Psychologists and philosophers are often tempted to make general claims about the importance of certain experimental results for our commonsense notions of intentional agency, moral responsibility, and free will. It is a strong intuition that if the agent does not intentionally control her own behavior, her behavior will not be an expression of agency, she will not be morally responsible for its consequences, and she will not be acting as a free agent. It therefore seems natural that the interest centers (...) on the notion of intentional control. If it can be experimentally shown that agents do as a matter of fact not control their own actions, even though they think they do, it will have far reaching consequences for our moral psychology. In this paper I look at recent eliminative arguments allegedly demonstrating that our commonsense notion of intentional control is incompatible with experimental data in support of the dual visual stream theory. (shrink)

Milner and Goodale's influential account of the primate cortical visual streams involves a division of consciousness between them, for it is the ventral stream that has the responsibility for visual consciousness. Hence, the dorsal visual stream is a ‘zombie’ stream. In this article, I argue that certain information carried by the dorsal stream likely plays a central role in the egocentric spatial content of experience, especially the experience of visual spatial constancy. Thus, the dorsal stream (...) contributes to a pervasive feature of consciousness. (shrink)

According to what I’ll call the ‘two visual systems account’ (TWO-SYSTEMS), the visual system is divided into two independent sub- systems, a ventral system implementing ‘vision for perception’ and a dorsal system implementing ‘vision for action’ (Milner and Goodale, 2006). TWO-SYSTEMS is widely discussed in philosophy due to the counter-intuitive role that it posits for conscious experience in the control of actions. However, recent evidence undermines the model’s core tenets: it no longer appears that the ventral and dorsal (...) streams constitute isolated processing systems, and there is now evidence for the involvement of both streams in conscious experience and online motor control. I articulate a new ‘direct dorsal control account’ (DORSAL-CONTROL), show that it is immune to three empirical challenges facing TWO-SYSTEMS, and show that it nonetheless has similarly significant implications for the perceiving mind. -/- Section 1 articulates TWO-SYSTEMS and its philosophical implications. Section 2 describes three empirical challenges to TWO-SYSTEMS. Section 3 articulates DORSAL-CONTROL and shows that it is immune to the three challenges. Section 4 articulates DORSAL-CONTROL’s philosophical implications. (shrink)

Norman's aim to reconcile two longstanding and seemingly opposed philosophies of perception, the constructivist and the ecological, by casting them as approaches to complementary subsystems within the visual brain is laudable. Unfortunately, Norman overreaches in attempting to equate direct perception with dorsal/unconscious visual processing and indirect perception with ventral/conscious visual processing. Even a cursory review suggests that the functional and neural segregation of direct and indirect perception is not as clear as the target article would suggest.

Philosophers and neuroscientists often suggest that we perceptually represent objects and their properties. However, they start from very different background assumptions when they use the term “perceptual representation”. On the one hand, sometimes philosophers do not need to properly take into consideration the empirical evidence concerning the neural states subserving the representational perceptual processes they are talking about. On the other hand, neuroscientists do not rely on a meticulous definition of “perceptual representation” when they talk about this empirical evidence that (...) is supposed to show that we perceptually represent such and such properties. It seems that, on both sides, something is missed. My aim is to show that, in the light of empirical evidence from neuroscience, the case of action properties is a good candidate in order to properly talk of perceptually represented properties. My claim is that the neurophysiological states encoding action properties are perceptual processes and that these perceptual processes are representational processes. That is, in the case of those neurophysiological states involved in the detection of action properties, it is correct to speak of perceptual representational states, and hence, ipso facto, of perceptually represented properties. First, I describe a reasonable and widely agreed upon conception of perceptual representation in the philosophical literature. Then, I report evidence from vision and motor neuroscience concerning the perception of action properties, which is subserved by the ventro-dorsal stream, a portion of the dorsal visual system. Finally, I show that a strong connection can be found between the philosophical idea of perceptual representation I have reported before and the neuroscientific evidence concerning the activity of the ventro-dorsal stream, whose job is, as said, to detect action properties. (shrink)

In this study, we use a conversation analysis framework to understand the systematic organization of interactions in Periscope live video streams, and its crucial features: the talking heads orientation for the video stream, in common with video-mediated communication; the expectation that the streamer should attend to all messages as much as possible; the ‘loose’ organization of viewers’ responses to streamers’ turn-at-talk, as in multi-party chats. We also identify a distinctive design for streamers’ responses to messages, the ‘read-aloud and respond’ (...) practice. These distinctive features are oriented to the highly asymmetrical communicative affordances of Periscope streams. Without precluding other forms of Periscope-based activities, this systematic organization of talk and messages, coupled with the affordances of the application, favors a basic mode of topic initiation resting on a typical and minimal adjacent pair: viewer’s noticing/streamers’ reading and responding. We argue that the particular salience of this organization of topic initiation may account for the emergence of the dominant kind of use for Periscope streams, that is, the online public exposure of youth to strangers in order to elicit some conversation. (shrink)

Today many philosophers of mind accept that the two cortical streams of visual processing in humans can be distinguished in terms of conscious experience. The ventral stream is thought to produce representations that may become conscious, and the dorsal stream is thought to handle unconscious vision for action. Despite a vast literature on the topic of the two streams, there is currently no account of the way in which the relevant empirical evidence could fit with basic Husserlian (...) phenomenology of vision. Here I offer such an account. In this article, I show how the empirical evidence ought to be understood in a way that is informed by phenomenology. The differences in the two streams are better described as differences in spatial and temporal processing. Rather than simply “unconscious,” the dorsal stream can be better described as making a special contribution to what Husserl identified as the visual horizon. (shrink)

The main function of vision in many animals is to control movement. In rodents, some visuomotor acts require the construction of models of the external world while others rely on Gibsonian invariants. Such findings support Norman's dual processing approach but it is not clear that the two types of processing rely on homologs of visual processing streams described in primates.

Some data concerning visual illusions are hardly compatible with the perception–action model, assuming that only the perception system is influenced by visual context. The planning–control dichotomy offers an alternative that better accounts for some controversy in experimental data. We tested the two models by submitting the patient I. G. to the induced Roelofs effect. The similitude of the results of I. G. and control subjects favoured Glover's model, which, however, presents a paradox that needs to be clarified.

Optic neuropathies are conditions that cause disease to the optic nerve, and can result in loss of visual acuity and/or visual field defects. An improved understanding of how these conditions affect the entire visual system is warranted, to better predict and/or restore the visual loss. In this article, we review visually-driven functional magnetic resonance imaging (fMRI) studies of optic neuropathies, including glaucoma and optic neuritis (ON); we also discuss traumatic optic neuropathy (TON). Optic neuropathy-related vision loss (...) results in fMRI deficit within the visual cortex, and is often strongly correlated with clinical severity measures. Using predominantly flickering checkerboard stimuli, glaucoma studies indicated retinotopic-specific cortical alteration with more prominent deficits in advanced than in early glaucoma. Some glaucoma studies indicate a reorganized visual cortex. ON studies have indicated that the impacted cortical areas are briefly hyperactive. For ON, brain deficits are greater in the acute stages of the disease, followed by (near) normalization of responses of the LGN, visual cortex, and the dorsal visual stream, but not the ventral extrastriate cortex. Visually-driven fMRI is sensitive, at least in ON, in discriminating patients from controls, as well as the affected eye from the fellow eye within patients. The use of a greater variety of stimuli beyond checkerboards (e.g., visual motion and object recognition) in recent ON studies is encouraging, and needs to continue to disentangle the results in terms of change over time. Finally, visually-driven fMRI has not yet been applied in TON, although preliminary efforts suggest it may be feasible. Future fMRI studies of optic neuropathies should consider using more complex visual stimuli, and inter-regional analysis methods including functional connectivity. We suggest that a more systematic longitudinal comparison of optic neuropathies with advanced fMRI would provide improved diagnostic and prognostic information. (shrink)

Reflection on the fine-grained information required for visual guidance of action has suggested that visual content is non-conceptual. I argue that in a common type of visually guided action, namely the use of manipulable artefacts, vision has conceptual content. Specifically, I show that these actions require visual attention and that concepts are involved in directing attention. In acting with artefacts, there is a way of doing it right as determined by the artefact’s conventional use. Attention must reflect (...) our understanding of the function and appropriate ways to use these artefacts, understanding that requires possession of the relevant concept. As a result, we attend to the artefact’s relevant functional properties. In these cases, attention is structured by concepts. This discussion has a bearing on the dual visual stream hypothesis. While it is often held that the two visual streams are functionally independent, the argument of this essay is that the constraints on attention suggest a functional interaction between them. (shrink)

Optic neuropathy refers to disease of the optic nerve and can result in loss of visual acuity and/or visual field defects. Combining findings from multiple fMRI modalities can offer valuable information for characterizing and managing optic neuropathies. In this article, we review a subset of resting-state functional magnetic resonance imaging (RS-fMRI) studies of optic neuropathies. We consider glaucoma, acute optic neuritis (ON), discuss traumatic optic neuropathy (TON), and explore consistency between findings from RS and visually driven fMRI studies. (...) Consistent with visually driven studies, glaucoma studies at rest also indicated reduced activation in the visual cortex and dorsal visual stream. RS-fMRI further reported varying levels of functional connectivity in the ventral stream depending on disease severity. ON patients show alterations within the visual cortex in both fMRI techniques. Particularly, higher-than-normal RS activity is observed in the acute phase and decreases as the disease progresses. A similar pattern is observed in the visual cortex of TON-like, open globe injury (OGI), patients. Additionally, visually driven and RS-fMRI studies of ON patients show recovery of brain activity in the visual cortex. RS-fMRI suggests recovery of signals in higher-tier visual areas MT and LOC as well. Finally, RS-fMRI has not yet been applied to TON, although reviewing OGI studies suggests that it is feasible. Future RS-fMRI studies of optic neuropathies could prioritize studying the fine scale RS activity of brain areas that visually driven studies have identified. We suggest that a more systematic longitudinal comparison of optic neuropathies with advanced fMRI would provide improved diagnostic and prognostic information. (shrink)

For almost half a century dual-stream advocates have vigorously defended the view that there are two functionally specialized cortical streams of visual processing originating in the primary visual cortex: a ventral, perception-related ‘conscious’ stream and a dorsal, action-related ‘unconscious’ stream. They furthermore maintain that the perceptual and memory systems in the ventral stream are relatively shielded from the action system in the dorsal stream. In recent years, this view has come under scrutiny. Evidence points to two overlapping (...) action pathways: a dorso-dorsal pathway that calculates features of the object to be acted on, and a ventro-dorsal pathway that transmits stored information about skilled object use from the ventral stream to the dorso-dorsal pathway. This evidence suggests that stored information may exert significantly more influence on visually guided action than hitherto assumed. I argue that this, in turn, supports the notion of skilled automatic action that is nonetheless agential. My focus here will be on actions influenced by implicit biases (stereotypes/prejudices). Action that is biased in this way, I argue, is in an important sense intentional and agential. (shrink)

There is growing interest in the effect of sound on visual motion perception. One model involves the illusion created when two identical objects moving towards each other on a two-dimensional visual display can be seen to either bounce off or stream through each other. Previous studies show that the large bias normally seen toward the streaming percept can be modulated by the presentation of an auditory event at the moment of coincidence. However, no reports to date provide sufficient (...) evidence to indicate whether the sound bounce-inducing effect is due to a perceptual binding process or merely to an explicit inference resulting from the transient auditory stimulus resembling a physical collision of two objects. In the present study, we used a novel experimental design in which a subliminal sound was presented either 150 ms before, at, or 150 ms after the moment of coincidence of two disks moving towards each other. The results showed that there was an increased perception of bouncing when the subliminal sound was presented at or 150 ms after the moment of coincidence compared to when no sound was presented. These findings provide the first empirical demonstration that activation of the human auditory system without reaching consciousness affects the perception of an ambiguous visual motion display. (shrink)

To learn a visual code in an unsupervised manner, one may attempt to capture those features of the stimulus set that would contribute significantly to a statistically efficient representation. Paradoxically, all the candidate features in this approach need to be known before statistics over them can be computed. This paradox may be circumvented by confining the repertoire of candidate features to actual scene fragments, which resemble the “what+where” receptive fields found in the ventral visual stream in primates. We (...) describe a single-layer network that learns such fragments from unsegmented raw images of structured objects. The learning method combines fast imprinting in the feedforward stream with lateral interactions to achieve single-epoch unsupervised acquisition of spatially localized features that can support systematic treatment of structured objects [1]. (shrink)

In order to extract the regularities underlying a continuous sensory input, the individual elements constituting the stream have to be encoded and their transitional probabilities (TPs) should be learned. This suggests that variance in statistical learning (SL) performance reflects efficiency in encoding representations as well as efficiency in detecting their statistical properties. These processes have been taken to be independent and temporally modular, where first, elements in the stream are encoded into internal representations, and then the co‐occurrences between them are (...) computed and registered. Here, we entertain a novel hypothesis that one unifying construct—the rate of information in the sensory input—explains learning performance. This theoretical approach merges processes related to encoding of events and those related to learning their regularities into a single computational principle. We present data from two large‐scale experiments with over 800 participants tested in support for this hypothesis, showing that rate of information in a visual stream clearly predicts SL performance, and that similar rate of information values leads to similar SL performance. We discuss the implications for SL theory and its relation to regularity learning. (shrink)

AimVisual functions of the dorsal stream are considered vulnerable in children with early brain damage. Considering the recognition of objects in suboptimal representations a dorsal stream dysfunction, we examined whether children with early brain damage and impaired object recognition had either general or selective dorsal stream dysfunctions.MethodIn a group of children with early brain damage we evaluated the dorsal stream functioning. To determine whether these patients had an increased risk of a dorsal stream dysfunction we compared the percentage of patients (...) with impaired object recognition, assessed with the L94, with the estimated base rate. Then we evaluated the performance levels on motion perception, visual attention and visuomotor tasks in patients with and without object recognition abnormalities. A general dorsal stream dysfunction was considered present if a patient showed at least one abnormally low score in two out of three additional dorsal stream functions.ResultsSix of the eighteen patients with object recognition problems scored abnormally low on at least two additional dorsal stream functions. This was significantly higher than the base rate. The difference of 24.1% between the patients with and without object recognition problems was not significant. Of the patients with object recognition problems 72.2% had at least 1 dorsal weakness, whereas this was only the case in 27.3% of patients without object recognition problems. Compared to patients with normal object recognition, patients with object recognition problems scored significantly more abnormally low on motion perception and visual attention but did not differ on visuomotor skills.ConclusionChildren with object recognition problems seem at risk for other dorsal stream dysfunctions, but dysfunctions might be rather specific than general. Multiple functions/aspects should be evaluated in neuropsychological assessment of children at risk. (shrink)

Patients with apraxia perform poorly when demonstrating how an object is used, particularly when pantomiming the action. However, these patients are able to accurately identify, and to pick up and move objects, demonstrating intact ventral and dorsal stream visuomotor processing. Appropriate object manipulation for skilled use is thought to rely on integration of known and visible object properties associated with ‘ventro-dorsal’ stream neural processes. In apraxia, it has been suggested that stored object knowledge from the ventral stream may be less (...) readily available to incorporate into the action plan, leading to an over-reliance on the objects’ visual affordances in object-directed motor behaviour. The current study examined grasping performance in left hemisphere stroke patients with (N = 3) and without (N = 9) apraxia, and in age-matched healthy control participants (N = 14), where participants repeatedly grasped novel cylindrical objects of varying weight distribution. Across two conditions, object weight distribution was indicated by either a memory-associated cue (object colour) or visual-spatial cue (visible dot over the weighted end). Participants were required to incorporate object-weight associations to effectively grasp and balance each object. Control groups appropriately adjusted their grasp according to each object’s weight distribution across each condition, whereas throughout the task two of the three apraxic patients performed poorly on both the memory-associated and visual-spatial cue conditions. A third apraxic patient seemed to compensate for these difficulties but still performed differently to control groups. Patients with apraxia performed normally on the neutral control condition when grasping the evenly weighted version. The pattern of behaviour in apraxic patients suggests impaired integration of visible and known object properties attributed to the ventro-dorsal stream: in learning to grasp the weighted object accurately, apraxic patients applied neither pure knowledge-based information (the memory-associated condition) nor higher-level information given in the visual-spatial cue condition. Disruption to ventro-dorsal stream predicts that apraxic patients will have difficulty learning to manipulate new objects on the basis of information other than low-level visual cues such as shape and size. (shrink)

Pessoa et al.'s target article shows that although filling-in of various kinds does appear to occur in the brain, it is not required in order to furnish a “bridge locus” where neural events are “isomorphic” to the features of visual consciousness. Some recently uncovered completion phenomena may well play a crucial role in the elaboration of normal visual experience, but others occur too slowly to contribute to normal visual content.

Which roles are played by subcortical pathways in models of cortical streams for visual processing? Through their thalamic relays, magnocellular (M) and parvocellular (P) projecting ganglion cells send complementary signals to V1, where their outputs are combined in several different ways. The synergic role of M and P cells in vision can be understood by estimating cell response entropy in all domains of interest.

The way in which vision represents objects as being the same despite movement and qualitative changes has been extensively investigated in contemporary psychology. However, the formal properties of the visual sameness relation are still unclear, for example, whether it is an identity-like, equivalence relation. The paper concerns one aspect of this problem: the transitivity of visual sameness. Results obtained by using different experimental paradigms are analysed, in particular studies using streaming/bouncing stimuli, multiple object tracking experiments and investigations concerning (...) object-specific preview benefit, and it is argued that the transitive interpretation of visual sameness is the most plausible given the current stage of knowledge. What is more, it is claimed that the way in which visual sameness is represented suggests that in some cases it should be characterized as a “primitive sameness”, similarly as in philosophical theories postulating “thisness”. (shrink)

When a piece of fruit is in a bowl, and the bowl is on a table, we appreciate not only the individual objects and their features, but also the relations containment and support, which abstract away from the particular objects involved. Independent representation of roles (e.g., containers vs. supporters) and “fillers” of those roles (e.g., bowls vs. cups, tables vs. chairs) is a core principle of language and higherlevel reasoning. But does such role-filler independence also arise in automatic visual (...) processing? Here, we show that it does, by exploring a surprising error that such independence can produce. In four experiments, participants saw a stream of images containing different objects arranged in forcedynamic relations — e.g., a phone contained in a basket, a marker resting on a garbage can, or a knife sitting in a cup. Participants had to respond to a single target image (e.g., a phone in a basket) within a stream of distractors presented under time constraints. Surprisingly, even though participants completed this task quickly and accurately, they false-alarmed more often to images matching the target’s relational category than to those that did not — even when those images involved completely different objects. In other words, participants searching for a phone in a basket were more likely to mistakenly respond to a knife in a cup than to a marker on a garbage can. Follow-up experiments ruled out strategic responses and also controlled for various confounding image features. We suggest that visual processing represents relations abstractly, in ways that separate roles from fillers. (shrink)

In his paper, “The Dorsal Stream and the Visual Horizon,” Michael Madary argues that “dorsal stream processing plays a main role in the spatiotemporal limits of visual perception, in what Husserl identified as the visual horizon” (Madary 2011, p. 424). Madary regards himself as thereby providing a theoretical framework “sensitive to basic Husserlian phenomenology” (Madary 2011). In particular, Madary draws connections between perceptual anticipations and the experience of the indeterminate spatial margins, on the one hand, and the (...) Husserlian spatiotemporal visual horizons, on the other. I argue that Madary’s arguments, for a Husserlian view of the two visual systems, are not convincing. When the notion of visual horizon is adequately understood as a constitutive notion, there will be reason to regard the connections between dorsal processing and the Husserlian spatiotemporal horizons as tenuous at best. (shrink)

Bowers et al. rightly emphasise that deep learning models often fail to capture constraints on visual perception that have been discovered by previous research. However, the solution is not to discard deep learning altogether, but to design stimuli and tasks that more closely reflect the problems that biological vision evolved to solve, such as understanding scenes and preparing skilled action.

As many as two million people in the United Kingdom repeatedly see people, animals, and objects that have no objective reality. Hallucinations on the border of sleep, dementing illnesses, delirium, eye disease, and schizophrenia account for 90% of these. The remainder have rarer disorders. We review existing models of recurrent complex visual hallucinations (RCVH) in the awake person, including cortical irritation, cortical hyperexcitability and cortical release, top-down activation, misperception, dream intrusion, and interactive models. We provide evidence that these can (...) neither fully account for the phenomenology of RCVH, nor for variations in the frequency of RCVH in different disorders. We propose a novel Perception and Attention Deficit (PAD) model for RCVH. A combination of impaired attentional binding and poor sensory activation of a correct proto-object, in conjunction with a relatively intact scene representation, bias perception to allow the intrusion of a hallucinatory proto-object into a scene perception. Incorporation of this image into a context-specific hallucinatory scene representation accounts for repetitive hallucinations. We suggest that these impairments are underpinned by disturbances in a lateral frontal cortex–ventral visual stream system. We show how the frequency of RCVH in different diseases is related to the coexistence of attentional and visual perceptual impairments; how attentional and perceptual processes can account for their phenomenology; and that diseases and other states with high rates of RCVH have cholinergic dysfunction in both frontal cortex and the ventral visual stream. Several tests of the model are indicated, together with a number of treatment options that it generates. Key Words: Blindness; Charles Bonnet; cholinergic; cortical release; delirium; dementia; dream intrusion; hallucination; Perception and Attention Deficit (PAD) model; schizophrenia. (shrink)

Several lines of evidence indicate that rapid target-aiming movements, involving both the eyes and hand, can be biased by the visual context in which the movements are performed. Some of these contextual influences carry-over from trial to trial. This research indicates that dissociation between the dorsal and ventral systems based on speed, conscious awareness, and frame of reference is far from clear.

Though dividing one’s attention between two input streams typically impairs performance, detecting a behaviorally relevant stimulus can sometimes enhance the encoding of unrelated information presented at the same time. Previous research has shown that selection of this kind boosts visual cortical activity and memory for concurrent items. An important unanswered question is whether such effects are reflected in processing quality and functional connectivity in visual regions and in the hippocampus. In this fMRI study, participants were asked to (...) memorize a stream of naturalistic images and press a button only when they heard a predefined target tone. Images could be presented with a target tone, with a distractor tone, or without a tone. Auditory target detection increased activity throughout the ventral visual cortex but lowered it in the hippocampus. Enhancements in functional connectivity between the ventral visual cortex and the hippocampus were also observed following auditory targets. Multi-voxel pattern classification of image category was more accurate on target tone trials than on distractor and no tone trials in the fusiform gyrus and parahippocampal gyrus. This effect was stronger in visual cortical clusters whose activity was more correlated with the hippocampus on target tone than on distractor tone trials. In agreement with accounts suggesting that subcortical noradrenergic influences play a role in the attentional boost effect, auditory target detection also caused an increase in locus coeruleus activity and phasic pupil responses. These findings outline a network of cortical and subcortical regions that are involved in the selection and processing of information presented at behaviorally relevant moments. (shrink)

Research over the past half century has produced extensive evidence that observers cannot report or retain all of the details of their visual world from one moment to the next. During the past decade, a new set of studies has illustrated just how pervasive these limits are. For example, early evidence for the failure to detect changes to simple dot patterns (Phillips, 1974) and arrays of letters (Pashler, 1988) generalizes to more naturalistic displays such as photographs and motion pictures (...) (e.g., Levin & Simons, 1997; Rensink, O’Regan, & Clark, 1997; see Rensink, 2002 for a recent review). This failure to report changes (change blindness) can be induced in both simple and naturalistic displays, whenever the change co-occurs with a visual disruption such as an eye movement (Currie, McConkie, Carlson-Radvansky, & Irwin, 1995; Hollingworth, Schrock, & Henderson, 2001), image shift (Blackmore, Brelstaff, Nelson, & Troscianko, 1995), flashed blank screen (Rensink et al., 1997), blink (O’Regan, Deubel, Clark, & Rensink, 2000), transient (O’Regan, Rensink, & Clark, 1999; Rensink, O’Regan, & Clark, 2000), movie cut or pan (Levin & Simons, 1997; Simons, 1996), or an occlusion event (Levin, Simons, Angelone, & Chabris, 2002; Simons & Levin, 1998). Change blindness can also occur in the absence of a disruption, provided the change occurs gradually enough that it does not attract attention (Simons, Franconeri, & Reimer, 2000). -/- Failures of visual awareness have been induced in a number of ways. For example, observers often fail to report a visible but unexpected stimulus when attention is focused on some other object or event in the display (inattentional blindness). As for change blindness, inattentional blindness occurs for both simple (Mack & Rock, 1998; Most et al., 2001) and naturalistic stimuli (Simons & Chabris, 1999). Similarly, repeated instances of an item often go undetected when embedded in a rapid sequence (repetition blindness), a phenomenon that occurs for both words and pictures (Kanwisher, 1987; Kanwisher & Potter, 1990). Observers can also fail to detect a stimulus in a rapid stream of stimuli provided they had to perform an attention-demanding task shortly before the stimulus appeared (Shapiro, Arnell, & Raymond, 1997). The surprisingly large variety of conditions that induce failures of conscious perception reinforces the broad conclusion that we are often unaware of what would otherwise be fully-visible stimuli. -/- Along with an increased appreciation of the limitations of visual awareness has come a renewed interest in using these limitations to explore the nature of the representations and processes underlying our visual experience. Are these limitations due to failures of perception? Of attention? Of memory? What is preserved with and without awareness? -/- The papers in this special issue of the Journal of Vision provide examples of exciting new work on induced failures of visual awareness and the mechanisms that underlie them. For example, several papers examine whether observers are drawn to parts of a display by the stimulus features or whether top-down control or semantic comprehension influence search through a display. Others investigate the nature of and limits on the information that is preserved from one view to the next and how much information needs to be retained for effective perception and action. As guest editors, we hope that this special issue will illustrate how studying the relationship between visual awareness and visual representations can lead to important new insights into the nature of seeing. (shrink)

Milner and Goodale have advanced a justly influential theory of the structure of the human visual system. In broad outline, Milner and Goodale hold that the ventral neural pathway is associated with recognition and experiential awareness, and with a kind of indirect control of action. And they hold that, by contrast, the dorsal neural stream is associated with the non-conscious, direct control of visually informed action. Most of the relevant empirical research has focused on the visual control of (...) close-in, “personal space,” reaching and/or grasping. While their view has not escaped controversy and debate, we think that Milner and Goodale have a compelling story to tell about the visual guidance of such close in, “personal space” action. However, the question of whether their scheme applies to behavior with visually specified targets that are outside of the space accessible by simply reaching and grasping is largely unstudied. And it should be studied, since this is the arena of much human behavior. We provide good reason to think that the Milner and Goodale scheme may well not apply to important classes of mid-range, ‘action space’ behavior. But the matter is in the end to be decided in the lab. We describe a research program to do this. (shrink)

An earlier version of this paper was presented at the 2011 IEEE International Symposium on Technology and Society at Saint Xavier University in Chicago, Illinois. We propose a cooperative approach by students in recording lecture activities such that the classroom becomes more visually accessible for everyone, especially for deaf, hard of hearing and low-vision students. Students utilize their personal camera-equipped smart phones to capture and share their views of a visually inaccessible classroom to students' devices. We show this approach virtually (...) retrofits a classroom to make it a more visually accessible learning environment. This approach can be used in meetings to get and share optimal views of the meeting for all participants. (shrink)

The paper argues that the English verb ‘to see’ can denote three different kinds of conscious states of seeing, involving visual experiences, visual seeming states and introspective seeming states, respectively. The case for the claim that there are three kinds of seeing comes from synesthesia and visual imagery. Synesthesia is a relatively rare neurological condition in which stimulation in one sensory or cognitive stream involuntarily leads to associated experiences in a second unstimulated stream. Visual synesthesia is (...) often considered a case of illusory visual experience. This, however, turns out to be a questionable characterization, as there is evidence suggesting that the brain must cognitively process the stimulus in order for the associated synesthetic experience to arise. Furthermore, some very vivid, visual forms of synesthesia do not involve additional processing in the visual cortex. Visual synesthetic experience is likely to be a non-veridical state of seeming rather than an illusory visual experience. Visual seeming states are cognitive states distinct from visual experiences in terms of their representational richness and their neural correlates. Visual seeming states that are non-deviantly causally related to the states of affair they represent constitute a type of non-experiental seeing. Introspective seeming states that are non-deviantly causally related to underlying visual images constitute a second type of non-experiental seeing. The English verb ‘to see’ can denote all three types of seeing, which is to say that ‘to see’ is polysemous. (shrink)

An object in continuous motion is perceived ahead of the briefly flashed object, although the two images are physically aligned , the phenomenon called flash-lag effect. Flash-lag effects have been found also with other continuously changing features such as color, pattern entropy, and brightness as well as with streamed pre- and post-target input without any change of the feature values of streaming items in feature space . We interpret all instances of the flash-lag as a consequence of a more fundamental (...) property of conscious perception in general: acceleration of the speed with which samples of perceptual information become represented in explicit format immediately after the stimulation onset. Decreased visual latency of the samples of stimulus information from the streamed input leads to the relative perceptual lag for the separately flashed stimulus because it is not preceded by adjacent sensory input that would have accelerated its perception. Experimental support for the notion of perceptual acceleration is reviewed. (shrink)

Visual stimuli as well as transcranial magnetic stimulation can be used: to suppress the visibility of a target and to recover the visibility of a target that has been suppressed by another mask. Both types of stimulation thus provide useful methods for studying the microgenesis of object perception. We first review evidence of similarities between the processes by which a TMS mask and a visual mask can either suppress the visibility of targets or recover such suppressed visibility. However, (...) we then also point out a significant difference that has important implications for the study of the time course of unconscious and conscious visual information processing and for theoretical accounts of the processes involved. We present evidence and arguments showing: that visual masking techniques, by revealing more detailed aspects of target masking and target recovery, support a theoretical approach to visual masking and visual perception that must take into account activities in two separate neural channels or processing streams and, as a corollary, that at the current stage of methodological sophistication visual masks, by acting in more highly specifiable ways on these pathways, provide information about the microgenesis of form perception not available with TMS masks. (shrink)

The cortical visual mechanisms involved in processing spatial relationships remain subject to debate. According to one current view, the ''dorsal stream'' of visual areas, emanating from primary visual cortex and culminating in the posterior parietal cortex, mediates this aspect of visual processing. More recently, others have argued that while the dorsal stream provides egocentric coding of visual location for motor control, the separate ''ventral'' stream is needed for allocentric spatial coding. We have assessed the (...) class='Hi'>visual form agnosic patient DF, whose lesion mainly affects the ventral stream, on a prehension task requiring allocentric spatial coding. She was presented with transparent circular disks. Each disk had circular holes cut in it. DF was asked to reach out and grasp the disk by placing her fingers through the holes. The disks either had three holes (for forefinger, middle finger, and thumb) or two holes (for forefinger and thumb). The distance between the forefinger and thumb holes, and the orientation of the line formed by them, were independently varied. DF was quite unable to adjust her grip aperture or her hand orientation in the three-hole task. Although she was able to orient her hand appropriately for the two-hole disks, she still remained unable to adjust her grip aperture to the distance between the holes. These findings are consistent with the idea that allocentric processing of spatial information requires a functioning ventral stream, even when the information is being used to guide a motor response. (shrink)

From a theoretical perspective, most discussions of statistical learning have focused on the possible “statistical” properties that are the object of learning. Much less attention has been given to defining what “learning” is in the context of “statistical learning.” One major difficulty is that SL research has been monitoring participants’ performance in laboratory settings with a strikingly narrow set of tasks, where learning is typically assessed offline, through a set of two-alternative-forced-choice questions, which follow a brief visual or auditory (...) familiarization stream. Is that all there is to characterizing SL abilities? Here we adopt a novel perspective for investigating the processing of regularities in the visual modality. By tracking online performance in a self-paced SL paradigm, we focus on the trajectory of learning. In a set of three experiments we show that this paradigm provides a reliable and valid signature of SL performance, and it offers important insights for understanding how statistical regularities are perceived and assimilated in the visual modality. This demonstrates the promise of integrating different operational measures to our theory of SL. (shrink)

Spontaneous eye blinks are modulated around perceptual events. Our previous study, using a visual ambiguous stimulus, indicated that blink probability decreases before a reported perceptual switch. In the current study, we tested our hypothesis that an absence of blinks marks a time in which perceptual switches are facilitated in‐ and outside the visual domain. In three experiments, presenting either a visual motion quartet in light or darkness or a bistable auditory streaming stimulus, we found a co‐occurrence of (...) blink rate reduction with increased perceptual switch probability. In the visual domain, perceptual switches induced by a short interruption of visual input (blank) allowed an estimate of the timing of the perceptual event with respect to the motor response. This provided the first evidence that the blink reduction was not a consequence of the perceptual switch. Importantly, by showing that the time between switches and the previous blink was significantly longer than the inter‐blink interval, our studies allowed to conclude that perceptual switches did not happen at random but followed a prolonged period of nonblinking. Correspondingly, blink rate and switch rate showed an inverse relationship. Our study supports the idea that the absence or presence of blinks maps perceptual processes independent of the sensory modality. (shrink)