EIDETIC IMAGERY (Photographic Memory)

Mental imagery, usually visual, which closely resembles actual perception.Some people are able to look at a drawing or page of print for a short time and later see it in their “mind’s eye” with amazing vividness. They appear to “project” the image on a mental screen and are able to describe every detail as if they were still looking at the object itself. Some “Eidetikers” claim they can even enlarge portions of the mental picture in order to see them more clearly.Eidetic imagery is found in 5 to 10 per cent of children, but usually disappears before adolescence. The few adults who retain this ability can often perform feats of “photographic memory,” such as repeating the entire content of a newspaper page after looking at it for only a few minutes. Some “lightning calculators” are Eidetikers who are able to keep one part of a long problem on their “mental blackboard” while working on another. In addition, adults occasionally experience a form of eidetic imagery for a short time after engaging in fatiguing activity of a monotonous nature, such as playing cards or closely studying blueprints. The images are so vivid and realistic that they are sometimes momentarily mistaken for the actual objects. A similar if not identical phenomenon is occasionally found in patients with tetany and Basedow’s disease (hyperthyroidism).A common test for eidetic imagery is to ask a subject to look briefly at a picture containing many details, including, say, a twelve-digit figure, or a long word in a language he does not know. If he is a genuine Eidetiker, he will be able to describe every detail and repeat the number or the letters of the word forward and backward. An even simpler test is to show him a comb for a moment, then ask him how many teeth it contained. A true Eidetiker will summon up the image and count the teeth even after several minutes or even hours have elapsed. Occasionally one comes across an acoustic,or auditory, Eidetiker. Here the test is to read aloud a long list of digits and ask the subject to repeat them. An Eidetiker will be able to repeat three or four times as many as the average individual.