Advances in neuroscience implicate reentrant signaling as the predominant form of communication between brain areas. This principle was used in a series of masking experiments that defy explanation by feed-forward theories. The masking occurs when a brief display of target plus mask is continued with the mask alone. Two masking processes were found: an early process affected by physical factors such as adapting luminance and a later process affected by attentional factors such as set size. This later process is called (...) masking by object substitution, because it occurs whenever there is a mismatch between the reentrant visual representation and the ongoing lower level activity. Iterative reentrant processing was formalized in a computational model that provides an excellent fit to the data. The model provides a more comprehensive account of all forms of visual masking than do the long-held feed-forward views based on inhibitory contour interactions. (shrink)

This paper inquires into the nature of intertheoretic relations between psychology and neuroscience. This relationship has been characterized by some as one in which psychological explanations eventually will fall away as otiose, overthrown completely by neurobiological ones. Against this view it will be argued that it squares poorly with scientific practices and empirical developments in the cognitive neurosciences. We analyse a case from research on visual perception, which suggests a much more subtle and complex interplay between psychology and neuroscience than (...) a complete take-over of the former by the latter. In the case of vision, cross-theory influences between psychology and neuroscience go back and forth, resulting in refinement in both disciplines.We interpret this case study as showing that:(1) Mutual co-evolution of psychological and neurobiological theories, exemplifying persisting top-down influences from psychology, is a more empirically adequate way to describe psychoneural theory relations than a view on co-evolution, favoured by reductionists, which regards the cross-theory contributions from psychology as merely heuristically useful with no enduring influence on neurobiological theorizing;(2) In research on vision, discovering (or hypothesizing) the neural basis of functions vindicates psychological approaches, it does not eliminate them;(3) Current work on vision shows that many perceptual phenomena must be understood in terms of dynamical interactions between an observer and his/her environment. Therefore, we argue that internalist characterizations of the visual system must be supplemented with externalist accounts that address these reciprocal observer-environment interactions involved in vision. Such processes seem quite different from (internal) cellular and molecular ones, and as such seem to lie outside the scope of neuroscientific inquiry. We conclude that psychoneural reduction or elimination is implausible as a meta-theoretical prediction of theory choice in empirical work. Instead, this case study of vision shows that both psychology and neuroscience contribute to, and complement one another in the study of visual perception. 1. Psychoneural reductionism1.1Introduction1.2New Wave Reductionism1.3NWR and psychology: three characteristics of psychoneural reductionism1.4NWR and the problem of mutual feedback1.4.1The ‘Mere Heuristics’ claim1.4.2The disappearance of psychology as an irrelevant historical accident1.5Summary: three claims of NWR on psychoneural reduction2. Vision: a case study2.1Introduction2.1.1Three opposing claims2.1.2Psychology and neuroscience of vision: the orthodoxy2.2Testing claim 1: vanishing heuristics or persisting influences?2.2.1From what and where to perception and action2.2.2Real co-evolution: more than vanishing heuristics2.2.3First moral2.3Testing claim 2: replacement or vindication?2.3.1Perception and action revisited: mapping approaches on systems2.3.2Vindicating psychological approaches2.3.3Second moral2.4Testing claim 3: equipotent image or explanatory loss?2.4.1Perception and action extended: including the environment2.4.2Distinguishing levels, widening explanations2.4.3Third moral3. Conclusion: three morals. (shrink)

One of the more powerful impressions created by vision is that of a coherent, richly-detailed world where everything is present simultaneously. Indeed, this impression is so compelling that we tend to ascribe these properties not only to the external world, but to our internal representations as well. But results from several recent experiments argue against this latter ascription. For example, changes in images of real-world scenes often go unnoticed when made during a saccade, flicker, blink, or movie cut. This "change (...) blindness" provides strong evidence against the idea that our brains contain a picture-like representation of the scene that is everywhere detailed and coherent. (shrink)

This paper examines the status of unattended visual stimuli in the light of recent work on the role of attention in visual perception. Although the question of whether attention is required for visual experience seems very interesting, this paper argues that there currently is no good reason to take a stand on the issue. Moreover, it is argued that much of the allure of that question stems from a continued attachment to the defective ‘inner picture view’ of experience and a (...) mistaken notion that the ultimate goal of vision is to produce visual experience. The paper considers a promising general account of the content and structure of vision and presents reasons for not taking that account to be committed to any substantive claims about the experiential status of unattended visual stimuli. Also addressed are the active nature of vision and the role of vision in enabling our ecological success. These considerations highlight that visual experience is not the whole of vision and that a much more important question about unattended visual stimuli than whether they are consciously experienced is what contribution they make to how we interact with the world. (shrink)

Consider the much-discussed case of the distracted driver, who is alleged to successfully navigate his car for miles despite being completely oblivious to his visual states. Perhaps he is deeply engrossed in the music playing over the radio or in philosophical reflection, and as a result he goes about unaware of the scene unfolding before him on the road. That the distracted driver has visual experiences of which he is not aware is a possibility that first-order representationalists happily accept, but (...) higher-order representationalists steadfastly deny. HOR claims that perceptual states become conscious only as the object of higher-order states; perceptual states are not intrinsically conscious. According to HOR, since the driver is supposed to be completely distracted by other cognitive tasks, he cannot form higher-order representations of his visual states, with the result that those states are disqualified as experiences.1 HOR theories have come in two flavors, those that claim that the relevant higher-order representations are thought-like and those that that rely on an inner perception-like mechanism that is directed toward one. (shrink)

When we look around us, some things look “alive,” others do not. What is it to “look alive”—to perceive animacy? Empirical work supports the view that animacy is genuinely perceptual. We should construe perception of animacy as perception of agents and behavior. This proposal explains how static and dynamic animacy cues relate, and explains how animacy perception relates to social cognition more broadly. Animacy perception draws attention to objects that are apt to be well‐understood folk psychologically, enabling us to marshal (...) our folk psychological resources efficiently. (shrink)

What is the philosophical significance of attention? The present article provides an overview of recent debates surrounding the connections between attention and other topics of philosophical interest. In particular, it discusses the interplay between attention and consciousness, attention and agency, and attention and reference. The article outlines the questions and contemporary positions concerning how attention shapes the phenomenal character of experience, whether it is necessary or sufficient for consciousness, and whether it plays a special role in the best philosophical theories (...) of action or conceptual reference. Various interdependencies between the answers to these questions are indicated, as well as how these answers might depend on the metaphysics of attention. Together with its companion piece this article serves as an introduction to the philosophy of attention. (shrink)

I propose that primary conscious awareness arises from synchronized activity in dendrites of neurons in dorsal thalamic nuclei, mediated particularly by inhibitory interactions with thalamic reticular neurons. In support, I offer four evidential pillars: consciousness is restricted to the results of cortical computations; thalamus is the common locus of action of brain injury in vegetative state and of general anesthetics; the anatomy and physiology of the thalamus imply a central role in consciousness; neural synchronization is a neural correlate of consciousness.

We adapted the Bubbles procedure [Vis. Res. 41 (2001) 2261] to examine the effective use of information during the first 282 ms of face identification. Ten participants each viewed a total of 5100 faces sub-sampled in space–time. We obtained a clear pattern of effective use of information: the eye on the left side of the image became diagnostic between 47 and 94 ms after the onset of the stimulus; after 94 ms, both eyes were used effectively. This preference for the (...) eyes increased with practice, and was not solely due to the informativeness of the eyes for the task at hand. The bias for the eye on the left side of the image is explained in terms of hemispheric specialization. Although there were individual differences, most participants exhibited this pattern of effective use of information. An intriguing finding is that most participants displayed a clear sinusoidal modulation of effective use of attention through time with a frequency of about 10.6 Hz. (shrink)

We adapted the Bubbles procedure [Vis. Res. 41 (2001) 2261] to examine the effective use of information during the first 282 ms of face identification. Ten participants each viewed a total of 5100 faces sub-sampled in space–time. We obtained a clear pattern of effective use of information: the eye on the left side of the image became diagnostic between 47 and 94 ms after the onset of the stimulus; after 94 ms, both eyes were used effectively. This preference for the (...) eyes increased with practice, and was not solely due to the informativeness of the eyes for the task at hand. The bias for the eye on the left side of the image is explained in terms of hemispheric specialization. Although there were individual differences, most participants exhibited this pattern of effective use of information. An intriguing finding is that most participants displayed a clear sinusoidal modulation of effective use of attention through time with a frequency of about 10.6 Hz. (shrink)

We often feel that our perceptual experience is richer than what we can express. For instance, when flashed with a large set of letters, we feel that we can see them all, while we can report only a few. However, the nature of this subjective impression remains highly debated: while many favour a dissociation between two forms of consciousness , others contend that the richness of phenomenal experience is a mere illusion. Here we addressed this question with a classical partial-report (...) paradigm now modified to include unexpected items in the unreported parts of the stimuli. We show that even in the presence of unexpected pseudo-letters, participants still felt that there were only letters. Additionally, we show that this feeling reflects an illusion whereby participants reconstruct letters using partial letter-like information. We propose that the feeling of seeing emerges from the interplay between partially accessible information and expectations. (shrink)

Many artists, art critics, and poets suggest that an aesthetic appreciation of artworks may modify our perception of the world, including quotidian things and scenes. I call this Art-to-World, AtW. Focusing on visual artworks, in this paper I articulate an empirically-informed account of AtW that is based on content related views of aesthetic experience, and on Goodman’s and Elgin’s concept of exemplification. An aesthetic encounter with artworks demands paying attention to its aesthetic, expressive, or design properties that realize its purpose. (...) Attention to these properties make percipients better able to spot them in other entities and scenes as well. The upshot is that an aesthetic commerce with artworks enlarges the scope of what we are able to see and has therefore momentous epistemic consequences. (shrink)

Many artists, art critics, and poets suggest that an aesthetic appreciation of artworks may modify our perception of the world, including quotidian things and scenes. I call this Art-to-World, AtW. Focusing on visual artworks, in this paper I articulate an empirically-informed account of AtW that is based on content-related views of aesthetic experience, and on Goodman’s and Elgin’s concept of exemplification. An aesthetic encounter with artworks demands paying attention to its aesthetic, expressive, or design properties that realize its purpose. Attention (...) to these properties make percipients better able to spot them in other entities and scenes as well. The upshot is that an aesthetic commerce with artworks enlarges the scope of what we are able to see and has therefore momentous epistemic consequences. (shrink)

Colour has been shown to facilitate the recognition of scene images, but only when these images contain natural scenes, for which colour is ‘diagnostic’. Here we investigate whether colour can also facilitate memory for scene images, and whether this would hold for natural scenes in particular. In the first experiment participants first studied a set of colour and greyscale natural and man-made scene images. Next, the same images were presented, randomly mixed with a different set. Participants were asked to indicate (...) whether they had seen the images during the study phase. Surprisingly, performance was better for greyscale than for coloured images, and this difference is due to the higher false alarm rate for both natural and man-made coloured scenes. We hypothesized that this increase in false alarm rate was due to a shift from scrutinizing details of the image to recognition of the gist of the image. A second experiment, utilizing images without a nameable gist, confirmed this hypothesis as participants now performed equally on greyscale and coloured images. In the final experiment we specifically targeted the more detail-based perception and recognition for greyscale images versus the more gist-based perception and recognition for coloured images with a change detection paradigm. The results show that changes to images are detected faster when image-pairs were presented in greyscale than in colour. This counterintuitive result held for both natural and man-made scenes and thus corroborates the shift from more detailed processing of images in greyscale to more gist-based processing of coloured images. (shrink)

It has been suggested that there maybe no olfactory illusions. This manuscript examines this claim and argues that it arises because olfactory illusions are not typically accompanied by an awareness of their illusory nature. To demonstrate that olfactory illusions do occur, the relevant empirical literature is reviewed, by examining instances of where the same stimulus results in different percepts, and of where different stimuli result in the same percept. The final part of the manuscript evaluates the evidence favoring the existence (...) of olfactory illusions, and then examines why they may not typically be accompanied by awareness. Three contributory mechanisms are discussed, relating to difficulty of verification and paucity of olfactory knowledge, the role of change blindness, and restricted access consciousness in this sense. (shrink)

Studies of change detection suggest that people tend to overestimate their ability to detect visual changes. In a recent laboratory study of change detection and human intention, Beck et al., found that individuals have an inadequate understanding that intention can improve change detection performance and that its importance increases with scene complexity. We note that these findings may be specific to unfamiliar situations such as those generated routinely in studies of change detection. In two questionnaire studies, we demonstrate that when (...) participants consider real world scenarios such as driving, people are well aware that the intention to detect changes improves detection performance, especially in complex scenes. We suggest several reasons why change detection findings like Beck et al.’s do not generalize to real world situations. More broadly, we suggest a possible way to bridge the gap between lab and life. (shrink)

People often fail to detect large changes to scenes, provided that the changes occur during a visual disruption. This phenomenon, known as ''change blindness,'' occurs both in the laboratory and in real-world situations in which changes occur unexpectedly. The pervasiveness of the inability to detect changes is consistent with the theoretical notion that we internally represent relatively little information from our visual world from one glance at a scene to the next. However, evidence for change blindness does not necessarily imply (...) the absence of such a representation-people could also miss changes if they fail to compare an existing representation of the pre-change scene to the post-change scene. In three experiments, we show that people often do have a representation of some aspects of the pre-change scene even when they fail to report the change. And, in fact, they appear to ''discover'' this memory and can explicitly report details of a changed object in response to probing questions. The results of these real-world change detection studies are discussed in the context of broader claims about change blindness. (shrink)

Change blindness is the striking failure to see large changes that normally would be noticed easily. Over the past decade this phenomenon has greatly contributed to our understanding of attention, perception, and even consciousness. The surprising extent of change blindness explains its broad appeal, but its counterintuitive nature has also engendered confusions about the kinds of inferences that legitimately follow from it. Here we discuss the legitimate and the erroneous inferences that have been drawn, and offer a set of requirements (...) to help separate them. In doing so, we clarify the genuine contributions of change blindness research to our understanding of visual perception and awareness, and provide a glimpse of some ways in which change blindness might shape future research. (shrink)

Our recent opinion article [1] examined what change blindness can and cannot tell us about visual representations. Among other things, we argued that change blindness can tell us a lot about how visual representations can be used, but little about their extent. We and others found the ‘sparse representations’ view appealing (and still do), and initially made the overly strong claim that change blindness supports the conclusion of sparse representations [2,3]. We wrote our article because change blindness continues to be (...) taken as evidence for sparse – or even absent – representations, and we used O’Regan and Noë’s influential paper [4] as an example. However, as has been noted for some time [5–8], this conclusion is logically flawed: lack of ability need not be caused by lack of representation. (shrink)

In a series of three experiments, we explored the nature of implicit representations in change blindness . Using 3 × 3 letter arrays, we asked subjects to locate changes in paired arrays separated by 80 ms ISIs, in which one, two or three letters of a row in the second array changed. In one testing version, a tone followed the second array, signaling a row for partial report . In the other version, no PR was required. After Ss reported whether (...) a change had been detected and the PR had been completed , they were asked to identify a degraded letter trigram that was either novel, or from a previously shown row . Our findings indicate that when CB occurs, both the pre-change and post-change stimulus information primes despite its unavailability to consciousness. Surprisingly, findings also indicate that when change detection occurs only the post-change information primes. (shrink)

To make behavioral choices that are in line with our goals and our moral beliefs, we need to gather and consider information about our current situation. Most information present in our environment is not relevant to the choices we need or would want to make and thus could interfere with our ability to behave in ways that reflect our underlying values. Certain sources of information could even lead us to make choices we later regret, and thus it would be beneficial (...) to be able to ignore that information. Our ability to exert successful self-governance depends on our ability to attend to sources of information that we deem important to our decision-making processes. We generally assume that, at any moment, we have the ability to choose what we pay attention to. However, recent research indicates that what we pay attention to is influenced by our prior experiences, including reward history and past successes and failures, even when we are not aware of this history. Even momentary distractions can cause us to miss or discount information that should have a greater influence on our decisions given our values. Such biases in attention thus raise questions about the degree to which the choices that we make may be poorly informed and not truly reflect our ability to otherwise exert self-governance. (shrink)

Determining the nature of binding in grapheme-color synaesthesia has consequences for understanding the neural basis of synaesthesia and visual awareness in general. We evaluated type- and token-based letter-color binding using a synaesthetic version of the object-reviewing paradigm. Although mean response times failed to reveal any significant differences between synaesthetes and control participants, RT analyses with ex-Gaussian distributions revealed that the response facilitation in the synaesthesia group reflected type representations exclusively, while response facilitation in the control group, who learned letter-color associations, (...) was dominated by token representations. Thus, letter-color associations in associator synaesthetes are type-based, and do not involve binding to object tokens, consistent with their subjective reports. Contrary to recent studies that failed to find differences between synaesthetes and non-synaesthetes with behavioral measures, response time distribution analyses indicate that color sensations in synaesthetes are not simply the extreme form of normal letter-color associations, and cannot be attributed to demand characteristics. (shrink)

It is argued here that cognitive science currently neglects an important source of insight into the human mind: the effects created by magicians. Over the centuries, magicians have learned how to perform acts that are perceived as defying the laws of nature, and that induce a strong sense of wonder. This article argues that the time has come to examine the scientific bases behind such phenomena, and to create a science of magic linked to relevant areas of cognitive science. Concrete (...) examples are taken from three areas of magic: the ability to control attention, to distort perception, and to influence choice. It is shown how such knowledge can help develop new tools and indicate new avenues of research into human perception and cognition. (shrink)

Human vision briefly retains a trace of a stimulus after it disappears. This trace—iconic memory—is often believed to be a surrogate for the original stimulus, a representational structure that can be used as if the original stimulus were still present. To investigate its nature, a flicker-search paradigm was developed that relied upon a full scan (rather than partial report) of its contents. Results show that for visual search it can indeed act as a surrogate, with little cost for alternating between (...) visible and iconic representations. However, the duration over which it can be used depends on the type of task: some tasks can use iconic memory for at least 240 ms, others for only about 190 ms, while others for no more than about 120 ms. The existence of these different limits suggests that iconic memory may have multiple layers, each corresponding to a particular level of the visual hierarchy. In this view, the inability to use a layer of iconic memory may reflect an inability to maintain feedback connections to the corresponding representation. (shrink)

The capacity of visual attention/STM can be determined by change-detection experiments. Detecting the presence of change leads to an estimate of 4 items, while detecting the absence of change leads to an estimate of 1 item. Thus, there are two magical numbers in vision: 4 and 1. The underlying limits, however, are not necessarily those of central STM.

Large changes that occur in clear view of an observer can become difficult to notice if made during an eye movement, blink, or other such disturbance. This change blindness is consistent with the proposal that focused visual attention is necessary to see change, with a change becoming difficult to notice whenever conditions prevent attention from being automatically drawn to it. -/- It is shown here how the phenomenon of change blindness can provide new results on the nature of visual attention, (...) including estimates of its capacity and the extent to which it can bind visual properties into coherent descriptions. It is also shown how the resultant characterization of attention can in turn provide new insights into the role that it plays in the perception of scenes and events. (shrink)

Five aspects of visual change detection are reviewed. The first concerns the concept of change itself, in particular the ways it differs from the related notions of motion and difference. The second involves the various methodological approaches that have been developed to study change detection; it is shown that under a variety of conditions observers are often unable to see large changes directly in their field of view. Next, it is argued that this “change blindness” indicates that focused attention is (...) needed to detect change, and that this can help map out the nature of visual attention. The fourth aspect concerns how these results affect our understanding of visual perception—for example, the implication that a sparse, dynamic representation underlies much of our visual experience. Finally, a brief discussion is presented concerning the limits to our current understanding of change detection. (shrink)

This paper argues that a theory of situated vision, suited for the dual purposes of object recognition and the control of action, will have to provide something more than a system that constructs a conceptual representation from visual stimuli: it will also need to provide a special kind of direct (preconceptual, unmediated) connection between elements of a visual representation and certain elements in the world. Like natural language demonstratives (such as `this' or `that') this direct connection allows entities to be (...) referred to without being categorized or conceptualized. Several reasons are given for why we need such a preconcep- tual mechanism which individuates and keeps track of several individual objects in the world. One is that early vision must pick out and compute the relation among several individual objects while ignoring their properties. Another is that incrementally computing and updating representations of a dynamic scene requires keeping track of token individuals despite changes in their properties or locations. It is then noted that a mechanism meeting these requirements has already been proposed in order to account for a number of disparate empiri- cal phenomena, including subitizing, search-subset selection and multiple object tracking (Pylyshyn et al., Canadian Journal of Experimental Psychology 48(2) (1994) 260). This mechanism, called a visual index or FINST, is brie. (shrink)

It is generally accepted that there is something special about reasoning by using mental images. The question of how it is special, however, has never been satisfactorily spelled out, despite more than 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 taken literally, as a claim about how images are physically instantiated in the brain, and that the literal view fails for a number of empirical reasons – for example, because of the cognitive penetrability of the phenomena cited in its favor. Similarly, while it is arguably the case that imagery and vision involve some of the same mechanisms, this tells us very little about the nature of mental imagery and does not support claims about the pictorial nature of mental images. Finally, I consider whether recent neuroscience evidence clarifies the debate over the nature of mental images. I claim that when such questions as whether images are depictive or spatial are formulated more clearly, the evidence does not provide support for the picture-theory over a symbol-structure theory of mental imagery. Even if all the empirical claims were true, they do not warrant the conclusion that many people have drawn from them: that mental images are depictive or are displayed in some (possibly cortical) space. Such a conclusion is incompatible with what is known about how images function in thought. We are then left with the provisional counterintuitive conclusion that the available evidence does not support rejection of what I call the “null hypothesis”; namely, that reasoning with mental images involves the same form of representation and the same processes as that of reasoning in general, except that the content or subject matter of thoughts experienced as images includes information about how things would look. (shrink)

People can maintain accurate representations of visual changes without necessarily being aware of them. Here, we investigate whether a similar phenomenon also exists in touch. In Experiments 1 and 2, participants detected the presence of a change between two consecutively-presented tactile displays. Tactile change blindness was observed, with participants failing to report the presence of tactile change. Critically, however, when participants had to make a forced choice response regarding the number of stimuli presented in the two displays, their performance was (...) significantly better than chance . Experiment 3 demonstrated that tactile change detection does not necessarily involve a shift of spatial attention toward the location of change, regardless of whether the change is explicitly detected. We conclude that tactile change detection likely results from comparing representations of the two displays, rather than by directing spatial attention to the location of the change. (shrink)

In this article we present a new experimental paradigm: comparative visual search. Each half of a display contains simple geometrical objects of three different colors and forms. The two display halves are identical except for one object mismatched in either color or form. The subject's task is to find this mismatch. We illustrate the potential of this paradigm for investigating the underlying complex processes of perception and cognition by means of an eye‐tracking study. Three possible search strategies are outlined, discussed, (...) and reexamined on the basis of experimental results. Each strategy is characterized by the way it partitions the field of objects into “chunks.” These strategies are: (i) Stimulus‐wise scanning with minimization of total scan path length (a “traveling salesman” strategy), (ii) scanning of the objects in fixed‐size areas (a “searchlight” strategy), and (iii) scanning of object sets based on variably sized clusters defined by object density and heterogeneity (a “clustering” strategy). To elucidate the processes underlying comparative visual search, we introduce besides object density a new entropy‐based measure for object heterogeneity. The effects of local density and entropy on several basic and derived eye‐movement variables clearly rule out the traveling salesman strategy, but are most compatible with the clustering strategy. (shrink)