Symposia

Symposium 1: Attention and Consciousness

Chair: Tobias Schlicht
Institut für Philosophie
Ruhr-Universität Bochum

Summary: The symposium addresses conceptual and empirical issues regarding the relationship between attention and consciousness: Is attention necessary or sufficient for consciousness? What is the impact of an investigation of attention on the relation between phenomenal consciousness and access consciousness? Can we have phenomenology as of the specific details of a scene or object in the absence of attention and cognitive accessibility? Is an investigation of atten- tion a reliable guide to conscious experience? Is it possible to isolate the mechanisms of atten- tion from the mechanisms of subjective experience? How should we adequately interpret experimental demonstrations of change blindness and inattentional blindness in this context? In what way do these phenomena inform us about the nature and content of our mental representations? Based on their impressive previous work in the field of consciousness studies, the three speakers try to shed more light on these issues, arguing for different perspectives.

Talk 1: Does phenomenal consciousness outstrip cognitive access?

Alva Noë
Department of Philosophy
University of California, Berkeley

Does phenomenal consciousness outstrip cognitive access, as Block (2007) has argued? In this talk I explore this question. I give close attention to the interpretation of empirical evidence bearing on the issue. I discuss change blindness – what does it really teach us about visual consciousness? – looking closely at recent work from the laboratory of Lamme (e.g. Sligte et al 2008). I also consider evidence from the neurosciences bearing on the neural substrates of states of phenomenal consciousness. I suggest, finally, that we need new ideas about consciousness, cognition and their neural substrates to untangle these puzzles. I show how a new approach (O’Reagan and Noë 2001; No‘ 2004, 2009) provides the needed resources.

Talk 2: Towards a Taxonomy of Visual Attention

Ronald Rensink
Departments of Psychology and Computer Science
University of British Columbia

Although recent work has improved our understanding of visual attention, it remains poorly understood. In fact, it is not even clear how best to talk about it: Is it a faculty or a resource, a process or a thing? Should it be characterized in terms of limited capacity or selectivity, effort or clarity? And how does it relate to awareness? It is proposed that a useful way to analyze visual attention is via a computational approach similar to that advocated by Marr (1982). It is argued that processes requiring attention are exactly those that require selection in their input. Possible types of selectivity are discussed and suggestions made as to how these relate to each other. It is also suggested that there may be a similar fractionation of visual awareness into several different modes, and that these may be related to different types of attention.

Talk 3: Attention, Seeing, and Change Blindness

Michael Tye
Department of Philosophy
The University of Texas at Austin

Some theorists maintain that there is a very tight connection between attending to a thing and seeing (or being visually conscious) of that thing. This talk sides with those who hold that there is such a connection but it is denied both that attending to a thing in the visual case requires seeing it and that seeing a thing requires attending to it. The talk also draws out the consequences of a proper understanding of the relationship of attention and seeing for a proper understanding of change blindness.

Symposium 2: Mirroring the Self and Others

Chair: Noam Sagiv
Centre for Cognition and Neuroimaging
Brunel University

Summary: Our perception of our own body and our senses of self can sometimes be disrupted. Indeed we have learnt a great deal from studying the deficits of neurological patients. However, there is much to be learnt from positive symptoms shown by patients, and in some cases otherwise healthy individuals. These often force us to examine our own assumptions about the mind and brain and doubt what many have been taking for granted. Phantom limbs, for example, have fascinated scientists and philosophers alike. The present symposium, Peter Brugger will examine a number of problems from duplicated limbs and anarchic limbs and to whole body duplication. Out-of-body experience and the double illusion belong to a class of ‘autoscopic phenomena’. While such mirroring of oneself can occur in clinical populations, Olaf Blanke will show that it can also be induced experimentally in the laboratory. A different kind of mirroring will be discussed by Jamie Ward – mirror touch synaesthesia in which individuals actually have tactile experiences while watching others receive a tactile stimulus. The speakers will discuss the phenomenological, cognitive, and neural basis of several anomalies of bodily awareness. Some of the phenomena presented here received very little attention in the scientific literature so far, but it becomes increasingly clear that they offer a unique point of view of the topic and provide an opportunity to test theories concerning the self.

Talk 1: Your body is my body: The remarkable ‘mirror touch’ synaesthesia

Jamie Ward
Department of Psychology
University of Sussex

For some people, watching other people being touched may trigger conscious tactile experiences projected on to their own body – this has been termed ‘mirror touch’ synaesthesia. In this talk, I’ll outline its cognitive and phenomenological characteristics. Visuo-tactile cuing experiments show that it occurs automatically; it may be as common as 1–2% of the population; it depends primarily on observed touch to humans, not objects; and is sensitive to the spatial relationship between self and other. It may reflect hyper-activity within an observed touch network which is common to synaesthetes and non-synaesthetes alike, but in which these individuals tend to incorporate observed bodies of other people within their own body schema Ð resulting in a blurring between self and other at some sensorimotor level.

Talk 2: Anarchic limbs, anarchic bodies: hostility in the breakdown of corporeal awareness

Peter Brugger
Neuropsychology Unit, Department of Neurology
University Hospital, Zurich

While “alien” limbs are characterized by the sense of non-belonging to the own body, the sign of the “anarchic limb” involves the loss of control over intentional, goal- directed motor behaviour. Anarchism against the own self ranges from the mildly queer (one hand hinders the other) to highly embarrassing acts (e.g. masturbation in public). Often, self-destructive tendencies are obvious (pinching one’s nipples, attempts at strangling or drowning oneself). The view of a smooth transition from the personification of single limbs to heautoscopy, i.e. the encounter with a second self, or doppelganger, would predict that similar forms of self-destruction can also be observed between a patient and his or her phantom double. The present talk provides an overview of different manifestations of anarchic behaviour displayed by doppelgangers, both as described in the belletristic literature and in neuropsychiatric case reports. The role of the right hemisphere in mediating hostility is specifically addressed.

Talk 3: Merging cognitive neuroscience with virtual reality to study self-consciousness

Olaf Blanke
Laboratory of Cognitive Neuroscience, Brain Mind Institute
Swiss Federal Institute of Technology, Lausanne, and
Department of Neurology, University Hospital, Geneva

I will present three lines of research investigating brain correlates of the bodily self- consciousness. (1) Pathological states of self location, first-person perspective, and self-identification (such as out-of-body experiences and autoscopic hallucinations) due to disturbed multisensory integration after focal brain damage to temporo-parietal cortex and extrastriate cortex in neurological patients. (2) The experimental manipulation of bodily self-consciousness in healthy subjects using multisensory visuo-tactile conflict and virtual reality technology. (3) Neuroimaging data during experimentally altered states of self-location and self-identification using an exciting new research platform (linking virtual reality and high resolution EEG). I will conclude by describing a philosophically-informed neurobiological model of self consciousness.

Symposium 3: Visual Perception Across Short Timescales

Chair: Niko Busch
Centre de Recherche Cerveau et Cognition (CerCo)
Facultè de Mèdecine Rangueil, Toulouse

Summary: Perception that unfolds over short timescales (lasting a few hundred milliseconds or less) exhibits a number of interesting temporal phenomena. Such phenomena include temporal illusions such as the wagon wheel illusion, the flash lag illusion and coincidence (or fusion) thresholds, which presumably illustrate the constraints of underlying neural processes. The neural basis of these temporal phenomena has received increased attention in recent years but we are still some way from fully understanding their underlying causes. Most of this research has been done with visual stimuli, and only lately have studies begun to look at the occurrence of these phenomena in other sensory systems and at crossmodal stimuli. This symposium will explore three themes relating to visual perception over short timescales, by focusing on the following topics: the discreteness of visual perception, temporal illusions and, the perception of simultaneity.

Talk 1: Is perception discrete or continuous?

Rufin VanRullen
Centre de Recherche Cerveau et Cognition (CerCo)
Faculté de Médecine Rangueil, Toulouse

The widespread idea that brain oscillations and rhythmic neuronal processes participate in sensory processing, and more particularly in conscious perception, could imply that perception is generated cyclically, as a sequence of individual “snapshots”. What is the behavioral evidence for such “discrete perception”? I will present a series of experiments showing that perception and attention sometimes follow the intrinsically rhythmic dynamics of particular oscillatory brain processes in the theta (4–8Hz) and alpha (8–13Hz) frequency bands.

Talk 2: Perceived timing, transients and feature binding

Ryota Kanai
Institute of Cognitive Neuroscience
University College London

Visual illusions such as the flash-lag effect and asynchronous feature processing revealed our perception of temporal relationship of events could be dissociated from physical input. In this talk, I discuss that tokenization of an event – a process of constructing an object-surface representation to which features are bound – takes an additional time to complete and results in a delay in perceived timing. I present experiments showing that perceived timing of a visual event is delayed when it is defined as an appearance of a new object, whereas feature changes are updated instantaneously. The delay for tokenization offers an explanation to various visual illusions of time as well as impairments in temporal processing observed in parietal patients. On the other hand, perceived duration of an event is determined by an initial onset transient, which is processed unconsciously before the tokenization.

Talk 3: Vision and perceived simultaneity

Valtteri Arstila
Department of Philosophy & Centre Cognitive Neuroscience
University of Turku, Finland

The simultaneity of external events does not imply that these events are perceived as simultaneous. Likewise, events that are perceived as simultaneous do not necessarily occur simultaneously. On the other hand, when two stimuli are not perceived as simultaneous, one would assume that their temporal order can be determined. Yet this is not the case. In this talk, we consider these issues in the context of vision. It will be argued that this visual simultaneity is due to mechanisms that are largely independent of mechanisms related to temporal order judgments. Visual simultaneity is nevertheless a transitive relation: if events A and B are perceived as simultaneous and events B and C are perceived as simultaneous then A and C must also be perceived as simultaneous. This latter claim has been challenged by some philosophers and by recent work in cognitive neuroscience.

Symposium 4: Measuring consciousness: Neurophysiological and behavioral approaches

Chair: Anil Seth
Department of Informatics
University of Sussex

Summary: How can we measure whether a particular sensory, motor, or cognitive event is consciously experienced or remains unconscious? Such measurements provide the essential data on which a science of consciousness depends, yet there is no clear consensus on how such measurements should be made. Our speakers will describe both behavioral and neurophysiological approaches to measuring consciousness, relating these approaches to each other and to relevant theoretical frameworks. Issues include (i) graded versus dichotomous notions and measures of consciousness, (ii) convergence and divergence among measures, and what this reveals about the unity of consciousness, (iii) measures of conscious content versus conscious level, and (iv) the role of higher-order cognition in conscious report. Advances in measuring consciousness have implications for basic cognitive science and neuroscience, for comparative studies of consciousness, and for clinical applications.

Talk 1: A framework for measuring consciousness

Anil Seth
Department of Informatics
University of Sussex

Measures of consciousness cannot exist independently of theory. Only by behaving sensibly in a theoretical context do proposed measures pick themselves up by the bootstraps, validating both themselves as measures of what they say they measure and also validating the theories involved. Much of what we know derives from subjective (introspective) verbal report, but on some theories such reports confound mechanisms of metacognitive access with mechanisms of consciousness and are also susceptible to biases. In response, there has been a growing emphasis on neurophysiological measures as well as on behavioral measures that do not rely on introspection. But for these ‘objective’ measures it can be hard to guarantee that they are measuring consciousness per se. I will review definitional, methodological, and conceptual issues surrounding the problem of measuring consciousness and describe some specific examples based on measures of complexity and causal density in neural dynamics.

Talk 2: Confidence, gambling and control: Dissociating measures of the conscious status of knowledge

Zoltan Dienes
Department of Psychology
University of Sussex

Unconscious knowledge is knowledge we have, and could very well be using, but we are not aware of. The most straightforward method of determining whether a person is aware of knowing is to ask the person after a judgment whether they knew the answer (to some degree) or were guessing (verbal confidence). Confidence can also be measured with gambling, though not with wagering, and also imperfectly by whether the person is willing to base control on the knowledge (Jacoby’s process dissociation procedure). Such confidence measures show whether or not the person is aware of knowing the content of the judgment, but not whether the person is aware of what any knowledge was that enabled the judgment. Thus, a distinction is made between judgment and structural knowledge, and it is shown how the conscious status of the latter can also be assessed, which is important for implicit learning research. I will show empirical dissociations between all these different measures, and on what basis any one of them could take precedence.

Talk 3: Measuring consciousness through neural coherence

Andreas Engel
Dept. of Neurophysiology and Pathophysiology
University Medical Center Hamburg-Eppendorf

It has been proposed that synchronization of neural signals may be involved in several processes indispensable for awareness, including arousal, perceptual integration, attentional selection, and working memory. Indeed, recent evidence from both animal and human studies demonstrates specific changes in neuronal coherence and, moreover, the emergence of fast oscillations with frequencies in the gamma-range during these processes. These results suggest that assessing neuronal coherence may be of critical importance for “measuring consciousness”. The presentation will focus on changes of coherence under anesthesia and in bistable stimulus paradigms. While the former suggests that neural coherence may provide an important variable for measuring changes in levels of consciousness, the latter indicates that it may also be useful for predicting changes in the contents of conscious states.