experiments comparing his memory to that of college students, Rajan Mahade-
van dramatically outperformed the students on any memory test involving
numbers (Thompson, Cowan, Frieman, Mahadevan, & Vogel, 1991). For exam-
ple, he recalled 43 randomly ordered digits presented to him once, while the
college students recalled an average of only about 7 digits. Rajan Mahadevan
claims that he does not use imagery to help him remember numbers but instead
uses a rather vaguely described mnemonic system whereby numbers are asso-
ciated with numerical locations in a series. It does not seem that he has any-
thing analogous to a videotape or photographic memory, however. His recall
for nonnumerical information, such as word lists or meaningful stories, was
about equal to that of the average college student. For example, he recalled an
average of about 41 ideas from several previously read Native American folk
tales similar to ‘‘The War of the Ghosts,’’ while the college students recalled
about 47 ideas on average from the same stories.
A reasonable conclusion, then, is that individuals likeSand Rajan Mahade-
van make use of mnemonic devices that others could use to help make infor-
mation more memorable (Ericsson & Polson, 1988; Hunt & Love, 1972). While
the memorizing skill of these mnemonists can seem phenomenal, it is clear that
their memories do not work like a videotape recorder; otherwise they would be
able to remember the details of any and all of their experiences. Instead, their
memory is good for classes of information in which they are experts (Elizabeth
was a skilled artist) or for which they have learned mnemonic memorizing
strategies. The Hollywood version of the person with a ‘‘photographic’’ mind
probably does not exist.
The Assimilation Principle
Making information distinctive or associating information with distinctive
images and ideas can promote better memory of that information. Such tech-
niques may be called learning strategies. What other learning strategies help
make information memorable? Another useful learning strategy is based on the
principle that memory for an event will be improved to the extent that the
event can be assimilated into something that already exists in memory (Stein &
Bransford, 1979; Stein, Littlefield, Bransford, & Persampieri, 1984). This princi-
ple is called theassimilation principle.
Assimilation means that new information is incorporated into relevant pre-
existing knowledge useful for interpreting the new information. For example, a
passagedescribingthenatureofelectricitywouldbemorememorableifthe
passage reminded readers of their knowledge of rivers. The passage would not
be as memorable if it did not remind readers of relevant knowledge, nor would
it be as memorable if it reminded readers of irrelevant knowledge, such as their
knowledge of baseball. The constructionist theory explains the assimilation
principle this way: When new information is assimilated into relevant pre-
existing knowledge, there is widespread activation of the cognitive system for
interpreting an event and an increase in the number and strength of the con-
nections among elements of that cognitive system. Reconstruction of the event
is improved to the extent that strong connections among elements in that cog-
nitive system can be found.
328 R. Kim Guenther