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).

Does visual imagery engage some of the same representations used in visual perception? The evidence collected by cognitive psychologists in support of this claim has been challenged by three types of alternative explanation: Tacit knowledge, according to which subjects use nonvisual representations to simulate the use of visual representations during imagery tasks, guided by their tacit knowledge of their visual systems; experimenter expectancy, according to which the data implicating shared representations for imagery and perception is an artifact of experimenter expectancies; and nonvisual spatial representation, according to which imagery representations are partially similar to visual representations in the way they code spatial relations but are not visual representations. This article reviews previously overlooked neuropsychological evidence on the relation between imagery and perception, and discusses its relative immunity to the foregoing alternative explanations. This evidence includes electrophysiological and cerebral blood flow studies localizing brain activity during imagery to cortical visual areas, and parallels between the selective effects of brain damage on visual perception and imagery. Because these findings cannot be accounted for in the same way as traditional cognitive data using the alternative explanations listed earlier, they can play a decisive role in answering the title question.

This dissertation presents a model of the knowledge a person has about the spatial structure of a large-scale environment: the "cognitive map." The functions of the cognitive map are to assimilate new information about the environment, to represent the current position, and to answer route-finding and relative-position problems. This model (called the TOUR model) analyzes the cognitive map in terms of symbolic descriptions of the environment and operations on those descriptions. Knowledge about a particular environment is represented in terms of route descriptions, a topological network of paths and places, multiple frames of reference for relative positions, dividing boundaries, and a structure of containing regions. The current position is described by the "You Are Here" pointer, which acts as a working memory and a focus of attention. Operations on the cognitive map are performed by inference rules which act to transfer information among different descriptions and the "You Are Here"...

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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.

It is generally accepted that there is something special about reasoning that uses mental images. The question of how it is special, however, has never been satisfactorily spelled out, despite over thirty years of research in the post-behaviorist tradition. This article considers some of the general motivation for the assumption that entertaining mental images involves inspecting a picture-like object. It sets out a distinction between phenomena attributable to the nature of mind, to what is called the cognitive architecture, and ones that are attributable to tacit knowledge used to simulate what would happen in a visual situation. With this distinction in mind the paper then considers in detail the widely held assumption that in some important sense images are spatially displayed or are depictive, and that examining images uses the same mechanisms that are deployed in visual perception. I argue that the assumption of the spatial or depictive nature of images is only explanatory if tak...

Contents 1. The puzzle of seeing......................................1-2 1.1 Why do things look the way they do? ..................................................................................1-2 1.2 What is seeing? .................................................................................................................1-3 1.3 Does vision create a "picture" in the head?...........................................................................1-4 1.3.1 The richness of visual appearances and the poverty of visual information: Reconciling the difference ...........................................................................................1-4 1.3.2 Some reasons for thinking there may be an inner display................................................1-6 1.4 Some problems with the Internal Display Assumption: Part I: What's in the display and how does it get there?....................................................................1-10 1.4.1 How is

Contents 6. Seeing with the mind's eye 1: The puzzle of mental Imagery..6-2 6.1 What is the puzzle about mental imagery?.............................................................................................................6-2 6.2 Content, form and substance of representations ....................................................................................................6-6 6.3 What is responsible for the pattern of results obtained in imagery studies? ..............................................................6-7 6.3.1 Cognitive architecture or tacit knowledge ....................................................................................................6-7 6.3.2 Problem-solving by "mental simulation": Some additional examples ............................................................. 6-11 6.3.3 A Note concerning tacit knowledge and the criterion of cognitive penetrability.......................................... 6-20 6.3.4 Summary of so

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.

this article (although this distinction is the subject of extensive discussion in Pylyshyn, 1984a, Chapter 7). This informal characterization and the following example will have to do for present purposes. To make this point in a more concrete way, I invented a somewhat frivolous but revealing example, involving a certain mystery box of unknown construction whose pattern of behavior has been assiduously recorded (Pylyshyn, 1984a). This box is known to emit long and short pulses with a reliable recurring pattern. The pattern (illustrated in Figure 6-1) can be described as follows: pairs of short pulses usually precede single short pulses, except when a pair of long-short pulses occurs first. In this example it turns out that the observed regularity, though completely regular when the box is in its "ecological niche," is not due to the nature of the box (to how it is constructed) but to an entirely extrinsic reason. These two sorts of "reasons" for the observed pattern (intrinsic or extrinsic) are analogous to the architecture versus tacit knowledge distinction and is crucial to understanding why the box works the way it does, as well as to why certain patterns of cognition occur. 6-9 Figure 6-1. Pattern of blips observed from a box in its typical mode of operation. The question is: Why does it exhibit this pattern of behavior? What does this behavior tell us about how it works? The reason why this particular pattern of behavior occurs in this case can only be appreciated if we know that the pulses are codes, and the pattern is due to a pattern in what they represent, in particular that the pulses represent English words spelled out in International Morse Code. The observed pattern does not reflect how the box is wired or its functional architecture -- it is due entirel...