Eidetic memory (//) is an ability to recall images, sounds, or objects in memory after only a few instances of exposure, with high precision for some time after exposure, 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 visual information, such as pages from books, magazines, and license plate numbers, in great detail after only brief exposure to it. It is found in early childhood (between 2 percent and 10 percent of that age group) and is unconnected with the person's intelligence level. Like other memories, they are often subject to unintended alterations usually because of outside influences (such as the way an adult may present a query about a memory). If the ability is not nurtured it usually begins to fade after the age of 6, perhaps as growing verbal skills alter the memory process.
Eidetic images are available only for a small percentage of children aged between six and twelve and are virtually nonexistent for adults. Extensive research, however, has failed to demonstrate consistent correlations 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 specialised. In extreme cases, like those of Solomon Shereshevsky, Adam Maida and Kim Peek, memory skills can reportedly hinder social skills. Shereshevsky was a trained mnemonist, not a photographic memoriser, and there are no studies that confirm whether Kim Peek had true photographic memory.
Persons identified as having a condition known as Hyperthymesia (also known as 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, nonautobiographical 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, 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.”
A high percentage of people on the autistic spectrum do have savant abilities, including diverse degrees of photographic memory. This ability is commonly associated with "thinking in pictures" instead of words,  and "excess of detail", or difficulties extracting conceptual information from visual data, for example remembering a specific dog in high detail, but not being able to perceive different dogs as belonging to the same kind of animal, or remembering a face in high detail, but not being able to recognise it after small changes, like a different hairstyle, use of hats or jewellery, or just by seeing the face in a different location (public places vs specific rooms).
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 nonexperts, 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 nonexperts, 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 methods used in the testing procedures could be considered questionable, (especially given the extraordinary nature of the claims being made) as is the fact that the researcher married his subject. Additionally, that the tests have never been repeated (Elizabeth has consistently refused to repeat them) raises further concerns.
With the questionable exception of Elizabeth, 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
- "Eidetic image", Encyclopaedia Britannica
- "Twenty years of haunting eidetic imagery: where's the ghost?"
- "Eidetic". American Heritage Dictionary, 4th ed. 2000. Retrieved 2007-12-12.
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- Searleman, Alan (12 March 2007). "Is there such a thing as a photographic memory? And if so, can it be learned?". Scientific American (Nature America). Retrieved 10 July 2013.
- "Does Photographic Memory Exist?"
- "Kaavya Syndrome: The accused Harvard plagiarist doesn't have a photographic memory. No one does."
- Barber, Nigel (December 22, 2010). "Remembering everything? Memory searchers suffer from amnesia!". Psychology Today (Sussex). Retrieved July 10, 2013.
- "Quirks of Memory: A Retrieval System Roundup"
- "When Memories Never Fade, The Past Can Poison The Present"
- "Total Recall: The Woman Who Can't Forget" It can be notified that there are still people that exist that are still eidetic to this day as mostly are more in metropolitan cities than anywhere else as there are more people percentage-wise comparable.
- Sahyoun, Chérif P.; John W. Belliveau; Isabelle Soulières; Shira Schwartz; Maria Mody (2010). "Neuroimaging of the Functional and Structural Networks Underlying Visuospatial versus Linguistic Reasoning in High-Functioning Autism" (PDF). Neuropsychologia 48: 86–95. doi:10.1016/j.neuropsychologia.2009.08.013. PMC 2795068. PMID 19698726. Retrieved 10 March 2013.
- Sacks, Temple Grandin ; with a foreword by Oliver (2006). Thinking in pictures : and other reports from my life with autism (2nd Vintage Books ed.). New York: Vintage Books. ISBN 978-0307275653.
- 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 memorise 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.
- Stromeyer, C. F., Psotka, J. (1970). "The detailed texture of eidetic images". Nature 225 (5230): 346–349. doi:10.1038/225346a0. PMID 5411116.
- Thomas, N.J.T. (2010). Other Quasi-Perceptual Phenomena. In The Stanford Encyclopedia of Philosophy.
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- Foer, Joshua (April 27, 2006). "Kaavya Syndrome: The accused Harvard plagiarist doesn't have a photographic memory. No one does.". Slate. Retrieved December 16, 2012.
- Photographic Memory on tvtropes.org, including a list of examples in popular culture