What is the purpose of perception? And how might the answer to this question help distinguish perception from other mental processes? Block’s landmark book, The.

It is an apparent truism about visual perception that we can see only what is visible to us. It is also frequently accepted that visual perception is dynamic: our visual experiences are extended through, and can evolve over time. I argue that taking the dynamism of visual experience seriously renders certain simplistic interpretations of the first claim, that a subject at a given time can see only what is visible to her at that time, false: we can be meaningfully said (...) to see invisible objects. This counterintuitive result in turn focuses our attention on the relationship between perception and memory. I show that it is difficult to draw a clear or simple distinction between the two. Memory and perception rely on, and blend with, one another. Together, these claims point us away from understanding visual perception as a simple reflection of the environment, and instead as closer to a process of dynamic modelling that draws together occurrent stimulation and stored information. (shrink)

Philosophical Issues, Volume 30, Issue 1, Page 273-292, October 2020.

We can perceive not only low-level features of events such as color and motion, but also seemingly higher-level properties such as causality. A prototypical example of causal perception is the ”launching effect’: one object moves toward a stationary second object until they are adjacent, at which point A stops and B starts moving in the same direction. Beyond these motions themselves --- and regardless of any higher-level beliefs --- this display induces a vivid visual impression of causality, wherein A is (...) seen to cause B’s motion. Do such percepts reflect a unitary category of visual processing, or might there be multiple distinct forms of causal perception? While launching is often simply equated with causal perception, researchers have sometimes described other phenomena such as ”triggering’ and ”entraining’. We used psychophysical methods to determine whether these labels really carve visual processing at its joints, and how putatively different forms of causal perception relate to each other. Previous research demonstrated retinotopically specific adaptation to causality: exposure to causal launching makes subsequent ambiguous events in that same location more likely to be seen as non-causal ”passing’. Here, after replicating this effect, we show that exposure to triggering also yields retinotopically specific adaptation for subsequent ambiguous launching displays, but that exposure to entraining does not. Collectively, these results reveal that visual processing distinguishes some types of causal interactions. (shrink)

The success of the Bayesian approach to perception suggests probabilistic perceptual representations. But if perceptual representation is probabilistic, why doesn't normal conscious perception reflect the full probability distributions that the probabilistic point of view endorses? For example, neurons in MT/V5 that respond to the direction of motion are broadly tuned: a patch of cortex that is tuned to vertical motion also responds to horizontal motion, but when we see vertical motion, foveally, in good conditions, it does not look at all (...) horizontal. This article argues that the best Bayesian approach to this problem does not require probabilistic representation. (shrink)

The notion of an object file figures prominently in recent work in philosophy and cognitive science. Object files play a role in theories of singular reference, object individuation, perceptual memory, and the development of cognitive capacities. However, the philosophical literature lacks a detailed, empirically informed theory of object files. In this paper, we articulate and defend the multiple-slots view, which specifies both the format and architecture of object files. We argue that object files represent in a non-iconic, propositional format that (...) incorporates discrete symbols for separate features. Moreover, we argue that features of separate categories are stored in separate memory slots within an object file. We supplement this view with a computational framework that characterizes how information about objects is stored and retrieved. (shrink)

There is a certain excitement in vision science concerning the idea of applying the tools of bayesian decision theory to explain our perceptual capacities. Bayesian models are thought to be needed to explain how the inverse problem of perception is solved, and to rescue a certain constructivist and Kantian way of understanding the perceptual process. Anticlimactically, I argue both that bayesian outlooks do not constitute good solutions to the inverse problem, and that they are not constructivist in nature. In explaining (...) how visual systems derive a single percept from underdetermined stimulation, orthodox versions of bayesian accounts encounter a problem. The problem shows that such accounts need to be grounded in Natural Scene Statistics (NSS), an approach that takes seriously the Gibsonian insight that studying perception involves studying the statistical regularities of the environment in which we are situated. Additionally, I argue that bayesian frameworks postulate structures that hardly rescue a constructivist way of understanding perception. Except for percepts, the posits of bayesian theory are not representational in nature. bayesian perceptual inferences are not genuine inferences. They are biased processes that operate over nonrepresentational states. (shrink)

Zenon Pylyshyn argues that cognitively driven attentional effects do not amount to cognitive penetration of early vision because such effects occur either before or after early vision. Critics object that in fact such effects occur at all levels of perceptual processing. We argue that Pylyshyn’s claim is correct—but not for the reason he emphasizes. Even if his critics are correct that attentional effects are not external to early vision, these effects do not satisfy Pylyshyn’s requirements that the effects be direct (...) and exhibit semantic coherence. In addition, we distinguish our defense from those found in recent work by Raftopoulos and by Firestone and Scholl, argue that attention should not be assimilated to expectation, and discuss alternative characterizations of cognitive penetrability, advocating a kind of pluralism. (shrink)

After presenting evidence about categorization behavior, this paper argues for the following theses: 1) that there is a border between perception and cognition; 2) that the border is to be characterized by perception being modular (and cognition not being so); 3) that perception outputs conceptualized representations, so views that posit that the output of perception is solely non-conceptual are false; and 4) that perceptual content consists of basic-level categories and not richer contents.

Thomas Reid was a philosopher who founded the Scottish school of 'common sense'. Much of Reid's work is a critique of his contemporary, David Hume, whose empiricism he rejects. In this work, written after Reid's appointment to a professorship at the university of Glasgow, and published in 1785, he turns his attention to ideas about perception, memory, conception, abstraction, judgement, reasoning and taste. He examines the work of his predecessors and contemporaries, arguing that 'when we find philosophers maintaining that there (...) is no heat in the fire, nor colour in the rainbow … we may be apt to think the whole to be only a dream of fanciful men, who have entangled themselves in cobwebs spun out of their own brain'. Written by one of the Scottish Enlightenment's most important thinkers, this work brings to life the intellectual debates of the time. (shrink)

There are several differences between (i) seeing rain outside one’s window and (ii) episodically remembering seeing rain outside one’s window. One difference appears to pertain to felt temporal orientation: in episodically remembering seeing the rain, we experience the rain, and/or the seeing of it, as (having occurred in the) past; in perceiving the rain, we experience the rain as (in the) present. However, according to (what is widely regarded as) the most plausible metaphysics of time, there are no such properties (...) as being past and being present. This seems to lead to an error theory about all perception and episodic memory. In this paper, I show how to get out of this untoward result. The crucial move is a distinction between representing an event-as-present/past and representing-as-present/past an event. (shrink)

The distinction between top-down and bottom-up effects is widely relied on in experimental psychology. However, there is an important problem with the way it is normally defined. Top-down effects are effects of previously-stored information on processing the current input. But on the face of it that includes the information that is implicit in the operation of any psychological process – in its dispositions to transition from some types of representational state to others. This paper suggests a way to distinguish information (...) stored in that way from the kind of influence of prior information that psychologists are concerned to classify as a top-down effect. So-drawn, the distinction is not just of service to theoretical psychology. Asking about the extent of top-down processing is one way to pose some of the questions at issue in philosophical debates about cognitive penetrability – about the extent of the influence of cognitive states on perception. The existence of a theoretically-useful perception-cognition distinction has come under pressure, but even if it has to be abandoned, some of the concerns addressed in the cognitive penetrability literature can be recaptured by asking about the extent of top-down influences on any given psychological process. That formulation is more general, since it can be applied to any psychological process, not just those that are paradigmatically perceptual. (shrink)

The paper develops an objection to the extensional model of time consciousness—the view that temporally extended events or processes, and their temporal properties, can be directly perceived as such. Importantly, following James, advocates of the extensional model typically insist that whole experiences of temporal relations between non-simultaneous events are distinct from mere successions of their temporal parts. This means, presumably, that there ought to be some feature(s) differentiating the former from the latter. I try to show why the extensional models (...) offers no credible ground for positing such a difference. (shrink)

Can the phenomenal character of perceptual experience be altered by the states of one's cognitive system, for example, one's thoughts or beliefs? If one thinks that this can happen then one thinks that there can be cognitive penetration of perceptual experience; otherwise, one thinks that perceptual experience is cognitively impenetrable. I claim that there is one alleged case of cognitive penetration that cannot be explained away by the standard strategies one can typically use to explain away alleged cases. The case (...) is one in which it seems subjects' beliefs about the typical colour of objects affects their colour experience. I propose a two-step mechanism of indirect cognitive penetration that explains how cognitive penetration may occur. I show that there is independent evidence that each step in this process can occur. I suspect that people who are opposed to the idea that perceptual experience is cognitively penetrable will be less opposed to the idea when they come to consider this indirect mechanism and that those who are generally sympathetic to the idea of cognitive penetrability will welcome the elucidation of this plausible mechanism. (shrink)

Only human beings have a rich conceptual repertoire with concepts like tort, entropy, Abelian group, mannerism, icon and deconstruction. How have humans constructed these concepts? And once they have been constructed by adults, how do children acquire them? While primarily focusing on the second question, in The Origin of Concepts , Susan Carey shows that the answers to both overlap substantially. Carey begins by characterizing the innate starting point for conceptual development, namely systems of core cognition. Representations of core cognition (...) are the output of dedicated input analyzers, as with perceptual representations, but these core representations differ from perceptual representations in having more abstract contents and richer functional roles. Carey argues that the key to understanding cognitive development lies in recognizing conceptual discontinuities in which new representational systems emerge that have more expressive power than core cognition and are also incommensurate with core cognition and other earlier representational systems. Finally, Carey fleshes out Quinian bootstrapping, a learning mechanism that has been repeatedly sketched in the literature on the history and philosophy of science. She demonstrates that Quinian bootstrapping is a major mechanism in the construction of new representational resources over the course of childrens cognitive development. Carey shows how developmental cognitive science resolves aspects of long-standing philosophical debates about the existence, nature, content, and format of innate knowledge. She also shows that understanding the processes of conceptual development in children illuminates the historical process by which concepts are constructed, and transforms the way we think about philosophical problems about the nature of concepts and the relations between language and thought. (shrink)

Being Known is a response to a philosophical challenge which arises for every area of thought: to reconcile a plausible account of what is involved in the truth of statements in a given area with a credible account of how we can know those statements. Christopher Peacocke presents a framework for addressing the challenge, a framework which links both the theory of knowledge and the theory of truth with the theory of concept-possession.

In a dynamic world, mechanisms allowing prediction of future situations can provide a selective advantage. We suggest that memory systems differ in the degree of flexibility they offer for anticipatory behavior and put forward a corresponding taxonomy of prospection. The adaptive advantage of any memory system can only lie in what it contributes for future survival. The most flexible is episodic memory, which we suggest is part of a more general faculty of mental time travel that allows us not only (...) to go back in time, but also to foresee, plan, and shape virtually any specific future event. We review comparative studies and find that, in spite of increased research in the area, there is as yet no convincing evidence for mental time travel in nonhuman animals. We submit that mental time travel is not an encapsulated cognitive system, but instead comprises several subsidiary mechanisms. A theater metaphor serves as an analogy for the kind of mechanisms required for effective mental time travel. We propose that future research should consider these mechanisms in addition to direct evidence of future-directed action. We maintain that the emergence of mental time travel in evolution was a crucial step towards our current success. (shrink)

Consider the skeptic about the external world. Let’s straightaway concede to such a skeptic that perception gives us no conclusive or certain knowledge about our surroundings. Our perceptual justification for beliefs about our surroundings is always defeasible—there are always possible improvements in our epistemic state which would no longer support those beliefs. Let’s also concede to the skeptic that it’s metaphysically possible for us to have all the experiences we’re now having while all those experiences are false. Some philosophers dispute (...) this, but I do not. The skeptic I want to consider goes beyond these familiar points to the much more radical conclusion that our perceptual experiences can’t give us any knowledge or even justification for believing that our surroundings are one way rather than another. (shrink)

A venerable view holds that a border between perception and cognition is built into our cognitive architecture and that this imposes limits on the way information can flow between them. While the deliverances of perception are freely available for use in reasoning and inference, there are strict constraints on information flow in the opposite direction. Despite its plausibility, this approach to the perception-cognition border has faced criticism in recent years. This article develops an updated version of the architectural approach, which (...) I call the dimension restriction hypothesis (DRH). According to DRH, perceptual processes are constrained to compute over a bounded range of dimensions, while cognitive processes are not. This view allows that perception is cognitively penetrable, but places strict limits on the varieties of penetration that can occur. The article argues that DRH enjoys both theoretical and empirical support, and also defends the view against several objections. (shrink)

Philosophers frequently comment on the intimate connection there is between something’s being present in perceptual experience and that thing’s being, or at least appearing to be, temporally present. Yet, there is relatively little existing work that goes beyond asserting such a connection and instead examines its specific nature. In this paper, I suggest that we can make progress on the latter by looking at two more specific debates that have hitherto been conducted largely isolation from each other: one about the (...) nature of conscious experience and one about the nature of time itself. The first concerns the extent to which the temporal properties of experience form an exception to the transparency of experience, meaning that introspection can provide support for one particular view of how experience itself is structured temporally; the second concerns the question as to whether there is something about experience that gives us grounds for thinking that the present is somehow metaphysically special. As I argue, the idea of a connection between experiential presence and temporal presence plays a key background role in each of these debates. Yet it can also, in each of them, be seen to draw one side towards making claims that are supposed to express an important truth but are at the same time, on the face of it, self-contradictory. In each case, resolving what it actually is that these claims are trying to get at turns on recognizing a distinctive feature of perceptual experience, which I refer to as its lack of temporal viewpointedness. Recognising this feature also helps in making sense of what the issues at stake actually are in the intuition of an intimate connection between experiential presence and temporal presence. (shrink)

The distinction between perception and cognition has always had a firm footing in both cognitive science and folk psychology. However, there is little agreement as to how the distinction should be drawn. In fact, a number of theorists have recently argued that, given the ubiquity of top-down influences, we should jettison the distinction altogether. I reject this approach, and defend a pluralist account of the distinction. At the heart of my account is the claim that each legitimate way of marking (...) a border between perception and cognition deploys a notion I call ‘stimulus-control.’ Thus, rather than being a grab bag of unrelated kinds, the various categories of the perceptual are unified into a superordinate natural kind. (shrink)

Philosophy, scientific psychology, and common sense all distinguish perception from cognition. While there is little agreement about how the perception–cognition boundary ought to be drawn, one prominent idea is that perceptual states are dependent on a stimulus, or stimulus-dependent, in a way that cognitive states are not. This paper seeks to develop this idea in a way that can accommodate two apparent counterexamples: hallucinations, which are prima facie perceptual yet stimulus-independent; and demonstrative thoughts, which are prima facie cognitive yet stimulus-dependent. (...) The payoff is not only a specific proposal for marking the perception–cognition boundary, but also a deeper understanding of the natures of hallucination and demonstrative thought. (shrink)

How is it that thoroughly physical material beings such as ourselves can think, dream, feel, create and understand ideas, theories and concepts? How does mere matter give rise to all these non-material mental states, including consciousness itself? An answer to this central question of our existence is emerging at the busy intersection of neuroscience, psychology, artificial intelligence, and robotics.In this groundbreaking work, philosopher and cognitive scientist Andy Clark explores exciting new theories from these fields that reveal minds like ours to (...) be prediction machines - devices that have evolved to anticipate the incoming streams of sensory stimulation before they arrive. These predictions then initiate actions that structure our worlds and alter the very things we need to engage and predict. Clark takes us on a journey in discovering the circular causal flows and the self-structuring of the environment that define "the predictive brain." What emerges is a bold, new, cutting-edge vision that reveals the brain as our driving force in the daily surf through the waves of sensory stimulation. (shrink)

Subjective probability plays an increasingly important role in many fields concerned with human cognition and behavior. Yet there have been significant criticisms of the idea that probabilities could actually be represented in the mind. This paper presents and elaborates a view of subjective probability as a kind of sampling propensity associated with internally represented generative models. The resulting view answers to some of the most well known criticisms of subjective probability, and is also supported by empirical work in neuroscience and (...) behavioral psychology. The repercussions of the view for how we conceive of many ordinary instances of subjective probability, and how it relates to more traditional conceptions of subjective probability, are discussed in some detail. (shrink)

In ordinary conscious experience, consciousness of time seems to be ubiquitous. For example, we seem to be directly aware of change, movement, and succession across brief temporal intervals. How is this possible? Many different models of temporal consciousness have been proposed. Some philosophers have argued that consciousness is confined to a momentary interval and that we are not in fact directly aware of change. Others have argued that although consciousness itself is momentary, we are nevertheless conscious of change. Still others (...) have argued that consciousness is itself extended in time. In this entry, the motivations and merits of these and other positions will be expounded and assessed. (shrink)

This textbook on vision reflects the integrated computational approach of modern research scientists, combining psychological, computational and neuroscientific perspectives.

How must experience of time be structured in time? In particular, does the following principle, which I will call inheritance, hold: for any temporal property apparently presented in perceptual experience, experience itself has that same temporal property. For instance, if I hear Paul McCartney singing ‘Hey Jude’, must my auditory experience of the ‘Hey’ itself precede my auditory experience of the ‘Jude’, or can the temporal order of these experiences come apart from the order the words are experienced as having? (...) A number of recent authors (Phillips Experience and Time, ‘The Temporal Structure of Experience’, Soteriou ‘Perceiving Events’, Hoerl ‘“A Succession of Feelings, in and of Itself, is Not a Feeling of Succession”’, Rashbrook) claim, to paraphrase Martin (399), that inheritance best characterises how our temporal experience seems to initial reflective intuition. For this reason, Phillips takes the principle to form part of our naïve view of temporal experience. An opposing group of theorists object that inheritance is subject to empirical counter-example. This article surveys such challenges. Section 2 considers Grush's case against inheritance based on postdiction. Section 3 examines Watzl's anti-inheritance argument based on silencing effects. Finally, Section 4 explores a number of alleged counter-examples proposed by Lee (‘Temporal Experience and the Temporal Structure of Experience’). Section 1 provides essential background to the debate. (shrink)

Philosophers have lately seized upon Sperling's partial report technique and subsequent work on iconic memory in support of controversial claims about perceptual experience, in particular that phenomenology overflows cognitive access. Drawing on mounting evidence concerning postdictive perception, I offer an interpretation of Sperling's data in terms of cue-sensitive experience which fails to support any such claims. Arguments for overflow based on change-detection paradigms (e.g. Landman et al., 2003; Sligte et al., 2008) cannot be blocked in this way. However, such paradigms (...) are fundamentally different from Sperling's and, for rather different reasons, equally fail to establish controversial claims about perceptual experience. (shrink)

In what sense does time exist? Is it an objective feature of the external world? Or is its real nature dependent on the way man experiences it? Has modern science brought us closer to the answer to St. Augustine's exasperated outcry, 'What, then, is time?'? Ever since Aristotle, thinkers have been struggling with this most confounding and elusive of philosophical questions. How long does the present moment last? Can we make statements about the future that are clearly true or clearly (...) false? And if so, must we be fatalists? This volume presents twenty-three discussions of the problem of time. A section on classical and modern attempts at definition is followed by four groups of essays drawn largely from contemporary philosophy, each preface with an introduction by the editor. First, in a chapter entitled 'The Static versus the Dynamic Temporal', four philosophers advance solutions to McTaggart's famous proof of time's unreality. In the next two sections, the discussion turns to the meaning of the 'open future' and to the much-debated nature of 'human time'. Finally, modern science and philosophy tackle Zeno's celebrated paradoxes. The essays by Adolf Grnbaum, Nicholas Rescher, and William Barrett are published for the first time in this volume. (shrink)

While we perceive events in our environment through multiple sensory systems, we nevertheless perceive all of these events as occupying a single unified timeline. Time, as we perceive it, is unified. I argue that existing accounts of the perceived unity of time fail. Instead, the perceived unity of time must be constructed by integrating our initially fragmented timekeeping capacities. However, existing accounts of multimodal integration do not tell us how this might occur. Something new is needed. I finish the paper (...) by articulating the hurdles that must be overcome to provide an account of the perceived unity of time. (shrink)

Experts from wine tasters to radiologists to bird watchers have all undergone perceptual learning-long-term changes in perception that result from practice or experience. Philosophers have been discussing such cases for centuries, from the 14th-century Indian philosopher Vedanta Desika to the 18th-century Scottish philosopher Thomas Reid, and into contemporary times. -/- This book uses recent evidence from psychology and neuroscience to show that perceptual learning is genuinely perceptual, rather than post-perceptual. It also offers a taxonomy for classifying cases in the philosophical (...) literature. In some cases, perceptual learning involves changes in how one attends; in other cases, it involves a learned ability to differentiate two properties, or to perceive two properties as unified. Connolly uses this taxonomy to rethink several domains of perception in terms of perceptual learning, including multisensory perception, color perception, and speech perception. -/- As a whole, the book offers a theory of the function of perceptual learning. Perceptual learning embeds into our quick perceptual systems what would be a slower task were it to be done in a controlled, cognitive manner. A novice wine taster drinking a Cabernet Sauvignon might have to think about its features first and then infer the type of wine, while an expert can identify it immediately. This learned ability to immediately identify the wine enables the expert to think about other things like the vineyard or the vintage of the wine. More generally, perceptual learning serves to free up cognitive resources for other tasks. This book offers a comprehensive empirically-informed account, and explores the nature, scope, and theoretical implications of perceptual learning. (shrink)

Phenomenologically speaking, we perceive the present, recall the past, and anticipate the future. We offer an account of the temporal content of the perceptual present that distinguishes it from the recalled past and the anticipated future. We distinguish two views: the Token Reflexive Account and the Minimal Account. We offer reasons to reject the Token Reflexive Account, and defend the Minimal Account, according to which the temporal content of the perceptual present is exhausted by its direct reference to the interval (...) of time over which it occurs. (shrink)

You know what someone else is thinking and feeling by observing them. But how do you know what you are thinking and feeling? This is the problem of self-knowledge: Alex Byrne tries to solve it. The idea is that you know this not by taking a special kind of look at your own mind, but by an inference from a premise about your environment.

The question of whether perception is encapsulated from cognition has been a major topic in the study of perception in the past decade. One locus of debate concerns the role of attention. Some theorists argue that attention is a vehicle for widespread violations of encapsulation; others argue that certain forms of cognitively driven attention are compatible with encapsulation, especially if attention only modulates inputs. This paper argues for an extreme thesis: no effect of attention, whether on the inputs to perception (...) or on perceptual processing itself, constitutes a violation of the encapsulation of perception. (shrink)

Cognitive representation is the single most important explanatory notion in the sciences of the mind and has served as the cornerstone for the so-called 'cognitive revolution'. This book critically examines the ways in which philosophers and cognitive scientists appeal to representations in their theories, and argues that there is considerable confusion about the nature of representational states. This has led to an excessive over-application of the notion - especially in many of the fresher theories in computational neuroscience. Representation Reconsidered shows (...) how psychological research is actually moving in a non-representational direction, revealing a radical, though largely unnoticed, shift in our basic understanding of how the mind works. (shrink)

Some philosophers believe that the passage of time is a real phenomenon. And some of them find a reason to believe this when they attend to features of their conscious experience. In fact this “argument from experience” is supposed to be one of the main arguments for passage. What exactly does this argument look like? Is it any good?

It is argued that perception is based on the same kinds of operations that characterize thought. However perception differs from thought in being rooted in the stimulus and predicated on a narrower range of (nonconscious) "knowledge". Other theories fail to do justice to the ambiguity inherent in the stimulus and the organization and enrichment inherent in the percept. Examples of perception are given that suggest determination by cognitive processing such as description, inference, and problem solving. One percept is often based (...) upon another percept. The final percept is a preferred solution and adequately accounts for and is supported by the proximal stimulus or an initial percept to which the stimulus gives rise. (shrink)

Object files (OFs) are hypothesized mid-level representations which mediate our conscious perception of persisting objects—e.g. telling us ‘which went where’. Despite the appeal of the OF framework, not previous research has directly explored whether OFs do indeed correspond to conscious percepts. Here we present at least one case wherein conscious percepts of ‘which went where’ in dynamic ambiguous displays diverge from the analogous correspondence computed by the OF system. Observers viewed a ‘bouncing/streaming’ display in which two identical objects moved such (...) that they could have either bounced off or streamed past each other. We measured two dependent variables: (1) an explicit report of perceived bouncing or streaming; and (2) an implicit ‘object-specific preview benefit’ (OSPB), wherein a ‘preview’ of information on a specific object speeds the recognition of that information at a later point when it appears again on the same object (compared to when it reappears on a different object), beyond display-wide priming. When the displays were manipulated such that observers had a strong bias to perceive streaming (on over 95% of the trials), there was nevertheless a strong OSPB in the opposite direction—such that the object files appeared to have ‘bounced’ even though the percept ‘streamed’. Given that OSPBs have been taken as a hallmark of the operation of object files, the five experiments reported here suggest that in at least some specialized (and perhaps ecologically invalid) cases, conscious percepts of ‘which went where’ in dynamic ambiguous displays can diverge from the mapping computed by the object-file system. (shrink)

In three experiments, subjects attempted to track multiple items as they moved independently and unpredictably about a display. Performance was not impaired when the items were briefly (but completely) occluded at various times during their motion, suggesting that occlusion is taken into account when computing enduring perceptual objecthood. Unimpaired performance required the presence of accretion and deletion cues along fixed contours at the occluding boundaries. Performance was impaired when items were present on the visual field at the same times and (...) to the same degrees as in the occlusion conditions, but disappeared and reappeared in ways which did not implicate the presence of occluding surfaces (e.g. by imploding and exploding into and out of existence, instead of accreting and deleting along a fixed contour). Unimpaired performance did not require visible occluders (i.e. Michotte’s tunnel effect) or globally consistent occluder positions. We discuss implications of these results for theories of objecthood in visual attention. (shrink)

When we remember a scene, the scene’s boundaries are wider than the boundaries of the scene we saw. This phenomenon is called boundary extension. The most important philosophical question about boundary extension is whether it is a form of perceptual adjustment or adjustment during memory encoding. The aim of this paper is to propose a third explanatory scheme, according to which the extended boundary of the original scene is represented by means of mental imagery. And given the similarities between perception (...) and mental imagery, the memory system encodes both the part of the scene that is represented perceptually and the part of the scene that is represented by means of mental imagery. (shrink)