Vision Science

distractors. According to Pylyshyn’s account, tracking uses a preattentive mechanism called a Visual Index (or FINST). Several people have challenged the assumption that MOT is preattentive. Treisman (1993) showed that a simultaneous task of monitoring color changes at the screen border results in poorer performance on both tasks. We hypothesize that a task that involves indexing an additional visual object (e.g., the border) may interfere with tracking, but that a task that involves an already-indexed object might not. Subjects performed a MOT task with 4 targets as well as a simultaneous task involving monitoring the occurrence of a specific color change at one of four locations: on a target, non-target, border, and fixation. Both tracking and monitoring performance were recorded. The results showed that tracking was not significantly affected by the monitoring task regardless of its location (although the trend was in the expected direction, with the best performance occurring when the monitored change was on the target and the worst when on the border). There were, however, significant differences in reaction times to the secondary monitoring task, as well as differences in the frequency with which the monitored events was missed. The longest RT occurred when the change was at fixation and the shortest when it was on the border. Perhaps even more surprising was the consistent finding that the frequency with which the monitored event was missed was very much higher when it occurred on a target. An attempt is made to reconcile these findings with the general assumption that MOT requires attention. Among the relevant factors that are considered is the difficulty of the tracking task and the possible role of inattentional blindness and nontarget inhibition.

Hermit crabs hide into shells when confronted with potential dangers, including images presented on a monitor. We do not know, however, what hermit crabs can see and how they perceive different objects.We examined the hiding response of the Caribbean hermit crab (Coenobita clypeatus) to various stimuli presented on a monitor in seven experiments to explore whether crabs could discriminate different properties of a threatening digital image, including color, brightness, contrast, shape and orientation. We found crabs responded differently to expanding circles presented in wavelengths of light corresponding to what humans see as red, blue, and green. “Blue” stimuli elicited the strongest hiding response (Experiments 1, 2, & 7). “Blue” was also more effective than a gray stimulus of similar brightness (Experiment 3). Hermit crabs were sensitive to the amount of contrast between a stimulus and its background rather than absolute brightness of the stimulus (Experiment 4). Moreover, we did not find evidence that crabs could discriminate orientation (Experiment 6), and mixed evidence that they could discriminate stimulus shape(Experiments 5 & 7). These results suggest that the Caribbean hermit crab is sensitive to color features,but not spatial features, of a threatening object presented on a computer screen. This is the first study to use the hiding response of the hermit crab to examine its visual ability, and demonstrates that the hiding response provides a useful behavioral approach with which to study learning and discrimination in the hermit crab.

BACKGROUND Alzheimer disease (AD) primarily affects cognition. A variety of visual disorders was established in AD. Fechner illusory colors are produced by a rotating disk with a black and white pattern. The purpose of our research was to explore the perception of illusory colors in AD. MATERIAL AND METHODS W recruited 40 AD patients (MMSE ≥14) and 40 normal controls (CG group) matched by age, education, gender in this prospective, cross-sectional, case-control study. An achromatic Benham's disk attached to a device to control the speed and direction of rotation was used to produce illusory colors. Primary, secondary, and tertiary RGB system colors were used for matching of illusory and physical colors. RESULTS Subjects in the AD group perceived less illusory colors in 5 arcs (p<0.05) of the 8 arcs assessed. The biggest difference was found between AD and CG groups for pure blue (χ²=26.87, p<0.001 clockwise, χ²=22.75, p<0.001 counter-clockwise). Groups did not differ in...

Importance During emmetropization, the refractive state of the left and right eyes fluctuate randomly in an unpredictable way. Objective The objective of this report is to quantify left-right refractive state differentials, measured in diopters, resulting from the accumulation of naturally occurring random fluctuations. Design, Setting, and Participants Design methods include 1-st order control theory with system input determined by the average visual environment and superimposed random fluctuations. The left-right refractive-state disparity is measured for 20 normal human emmetropes during development. Main Outcomes and Measures Results include random fluctuations for left and right eyes of 20 human subjects ages 11 to 23 years. The ensemble L-R differential measurement for this group is +/-0.213 diopters RMS. Results The 40 nearly emmetropic eyes exhibit a slow and steady trend towards myopia, at the rate of-0.4 to-0.5 diopt. / decade. Statistically, 15.9% are expected to progress into myopia during ages 12 to 22 years. Conclusions and Relevance The eye tracks its environment with a RMS error of +/-0.15 to +/-0.35 diopters. Visual environment shifts of +/-0.1 diopt. will be partially masked by the internal optical perturbations of the eye. Substantial shifts of greater than +/-0.4 diopters will produce a time constant response in the focal status of the eye. Left-Right human coupling ratio is determined to be CR = 0.88 for differential <L-R> and average <L+R>/2 input variables. Statistics indicate fluctuations of +/-0.15 to +/-0.35 D for the left and right eyes (N=20). Abstract Importance/Objectives The purpose of this report is to quantify left-right refractive state differentials, measured in diopters, resulting from the accumulation of naturally occurring random fluctuations. Design/Setting/Participants Methods include 1-st order control theory, with system input determined by the average visual environment and superimposed random fluctuations. Interventions None. Main Outcome Measures Results include random fluctuations for left and right eyes of 20 human subjects ages 11 to 23 years. The ensemble L-R differential measurement for this group is +/-0.213 diopters RMS. Results The 40 nearly emmetropic eyes exhibit a slow and steady trend towards myopia, at the rate of-0.4 to-0.5 diopt. / decade. Statistically, 15.9% are expected to progress into myopia during ages 12 to 22 years. Conclusions/Relevance The eye tracks its environment with a RMS error of +/-0.15 to +/-0.35 diopters. Visual environment shifts of +/-0.1 diopt. will be partially masked by the internal optical perturbations of the eye. Substantial shifts of greater than +/-0.4 diopters will produce a time constant response in the focal status of the eye. Left-Right human coupling ratio is determined to be CR = 0.88 for differential <L-R> and average <L+R>/2 input variables. Statistics indicate fluctuations of +/-0.15 to +/-0.35 D for the left and right eyes (N=20).

In order to conduct a exclusively-prevention study at a military college (when at 20/40), it is necessary that each pilot-student understand the history of preventive efforts at a military college.  Here is that history.
"The visual standards for the line of the Navy, the branch which handles the naval vessels of the United States, have always been based on the fact that it is essential for navigation, watch and gunnery officers to have normal vision and not to have to wear glasses, which may become fogged in bad weather or may even be broken or lost, with consequence serious impairment of vision. For many years the high incidence of myopia which apparently developed among midshipmen after admission to the United States Naval Academy with supposedly normal vision was a cause of serious concern to all those interested. For years every effort was made to save such men to the service by giving them extended complete rest of their eyes before reexamination of their vision, and by retaining many of them in the Naval Academy for one to three years in the hope that their vision would improve. Every effort was also made to improve the illumination of both study rooms and class rooms for midshipmen. Decisions to retain such men were largely based on the recommendations of ophthalmologists. In the vast majority of cases, however, the vision did not improve, and the midshipman was forced to leave the naval service after two to four years in the Naval Academy. Experience showed that only about 1 percent of such men had 20/20 vision on their final physical examination. Prior to 1937 the visual requirement for admission to the Naval Academy was 20/20 vision in each eye unaided by lenses. The percent of physical disqualifications of midshipmen for defective vision was so high however, ranging from 14.14 percent to 31.46 percent of the classes of 1934 to 1940 during the four year course, that it became evident that more strenuous preventive measures were necessary. Furthermore, and excessive number of junior line officers were being retired because of defective vision, and the records showed that the vision of three fourths of these had become defective (vision less than 20/20 for each eye) at the Naval Academy. ARCHIVES OF OPHTHALMOLOGY, PAGE 540

It is well established that vision, and in particular color, may modulate our experience of flavor. Such cross-modal correspondences have been argued to be bilateral, in the sense that one modality can modulate the other and vice versa. However, the amount of literature assessing how vision modulates flavor is remarkably larger than that directly assessing how flavor might modulate vision. This is more exaggerated in the context of cross-modal contrasts (when the expectancy in one modality contrasts the experience through another modality). Here, using an embodied mixed reality setup in which participants saw a liquid while ingesting a contrasting one, we assessed both how vision might modulate basic dimensions of flavor perception and how the flavor of the ingested liquid might alter the perceived color of the seen drink. We replicated findings showing the modulation of flavor perception by vision but found no evidence of flavor modulating color perception. These results are discussed in regard to recent accounts of multisensory integration in the context of visual modulations of flavor and bilateral cross-modulations. Our findings might be important as a step in understanding bilateral visual and flavor cross-modulations (or the lack of them) and might inform developments using embodied mixed reality technologies.

This paper is a brief, critical review of the claims that attention is necessary for perception, whether conscious or not. I focus largely on attention as a gatekeeper for perceptual consciousness, a claim that many endorse but which I argue against. I also make remarks about attention as limiting unconscious perception.

Encryption algorithms provide the securely transmitted data over insecure communication channels. In this paper a different stream cipher scheme is presented which is very simple in hardware implementation and provides relatively high level of security. Geffe generator is used for the generation of a complex key in a unique way. In this modified scheme, keystream is dependent not only on the inputs of the Geffe generator but also on the Gold Codes generated with the help of outputs of pseudo noise (PN) sequences of the two inputs of Geffe generator. Further complexity of the key is increased by introducing automatic shift of the contents of one LFSR to generate a new Gold code. Keywords— ―Geffe generator‖, ―Gold Code (GC)‖, ―Maximal Sequence (m-sequence)‖, ―Linear Feedback Shift Register (LFSR)‖, ―Pseudorandom number generator (PRNG)‖.

Background: Two models of artificial intraocular lenses with a "pure" EDOF structure, i.e. Soleco Evolve and Lucidis, were used in 36 patients in 43 eyes. Results of postoperative visual function were analysed, like also a correlation between preoperatively measured parameters of pupil size, kappa and alpha angles.

The purpose of this thesis is to investigate potential key determinants of the success, or otherwise, of endeavours to address avoidable Visual Impairment (VI) by addressing Uncorrected Refractive Error (URE) in Mozambique and the wider region of sub-Saharan Africa by providing optometric services. It includes a Cost Benefit Analysis (CBA) of a higher education optometry training programme, barriers that might prevent the realisation of overarching goals despite a successful training programme, and a Willingness to Pay (WTP) analysis to inform the pricing structure and to determine the financial sustainability of the system. Methods A standard CBA methodology was applied to ascertain societal net benefit. Costs including those associated with establishing an optometry service. Benefits were calculated by considering how addressing URE could increase productivity. Disability weighting (DW) for VI was applied …

Here's the entire book, for free. I found it posted several places on the internet, so even though it's still in copyright, I thought I'd post it here.

I am currently working on a book that's a kind of sequel, except the new book will be on a much larger scale. It's called, tentatively, "Our Visual World." My co-author is the historian Erna Fiorentini, and our publisher is Oxford. There's more about it on this site, and also on my website at

http://www.jameselkins.com/index.php/experimental-writing/257-our-visual-world

All comments are welcome! (Except comments on the chapter "How to Look at an Engineering Drawing": that chapter has an error, and if you're clever enough to find it, you're lucky.)

Tertiary sediments are thickly deposited in most part of the northeast India attaining a maximum thickness of ±7 km sedimentary succession. Surma basin located in the eastern proximity of India is also characterized by a thick sedimentary column which can be considered as the northeastern extension of Greater Bengal basin. This basin was initiated due to the mutual collision between Indian and Burmese Plate. Due to this collision, the bed rocks have undergone folding which are oriented N-S trending hill ranges. The basin was also cut by a number of parallel to sub-parallel transverse faults and thrusts. The litho association is consisting of sandstone, siltstone, shale and their various proportions. The present study focused on the provenance of the sediments, tectonic settings of the basin and various paleoclimatic conditions prevailing during the time of deposition by using petrography, granulometric and heavy mineral analysis of representative rock samples which were collected fr...

The unconscious mind tends to disregard negations in its processing of semantic meaning. Therefore, messages containing negated concepts can ironically prime mental representations and evaluations that are opposite to those intended. We hypothesized that the subtle presentation of a negated concept (e.g., “no smoking”) would activate ironic motivational orientations as well. We tested this hypothesis in a public health context. Smokers viewed photographs in which no-smoking signs were either inconspicuously embedded (prime) or edited out (control). Primed smokers showed amplified automatic approach tendencies toward smoking-related stimuli, but not toward smoking-unrelated stimuli. Since passive priming effects generally serve to facilitate forms of action, not inhibit them, anti-smoking and other public health campaigns may ironically increase the very behaviors they seek to reduce.

Cet article explore l'ensemble des caractéristiques, des fonctions et de la perception des graphismes, sous les angles de la physiologie, de la sémiologie visuelle (science des signes) et des neurosciences. Au titre des fonctions, ce document en détaille tous les effets possibles en terme d'interprétation visuelle. Au titre des perceptions, il discute des effets de la perception nonconsciente du signe graphique, à l'origine d'une interprétation qui peut devenir connotative.

This is a chapter from a textbook called Visual Worlds, co-authored with Erna Fiorentini. The book covers theories and practices of seeing and vision in many fields, including art, business, science, medicine, law, the military.

The entire book is on Amazon:
https://www.amazon.com/gp/product/0199390916

Its ability to deal with visual information is one of the mind's most powerful capacities.  Visual thinking, high-level manipulation of visual information, is important to computer science because, with the flowering of computer graphics and image processing, it provides the basis for a rich and intuitively satisfying channel of man-machine interaction.  Just as writing evolved to help the verbal mind, so various media have evolved to help the visual mind. I propose that visual thinking involves the internalization of visuo-manipulative activity and of movement through the environment.  We move through the physical environment, sometimes in a familiar place, sometimes in a strange place; we handle objects, sometimes to accomplish a specific task, sometimes simply to inspect the object.  Visual thinking involves imagined locomotion in imagined settings, imagined  manipulation of imagined objects.  The settings and objects may be real, but not present, or they may exist only in imagination.

Matlab and Psychophysics Toolbox Introduction (in German), extended version (2009, past version was 2007)
aimed at students, not experts

Not a paper but class material; put in this section because academia.edu provides nicer stats for papers than for teaching material.

Einführung in Matlab und die Psychophysics Toolbox.

Objectives
The ability to perform a context-free 3-dimensional multiple object tracking (3D-MOT) task has been highly related to athletic performance. In the present study, we assessed the transferability of a perceptual-cognitive 3D-MOT training from a laboratory setting to a soccer field, a sport in which the capacity to correctly read the dynamic visual scene is a prerequisite to performance.
Design
Throughout pre- and post-training sessions, we looked at three essential skills (passing, dribbling, shooting) that are used to gain the upper hand over the opponent.
Method
We recorded decision-making accuracy during small-sided games in university-level soccer players (n=23) before and after a training protocol. Experimental (n=9) and active control (n=7) groups were respectively trained during 10 sessions of 3D-MOT or 3D soccer videos. A passive control group (n=7) did not received any particular training or instructions.
Results
Decision-making accuracy in passing, but not in dribbling and shooting, between pre- and post-sessions was superior for the 3D-MOT trained group compared to control groups. This result was correlated with the players’ subjective decision-making accuracy, rated after pre- and post-sessions through a visual analogue scale questionnaire.
Conclusions
To our knowledge, this study represents the first evidence in which a non-contextual, perceptual-cognitive training exercise has a transfer effect onto the field in athletes.

Partiendo de la revisión documental existente con relación a la aplicación de pruebas optométricas, es pertinente diferenciar el examen convencional encaminado a la determinación y corrección de los defectos visuales de un estudio optométrico ocupacional, donde se involucran además de las pruebas de perimetría, visión cromática y estereoscópica, un análisis exhaustivo de la sensibilidad al contraste.

This piece documents the earliest recorded spectacle makers in late medieval England. As they were immigrants, the article also connects their occupations with the wider context of the importation of foreign expertise to England through immigration.

The study of emotions is one of the most interesting, and interdisciplinary topic in contemporary international research, but it is rarely supported by a substantial historical background. This essay aims at reconstructing one of the most significant turning points in the field of affective studies in the seventeenth Century French culture. René Descartes' last work, Les Passions de l'âme, proposes an innovative, scientific approach to the study of emotions and their expression, based on a new theory of perception and light. The role played by the visible expression of passions in Descartes' treatise inaugurates a new and fruitful path of research. Furthermore, the essay analyzes the writings by the painter Charles Le Brun, who proposes a visual interpretation of the expression of emotions, and some works by the physician Marin Cureau de la Chambre, who interprets the passions and their expression from a medical and optical perspective.

The theme of the current work is the vision of the forest in the Russian and Ukrainian literatures of the second half of the nineteenth and the twentieth centuries. The author, based on the songs taken from East Slavic literatures shows that image in works of fiction, also referring to the folklore and the lives of the saints (hagiographies). The vision of the forest, whose numerous examples can be found in those works, is subject to continuous transformations. Both in the folk songs, and in the earlier literary periods, the forest is most common as a background against which events develop, like in feature films, while later the vision of the forest is transformed into a dynamic part of the work, gaining the right to vote, gradually engaging in dialogue with the character, exerting influence upon him and shaping his psychological states.

Aunque pareciera a simple vista que la forma característicamente esférica que presentan los ojos
de los individuos de muchas especies, junto con la depresión semiesférica que poseen sus fóveas no sirvieran de mucho, la cruda realidad es que es la única manera física y fisiológicamente posible de codificar bordes con disparidades estructuradas tridimensionalmente en un Sistema de
Coordenadas Euclidianas Esféricas dentro de cada uno de sus cerebros, con el fin de ejecutar todo
proceso perceptual, motor y cognitivo por aferencias visuales.
Todo esto confirma que el excepcional diseño del sistema visual humano no es producto del azar, es en realidad un código estructural que viene escrito en nuestros genes más antiguos, configurado para interiorizar y utilizar el Sistema de Coordenadas Euclidianas Esféricas en toda
actividad que los grupos neuronales puedan controlar.

The Naval Academy requires unaided visual acuity of 20/20 in each eye as a basic entrance requirement.  Prospective pilots are required to have normal vision on graduation. A substantial number of midshipmen, entering with 20/20 vision, become myopic during their four years at the Academy.

A reasonable assessment of the experimental evidence suggests that the eye sets its long-term focus by a servo control process. This engineering analysis of the eye’s control action predicts that a significant percentage of midshipmen could avoid the myopia problem is they wear a convex lens while reading.