Your peripheral vision may be an optical illusion

According to a recently published study, the human brain can in some circumstances deceive you into seeing things in your periphery that aren’t really there by ‘filling in the blanks’.Researchers from the UK and Netherlands believe it does this by tricking us into thinking we have the same capacity for processing visual information at the edge of our vision as we do in the centre field.As a result, Ms Marte Otten – a professor of cognitive and social psychology involved in the study – believes under the right circumstances a large part of the periphery may in fact be a visual illusion. This effect ses to hold for many basic visual features, indicating that this ‘filling in’ is a general, and fundamental, perceptual mechanism, she said.To test the theory, Otten and her team recruited 20 volunteers who were shown a series of images – each one containing a subject at the centre – which were then gradually joined by a different picture fading in from the edge.The test participants were asked to click a mouse button the moment they saw both parts become a singular image, ie when the central image matched that of the picture in the periphery.In some instances, participants incorrectly identified a uniform image before the two pictures had actually matched.Researchers believe the brain trying to compensate for the lack of detail in the second image, in order to match it with the first, could have triggered this response. Perhaps our brain fills in what we see when the physical stimulus is not rich enough, Otten said.The team also changed attributes of the images in terms of shape, shade, luminosity, motion and orientation, but this had no documented effect on the optical illusions.However, the illusion was less likely to occur when the central and periphery images were significantly different – and in cases where it did, the ‘filled in’ image took longer to appear.The team pointed out that the results could not be generally conclusive because only 20 people were tested, but it did open up avenues for further research on central and peripheral vision. We hope to use this illusion as a tool to uncover why peripheral vision ses so rich and detailed, Otten said. More generally, we want to understand how the brain creates our visual perceptual experiences.