Thursday, August 21, 2014

The source of consciousness.

Paller and Suzuki do a compact review on efforts to define the source of consciousness, arguing against the mysterian position that consciousness is beyond the scope of human understanding. They suggest that this position is like many other flaws in our common intuitions about consciousness. One of these is that if you direct your attention to something you must be aware of it. Not so, as this motion-induced blindness example demonstrates when you focus your attention on the central dot, with three surrounding yellow dots:

(to convince yourself the disappearing yellow dots are in fact always there enlarge the graphic to full screen and simply look at the wall or view beyond your tablet or monitor, perhaps scanning it back and forth, while letting the yellow dots remain in your peripheral vision.)

If paying attention doesn't guarantee awareness (as is the case in blindsight - in which objects can be discriminated without awareness of seeing them), what is the crucial ingredient? Current work suggests that exchange of information between specific cortical areas seems to be essential.

A clip:
The awareness we each have of our own body and our place in the world seems to be distinctly natural and fundamental. Yet the conscious experience of having a body can be bizarrely disrupted in patients with right parietal damage, who sometimes deny ownership of an entire arm. The rubber-hand illusion is another striking phenomenon, whereby seeing someone rubbing a fake hand while feeling the simultaneous tactile sensation on your own hand momentarily makes you feel that the fake hand is yours. In an even more extreme way, altered neural activity can produce an out-of-body experience.
These unusual perceptual experiences are no less ‘real’ than the sensation of a self inside a body. This standard way we each think of our self is a manufactured sensation, learned on the basis of sensory relationships across modalities. Awareness of a self inhabiting a body is not as obligatory as it seems: it is likely to have evolved for a behavioral advantage.
Why does the brain construct the sensation of a self inside a body? One answer appeals to the idea that you fare better in a social environment when you can attend to your own needs and predict what will happen next, including what other people are going to do. To make this work, specific brain mechanisms evolved to construct models of the attention and intentions of others and to localize them in the corresponding people's heads. The social neuroscience theory of consciousness [see my post on Graziano's ideas] postulates that these same brain mechanisms were adapted to construct a model of one's own attention and intentions, localized in one's own head and perceived as consciousness. If so, a primary function of consciousness is to allow us to predict our own behavior.
Another fragment of text:
...the neural processes that generate the subjective timing of a conscious decision that is seemingly instantaneous may be separate from the more protracted, unconscious processes that generate the content of the decision. The feeling of freely deciding at the precise time of our choosing may be a widespread illusion, albeit a beneficial one that promotes moral behavior and helps us to flourish as social beings.
When we recognize the shortcomings of common assumptions about consciousness, we are in a better position to develop an integrative understanding of the origin, evolution, development, and subjectivity of consciousness. Instead of emphasizing a single paradigm for examining awareness, we can be enriched by enlisting a variety of approaches, combining functional, biological, social, and computational perspectives.

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