memory expert on stage. People would call out words or numbers for him to
remember and he would try to recall them exactly. Interestingly, though,S
sometimes needed to develop new mnemonic techniques to overcome occa-
sional errors in memory and so improve his act. For example, he had difficulty
remembering names and faces. IfS had a photographic memory, he would
have been able to memorize accurately any kind of information presented to
him. His extraordinary memory, then, was not a result of possessing anything
analogous to a photographic mind, but was rather a result of having an ap-
propriate mnemonic strategy. Tragically,Sended his life in a Russian asylum
for the mentally ill.
Some people, calledeidetic imagers, seem to have an extraordinary ability to
remember visual details of pictures. Eidetic imagers report that, after viewing a
picture, they see an image of the picture localized in front of them and that the
visual details disappear part by part. While they remember many more visual
details of a picture than would the ordinary person, often the accuracy of their
reports is far from perfect (Haber & Haber, 1988; see Searleman & Herrmann,
1994).
The all-time champion eidetic imager was an artist known as Elizabeth. Her
most remarkable achievement had to do with superimposing two random-dot
patterns to see a three-dimensional image. In one experiment (Stromeyer &
Psotka, 1970), she was first presented with a 10,000-random-dot pattern to her
right eye for 1 minute. The first pattern was then removed for 10 seconds and
a second 10,000-random-dot pattern was presented to her left eye. She was
instructed to superimpose her memory of the image of the first pattern onto the
second. The patterns were designed so that when superimposed and examined
through both eyes, a three-dimensional figure (e.g., a square floating in space)
would appear. It was impossible to determine the three-dimensional image
from either pattern alone, however. Elizabeth was able to superimpose a mem-
ory of the first pattern onto the second pattern and thus accurately identify the
three-dimensional image. In fact, in one case, she was able to hold a 1,000,000-
random-dot pattern in memory for 4 hours and then superimpose her memory
of that pattern onto a second 1,000,000-random-dot pattern to identify success-
fully the three-dimensional image! It is possible to see the three-dimensional
figure in the superimposed patterns even when one of the patterns is sig-
nificantly blurred, although the blurring will also make the edges of the three-
dimensional image more rounded. So Elizabeth need not have remembered the
exact position of all of the dots to accomplish seeing the three-dimensional fig-
ure, although she claimed that the edges of her three-dimensional image were
sharp and not rounded.
No one else has yet been found who can come close to Elizabeth’s visual
memory; indeed, some people are skeptical of her feats (see Searleman &
Herrmann, 1994). As far as I know, Elizabeth was not tested for memory of
anything other than visual information. It remains unclear, then, whether she
had an outstanding all-purpose memory or an extraordinary memory for only
visual information.
Another remarkable memorizer is Rajan Mahadevan, who has a phenomenal
memory for numbers. He is able to recite the first 31,811 digits of pi from
memory (I’m lucky if I can remember the first four digits!). In a series of
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