Riddoch Phenomenon’: When Blind Persons Can See Moving Objects


4th September 2018

Riddoch Phenomenon’: When Blind Persons Can See Moving Objects

Can a person, who is otherwise blind, perceive moving objects?  Yes, it is possible. People suffering from the rarer visual problem ‘Riddoch phenomenon’ can perceive objects in motion, but are blind to other visual stimuli.

A century-long mystery, Riddoch Phenomenon, has resurfaced, hinting some of the underlying neural mechanisms involved in it. In a decade-long study, Jody Culham of Western University in Ontario and her team confirmed the presence of the Riddoch Phenomenon in one of the patients, as reported in their paper recently.  She confirmed that their patient could see a hand approaching towards her; she could also catch a ball thrown at her. Initially thought to be hallucinations, the motion perception of the blind patient has been confirmed with the help of psychophysical and neuroimaging techniques.

The facts that emerged in the study revealed the existence of the different routes taken by the signals from the retina to different regions, which opens up new paradigms to better understand visual processing by the brain. This also opens up new possibilities of studying the evolutionary aspects of our brain in separating signals from the eye to different brain regions for giving different effects.

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