by emad » Wed Oct 26, 2005 11:39 am
<br>People with schizophrenia may be well attuned to spotting visual illusions, a study suggests. <br><br>Despite experiencing hallucinations as part of their condition, schizophrenic volunteers to a study were better able to spot "real" visions than others. <br><br>The Current Biology work could help shed light on the brain mechanisms involved in schizophrenia, the University College London authors say. <br><br>It might be down to a difficulty dealing with context, they believe. <br><br>For example, people with schizophrenia tend to take less account of the circumstances and conditions that surround a situation or event that often help us to interpret it. <br><br>This could explain why some people with schizophrenia might mis-attribute people's actions or feel persecuted. <br><br>It could also explain why they perform better on visual illusion tests, says Dr Steven Dakin, of UCL's Institute of Ophthalmology. <br><br>"We often think of people with schizophrenia as not seeing the world the way it really is. But we have shown that sometimes their vision can be more accurate than non-sufferers." <br><br> THE VISUAL ILLUSION USED IN THE STUDY <br> <br>The people with schizophrenia were better at spotting that the true match for the central target disc was the peripheral disc at 6 o'clock, while others often mistook the peripheral disc at 10 o'clock as the best match <br><br>His team used an illusion where a failure to use context worked to the advantage of people with schizophrenia. <br><br>He said 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. <br><br>The participants were asked to select which of one of eight peripheral patterned discs was the best match for a central patterned disc that was located within the middle of a larger "distracting" patterned circle. <br><br>The illusion works because normal visual perception leads the individual to believe that the central disc is of lower contrast than it actually is because it is set against a higher-contrast background - the distracting circle. <br><br>Better performance <br><br>Of the 15 volunteers with chronic schizophrenia, 12 were found to make more accurate judgements than the most accurate person in the control group of 33 non-schizophrenic volunteers. <br><br>Dr Dakin said: "Our findings may shed some light on the brain mechanisms involved in schizophrenia. <br><br>"Normally, contextual processes in the brain help us to focus on what's relevant and stop our brains being overwhelmed with information. <br><br>"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." <br><br>Paul Corry, of the charity Rethink, said: "We welcome any new research or progress into understanding the causes of schizophrenia, but it would need to be checked before it would make a difference to the thousands of people living with severe mental illness in the UK. <br><br>"In the meantime, reaching people early with the right care and treatment is the best way of recovering a meaningful and fulfilling life." <br><!--EZCODE AUTOLINK START--><a href="http://news.bbc.co.uk/1/hi/health/4360572.stm">news.bbc.co.uk/1/hi/health/4360572.stm</a><!--EZCODE AUTOLINK END--><br><br> <p></p><i></i>
