eidetic image

   Also referred to as eidetic imagery, eidetic phenomenon, mental imagery, imagery, and photographic memory. The adjective eidetic comes from the Greek noun eidos, which means appearance or idea. The term eidetic image was introduced in or shortly before 1909 by the German philosopher and psychologist Erich Jaen-sch (1883-1940) to denote an unusually vivid visual representation of an object or stimulus in the external world that is no longer within eyesight. In so-called eidetic individuals, such images can be evoked through simple visual inspection of a physical object or stimulus. When the object or stimulus is removed, the individual retains a detailed memory image that may or may not appear to be projected into external physical space. Historically various classifi-catory arrangements of eidetic images have been proposed. When the quality of the image resembled that of a regular visual percept, it was formerly referred to as an eidetic phenomenon of the tetanoid or T-type, after the purported relation with calcium metabolism and tetany. When it resembled a memory image rather than a regular visual percept, it was referred to as an eidetic phenomenon of the Basedowoid or B-type, after the alleged relation with thyroid function. Various mixed types have been proposed as well, including BT (Basedowoid-Tetanoid), TB (Tetanoid-Basedowoid), TE (Tetanoid-Epileptoid), and BH (Basedowoid-Hysterical). Other historical classificatory arrangements are governed by psychoanalytic principles, personality characteristics, etc. Eidetic images have also been termed *voluntary hallucinations. They are generally distinguished from * hallucinations proper by their specific connection with objects in the external world, their ego-syntonic character, and sometimes by other phenomenological characteristics. Jaensch also distinguishes them from * afterimages, memory images, and products of the imagination. However, others have suggested that eidetic imagery may be related conceptually, phenomenologically, and perhaps (patho-) physiologically to other mnestic events, such as * memory-afterimages, * flashbacks occurring in the context of post-traumatic stress disorder (PTSD), drug-related *flashbacks, hallucinogen-induced persistent perception disorder (HPPD), *palinopsia, * phantom pain, * reperceptive hallucinations, and * flashbulb memories. Conceptually, eidetic images are regarded either as discrete phenomena or as phenomena that lie on a continuum which includes regular memory images and/or afterimages. An extreme variant of the latter conceptual current is advocated by the American psychologist Gordon Allport (1897-1967), who tends to downplay the differences between eidetic images and lively memory images. Eide-tic imagery is reputed to occur in 2-15% of children between the ages of 7 and 14. Jaen-sch claims that no less than 50% of all children of elementary school age are capable of forming eidetic images. However, in 1964 the American psychologists Ralph Norman Haber and Ruth Haber tested 179 school children, and found that no more than 8% of them were capable of calling up eidetic images. It is generally agreed that the ability to form eidetic images tends to diminish with age, and eventually disappears. In adults, it is a rare talent that hardly manifests itself spontaneously. There are exceptions, however, such as 'S', the man described by the Russian neuropsychologist Aleksandr Romanovitch Luria (1902-1977) in The Mind of a Mnemonist. Eidetic imagery, especially in children, has been studied at least since 1819, as witness a publication by the Bohemian physiologist Johannes Evangelista Purkyne (1787-1869). Various other important studies were carried out around the turn of the century by the British scientist Sir Francis Galton (1822-1911), by the French psychologist Alfred Binet (1857-1911), and by Jaen-sch. Before Jaensch introduced the term eide-tic imagery, the phenomenon was referred to in German as Anschauungsbild, and in English as imagery or mental imagery. The scientific interest in eidetic imagery declined significantly with the advent of behaviourism. Today the phenomenon enjoys something of a cult status among individuals who call themselves eidetikers,and who exchange scientific as well as personal views via the popular press and the internet.

   References

   Haber, R.N., Haber, R.B. (1964). Eidetic imagery: I. Frequency. Perceptual and Motor Skills, 19, 131-138.

   Jaensch, E. (1930). Eidetic imagery and typological methods of investigation. Their importance for the psychology ofchildhood, the theory ofeducation, general psychology, and the psychophysiology of human personality .Translated by Oeser, O. London: Harcourt Brace and Company.

   Luria, A.R. (1968). The mind of a mnemonist. A little book about a vast memory. Translated by Solotaroff, L. New York, NY: Basic Books.