83. A Rare Disorder!


Visual perception is one of the most complex tasks performed by the brain. If anything goes wrong between the reception of the light rays by the eyes and its perception by the brain, the effects become alarmingly dramatic!

Visual Agnosia is a very rare visual disorder, in which a person, who has healthy and fully operational visual system, has difficulty in interpreting the information presented to his brain.

Other visual disorders involve slow degradation of the image, blurring of vision, loss of color vision etc. But in Visual Agnosia, the fault lies in the gross error of perception.

The words “Foot” and “Food”, though very much similar in form and sound, give rise to completely different images in our mind, when we read them. Each of these words is a separate unit with a different meaning and different image.

Our visual perception seems to work in the same way by seeing or perceiving objects in their complete forms as whole objects and not as a sum total of their different constituent parts.

Persons suffering from Visual Agnosia, may be able to perceive the different details of the object, but are unable to put them together and identify the object as a whole. They may have difficulty in recognizing familiar faces and even inanimate objects used everyday.

In a classic case quoted by the neurologist Oliver Sacks, a man mistook his wife to be hat in a book of the same title. He lifted her hand and put it on his head–as if it were a hat!

Visual Agnosia can get a person into a real lot of troubles. Mercifully, God has made this disorder a very rare one.

Visalakshi Ramani

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