One commenter didn't like my take on Cotard's last week. I ran it past a couple of friends who said they had no problems with it and I'm not an expert, just an interested researcher. Its a good chance to say if I'm wrong or you disagree please let me know. If I need to change anything I will and if you want to argue then I might, depending on my free time :)

Following on from Cotard’s Syndrome last week I wanted to talk a little about a related condition that is equally interesting, Capgras Delusion. Where Cotard’s involved the patient doubting their own existence, Capgras is a disconnection between the conscious and unconscious ability to recognize faces resulting in a feeling that the person you are looking at is “not quite right”. This often results in the belief that the person is in fact an impostor, which can be pretty confusing.

I was watching old series of the show Scrubs and it has even come up in one of the later seasons.

It would seem that facial recognition is both a conscious and unconscious act and the disconnect of these two activities leads to problems. An old theory is that the unconscious activity picks up that we are looking a face, fish, block, house etc and provides general information while the conscious part then takes over to provide specifics (wife’s face, Murray Cod, Lego, Home, for example). If the unconscious part works but the conscious part doesn’t then it’s hard to add specifics to the image in your head. Conversely, if the unconscious part doesn’t work properly then you lack the immediate emotional input when faced with an image, leading to a sense of unease about the subject being viewed.

These two competing ideas were the basis for debate in scientific circles for a long time but in recent years more evidence has become available showing that the second theory, that the unconscious process of attributing general associations including emotions is impaired in Capgras patients appears to be gaining support.

While evidence mounts for this newer theory it is by no means beyond all reasonable doubt. Specialised cases where only one or a few faces trigger the disassociation don’t seem to fit and the complete answer may lie with understanding the contribution of the whole suite of mental heath problems that are sometimes associated with Capgras, like schizophrenia.

Like Cotard’s Syndrome, Capgras is fascinating and underlies just how much goes on behind our eyes without us even realizing, until it starts to malfunction.