Abstract: Areas and pathways subserving object and spatial vision are segregated in the visual system. Experiments show that the primate prefrontal cortex is similarly segregated into object and spatial domains. Neurons that code information related to stimulus identity are dissociable, both by function and region, from those that code information related to stimulus location. These findings indicate that the prefrontal cortex contains separate processing mechanisms for remembering "what" and "where" an object is.

Abstract: PURPOSE. To identify visual factors that are significantly associated with increased vehicle crashes in older drivers. METHODS. Several aspects of vision and visual information processing were assessed in 294 drivers aged 55 to 90 years. The sample was stratified with respect to age and crash frequency during the 5-year period before the test date. Variables assessed included eye health status, visual sensory function, the size of the useful field of view, and cognitive status. Crash data were obtained from state records. RESULTS. The size of the useful field of view, a test of visual attention, had high sensitivity (89%) and specificity (81%) in predicting which older drivers had a history of crash problems. This level of predictability is unprecedented in research on crash risk in older drivers. Older adults with substantial shrinkage in the useful field of view were six times more likely to have incurred one or more crashes in the previous 5-year period. Eye health status, visual sensory function, cognitive status, and chronological age were significantly correlated with crashes, but were relatively poor at discriminating between crash-involved versus crash-free drivers. CONCLUSIONS. This study suggests that policies that restrict driving privileges based solely on age or on common stereotypes of age-related declines in vision and cognition are scientifically unfounded. With the identification of a visual attention measure highly predictive of crash problems in the elderly, this study points to a way in which the suitability of licensure in the older adult population could be based on objective, performance-based criteria. Keywords: Driver distraction;

Abstract: SEVERAL examples of experience-dependent perceptual improve-ment (perceptual learning) suggest that plasticity in specific neu-ronal loci could underlie the learning process1–6. For a basic visual discrimination task (using an optimal stimulus for ‘automatic’ pre-attentive texture segregation7–10), discrete retinal input-dependent changes within a very early stage in the stream of visual processing were indicated as the locus of a large and consistent learning effect5. When do these changes occur? Here we report that except for a fast, rapidly saturating improvement early in the first practice session, performance was very stable within sessions. Indeed, observers showed little or no improvement until up to 8 hours after their last training session (latent phase). But large improvements occurred thereafter. Finally, there was almost no forgetting; what was gained was retained for at least 2–3 years. We conjecture that some types of perceptual experience trigger permanent neural changes in early processing stages of the adult visual system. These may take many hours to become functional.

Abstract: Processing of digital images destined for visual consumption raises many interesting questions regarding human visual sensitivity. This talk will survey some of these questions, including some that have been answered and some that have not. There will be an emphasis upon visual masking, and a distinction will be drawn between masking due to contrast gain control processes, and due to processes such as hypothesis testing, pattern recognition, and visual search.

Abstract: One of the most intriguing and controversial observations in oculomotor research in recent years is the phenomenon of express saccades in monkeys and man. These are saccades with such short reaction times (100 msec in man, 70 msec in monkeys) that some experts on eye movements still regard them as artifacts or as anticipatory reactions that do not need any further explanation. On the other hand, some research groups consider them not only authentic but also a valuable means of investigating the mechanisms of saccade generation, the coordination of vision and eye movements, and the mechanisms of visual attention.This target article puts together pieces of experimental evidence in oculomotor and related research – with special emphasis on the express saccade – to enhance our present understanding of the coordination of vision, visual attention, and the eye movements subserving visual perception and cognition.We hypothesize that an optomotor reflex is responsible for the occurrence of express saccades, one that is controlled by higher brain functions involved in disengaged visual attention and decision making. We propose a neural network as the basis for more elaborate mathematical models or computer simulations of the optomotor system in primates.

Abstract: Cerebral blood flow was measured using positron emission tomography (PET) in three experiments while subjects performed mental imagery or analogous perceptual tasks. In Experiment 1, the subjects either visualized letters in grids and decided whether an X mark would have fallen on each letter if it were actually in the grid, or they saw letters in grids and decided whether an X mark fell on each letter. A region identified as part of area 17 by the Talairach and Tournoux (1988) atlas, in addition to other areas involved in vision, was activated more in the mental imagery task than in the perception task. In Experiment 2, the identical stimuli were presented in imagery and baseline conditions, but subjects were asked to form images only in the imagery condition; the portion of area 17 that was more active in the imagery condition of Experiment 1 was also more activated in imagery than in the baseline condition, as was part of area 18. Subjects also were tested with degraded perceptual stimuli, which caused visual cortex to be activated to the same degree in imagery and perception. In both Experiments 1 and 2, however, imagery selectively activated the extreme anterior part of what was identified as area 17, which is inconsistent with the relatively small size of the imaged stimuli. These results, then, suggest that imagery may have activated another region just anterior to area 17. In Experiment 3, subjects were instructed to close their eyes and evaluate visual mental images of upper case letters that were formed at a small size or large size. The small mental images engendered more activation in the posterior portion of visual cortex, and the large mental images engendered more activation in anterior portions of visual cortex. This finding is strong evidence that imagery activates topographically mapped cortex. The activated regions were also consistent with their being localized in area 17. Finally, additional results were consistent with the existence of two types of imagery, one that rests on allocating attention to form a pattern and one that rests on activating stored visual memories.

Abstract: The way in which the brain integrates fragmentary neural events at multiple locations to produce unified perceptual experience and behaviour is called the binding problem. Binding has been proposed to involve correlated activity at different cortical sites during perceptuomotor behaviour, particularly by synchronization of narrow-band oscillations in the gamma-frequency range (30-80 Hz). In the rabbit olfactory system, inhalation induces increased gamma-correlation between sites in olfactory bulb and cortex. In the cat visual system, coherent visual stimuli increase gamma-correlation between sites in both the same and different visual cortical areas. In monkeys, some groups have found that gamma-oscillations transiently synchronize within striate cortex, superior temporal sulcus and somatosensorimotor cortex. Others have reported that visual stimuli produce increased broad-band power, but not gamma-oscillations, in several visual cortical areas. But the absence of narrow-band oscillations in itself does not disprove interregional synchronization, which may be a broad-band phenomenon. We now describe episodes of increased broad-band coherence among local field potentials from sensory, motor and higher-order cortical sites of macaque monkeys performing a visual discrimination task. Widely distributed sites become coherent without involving other intervening sites. Spatially selective multiregional cortical binding, in the form of broad-band synchronization, may thus play a role in primate perceptuomotor behaviour.

Abstract: Historical Foundations of Human Factors Historical Foundations of Human Factors Research Methods in Human Factors Reliability and Human Error in Systems Human Information Processing Perceptual Factors and Their Applications Visual Perception Perception of Objects in the World Hearing, Proprioception, and the Chemical Senses Display of Visual, Auditory, and Tactual Information Cognitive Factors and Their Applications Attention and the Assessment of Mental Workload Retention and Comprehension of Information Solving Problems and Making Decisions Experts and Expert Systems Action Factors and Their Applications Response Selection and Principles of Compatibility Control of Movement and Learning of Motor Skill Controls and Controlling Actions Environmental Factors and Their Applications Anthropometrics and Workspace Design Environmental Ergonomics Human Resource Management and Macroergonomics Practice of Human Factors Appendix 1 Appendix 2 Glossary References Index

Abstract: The performance of adult humans in simple visual tasks improves dramatically with practice. This improvement is highly specific to basic attributes of the trained stimulus, suggesting that the underlying changes occur at low-level processing stages in the brain, where different orientations and spatial frequencies are handled by separate channels. We asked whether these practice effects are determined solely by activity in stimulus-driven mechanisms or whether high-level attentional mechanisms, which are linked to the perceptual task, might control the learning process. We found that practicing one task did not improve performance in an alternative task, even though both tasks used exactly the same visual stimuli but depended on different stimulus attributes (either orientation of local elements or global shape). Moreover, even when the experiment was designed so that the same responses were associated with the same stimuli (although subjects were instructed to attend to the attribute underlying one task), learning did not transfer from one task to the other. These results suggest that specific high-level attentional mechanisms, controlling changes at early visual processing levels, are essential in perceptual learning.

Abstract: The neural processes that lead to visual perception and memory, thus subserving the identification of objects, have been assigned to the multi­ synaptic occipito-temporo-limbic projection that interconnects the striate, prestriate, inferior temporal, and hippocampal cortices (Gross 1972; Maunsell & Newsome 1987; Mishkin et al 1983). Recent advances in our understanding of the organization of the extra striate cortex revealed a mosaic of more than 25 visual areas beyond the striate cortex (Felleman & Van Essen 1991; Van Essen 1985; Zeki & Shipp 1988). The physical properties of a visuaJ object (such as its size, color, texture, and shape) are analyzed in the multiple subdivisions of the prestriate-posterior temporal complex. The anterior part of inferior temporal cortex has been hypo­ thesized not only to synthesize the analyzed attributes into a unique con­ figuration, but also to work as the storehouse for central representations of the objects (Mishkin 1982; Weiskrantz & Saunders 1984). The supporting evidence for this hypothesis has mainly been given by neuropsychological approaches (Milner 1990; Squire & Zola-Morgan 1991; Weiskrantz 1990). Recently, neuronal correlates of the visual long-term memory were found: The temporal-lobe neurons could reflect learned associative relations among stimuli (Miyashita 1988; Sakai & Miyashita 1991). The findings on this associational mechanism, together with that on the feature selectivity

Abstract: We used the technique of PET to determine whether visual signals reach visual area V5, specialized for visual motion, when a human patient, blinded by a lesion in area V1, discriminates the direction of motion of visual stimuli and shows, through his verbal reports, that he is consciously aware of both the nature of the visual stimulus and its direction of motion. The results showed that area V5 was active without a parallel activation of area V1, implying that the visual input can reach V5 without passing first through V1 and that such an input is sufficient for both the discrimination and the conscious awareness of the visual stimulus.

Abstract: The degree to which the process involved in visual perception and visual imagery share a common neuroanatomical substrate is unclear. Physiological evidence for localization of visual imagery early in the visual pathways would have important bearing on current theories of visual processing. A magnetic resonance imaging technique sensitive to regional changes in blood oxygenation was used to obtain functional activation maps in the human visual cortex. During recall of a visual stimulus, focal increases in signal related to changes in blood flow were detected in V1 and V2 cortex in five of seven subjects. These experiments show that the same areas of the early visual cortex that are excited by visual stimulation are also activated during mental representation of the same stimulus. Some of the processes used in topographically mapped cortical areas during visual perception may also be utilized during visual recall.

Abstract: There are many instances in which human subjects perceive a component which is not physically present in a visual stimulus. To study the cerebral activity which correlates with the perception of such an illusory component, we chose Enigma, a static figure in which many subjects perceive illusory motion. By using the technique of positron emission tomography (PET) we recorded the relative regional cerebral blood flow (rCBF) in the brain of 13 subjects while they viewed it and reported seeing the illusory motion. We found that, when subjects perceived illusory motion, the increases in rCBF took place in regions of the brain closely related to, and perhaps identical with, area V5, as defined by the site of rCBF change that took place when the same subjects viewed a physically moving stimulus. In addition, there was activity in other cortical areas outside the visual cortex, not present when the subjects had been viewing objective motion. This suggests that the generation of illusory motion depends not only on a highly specific visual area but also on relative contributions from other parts of the brain that are not activated to the same extent when humans perceive objective motion.

Abstract: Disorders in perceiving and exploring the visual space contralateral to a brain lesion have been frequently described. Many patients with hemi-neglect for extrapersonal space also show neglect in a representational domain when the task requires imagining a well-known piazza from a given vantage point or comparing two visual images. Cognitive and psychophysiological studies show a functional parallelism between the perceptual and imaginative domain, indicating that spatial perception and imagery share the same neural substrata. Here we describe a patient with a persistent disorder in visual imagery for familiar piazzas in the absence of any neglect for stimuli located in a far or near space or on his own body. Contrary to previous cases involving imagery disorders, computerized tomography scans showed a lesion confined to the right frontal lobe, suggesting the role of the frontal lobe in some specific types of mental imagery.

Abstract: Three experiments establish the size-weight illusion as a primarily haptic phenomenon, despite its having been more traditionally considered an example of vision influencing haptic processing. Experiment 1 documents, across a broad range of stimulus weights and volumes, the existence of a purely haptic size-weight illusion, equal in strength to the traditional illusion. Experiment 2 demonstrates that haptic volume cues are both sufficient and necessary-for a full-strength illusion. In contrast, visual volume cues are merely sufficient, and produce a relatively weaker effect. Experiment 3 establishes that congenitally blind subjects experience an effect as powerful as that Of blindfolded sighted observers, thus demonstrating that visual imagery is also unnecessary for a robust size-weight illusion. The results are discussed in terms of their implications for both sensory and cognitive theories of the size-weight illusion. Applications of this work to a human factors design and to sensor-based systems for robotic manipulation are also briefly considered.

Abstract: Ibotenic acid lesions were placed in two monkeys in a portion of cortical area V2 that corresponds to a lower quadrant of the visual field extending approximately 3-7 degrees from the fovea. For purposes of comparison, another lesion was placed in area V1 in one animal. A wide range of visual capacities were then measured, using a discrimination between vertical and horizontal orientation, in and near the affected regions of the visual field. Visual acuity declined sharply as the test stimulus approached the visual field location corresponding to the V1 lesion, and no threshold could be measured at its center. In contrast, lesions of area V2 caused no measurable decrease in acuity, nor was there any substantial effect on several measures of contrast sensitivity. Subsequently, two types of more complex visual discriminations were measured (also using a vertical-horizontal discrimination), and these discriminations were severely disrupted by V2 lesions. The first discrimination was of the orientation of two parallel lines of five colinear dots each. We measured the number of background dots that would bring the discrimination to threshold, and this number of dots was greatly decreased by a V2 lesion. The second discrimination was of the orientation of a group of three distinctive texture elements embedded in a six by six element texture. This task could not be done in the visual field region affected by the V2 lesion when the distinctive elements differed in orientation from the others. Control experiments showed that the discrimination could be done when the three distinctive elements differed in size or color. These results suggest that cortical area V2 is not needed for some low-level discriminations, but may be essential for tasks involving complex spatial discriminations.

Abstract: HONEYBEES remember the shapes of flowers and are guided by visual landmarks on their foraging trips1,2. How insects recognize visual patterns is poorly understood. Experiments suggest that they try to match retinotopically the incoming visual pattern with a previously stored memory image2–7. But bees can be conditioned to individual pattern parameters such as orientation of contours, colour or size2,8–11. These and other results are difficult to reconcile with simple template matching. In such investigations, freely moving animals are observed; their behaviour and visual input, therefore, are not well known. Mostly, processing strategies are inferred from stimulus design. We have studied visual pattern recognition with tethered flies (Drosophila melanogaster) in a flight simulator and report here that flies store visual images at, or together with, fixed retinal positions and can retrieve them from there only5. Position invariance, an acknowledged property of human pattern recognition, may not exist as a primary mechanism in insects.

Abstract: From the Publisher: This book examines the current status of what is known (and not known) about human vision, how human observers interpret visual data, and how to present such data to facilitate their interpretation and use. Written by experts who are able to cross disciplinary boundaries, the book provides an educational pathway through several models of human vision; describes how the visual response is analyzed and quantified; presents current theories of how the human visual response is interpreted; discusses the cognitive responses of human observers; and examines such applications as space exploration, manufacturing, surveillance, earth and air sciences, and medicine. The book is intended for everyone with an undergraduate-level background in science or engineering with an interest in visual science.

Abstract: Ss were taught novel mappings between visual space and motor space with either a variant on a prism adaptation paradigm (Experiments 1 and 2) or a nonperceptual cognitive task (Experiments 3 and 4). First, discrimination training specified that 1 visual location required a new pointing response but another location did not. This led to unusual generalization unlike typical generalization decrement. Second, training at 9 locations specified that 1 location required a new response but that the remaining 8 did not. This simple isolation mapping was unlearnable and instead a flat function fit through all of space. In contrast, for the cognitive paradigm, not only was isolation of one region of space easily learned, it was the preferred pattern of generalization. Implications for perceptual learning, as well as the qualitative distinctions between perceptual and cognitive learning, are discussed. Language: en

Abstract: Cognitive performance and development is negatively correlated with fixation duration patterns during infancy, and evidence suggests that long-looking infants may process visual information more slowly than short-looking infants. 3 experiments described here tested the possibility that these differences may be due to differential sensitivity to global and local visual information. Infants were administered discrimination and generalization tasks involving global and local information at varying levels of familiarization time. Results indicated that 4-month-olds process visual information in a global-to-local sequence. Both long- and short-looking infants were sensitive to both types of information, although long lookers required additional familiarization time to match the performance of short lookers. Finally, apparent "generalization" of global information at brief familiarization levels was traced to insensitivity to local stimulus properties. The results do not support the hypothesis that long- and short-looking infants are differentially sensitive to global versus local visual information at 4 months of age.

Abstract: The question of whether phenomena of human perception such as amodal completion are also present in visual perception in the mouse was investigated. Three experiments based on a simultaneous-discrimination task were carried out with the aid of a jumping-stand similar to the one used by Lashley. The subjects were 36 male mice (DBA/J); 12 took part in each experiment. After reaching the learning criterion (87% correct responses), the mice performed 15 test trials which were interpolated between the learning trials. The test trials were constructed so as to allow the observation of any perceptual phenomena similar to amodal perception. Of the 36 subjects, 23 reached the criterion necessary to access the test phase. A significant number of them (17 out of 23, chi 2 = 5.261, p = 0.021) adopted a decisional strategy that seemed to indicate the occurrence of phenomena similar to amodal completion, and a trend in the same direction was observed in the performance of the other 6 subjects. The results allow the conclusion that a perceptual phenomenon which is similar to amodal completion in humans is present even at this phylogenetic level. Alternative interpretations are discussed.

Abstract: A method of statistical graphics consists of two parts: a selection of statistical information to be displayed and a selection of a visual display method to encode the information. Some display methods lead to efficient, accurate visual decoding of encoded information, and others lead to inefficient, inaccurate decoding. It is only through rigorous studies of visual decoding that informed judgments can be made about how to choose display methods. A model has been developed to provide a framework for the study of visual decoding. The model consists of three parts: (1) a two-way classification of information on displays—quantitative-scale, quantitative-physical, categorical-scale, and categorical-physical; (2) a division of the visual processing of graphical displays into pattern perception and table look-up; (3) a specification of visual operations that are employed to carry out pattern perception and table look-up. Display methods are assessed by studying the visual operations to which they lead....

Abstract: One of the major tasks facing the central nervous system is choosing which sensory events to use for perception and directed behavior. All organisms live in a rich sensory environment, and it is impossible to attend and respond to everything. Certain brain regions and systems must evaluate sensory signals and then determine which are salient. Based on recent data derived from diverse studies of the pulvinar of primates, it is the hypothesis of this paper that a major role of the pulvinar is to participate in the generation of visual salience, those processes which precede perception and action. This process of salience generation makes use of two broad mechanisms, the suppression of noise and the enhancement of significant signals. Outlined above are experiments which show that the visual activity which might be caused by eye movements is filtered from some pulvinar cells. Visual responses associated with certain directions of gaze are removed. Finally the ability to suppress the activity of distracting visual stimuli is dependent on the integrity of the pulvinar. Conversely, there are neurons within the pulvinar which respond best when animals actively select and thus engender certain stimuli with salience. Modulation of pulvinar functioning with transmitter-related drugs changes performance as if salience is being modulated. Humans and monkeys with destruction of the pulvinar behave as if they too cannot create or evaluate salience. Finally, when salience is demanded of humans by making their visual tasks more demanding, there is an increase in PET activity. The hypothesis here is that the pulvinar functions as an early center for the generation of visual salience. This is similar to the view of striate cortex as an early integration stage for the basic elements of visual processing (Hubel and Wiesel, 1968; Zeki, 1976; Allman et al., 1981). Vision does not take place within the complex microstructure of striate neurons, but all of the essential components are present there, and these are distributed to other cortical areas which construct specific aspects of visual perception. Similarly, regions of the pulvinar contain building blocks for visual/behavioral/oculomotor integration which they distribute to various cortical sites for shifts of attention and other types of response specification. When an organism must determine external visual salience, there are neurons within the pulvinar which signal this. Since the major efferents of these thalamic regions are the visual cortices (Benevento and Rezak, 1976; Lin and Kaas, 1979; Kennedy and Bullier, 1985), our present hypothesis is that these signals are used for the construction of visuomotor and visuo-perceptual states.(ABSTRACT TRUNCATED AT 400 WORDS)