Eidetic memory (//) is an ability to recall images, sounds or objects in memory with high precision for a few minutes without using mnemonics. It occurs in a small number of children and generally is not found in adults. The word eidetic comes from the Greek word εἶδος (pronounced [êːdos], eidos, "seen").
Eidetic memory is the ability to recall images in great detail for several minutes. It is found in early childhood (between 2% and 10% of that age group) and is unconnected with the person's intelligence level. Like other memories, they are often subject to unintended alterations. The ability usually begins to fade after the age of six years, perhaps as growing verbal skills alter the memory process.
Eidetic images are only available to a small percentage of children 6–12 years old, and are virtually nonexistent in adults. However, extensive research has failed to demonstrate consistent correlates between the presence of eidetic imagery and any cognitive, intellectual, neurological, or emotional measure.
The popular culture concept of "photographic memory", where someone can briefly look at a page of text and then recite it perfectly from memory, is not the same as seeing eidetic images, and photographic memory has never been demonstrated to exist.
A few adults have had phenomenal memories (not necessarily of images), but their abilities are also unconnected with their intelligence levels and tend to be highly specialized. In extreme cases, like those of Solomon Shereshevsky and Kim Peek, memory skills can reportedly hinder social skills. Shereshevsky was a trained mnemonist, not a photographic memorizer, and there are no studies that confirm whether Kim Peek had true photographic memory.
Persons identified as having a condition known as Hyperthymesia (a.k.a., Highly Superior Autobiographical Memory or HSAM) are able to remember very intricate details of their own personal life, but this ability seems not to extend to other, non-autobiographical information. People with hyperthymesia have vivid recollections of such minutiae as what shoes a stranger wore or what they ate and how they felt on a specific date many years in the past. In cases where HSAM has been identified and studied, patients under study may show significantly different patterns of MRI brain activity from other individuals, or even have differences in physical brain structure. Possibly because of these extraordinary abilities, certain individuals have difficulties in social interactions with others who have normal memories (only 2 of 55 in the US have successful marriages), and may additionally suffer from depression stemming from the inability to forget unpleasant memories and experiences from the past. It has also been proposed that HSAM can be explained as a result of obsessive-compulsive thoughts about memories rather than "photographic memory".
Skeptical views on photographic memory
An example of extraordinary memory abilities being ascribed to photographic memory comes from the popular interpretations of Adriaan de Groot's classic experiments into the ability of chess Grandmasters to memorize complex positions of chess pieces on a chess board. Initially it was found that these experts could recall surprising amounts of information, far more than non-experts, suggesting eidetic skills. However, when the experts were presented with arrangements of chess pieces that could never occur in a game, their recall was no better than the non-experts, suggesting that they had developed an ability to organize certain types of information, rather than possessing innate eidetic ability.
Scientific skepticism about the existence of photographic memory was fueled around 1970 by Charles Stromeyer who studied his future wife Elizabeth, who claimed that she could recall poetry written in a foreign language that she did not understand years after she had first seen the poem. She also could, apparently, recall random dot patterns with such fidelity as to combine two patterns into a stereoscopic image. She remains the only person documented to have passed such a test. However, the methodology of the testing procedures used is questionable (especially given the extraordinary nature of the claims being made) as is the fact that the researcher married his subject, and that the tests have never been repeated (Elizabeth has consistently refused to repeat them) raises further concerns.
With the questionable exception of Elizabeth (discussed above), as of 2008, an article claims that of the people rigorously scientifically tested, no one claiming to have long-term eidetic memory has proven this ability. There are a number of individuals with extraordinary memory who have been labeled eidetic, but many use mnemonics and other, non-eidetic memory enhancing exercises. Others have not been thoroughly tested.
- Ayumu – a chimpanzee whose performance in short-term memory tests is higher than university students
- Exceptional memory – scientific background to the research into exceptional memory
- Funes the Memorious – short story discussing the consequences of eidetic memory
- Hyperthymesia – a condition characterised by superior autobiographical memory
- Synaptic plasticity – ability of the strength of a synapse to change
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- Minsky, Marvin (1998). Society of Mind. Simon & Schuster. p. 153. ISBN 978-0-671-65713-0. "...we often hear about people with 'photographic memories' that enable them to quickly memorize all the fine details of a complicated picture or a page of text in a few seconds. So far as I can tell, all of these tales are unfounded myths, and only professional magicians or charlatans can produce such demonstrations."
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