Blind Patient Who ‘Recognises’ Emotion – Is This A ’Sixth Sense’?

A patient who is technically blind, having suffered damage to the areas of the brain that process visual signals, has been able to react to certain visual signals. The case, described in this week’s online edition of Nature Neuroscience (Nature Neuroscience advance online publication, 12.12.02 at www.nature.com/neuro/) establishes beyond doubt, for the first time, that certain specific ‘visual recognition’ functions are processed in an area of the brain other than those normally associated with visual processing.

When ‘Patient x’, who is technically blind, reports that he ‘sees’ only darkness and walks with the aid of a white cane, was shown images of shapes such as circles and square, faces and unrecognisably jumbled faces, his guesses would be correct with no more than random frequency. However, when ‘patient x’ was shown faces displaying emotions such as happiness, anger, fear or sadness, his guesses as to whether the faces were happy or displaying a negative emotion registered well above the levels of chance.

This led Dr Alan Pegna, of the University of Wales, Bangor’s School of Psychology, with research colleagues at Bangor and Geneva University Hospital, to establish that emotion displayed on a human face is registered in an area other than the visual cortex. The area involved was identified as the right amygdala, an almond-shape structure situated deep within the brain’s temporal lobe.

What the better than random results of ‘Patient X’s apparent ‘guessing’ showed was that, although not able to ‘see’ in the conventional sense, ‘Patient x’ was able to process this information, as the processing occurs elsewhere in the brain. Although not aware of ‘seeing’ the faces, he was able to react to unconscious processing in his brain of the images placed in front of him.

“This discovery is also interesting for behavioural scientists as the right amygdala has been associated with subliminal processing of emotional stimuli in clinically ‘healthy’ individuals. What ‘Patient x’ has assisted us in establishing is that this area undoubtedly processes visual facial signals connected with all types of emotional facial expressions,” explains Pegna.