What is Consciousness?

On one level this might seem like a stupid question1. Of course, you might say, we experience consciousness most of the time when we are awake and even some of the time when we are asleep. Although this is true, the nature and role of consciousness are matters of intense debate within psychology and philosophy with little prospect of being resolved soon. That is why it is so refreshing that recent theory and data in neuroscience are offering some insight into how consciousness is manifest in the brain.

It is called the global workspace theory and was first presented by Bernard Baars of the Neuroscience Institute in San Diego, California. According to this theory, non-conscious experiences are processed locally within separate regions of the brain. We only become conscious of this information if these signals are broadcast to assembly of neurons distributed across many different regions of the brain—the global workspace, which then reverberates in a flash of coordinated activity. This coordinated activity produces a mental interpretation of the world that has integrated all the senses into a single picture. This is obviously related to the previous blog post “The Two System View of Cognition.” The two systems are System 1, Intuition, and System 2, Reasoning. System 1 processes information every quickly below the level of consciousness. When a visual event occurs it would be processed locally in the visual cortex. For the even to become conscious it would need to be broadcast to an assembly of neurons distributed across many regions of the brain. This produces consciousness and is a limited System 2 Process. We are extremely limited in the amount of information to which we can attend. Apparently this is due to this activation of large areas of the brain. When we driving most of the activation is local and occurs below the level of awareness. A slowing or stopping vehicle ahead of us can lead to this wider broadcast to many regions of the brain. We then become conscious of the need to slow down or stop and act accordingly.

This neural activity has been documented in brain imaging studies (See the blog post, “How Can the Brain Be Imaged?”).

Conflicting pieces of information are filtered out. This is an important feature as our attentional resources are quite limited. We cannot perceive two perceptions at once. This is evident in such ambiguous visual illusions as the Necker Cube, which changes in depth, the profile/vase illusions, in which you see either two human profiles or a vase, and the My Wife and My Mother-in-Law illusion, in which the two perceptions are of a beautiful young lady with her head turned away, or the profile of a very old woman. Although we can rapidly alternate between the two percepts, they cannot be perceived simultaneously. They also do experiments in which different images are projected to each eye. Rather than merge the two percepts, only one percept can be perceived at a time.

1This post is based largely on an article by Anil Ananthaswamy. (2010). Brain Chat. New Scientist, 20 March, 38-41.

© Douglas Griffith and healthymemory.wordpress.com, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.


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