Abstract-There is considerable evidence that visual attention is concentrated at a single locus in the visual field, and that this locus can be moved independent of eye movements. Two studies are reported which suggest that, while certain aspects of attention require that locations\be scanned serially, at least one operation may be carried out in parallel across several independent loci in the visual field. That is the operation of indexing features and tracking their identity. The studies show that: (a) subjects are able to track a subset of up to 5 objects in a field of 10 'identical randomly-moving objects in order to distinguish a change in a target from a change in a distractor; and (b) when the speed and distance parameters of the display are designed so that, on the basis of some very conservative assumptions about the speed of attention movement and encoding times, the predicted performance of a serial scanning and updating algorithm would not exceed about 40 % accuracy, subjects still manage to do the task with 87 % accuracy. These findings are discussed in relation to an earlier, and independently motivated model of featurebinding-called the FINST model-which posits a primitive identity maintenance mechanism that indexes and tracks a limited number ofvisual objects in parallel. These indexes are hypothesized to serve the function of binding visual features prior to subsequent pattern recognition.

This article defends the claim that a significant part of visual perception (called "early vision") is impervious to the influence of beliefs, expectations or knowledge. We examine a wide range of empirical evidence that has been cited in support of the continuity of vision and cognition and argue that the evidence either shows withinvision top-down effects, or else the extra-visual effects that are demonstrated occur before the operation of the autonomous early vision system (through the allocation of focal attention) or after the visual system has produced its 3D shape-description (through the intervention of post-visual decision processes).

This article pursues the possibility that perceivers are sensitive to implicit dynamic information even when they are not able to observe real-time change. Recent empirical results in the domains of handwriting recognition and picture perception are discussed in support of the hypothesis that perception involves acquiring information about transitions, whether the stimuli are static or dynamic. It is then argued that dynamic information has a special status in mental representation as well as in perception. In particular I propose that some mental representations may be dynamic, in that a temporal dimension is necessary to the representation. Recent evidence that mental representations may exhibit a form of momentum is discussed in support of this claim. There has been a growing appreciation of the impressive ability that the human mind has for perceiving events that take place over time. J. J. Gibson (1979), Johansson (1975), and others have noted that we are particularly receptive to information contained in patterns of change in the environment, as opposed to static information (such as that contained in a snapshot). In this article I will first propose that people perceive dynamic information even when the stimuli being inspected (such as snapshots) are not changing in real time. I will then propose that the importance of dynamic information to perception has implications for mental representation. In particular I will argue that mental representations may sometimes contain a temporal dimension and may thus themselves he dynamic. Perceiving Transitions I pr~ose that in oerception, acquiring information about transitions between states is as important as acquiring information about the states themselves. I believe that the proclivity oeople show for picking up transitional information extends to situations in which the stimuli are static. A more precise proposition can be stated as follows: When the perceptual system cannot directly perceive change over time it will seek out implicit Sections of this article are based on portions of a dissertation I submitted

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Our approach to studying the architecture of mind has been to look for certain extremely simple mechanisms which we have good reason to suspect must exist, and to confirm these empirically. We have been concerned primarily with certain low-level mechanisms in vision which allow the visual system to simultaneously index items at multiple spatial locations, and have developed a provisional model (called the FINST model) of these mechanisms. Among the studies we have carried out to support these ideas are ones showing the subjects can track multiple independent moving targets in a field of identical distractors, that their ability to track these targets and detect changes occurring on them does not generalize to nontargets nor to items lying inside the convex polygon that they form (so that a zoom-lens of attention does not fit the data). We have used a visual search paradigm to show that (serial or parallel) search can be confined to a subset of indexed items and the layout of these item...

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We present the results of a study of spatial cognition and its

Findings in the social psychology literatures on attitudes, social perception, and emotion demonstrate that social information processing involves embodiment, where embodiment refers both to actual bodily states and to simulations of experience in the brain’s modality-specific systems for perception, action, and introspection. We show that embodiment underlies social information processing when the perceiver interacts with actual social objects (online cognition) and when the perceiver represents social objects in their absence (offline cognition). Although many empirical demonstrations of social embodiment exist, no particularly compelling account of them has been offered. We propose that theories of embodied cognition, such as the Perceptual Symbol Systems (PSS) account (Barsalou, 1999), explain and integrate these findings, and that they also suggest exciting new directions for research. We compare the PSS account to a variety of related proposals and show how it addresses criticisms that have previously posed problems for the general embodiment approach. Consider the following findings. Wells and Petty (1980) reported that nodding the head (as in agreement)

This paper addresses the issue of the functional correlates of motor imagery, using mental chronometry, monitoring the autonomic responses and measuring cerebral blood flow in humans. The timing of mentally simulated actions closely mimic actual movement times. Autonomic responses during motor imagery parallel the autonomic responses to actual exercise. Cerebral blood flow increases are observed in the motor cortices involved in the programming of actual movement (i.e. premotor cortex, anterior cingulate, inferior parietal lobule and cerebellum). These three sources of data provide converging support for the hypothesis that imagined and executed actions share, to some extent, the same central structures.

Can theories of mental imagery, conscious mental contents, developed within cognitive science throw light on the obscure (but culturally very significant) concept of imagination? Three extant views of mental imagery are considered: quasi-pictorial, description, and perceptual activity theories. The first two face serious theoretical and empirical difficulties. The third is (for historically contingent reasons) little known, theoretically underdeveloped, and empirically untried, but has real explanatory potential. It rejects the “traditional ” symbolic computational view of mental contents, but is compatible with recent situated cognition and active vision approaches in robotics. This theory is developed and elucidated. Three related key aspects of imagination (non-discursiveness, creativity, and seeing as) raise difficulties for the other theories. Perceptual activity theory presents imagery as non-discursive and relates it closely to seeing as. It is thus well placed to be the basis for a general theory of imagination and its role in creative thought.