Perceptual Consciousness Research Articles

Imagery and overflow: We see more than we report

The question of whether our conscious experience is rich or sparse remains an enduring controversy in philosophy. The “overflow” account argues that perceptual consciousness is far richer than cognitive access: when perceiving a complex scene, subjects see more than they can report. This paper draws on aphantasia (the condition of absent voluntary imagery) to propose a new argument in favor of overflow. First, it shows that opponents of overflow explain subjects’ performance in a change detection paradigm by appealing to a type of “internal imagery.” Second, it provides empirical evidence to demonstrate that aphantasics are incapable of generating this imagery. However, aphantasics perform equally well in this task; and so the no-overflow account fails to explain their performance. This means that proponents of this view are committed to an unsupported view of perception.

Target bottom-up strength determines the extent of attentional modulations on conscious perception.

A sufficient level of alerting, bottom-up stimulus strength, and attention have been proposed as important pre-requisites for conscious perception (Dehaene et al. in Trends Cogn Sci 10:204-211, 2006). The combination of different levels of each of these processes might differentially bias the access to consciousness, so that the impact of a specific factor on conscious access would depend on the levels of the other factors. To explore this possibility, we measured how the interaction between different levels of (phasic and tonic) alerting, stimulus bottom-up activation, and endogenous spatial attention, influences conscious perception. We observed that endogenous spatial attention affected conscious perception mainly when target bottom-up strength was low, by improving perceptual sensitivity and making the response criterion stricter. Attention-driven increases of perceptual sensitivity (without variations in response criterion) were also observed for higher levels of bottom-up strength, but only when tonic alerting decreased. Phasic alerting boosted perceptual sensitivity independently of target bottom-up strength, even though it differently affected response bias, yielding a more liberal response criterion when target bottom-up strength increases. These results suggest that a more exhaustive approach to the study of conscious perception should consider the interaction of the multiple factors that are susceptible to modulate perceptual consciousness, rather than studying their effects in isolation.

Merleau-Ponty’s Immanent Critique of Gestalt Theory

Merleau-Ponty’s appropriation of Gestalt theory in The Structure of Behavior is central to his entire corpus. Yet commentators exhibit little agreement about what lesson is to be learned from his critique, and provide little exegesis of how his argument proceeds. I fill this exegetical gap. I show that the Gestaltist’s fundamental error is to reify forms as transcendent realities, rather than treating them as phenomena of perceptual consciousness. From this, reductivist errors follow. The essay serves not only as a helpful guide through parts of The Structure of Behavior for newcomers, but also offers a corrective to recent trends in philosophy of mind. Such influential commentators as Hubert Dreyfus, Taylor Carmen, and Evan Thompson have, I argue, risked serious misunderstanding of Merleau-Ponty’s view, by mistakenly treating “circular causality” as central to Merleau-Ponty’s own acausal (dialectical) view of forms.

Naïve Realism In Kantian Phrase

Early twentieth-century philosophers of perception presented their naive realist views of perceptual experience in anti-Kantian terms. For they took naive realism about perceptual experience to be incompatible with Kant’s claims about the way the understanding is necessarily involved in perceptual consciousness. This essay seeks to situate a naive realist account of visual experience within a recognisably Kantian framework by arguing that a naive realist account of visual experience is compatible with the claim that the understanding is necessarily involved in the perceptual experience of those rational beings with discursive intellects. The effect is a middle-way between recent conceptualist and non-conceptualist interpretations of Kant: one which holds that the understanding is necessarily involved in the kind of perceptual consciousness that we, as rational beings, enjoy whilst allowing that the relations of apprehension which constitute perceptual consciousness are independent of acts of the understanding.

Predictions Shape Confidence in Right Inferior Frontal Gyrus.

Perceptual decision-making is typically conceived as an integration of bottom-up and top-down influences. However, perceptual decisions are accompanied by a sense of confidence. Confidence is an important facet of perceptual consciousness yet remains poorly understood. Here we implicate right inferior frontal gyrus in constructing confidence from the discrepancy between perceptual judgment and its prior probability. Furthermore, we place right inferior frontal gyrus within an occipitofrontal network, consisting of orbitofrontal cortex and intracalcarine sulcus, which represents and communicates relevant top-down and bottom-up signals. Together, our data reveal a role of frontal regions in the top-down processes enabling perceptual decisions to become available for conscious report.

Epistemic Immodesty and Embodied Rationality

ABSTRACT Based on Pritchard's distinction (2012, 2016) between favoring and discriminating epistemic grounds, and on how those grounds bear on the elimination of skeptical possibilities, I present the dream argument as a moderate skeptical possibility that can be reasonably motivated. In order to block the dream argument skeptical conclusion, I present a version of phenomenological disjunctivism based on Noe's actionist account of perceptual consciousness (2012). This suggests that perceptual knowledge is rationally grounded because it is a form of embodied achievement - what I call embodied rationality -, which offers a way of dissolving the pseudo-problem of epistemic immodesty, namely, the seemingly counterintuitive thesis that one can acquire rationally grounded knowledge that one is not in a radical skeptical scenario.

Interactions between phasic alerting and consciousness in the fronto-striatal network.

Only a small fraction of all the information reaching our senses can be the object of conscious report or voluntary action. Although some models propose that different attentional states (top-down amplification and vigilance) are necessary for conscious perception, few studies have explored how the brain activations associated with different attentional systems (such as top-down orienting and phasic alerting) lead to conscious perception of subsequent visual stimulation. The aim of the present study was to investigate the neural mechanisms associated with endogenous spatial attention and phasic alertness, and their interaction with the conscious perception of near-threshold stimuli. The only region demonstrating a neural interaction between endogenous attention and conscious perception was the thalamus, while a larger network of cortical and subcortical brain activations, typically associated with phasic alerting, was highly correlated with participants’ conscious reports. Activation of the anterior cingulate cortex, supplementary motor area, frontal eye fields, thalamus, and caudate nucleus was related to perceptual consciousness. These data suggest that not all attentional systems are equally effective in enhancing conscious perception, highlighting the importance of thalamo-cortical circuits on the interactions between alerting and consciousness.

Epistemic Warrants and Higher‐Order Theories of Conscious Perception

AbstractWe present a new account of perceptual consciousness, one which gives due weight to the epistemic commitment of normal perception in familiar circumstances. The account is given in terms of a higher‐order attitude for which the subject has an immediate perceptual epistemic warrant in the form of an appropriate first‐order perception. We develop our account in contrast to Rosenthal's higher‐order account, rejecting his view of consciousness in virtue of so‐called ‘targetless’ higher‐order states. We explain the key notion of an immediate perceptual warrant and show both that it requires the content of the higher‐order attitude to match that of the first‐order perception, and also that it gives a new perspective on the intimate relationship, rightly emphasised by Rosenthal, between consciousness and a subject's testimony as to ‘how it is with her’.

Multisensory Processing and Perceptual Consciousness: Part I

AbstractMultisensory processing encompasses all of the various ways in which the presence of information in one sensory modality can adaptively influence the processing of information in a different modality. In Part I of this survey article, I begin by presenting a cartography of some of the more extensively investigated forms of multisensory processing, with a special focus on two distinct types of multisensory integration. I briefly discuss the conditions under which these different forms of multisensory processing occur as well as their important perceptual consequences and interrelations. In Part II, I then turn to examining of some of the different possible ways in which the structure of conscious perceptual experience might also be characterized as multisensory. In addition, I discuss the significance of research on multisensory processing and multisensory consciousness for philosophical attempts to individuate the senses.

Task relevance differentially shapes ventral visual stream sensitivity to visible and invisible faces.

Top-down modulations of the visual cortex can be driven by task relevance. Yet, several accounts propose that the perceptual inferences underlying conscious recognition involve similar top-down modulations of sensory responses. Studying the pure impact of task relevance on sensory responses requires dissociating it from the top-down influences underlying conscious recognition. Here, using visual masking to abolish perceptual consciousness in humans, we report that functional magnetic resonance imaging (fMRI) responses to invisible faces in the fusiform gyrus are enhanced when they are task-relevant, but suppressed when they are task-irrelevant compared to other object categories. Under conscious perceptual conditions, task-related modulations were also present but drastically reduced, with visible faces always eliciting greater activity in the fusiform gyrus compared to other object categories. Thus, task relevance crucially shapes the sensitivity of fusiform regions to face stimuli, leading from enhancement to suppression of neural activity when the top-down influences accruing from conscious recognition are prevented.

XI—Writing on the Page of Consciousness

I identify one particular strand of thought in Thomas Nagel's ‘What Is It Like to Be a Bat?’ (1974), which I think has helped shape a certain conception of perceptual consciousness that is still prevalent in the literature. On this conception, perceptual consciousness is to be explained in terms of a special class of properties perceptual experiences themselves exhibit. I also argue that this conception is in fact in conflict with one of the key ideas that supposedly animates Nagel's argument in ‘What Is It Like to Be a Bat?', which is the idea of an intimate connection between the idea of consciousness and that of a point of view.

Body-scaled affordances in sensory substitution.

The research field on sensory substitution devices has strong implications for theoretical work on perceptual consciousness. One of these implications concerns the extent to which the devices allow distal attribution. The present study applies a classic empirical approach on the perception of affordances to the field of sensory substitution. The reported experiment considers the perception of the stair-climbing affordance. Participants judged the climbability of steps apprehended through a vibrotactile sensory substitution device. If measured with standard metric units, climbability judgments of tall and short participants differed, but if measured in units of leg length, judgments did not differ. These results are similar to paradigmatic results in regular visual perception. We conclude that our sensory substitution device allows the perception of affordances. More generally, we argue that the theory of affordances may enrich theoretical debates concerning sensory substitution to a larger extent than has hitherto been the case.

Nietzsche's Pluralism about Consciousness

In this paper I argue that Nietzsche's view on consciousness is best captured by distinguishing different notions of consciousness. In other words, I propose that Nietzsche should be read as endorsing pluralism about consciousness. First, I consider the notion that is preeminent in his work and argue that the only kind of consciousness which may fit the characterization Nietzsche provides of this dominant notion is self-consciousness (Sconsciousness). Second, I argue that in light of Nietzsche's treatment of perceptions and sensations we should conclude that he takes each of such state types to involve a specific kind of consciousness which differs from Sconsciousness. I label these two additional kinds of consciousness perceptual consciousness (Pconsciousness) and qualitative consciousness (Qconsciousness), respectively. I conclude the paper with some remarks on how, in Nietzsche's picture, these three different kinds of consciousness might relate.

P3b, consciousness, and complex unconscious processing

How can perceptual consciousness be indexed in humans? Recent work with ERPs suggests that P3b, a relatively late component, may be a neural correlate of consciousness (NCC). This proposal dovetails with currently prevailing cognitive theory regarding the nature of conscious versus unconscious processes, which holds that the latter are simple and very brief, whereas consciousness is ostensibly required for more durable, complex cognitive processing. Using a P3b oddball paradigm, we instead show that P3b and even later, related slow wave activity occur under rigorously subliminal conditions. Additional principal component analysis (PCA) further differentiated the presence of both P3a and P3b components, demonstrating that the latter indeed occurred subliminally. Collectively, our results suggest that complex, sustained cognitive processing can occur unconsciously and that P3b is not an NCC after all.

Sensorimotor Theory and Enactivism

The sensorimotor theory of perceptual consciousness offers a form of enactivism in that it stresses patterns of interaction instead of any alleged internal representations of the environment. But how does it relate to forms of enactivism stressing the continuity between life and mind (and more particularly autopoiesis, autonomy, and valence)? We shall distinguish sensorimotor enactivism, which stresses perceptual capacities themselves, from autopoietic enactivism, which claims an essential connection between experience and autopoietic processes or associated background capacities. We show how autopoiesis, autonomous agency, and affective dimensions of experience may fit into sensorimotor enactivism, and we identify differences between this interpretation and autopoietic enactivism. By taking artificial consciousness as a case in point, we further sharpen the distinction between sensorimotor enactivism and autopoietic enactivism. We argue that sensorimotor enactivism forms a strong default position for an enactive account of perceptual consciousness.

Electrostimulation mapping of comprehension of auditory and visual words

In order to spare functional areas during the removal of brain tumours, electrical stimulation mapping was used in 90 patients (77 in the left hemisphere and 13 in the right; 2754 cortical sites tested). Language functions were studied with a special focus on comprehension of auditory and visual words and the semantic system. In addition to naming, patients were asked to perform pointing tasks from auditory and visual stimuli (using sets of 4 different images controlled for familiarity), and also auditory object (sound recognition) and Token test tasks. Ninety-two auditory comprehension interference sites were observed. We found that the process of auditory comprehension involved a few, fine-grained, sub-centimetre cortical territories. Early stages of speech comprehension seem to relate to two posterior regions in the left superior temporal gyrus. Downstream lexical-semantic speech processing and sound analysis involved 2 pathways, along the anterior part of the left superior temporal gyrus, and posteriorly around the supramarginal and middle temporal gyri. Electrostimulation experimentally dissociated perceptual consciousness attached to speech comprehension. The initial word discrimination process can be considered as an “automatic” stage, the attention feedback not being impaired by stimulation as would be the case at the lexical-semantic stage. Multimodal organization of the superior temporal gyrus was also detected since some neurones could be involved in comprehension of visual material and naming. These findings demonstrate a fine graded, sub-centimetre, cortical representation of speech comprehension processing mainly in the left superior temporal gyrus and are in line with those described in dual stream models of language comprehension processing.

Feed-forward: on the future of twenty-first-century media

Even as media in myriad forms increasingly saturate our lives, we nonetheless tend to describe our relationship to it in terms from the twentieth century: we are consumers of media, choosing to engage with it. In Feed-Forward, Mark B. N. Hansen shows just how outmoded that way of thinking is: media is no longer separate from us but has become an inescapable part of our very experience of the world. Engaging deeply with the speculative empiricism of philosopher Alfred North Whitehead, Hansen reveals how new media call into play elements of sensibility that deeply affect human selfhood without in any way belonging to the human. From social media to datamining to new sensor technologies, media in the twenty-first century work largely outside the realm of perceptual consciousness, yet at the same time inflect our every sensation. Understanding that paradox, Hansen shows, offers us a chance to put forward a radically new vision of human becoming, one that enables us to reground the human in a non-anthropocentric view of the world and our experience in it.

Perceptual Objectivity and Consciousness: A Relational Response to Burge’s Challenge

My question is: does phenomenal consciousness have a critical role in explaining the way conscious perceptions achieve objective import? I approach it through developing a dilemma I label ‘Burge’s Challenge’, which is implicit in his approach to perceptual objectivity. It says, crudely: either endorse the general structure of his account of how objective perceptual import is achieved (an account I label ‘Caused Representation’), and give up on a role for consciousness. Or, relinquish Caused Representation, and possibly defend a role for consciousness. Someone I call Burge* holds we should embrace the first horn of the dilemma. A second response, roughly the relationalist approach, opts for the second horn. The third option, implicit in many current approaches to perceptual consciousness, is to reject the dilemma. The paper argues for a version of the second response. The key argument turns on the development of a sceptical challenge to justify the assumption that we perceive particular intrinsic property instantiations, rather than their structural equivalents. The suggestion will be that only the relationalist approach can meet it in the way we think it is met. If this is right, there is a prima facie case for taking relationalist responses to the dilemma seriously. I end with two objections to this response, which might be made by the real Burge in defence of opting for the first horn of the dilemma, and by phenomenal intentionalists in defence of rejecting the dilemma. I use discussion of these to highlight one of the main issues that should be pursued in order to make good the claim that we should embrace the horn of the dilemma that Burge* rejects.

Occipital MEG Activity in the Early Time Range (

Two electrophysiological components have been extensively investigated as candidate neural correlates of perceptual consciousness: An early, occipitally realized component occurring 130-320 ms after stimulus onset and a late, frontally realized component occurring 320-510 ms after stimulus onset. Recent studies have suggested that the late component may not be uniquely related to perceptual consciousness, but also to sensory expectations, task associations, and selective attention. We conducted a magnetoencephalographic study; using multivariate analysis, we compared classification accuracies when decoding perceptual consciousness from the 2 components using sources from occipital and frontal lobes. We found that occipital sources during the early time range were significantly more accurate in decoding perceptual consciousness than frontal sources during both the early and late time ranges. These results are the first of its kind where the predictive values of the 2 components are quantitatively compared, and they provide further evidence for the primary importance of occipital sources in realizing perceptual consciousness. The results have important consequences for current theories of perceptual consciousness, especially theories emphasizing the role of frontal sources.

Understanding visual consciousness in autism spectrum disorders.

The paper focuses on the question of what the (visual) perceptual differences are between individuals with autism spectrum disorders (ASD) and typically developing (TD) individuals. We argue against the view that autistic subjects have a deficiency in the most basic form of perceptual consciousness—namely, phenomenal consciousness. Instead, we maintain, the perceptual atypicality of individuals with autism is of a more conceptual and cognitive sort—their perceptual experiences share crucial aspects with TD individuals. Our starting point is Ben Shalom’s (2005, 2009) three-level processing framework for explaining atypicality in several domains of processing among autistics, which we compare with two other tripartite models of perception—Jackendoff’s (1987) and Prinz’s (2000, 2005a, 2007) Intermediate Level Hypothesis and Lamme’s (2004, 2006, 2010) neural account of consciousness. According to these models, whereas the second level of processing is concerned with viewer-centered visual representations of basic visual properties and incorporates some early forms of integration, the third level is more cognitive and conceptual. We argue that the data suggest that the atypicality in autism is restricted mainly to the third level. More specifically, second-level integration, which is the mark of phenomenal consciousness, is typical, yet third-level integration of perceptual objects and concepts is atypical. Thus, the basic experiences of individuals with autism are likely to be similar to typical subjects’ experiences; the main difference lies in the sort of cognitive access the subjects have to their experiences. We conclude by discussing implications of the suggested analysis of experience in autism for conceptions of phenomenal consciousness.