Blindsight and Prosopagnosia

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The two terms are both perceptual disorders that are the effects of physical pathology, albeit different end results. Let's look at the two terms a little closer.

PROSOPAGNOSIA

Generally, prosopagnosia is a perceptual disorder in which an individual cannot identify faces. It is a form of agnosia that manifests itself in perceptual deficits in the visual sensory modality, specifically as an inability to recognize faces. Let's look a little closer at this rare condition.

The effects of physical pathology may cause disturbances in complex aspects of perception, rather than a loss of sensitivity to a given stimulus dimension (i.e., blindness, impaired hearing etc.). Such effects are often caused by severe toxic conditions, such as carbon monoxide poisoning, as well as diseases or injuries that damage or reduce the functioning in some part s of the brain (Critchley, 1964; Davidoff, 1975; Luria, 1973). These can affect such complex functions as the ability to identify objects or to place them in space and also the ability to distribute attention. In general, such a problem is called an "agnosia" from the Greek meaning "not" and gnosis meaning "intuitive knowledge." People suffering from agnosias seem to perceive but are not capable of understanding the information presented to them.

While some of these perceptual effects are quite general, others are very specific, such as the rare disorder called prosopagnosia. In this type of ...