What is a photostatic memory

Question to the brain

Answer from Prof. Dr. Ulrich Ansorge, Faculty of Psychology, University of Vienna:There is no such thing as a photographic memory as it is colloquially meant. There are very few people who can remember visual details very well. But always there are deviations from the template. There is no such thing as a perfect visual representation.

What comes closest to photographic memory is iconic and eidetic memory. Iconic memory is a short-lived form of visual representation that usually only lasts a few hundred milliseconds. This is relatively extensive and practically the basis of what is stored in what is known as short-term memory. We all have an iconic memory, as experiments by George Sperling have shown. In it he presented a few characters to people for a very short time, for example twelve letters in three lines, and then asked them to report a certain line from memory. On average, the subjects were able to reproduce three out of four characters correctly - but only for a short time. When the time span between the presentation of the letters and the request to play them increased, from 300 to 500 milliseconds or even a second, they could only report individual letters. So for a short period of time we have a relatively extensive visual representation of the environment. So briefly that we are hardly aware of the information and can hardly distinguish it from the perception itself.

Eidetic memory is very rare and lasts much longer - supposedly up to several minutes. The so-called eidetics subjectively report that it feels as if the visual impression persists for this period of time, which non-eidetics might perceive as an afterimage, but with eidetics it takes on the character of a "projection". In contrast to iconic memory, such a subjective impression cannot easily be proven by objective measurements. But there are a few interesting individual cases that make this seem plausible. A famous example is Stephen Wiltshire, who was able to correctly trace the entire city after flying over New York City.

What is interesting about these cases is that most of them generally have a very good memory, not only for visual information, but also for heard and felt information. In addition, they often have psychological deviations: Many eidetics are autistic, like Wiltshire, or synesthetes, i.e. people who always have several sensory perceptions at the same time. For example, people with color-grapheme synesthesia feel certain colors when they hear or see certain numbers. A famous Eidetiker, Solomon Schereschewski, had this to an extreme. He also perceived every unimodal stimulus, i.e. stimuli that, for example, can only be seen or only heard, with three or four senses at the same time. For example, he tasted and felt what he saw. This form of multiple coding of perceived information should have massively supported his memory performance.

Exactly which physiological brain principles are responsible for the performance of eidetics has not yet been clarified. On the one hand, changes in the brain are either barely measurable - as in synaesthetes - or very varied - as in autistic people. On the other hand, today's ways of measuring healthy brain function are still limited. It is true that brains can be analyzed more closely after the death of a person, but then there is no connection to function, i.e. the demonstrable activation of the brain regions in question during memory tasks. Researchers speculate whether an eidetic memory may be associated with a weak connection between the two hemispheres of the brain. But not every person who does this has such a memory. So there have to be other factors.

There is also speculation about whether eidetic memory is more developed in children and whether this is then replaced with language acquisition by linguistic or meaning-centered, semantic memory. But this is not that common among children either, and since they have to be relatively young, motor skills such as drawing are still limited, making the tests less convincing than with adults.

Although some people want a photographic memory, forgetting is actually a good thing. And that doesn't just mean forgetting negative events. There is so much information that we only need intermittently. With the help of forgetting, our brain also concentrates on the essential things.

Recorded by Nicole Paschek