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Visual stimuli not only remain visible for some time after their physical offset, but information about their characteristics also persists; that is, not only does something that looks like the physical stimulus continue to persist for a brief time after stimulus offset, but information can also be extracted from the stimulus for a brief time after its offset in much the same way as when the stimulus was physically present. This latter type of persistence is usually called informational persistence. Visible persistence and informational persistence reflect related but different aspects of visual sensory memory. This chapter discusses the evidence behind this assertion and describes the current conception of these phenomena.

This chapter examines (1) whether some constraints or prewired attentional biases are present at birth; (2) if these constraints are general or specific; and (3) how they contribute to guide and shape cognitive activity. In order to address these issues, a peculiar class of visual stimuli, namely faces, will be taken into consideration, because faces form a special class of visual objects elaborated in adults by a specific face system. The first part of the chapter focuses on the mechanisms underlying infants' visual preference for faces, and on the visuoperceptual constraints that induce newborns to prefer faces. The second part of the chapter reviews the studies on the nature of the information newborns actually process and encode when they look at faces as compared to nonface stimuli; more specifically, whether the recognition of faces at birth requires the same nonspecific generalized perceptual abilities that are involved in processing all types of visual stimuli.

This chapter considers motion vision and eye movements. It analyzes the general features and properties of motion vision that apply to all animals and examines how these are tuned for the visual ecological requirements of different species—from small creatures such as fruit flies and jumping spiders to falcons and their prey. As it turns out, far more is known of motion vision in tiny animals than in any of the larger and more familiar species. The visual stimulus for motion is a shift in the position of an image, or portion of an image, on the retina. In almost all animals, the great majority of image shifts on the retina are generated by the animal itself, through its own movements. Only completely sessile animals with utterly stable eyes escape a sense of motion dominated by self-generated stimuli.

The results discussed in the preceding chapters lead to a paradox: On the one hand, data from a broad range of laboratory tasks implied that AH was severely impaired in perceiving the location and orientation of visual stimuli; yet, on the other hand, she was apparently leading a normal life, doing well in school and living independently with no special accommodations. This chapter attempts to resolve this paradox. In doing so, it develops three key points: First, AH is intact in extracting location and orientation information from certain forms of stimuli (e.g., moving visual stimuli), allowing her to succeed in many everyday tasks. Second, AH's performance in daily life is not, in fact, normal: Her self-reports and the results from laboratory tasks indicate that she encounters difficulty in a variety of circumstances. Third, compensatory processes help to reduce the impact of the deficit. These points, supported by AH's self-reports and data from several tasks, indicate that AH's performance in daily life can be reconciled with the laboratory evidence of a serious perceptual deficit.

The functioning of the orbitofrontal cortex is described. It is shown that it receives information about what stimulus is present from the sensory pathways, and represents this in terms of its reward value. There are reward outcome neurons (responding to taste and pleasant and unpleasant touch); expected value neurons (responding to visual stimuli according to the expected reward that they predict); and non-reward 'error' neurons that respond when an expected reward is less than expected. There are also neurons that respond to face identity and face expression, and to vocalization. The medial orbitofrontal cortex represents rewards and its activations are related to the pleasantness of stimuli. The lateral orbitofrontal cortex represents punishers and not receiving expected rewards (non-reward). Economic reward value is represented. An anterior region, the ventromedial prefrontal cortex, is implicated in decision-making between rewards of different value. The orbitofrontal cortex represents the reward and punishment value of stimuli, and not actions. Outputs of the orbitofrontal cortex to the cingulate cortex are involved in learning what actions to take to obtain rewards; and to the striatum for stimulus-response, habit, learning.

This chapter concerns the computational modeling of one of Les Cohen's most important discoveries in infant information processing—the developmental shift from learning about visual stimulus features to learning about correlations between these features. It describes the theoretical origins of this work, and reviews the relevant psychology experiments and the several attempts to simulate it with artificial neural networks, before presenting a new neural network model. The modeling suggests a somewhat different explanation than originally proposed, based on depth of learning rather than qualitative shifts in learning strategies. Computational models of this shift may be equally relevant to several other documented developmental shifts from learning about stimulus elements to learning about relations between those elements.

This chapter outlines evidence of the existence of a visual peripersonal space in humans that seems to be codified by an integrated visuotactile system. It describes the evidence of the existence of the peripersonal space centered on the hand and on the face. It also examines the functional properties of this space. It then considers the dynamic aspect of the peripersonal space, i.e., whether this space is fixed or whether it can be expanded or reduced depending on the action performed in space. The data shows the existence of an integrated system controlling both visual and tactile inputs within peripersonal space around the face and the hand and demonstrates how this system is functionally separated from that controlling visual information in the extrapersonal space. Moreover, evidence indicates that the visual experience of the body can somehow ‘boost’ the signal strength to neuronal circuits associated with the feel-touch experience. Furthermore, results illustrate that sight of the body part improves perception of visual stimuli presented in the peripersonal space.

This chapter provides an overview of non-invasive electrophysiological studies of the human visual system. It begins to explore the influences of passive visual stimulation using different stimuli, followed by a review of the effects of attention to location and other visual features on event-related brain potentials. It then considers recent findings linked to complex visual stimuli such as hierarchically structured objects and faces. A prevailing theme in experimental psychology is that selection of stimuli by the visual system is predominately obtained on the basis of location. Screening a complex visual scene for some relevant item or feature is a prerequisite for the survival of the individuum. It is shown that event-related potentials (ERPs) now provide a quite detailed picture of face-processing in humans. Event-related brain potentials, event-related magnetic fields, and induced activity are applied to track the fate of a visual stimulus on its way through the cortex.

This chapter shows that blindsight illustrates that at least a limited analysis of visual signals continues in some patients even in those parts of their visual field for which they are subjectively blind. It begins by presenting categories of residual visual capacities. There are two general approaches to indirect methods of testing for residual visual function that allow an inference without requiring the subject to guess ‘without seeing’: (1) reflexes to visual stimuli in the blind hemifield; (2) interactions between the intact and impaired hemifields. There can be no doubt that parallel extrastriate visual pathways can mediate visual discriminations, in humans as well as in other primates, but it is the dissociations that emerge, suggesting a segregation of functions, that we are only beginning to characterize.

The extent of the adult visual field gives important clues on brain functioning. Visual field deficits often accompany, and sometimes predict, the onset of neurological problems. It is therefore of utmost importance to have reliable methods of early assessment of the visual field, in addition to the assessment of visual resolution. The behavioural function that is used for visual acuity assessment is the spontaneous orienting towards a salient visual stimulus in preference to a homogeneous field. In this chapter, an overview on the achievements and limitations of the methods of visual perimetry used with infants and children is given, including correlative data from cats and monkeys.

This chapter is concerned with neuronal responses that carry information relating to the previous occurrence of visual stimuli. It concentrates on what is known of neuronal responses within this perirhinal system and their potential relationships to familiarity and recency discrimination for individual items. As early as 1987, the author of this chapter and his collaborators reported that neurons in extrahippocampal temporal cortex seemed to be more important for recognition memory than neurons in the hippocampus. They found that neurons in the perirhinal cortex of both rats and monkeys are sensitive to the familiarity and recency of visual stimuli. In addition, a system involving the hippocampus proper is thought to be important for recognition involving the recollection of associations and the spatial context of events.

Studies of oculomotor responses greatly contributed to the evaluation of sensory visual functions in non-verbal children. These developments result from a better understanding of the oculomotor behaviours of infants and from the introduction of objective techniques for measuring their eye movements. For this reason, the foundations of methods based on eye movement responses to study the detection and discrimination of visual stimuli is first reviewed. Second, the various techniques that are available today for measuring eye movements in children is presented. Third, how these developments applied to the evaluation of sensory visual functions are summarized. The purpose of this chapter is to provide a framework with references to the different reviews made in each of these specialties. In this review, the major problems involved with the evaluation of infants' sensory visual functions with oculomotor responses have been outlined.

Locusts often start to fly by jumping into the air. A decision to jump is not always accompanied by a decision to fly, but flight can result from the consequence of a jump setting up an air current to the head and a loss of tarsal contact with the ground. When in large numbers it is probably the contact with each other that leads to increased excitability, and when coupled with a lack of food leads to the swarms taking to the air. Many sensory clues can lead to this initial response; these include a looming visual stimulus, a shadow, a disruptive sound, or an air current detected by hairs on the head or the cerci. A wind stimulus to the head coupled with a loss of contact of the tarsi with the ground are the experimental stimuli most commonly used to evoke flight.

This chapter considers the physiological mechanisms that drive adaptation at higher processing levels in the nervous system. It discusses the mechanisms that generate beneficial alterations in the way that contrast and motion are coded, both of which require several levels of processing beyond the photoreceptors. Adaptation to contrast and motion is normally observed as an alteration in the visual perception of those attributes following prolonged exposure to a given visual stimulus. Perhaps the most striking example of higher-level adaptation in the visual system is the motion aftereffect (MAE). Following exposure to a stimulus moving in one direction, a stationary pattern appears to move in the opposite direction.

Can our behaviour be motivated by environmental signals that we are not aware of? This chapter casts light on this question, with a series of experiments investigating whether the human brain can deal with the reward-predicting properties of visual stimuli that subjects cannot consciously perceive. The experimental paradigms designed for this purpose bring together procedures that have been used for decades in separate scientific fields: subliminal perception on one side and incentive motivation on the other. It first sketches a short history of methods and concepts used in these two fields, and then presents psychophysics studies combining the two approaches to explore subliminal motivation in humans. Previous studies have shown that the human brain is able to translate higher subliminal incentives into higher physical effort, and to use subliminal cues that predict gambles outcomes to make profitable decisions. The chapter presents several novel variants of the original paradigms to further explore the roles of top-down attention, strategic control, and associative learning in conscious and subconscious incentive motivation.

This chapter first reviews some studies that have used adaptation as a tool to examine how information from different sensory modalities, vision and audition, becomes perceptually bound. It then describes some studies that have used adaptation to show that there is another form of the perceptual binding problem that occurs within a single sensory modality — vision. Together, the two forms of perceptual binding suggest that the brain uses a dynamic strategy that weights the available cues according to their relative reliability when integrating information from multiple sources. This strategy provides a means of adaptively binding information from within and across sensory modalities that, in turn, allows one to effortlessly perceive possibly disparate information in spite of vast changes in the environment.

This chapter presents some of recent experiments exploring age-related differences in the effects of irrelevant distractors in visual search and enumeration tasks. The first study shows that age differences in the effects of irrelevant distractors can vary depending on the perceptual load of relevant processing. The second study examines the ability to selectively facilitate the processing of new visual information by ignoring old irrelevant stimuli already present in the field (visual marking) and demonstrates age preservation for stationary stimuli but marked age decrements for moving stimuli. Finally, enumeration tasks again show that older adults' overall responses are disproportionately slowed by the presence of irrelevant distractors. Moreover, distractors have unexpected effects on age differences in enumeration rates that, together with investigations of eye movements, shed light on the specific task requirements of searching for versus enumerating visual stimuli.

Different visual stimuli elicit electrical and magnetic responses from the brain. This chapter covers attempts to use such electrical and magnetic brain responses to gain more knowledge on how the brain processes and interprets visual information. It also presents a discussion on spatial form processing in relation to luminance contrast, color contrast, texture contrast, and depth contrast. Magno/parvo stream distinction is also presented.

The ability of organisms to categorize objects may enable them to learn about their environment economically, with a decrease in the amount of information that they would otherwise have to acquire. Concepts allow the large number of stimuli to be reduced to a small number of categories. Categorization allows human and nonhuman animals to cope with the stimulus variability that exists in the environment. Numerous studies have shown that animals, particularly pigeons, can classify photographs that contain a particular type of natural object. However, little attention has been given to the relational structure of stimuli that enables animals to classify complex visual stimuli in accordance with the human taxonomies of real-world objects. This chapter reviews contemporary categorization studies in nonhuman animals, focusing on category structure and on theoretical issues surrounding the learning of prototype categories. The prototype effects shown by pigeons can be explained without the need to posit prototype-abstraction process.