Photographic Memory

Remember when you were a kid and there was always someone in your class who claimed to have a photographic memory? If you believed it, as many children tend to do, you were probably both impressed and jealous. Then by the time you got older, you'd heard of people with savantism, and champions in memory contests, and people who could remember every day of their lives; and you probably wished that you too could have a photographic or eidetic memory. Well how would you feel if I told you that there might not be any such thing as those abilities?

That's not to say that nobody has extraordinary or unusual memory prowess. Some do, and we'll talk about those; but what we want to focus on today is the idea that some people have the pop-culture version of a "photographic memory" that we've all heard about, which sounds a bit like a superpower. They can, at will, call to mind the page of a book they've read, a license plate they saw, a long string of numbers, what have you; and simply read it off that image in their mind's eye as if they're seeing it live. What makes this such a great thing is that it doesn't seem to come with any cost. They are not otherwise developmentally disabled, and haven't had to trade other cognitive or behavioral functioning. This is the version of "photographic memory" that so many of us grew up believing in: the superpower version.

There are two versions of this: photographic memory, and what we call eidetic memory. Paradoxically, it's an eidetic memory that has the ability to recall mental images in photographic detail, whereas a photographic memory isn't about images so much as it is about long numbers and passages of text. Eidetic memories do seem to be a real phenomenon, while the superpower-style photographic memory appears to be nothing more than an urban legend.

But before we look at these in more detail, let's talk about what it is not. There are several actual types of extreme memory conditions, and we want to avoid confusing them all together.

The first we'll talk about is savantism, as famously depicted in the movie Rain Man. Savants are individuals who have severe limitations. They are usually on the autism spectrum. They often have low IQs. Motor skills, social skills, and learning abilities are usually deficient. In savant syndrome, these disabilities are paired with surprisingly exceptional skills, almost always in a single area. The most common skill is calendar calculation, having an innate, unlearned ability to tell what day of the week any date in history fell upon. The second most common skill is feats of memory, memorizing phone books, databases, the texts of whole books, like the late great Kim Peek. Other skills are mathematical calculation; the ability to reproduce works of art (or even photos or visual scenes) with amazing precision, such as those done by the artist Stephen Wiltshire; and the ability to reproduce music, usually on a piano, and often after hearing the original only once. Worldwide there are only slightly more than 300 people known to have savant syndrome, with fewer than 100 being what we call prodigious savants, having the most remarkable skills. Interestingly, about 1 in 10 of those with savant syndrome acquired it as the result of a traumatic head injury. Those who were born with it sometimes, but not always, have anatomically abnormal brain structures.

But as rare as prodigious savants may be, there are far fewer of the other known type of natural memory champs: those with hyperthymesia, which means "excess remembering". Hyperthymestics have overdeveloped autobiographical memory. They remember everything they did of every day of their lives: what they saw and did, what was on TV, what was in the news, how they felt that day. They can recite conversations they had forty years ago, but it differs from what we normally think of as photographic memory in that it doesn't include every detail of every scene, or great long strings of numbers, or every word of every page of every book they read. In many cases, hyperthymestics acquired the ability sometime in childhood and can tell you all about that first day they remember and every day since, and little about any previous days. Most describe it as oppressive and annoying, and speak of their inability to turn off the constant replay of their pasts every time a date is mentioned. Only some 30 people worldwide have been confirmed as hyperthymestics, including the actress Marilu Henner, though there are probably many more who never stepped forward to seek treatment or study.

The other type of memory hero is the mnemonist. Mnemonists are people who have no special natural memory abilities, but have instead trained themselves to use highly developed memory techniques such as mnemonic devices. There are all sorts of tricks that can be used to remember different types of information. Some are relatively simple, some take years of practice. The World Memory Championships is an annual competition in which competitors must demonstrate extraordinary memory skills in ten diverse disciplines, and so every year, a mnemonist who has practiced all ten disciplines has won, and never a prodigious savant or anyone claiming any sort of innate ability such as an eidetic or photographic memory.

There are also a number of people from history who are claimed to have had photographic memories, but who are conveniently unavailable for modern testing. Certain historical dictators are interestingly to be found on this list, including former Philippine president Ferdinand Marcos and Abubakar Shekau, the leader of the terrorist group Boko Haram in Nigeria, both of whom claimed to be able to instantly memorize books. Many believe that some great scientists such as Leonhard Euler, Leonardo da Vinci, John von Neumann and Nikola Tesla possessed photographic memories. But it's a short list; these and about a dozen others are it, and all are unverified by modern controlled testing.

So with these relatively small numbers of people with innate super-memory, is there any room left for any significant percentage of the population to have a photographic memory? Apparently not; if there were, neuroscientists and psychologists who study memory would be thrilled to meet them. The belief that such people are around is pervasive enough that in 2006, when young-adult novelist Kaavya Viswanathan was accused of plagiarizing part of her book from another author, she claimed that she had a photographic memory and couldn't help but automatically remember passages of text. However we all remember some passages of text, especially those that stand out for us; we don't need photographic memories and we almost always know where we learned those remembered passages.

This brings us to eidetic memory, the ability to recall an image in perfect detail. For a long time, conventional wisdom has held that a small percentage of children are eidetikers, but that they lose the ability about the time they enter puberty. The hypothesis has long been that, somewhat like savants, children have not yet developed advanced thought processes such as the ability to store images more efficiently as conceptual abstractions. Thus, eidetikers' brains are forced to inefficiently store complete images, and this would be considered indicative of developmental immaturity. However, later data suggests this isn't necessarily so. A ten-year study of elementary schoolchildren concluded:

The evidence in the present review casts doubt on this hypothesis on numerous grounds: an extensive longitudinal study over the entire span of elementary school years found that eidetic abilities remain remarkably stable; there is no correlation between eidetic imagery and abstract thinking or reading performance; there is no higher incidence in preschool ages, among brain-injured subjects, or among illiterate subjects in crosscultural studies.

In short, how and why it happens, and why it's found only in prepubescent children, still remains elusive. There's strong evidence that some children have it, but no evidence that it's ever survived into adulthood.

Which brings us to the one popular tale of an exception to this rule. The most common story of an adult displaying eidetic memory is that of a 23-year-old teacher at Harvard whose name is given only as Elizabeth. It's said that in research published in the journal Nature in 1970, she was shown the right-eye pattern of a 3D random-dot stereogram image, only to her right eye; and then was later shown the left-eye pattern, only to her left eye, and was instantly able to identify the shape concealed within the stereogram. She displayed this ability even when shown the second image as long as 24 hours after the first. In articles discussing eidetic memories, the story of Elizabeth is almost always cited as the best example, but along with a strange footnote: Elizabeth was never retested because she married one of the experimenters. I am not sure why this should disqualify her from being retested, because when I read the research, I found it raised more questions than it answered.

For example, it never discussed whether Elizabeth might have been a prodigious savant, which is a potential explanation for her alleged ability. There were no other subjects involved in the research, which raises the question of whether it might have been possible for her to cheat. Only two images were used: a dark one that concealed a letter T, and a light one that concealed a square; it was very easy to tell which was which even if you're only seeing one half. There is no mention of any blinding, or of whether Elizabeth — known to have been romantically involved with one of the researchers — might have ever seen the stereograms normally or even heard them described, though they do say that they'd never projected the images on the screen in her presence. Moreover, the one time a control was employed, her ability apparently disappeared. While viewing the left-eye image of the square with the right-eye image supposedly held in her memory, she was supposed to point out the locations of the corners of the square to the researcher. Despite the ease of guesstimating them, she missed them. There were other odd things in the paper. In describing Elizabeth, said to be a skilled artist, they wrote:

Her eidetic ability is remarkable, for she can hallucinate at will a beard on a beardless man, or leaves on a barren tree.

Unless I'm missing something, I can do that too. It was a strange paper. Two years later, an effort to reproduce this effect was published in Psychonomic Science, with negative results. Of 270 subjects of varying ages, none demonstrated Elizabeth's somewhat apocryphal ability.

What we're left with is a lack of compelling evidence that eidetic memory exists at all among healthy adults, and no evidence that photographic memory exists. But there's a common theme running through many of these research papers, and that's that the difference between ordinary memory and exceptional memory appears to be one of degree. Some people have better memories than others, but it could well be that (with the possible unverified exception of a few standout individuals) there is no such thing as "superpower" memory. So feel a bit better about your ordinary, non-super memory; it turns out it's not that bad after all.

By Brian Dunning
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