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SUMMARY:Disturbing vision - Arnold Wilkins\, Professor of Visual Perceptio
 n at the University of Essex
DTSTART:20110302T160000Z
DTEND:20110302T170000Z
UID:TALK28722@talks.cam.ac.uk
CONTACT:Saba Hinrichs
DESCRIPTION:Images with certain spatial or temporal periodicity\, and stro
 ng colour contrast can be responsible for discomfort.  Images with these c
 haracteristics are rare in the natural images to which the human visual sy
 stem has adapted and\, perhaps for this reason\, natural images are genera
 lly more comfortable than those that are unnatural. Text has the character
 istics of an uncomfortable image\, and there are simple steps that can be 
 taken to reduce the discomfort. Uncomfortable (and unnatural) visual stimu
 lation gives rise to strong physiological excitation in the visual cortex 
 of the brain and some people\, such as those with migraine\, are far more 
 susceptible to such strong excitation than others. Functional magnetic res
 onance imaging and near infrared spectroscopy indicate that the excitation
  induced by strong visual stimulation can be reduced by coloured filters i
 ndividually chosen to reduce discomfort\, and filters of  different colour
  are without effect. The benefits of coloured filters on accommodation\, o
 n reading speed\, and on other higher perceptual function can be understoo
 d as due to a reduction of over-excitation\, with implications for treatme
 nt in a variety of medical conditions in which the cortex is hyperexcitabl
 e\, and with implications also for the idiosyncratic manner in which colou
 r is coded within the higher levels of the visual system. 
LOCATION:Arthur Marshall Meeting Room (next to EDC loft)\, Inglis Building
 \, Engineering Department
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