple postural activity with complex, multi-axis oscillations. On a ship at sea, we evaluated postural activity using measures of body movement, as such, and we separately evaluated a direct measure of coupling between body movement and ship motion. Participants were tested while facing fore-aft and athwartship. We compared postural activity between participants who had been seasick at the beginning of the voyage and those who had not. Coupling of postural activity with ship motion differed between body axes as a function of body orientation relative to the ship. In addition, coupling differed between participants who had been seasick at the beginning of the voyage and those who had not. We discuss the results in terms of implications for general theories of postural control, and for prediction of susceptibility to seasickness in individuals.
Research in developmental disabilities, Jan 12, 2015
Developmental coordination disorder (DCD) is a diagnosis for children who present with movement d... more Developmental coordination disorder (DCD) is a diagnosis for children who present with movement difficulties, but are of normal intelligence without neurological deficits. Previous studies have demonstrated that children with DCD exhibit perceptual deficits and lower cognition performance. To date, their autonomic nervous system (ANS) responses during tasks requiring cognitive and perceptual effort have not been compared to typically developing children (TDC). The present study investigated heart rate variability (HRV) as a marker for ANS response differences between DCD and TDC, and the impact of different levels of task difficulty. Participants were 60 individuals (9-10 years); 30 children at risk for DCD, and 30 TDC. Each participant performed two tasks each of which demanded enhanced cognitive effort: a visual signal detection task and a digit memory task-each task had two levels of difficulty, low (LD) and high (HD). Heart rate responses were continuously recorded during perfor...
The authors sought to evaluate the relative importance of locomotor control and postural control ... more The authors sought to evaluate the relative importance of locomotor control and postural control in the perception of affordances. While seated in a stationary wheelchair, participants made a series of judgments about the minimum lintel height under which they could roll in the wheelchair. Prior to making judgments, participants were given brief (∼2 min) experience with wheelchair locomotion. They expected that this practice would influence the accuracy of subsequent affordance judgments. During practice, participants moved under their own power (using their hands on the wheels) or with an experimenter pushing the wheelchair. Also during wheelchair locomotion the participant's head was restrained, or was not. Results revealed that head restraint during the practice session had no effect on the accuracy of subsequent judgments. By contrast, the judgments of participants who controlled locomotion during practice were significantly more accurate than the judgments of participants who had not controlled their locomotion during practice.
... To date, analyses of multi-segment control (eg, Nashner and McCollum, 1985) have concentrated... more ... To date, analyses of multi-segment control (eg, Nashner and McCollum, 1985) have concentrated on dynamical properties of the environment and the person, such as forces (torque and shear), surfaces (soft, short, etc.), and joints (ankle, hip). ...
We studied the influence of ship motion on postural activity during stance, varying stance width ... more We studied the influence of ship motion on postural activity during stance, varying stance width (the distance between the feet in side-by-side stance) and the difficulty of visual tasks. Participants (experienced crewmembers) were tested on land and then on successive ...
ABSTRACT We investigated the information that supports perception of whether an object is within ... more ABSTRACT We investigated the information that supports perception of whether an object is within reach using a locomotor task. Participants adjusted their own position relative to a fixed target by stepping or by propelling a wheelchair until they judged it to be within reach. The to-be-reached object was presented in virtual reality. The display of the target was driven in real time as a function of the observer's movement, thus depicting a stationary virtual object at a definite distance only through the relation across optical and nonoptical patterns of stimulation. We asked participants to judge the distance they could reach with their unaided hand or when holding a rod that extended their effective reach. They could see neither their body nor the rod thereby limiting available visual information about “reachability.” As expected, our results showed that despite the limited information that was available, participants' locomotor adjustments were influenced by (a) their simulated distance from the target, (b) their arm length, and (c) the presence or absence of the rod. The type of motion (stepping or wheelchair) had little influence. However, judgment accuracy was influenced by participants' initial simulated distance from the target. We compare the performance obtained in our locomotor judgment task with previous studies that have used different methods for measuring perceived reaching-ability. We discuss perceptual information that could have supported performance within the framework of the global array.
Cet article traite de la fidelite des simulateurs et des dispositifs de realite virtuelle. Un fac... more Cet article traite de la fidelite des simulateurs et des dispositifs de realite virtuelle. Un facteur classiquement utilise pour apprecier la fidelite d'une simulation est sa capacite a engendrer une sensation de presence, c'est-a-dire une experience illusoire de percevoir et/ou de controler la realite. Ce concept de presence est discute. Nous suggerons que les utilisateurs sont rarement «trompes» par la simulation et qu'une perception illusoire de la realite est extremement rare. La raison est que les co-variations energetiques emanant des situations reelles ou simulees different. La consequence est qu'une perception incorrecte de la realite pourrait en fait etre une perception correcte du realisme de la simulation. Cette distinction entre perception de la realite et perception du realisme a des implications importantes, tant au plan theorique qu'au plan des methodes utilisees pour apprecier la fidelite des simulateurs.
Behavior causes simultaneous changes in multiple forms of sensory stimulation, such as light, sou... more Behavior causes simultaneous changes in multiple forms of sensory stimulation, such as light, sound, and pressure. Research on multimodal perception has tended to focus on the integration (in the nervous system) of stimuli available to different sensory systems. However, potential sensory stimulation is not limited to patterns available to individual sensory systems. There are also patterns that extend across different forms of ambient energy. These superordinate, higher-order patterns make up the global array (Stoffregen ...
Uploads