Monday, January 29, 2007

Encephalon #15 and the Capgras Delusion

The 15th Edition of Encephalon is now out at SharpBrains!

An excellent roundup of blogposts as usual, however, one post caught my eye in particular: The limits of rational thought at Neurontic (Author: Orli). It discusses a book by Richard Powers ("The Echo Maker"), the subject of which is suffering from a rare condition known as Capgras Delusion (which manifests itself after severe head trauma). In this condition, the sufferer has the sincere belief that those persons closest to them (a sister in this story) is an imposter - i.e. the person is recognised as being known, however, the reaction is to think that it is someone impersonating the loved one. If I might use a quote from the blog post, which succinctly describes the neurological fault:

"Capgras Delusion is now believed to be a neurological syndrome caused by faulty wiring between the two areas of the brain involved in facial recognition: the temporal lobe, which contains pathways specializing in identifying faces, and the limbic system, which is responsible for attributing emotional significance to these faces. "

The first time I came across this syndrome was as a case study explored by V.S. Ramachandran ("Phantoms in the Brain"), where he described a young man, also suffering from Capgras Delusion, who thought his parents were imposters. Going back to the blog post, it was mentioned that Damasio studied people with brain damage such that they did not have the regions known to be required for emotion-related processing. His findings are quite astonishing: those with this disability were unable to make even the simplest of decisions. Again if I may, a quote of a quote in the blog post:

"And Damasio's conclusion is that unless you have the emotional inputs, you can never evaluate between the logical possibilities."

Orli's post finishes with a comment on making snap decisions: research conducted has indicated that snap decisions are often better than those made with the input of the 'higher cognitive processes'. My thoughts naturally turn to the implications of Damasio's conclusions to my own work: cognitive robotics. We, as humans, consider ourselves to be rational beings, capable of 'cold, hard logic'. However, the evidence provided by the sufferers of the Capgras Delusion suggest otherwise: that emotion in intimitely linked to cognitive processing, and more importantly, to decision making. This may have profound implications for the way in which cognitive models in general are approached - it seems as though an internal means of evaluating between the 'rational' choices is required, a value function if you will. In other words, emotions, or emotion-like constructs. From my perspective, it seems as though cognitive models are at the moment viewing the human cogntive system from the 'cold, hard logic' point of view, although I believe that this is slowly changing.

As always, thoughts and comments are more than welcome - I seek to learn.

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