Saturday, August 18, 2012

Michael Graziano - Consciousness and the Attention Schema


This is Michael Graziano's talk at the Evolution and Function of Consciousness Summer School ("Turing Consciousness 2012") held at the University of Montreal as part of Alan Turing Year. More info below.


Michael Graziano - Consciousness and the Attention Schema

Abstract:

One possible explanation of awareness is that it is a construct of the social perceptual machinery. Humans have specialized neuronal machinery that allows us to be socially intelligent. The primary role for this machinery is to construct models of other people--minds thereby gaining some ability to predict the behavior of other individuals. In the present hypothesis, specific cortical machinery, notably in the superior temporal sulcus and the temporo-parietal junction, is used to build the construct of awareness and attribute it to other people. The same cortical machinery, in this hypothesis, is also used to attribute awareness to oneself. Damage to this cortical machinery can lead to disruptions in consciousness such as hemispatial neglect. In this theory, the value of the construct of awareness, and the value of attributing it to a person, is to gain a useful predictive model of that person--attentional processing. Attention is a style of information processing in the brain in which neuronal signals compete. One interrelated set of signals rises in strength at the expense of others, and thereby dominates the control of behavior. Awareness, in the present hypothesis, is a construct, a useful schema, that models the dynamics and essential properties of attention. To be aware of X is to construct a model of one--attentional focus on X. A brain concludes it is aware of X, and assigns a high degree of certainty to that conclusion, and reports that conclusion, because of an informational model that depicts awareness of X.
Reference Article:
Graziano, MSA, and Kastner, S. (2011) Human consciousness and its relationship to social neuroscience: A novel hypothesis. Cognitive Neuroscience, 2: 98-113. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3223025/

Here is the abstract and introduction to the paper - they raise the possibility that "awareness is a construct of the social machinery in the brain."

Human consciousness and its relationship to social neuroscience: A novel hypothesis

Michael S. A. Graziano and Sabine Kastner
Princeton University, Department of Psychology, Green Hall, Princeton NJ 08544

Abstract:

A common modern view of consciousness is that it is an emergent property of the brain, perhaps caused by neuronal complexity, and perhaps with no adaptive value. Exactly what emerges, how it emerges, and from what specific neuronal process, is in debate. One possible explanation of consciousness, proposed here, is that it is a construct of the social perceptual machinery. Humans have specialized neuronal machinery that allows us to be socially intelligent. The primary role for this machinery is to construct models of other people’s minds thereby gaining some ability to predict the behavior of other individuals. In the present hypothesis, awareness is a perceptual reconstruction of attentional state; and the machinery that computes information about other people’s awareness is the same machinery that computes information about our own awareness. The present article brings together a variety of lines of evidence including experiments on the neural basis of social perception, on hemispatial neglect, on the out-of-body experience, on mirror neurons, and on the mechanisms of decision-making, to explore the possibility that awareness is a construct of the social machinery in the brain.

“Men ought to know that from the brain, and from the brain only, arise our
pleasures, joys, laughter and jests, as well as our sorrows, pains, griefs and tears.
Through it, in particular, we think, see, hear, and distinguish the ugly from the
beautiful, the bad from the good, the pleasant from the unpleasant…”
~ Hippocrates, Fifth Century, BC.

Introduction

A common neuroscientific assumption about human consciousness is that it is an emergent property of information processing in the brain. Information is passed through neuronal networks, and by an unknown process consciousness of that information ensues. In such a view, a distinction is drawn between the information represented in the brain, that can be studied physiologically, and the as-yet unexplained property of being conscious of that information. In the present article a novel hypothesis is proposed that differs from these common intuitive notions. The hypothesis is summarized in the following five points.

First, when a person asserts “I am conscious of X,” whatever X may be, whether a color, a tactile sensation, a thought, or an emotion, the assertion depends on some system in the brain that must have computed the information, otherwise the information would be unavailable for report. Not only the information represented by X, visual information or auditory information for example, but also the essence of consciousness itself, the inner feeling attached to X, must be information or we would be unable to say that we have it. In this hypothesis, consciousness is not an emergent property, or a metaphysical emanation, but is itself information computed by an expert system. This first point raises the question of why the brain would contain an expert system that computes consciousness. The question is addressed in the following points.

Second, people routinely compute the state of awareness of other people. A fundamental part of social intelligence is the ability to compute information of the type, “Bill is aware of X.” In the present proposal, the awareness we attribute to another person is our reconstruction of that person’s attention. This social capability to reconstruct other people’s attentional state is probably dependent on a specific network of brain areas that evolved to process social information, though the exact neural instantiation of social intelligence is still in debate.

Third, in the present hypothesis, the same machinery that computes socially relevant information of the type, “Bill is aware of X,” also computes information of the type, “I am aware of X.” When we introspect about our own awareness, or make decisions about the presence or absence of our own awareness of this or that item, we rely on the same circuitry whose expertise is to compute information about other people’s awareness.

Fourth, awareness is best described as a perceptual model. It is not merely a cognitive or semantic proposition about ourselves that we can verbalize. Instead it is a rich informational model that includes, among other computed properties, a spatial structure. A commonly overlooked or entirely ignored component of social perception is spatial localization. Social perception is not merely about constructing a model of the thoughts and emotions of another person, but also about binding those mental attributes to a location. We do not merely reconstruct that Bill believes this, feels that, and is aware of the other, but we perceive those mental attributes as localized within and emanating from Bill. In the present hypothesis, through the use of the social perceptual machinery, we assign the property of awareness to a location within ourselves.

Fifth, because we have more complete and more continuous data on ourselves, the perceptual model of our own awareness is more detailed and closer to detection threshold than our perceptual models of other people’s awareness.

The purpose of the present article is to elaborate on the hypothesis summarized above and to review some existing evidence that is consistent with the hypothesis. None of the evidence discussed in this article is conclusive. Arguably, little conclusive evidence yet exists in the study of consciousness. Yet the evidence suggests some plausibility to the present hypothesis that consciousness is a perception and that the perceptual model is constructed by social circuitry.

The article is organized in the following manner. First the hypothesis is outlined in greater detail (Awareness as a product of social perception). Second, a summary of recent work on the neuronal basis of social perception is provided (Machinery for social perception and cognition). A series of sections then describes results from a variety of areas of study, including hemispatial neglect, cortical attentional processing, aspects of self perception including the out-of-body illusion, mirror neurons as a possible mechanism of social perception, and decision-making as a means of answering questions about one’s own awareness. In each case the evidence is interpreted in light of the present hypothesis. One possible advantage of the present hypothesis is that it may provide a general theoretical basis on which to understand and fit together a great range of otherwise disparate and incompatible data sets.
Read the whole interesting paper.
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