October 24, 2005

Schizophrenia - Visual Context

Read more... Schizophrenia Biology

Scientists have discovered that schizophrenia sufferers are not fooled by a visual illusion and are able to judge it more accurately than observers who do not have schizophrenia. The study by UCL (University College London) and King's College London suggests that in everyday life, people who have schizophrenia take less account of visual context. If this is part of a more general failure to deal appropriately with context, it could explain why some sufferers might misattribute people's actions or feel persecuted.

The study, published in the journal Current Biology, used an illusion where an object's contrast appears reduced by its surroundings. A medium-contrast patterned disc was shown to volunteers, who had to judge its appearance in the presence of a high-contrast background. Of the 15 participants with chronic schizophrenia, 12 were found to make more accurate judgments than the most accurate person in a control group of 33 non-schizophrenic volunteers.

Dr Steven Dakin, of the UCL Institute of Ophthalmology, says: "We often think of people with schizophrenia as not seeing the world the way it really is – for example, during hallucinations – but we have shown that sometimes their vision can be more accurate than non-sufferers.

"The trick here was to use an illusion where a failure to use context worked to the advantage of people with schizophrenia. This was critical because people can perform poorly for lots of reasons, but superior performance tends to be for a specific reason and is more revealing of the underlying cause.

"Our findings may shed some light on the brain mechanisms involved in schizophrenia. Normally, contextual processes in the brain help us to focus on what's relevant and stop our brains being overwhelmed with information. This process seems to be less effective in the schizophrenic brain, possibly due to insufficient inhibition – that is, the process by which cells in the brain switch each other off."

For more information: BBC News: http://news.bbc.co.uk/1/hi/health/4360572.stm

Source: University College London


As a person who lives with someone with sch, I can say that this study seems very true and enlighting. We always think of people with sch as of those who lack skills or other, while in fact they have a trouble of having too much. They would easily spot a fear or doubt in someones eyes, dispate of what the person is saying or doing, and that fear would trigger their fear and they would get paranoid. They would stick to the detail they see on someones face, rather then to the whole persons doings.
Best wishes to all scientists.

Posted by: kattie at October 25, 2005 02:01 AM

This is fascinating to me as someone with sz. I am wondering what other "skills" we have. All this time, people have been trying to measure our "deficits" in various areas--memory, executive function, etc,. Perhaps we could find tasks where this type of skill would be useful. This type of study is very encouraging to me, reminding me that my mind simply works in a different way than that of others and that many of the day to day problems that I face are not actually my problems, but the fact that society is built around the way that non-sz's use their minds as opposed to mine.

Posted by: Lluvia Zuniga at October 25, 2005 09:19 PM

I'm pleased that the the posters think that the work rings true and it offers a more positive slant on differences arising from schizophrenia. In terms of looking for other ways that these perceptual differences might manifest themselves, we are, as the last poster suggests, now actively engaged in looking for other ways that less reliance on context might affect other perceptual abilities including the perception of motion, colour and more complex tasks like facial expression.

Posted by: Steven Dakin at October 27, 2005 01:22 AM

as a chizo I am also following al there is abouth it, an reading thit article I remember seeing a documentay long ago how this illness is threated in africa by old aincient medicin ,and I saw a medicine man treating scizo patients saying it is a disease of the eyes and used a sort of ointment.i'm very surprised to read this.I expirienced some strange vision delusions as perspective changing,surrounding changing size so for me its plausible that the medicineman whas right all the time.thanks!

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