Friday, January 7, 2011

Colour Blindness in Motion

A new illusion shows how our perception of objects changes as soon as they start moving.

At first, the ring of dots is motionless and it's easy to tell that the dots are changing color. When the ring begins to rotate, however, the dots suddenly appear to stop changing.

The faster the ring moves, the less the colours appear to change. But in reality, they were changing the whole time, at the same rate. As the video shows, the illusion also works for brightness, shape and size.

The phenomenon - change blindness - by which observers don't notice that an image is changing in front of their eyes, isn't new.

Nor is the notion that motion affects the way we see objects - watch our video special on moving illusions for lots of other cool examples - this new illusion designed by Jordan Sochow and George Alvarez at Harvard University demonstrates the principle especially well.

The pair believe the illusion occurs because the areas of the retina responsible for detecting these changes are local - each part of the visual field is monitored by a specific part of the retina. Because a fast moving object spends little time at any one location, a local detector only has a small window of time in which to assess the changing object - and therefore fails to detect the change. 

Journal Reference: Current Biology, DOI: 10.1016/j.cub.2010.12.019

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