Psychology2016

Memory 229

In real life, information that has just entered iconic memory will be pushed out very
quickly by new information, a process called masking (Cowan, 1988). Research suggests
that after only a quarter of a second, old information is replaced by new information.
Although it is rare, some people do have what is properly called eidetic imagery,
or the ability to access a visual sensory memory over a long period of time. Although
the popular term photographic memory is often used to mean this rare ability, some peo-
ple claiming to have photographic memory actually mean that they have an extremely
good memory. Having a very good memory and having eidetic imagery ability are two
very different things. People with eidetic imagery ability might be able to look quickly
at a page in a book, then by focusing on a blank wall or piece of paper, “read” the words
from the image that still lingers in their sensory memory. Although it might sound like
a great ability to have while in college, it actually provides little advantage when taking
tests, because it’s just like having an open-book test. If a student can’t understand what’s
written on the pages, having the book open is useless. It is unknown why some people
have this ability, but it is more common in children and tends to diminish by adoles-
cence or young adulthood (Haber, 1979; Leask et al., 1969; Stromeyer & Psotka, 1971).

If iconic memory lasts such a brief time, what use is it to us?

Iconic memory actually serves a very important function in the visual system.
Chapter Three discussed the way the eyes make tiny little movements called microsaccades
that keep vision from adapting to a constant visual stimulus, so that what is stared at
steadily doesn’t slowly disappear. Iconic memory helps the visual system view sur-
roundings as continuous and stable in spite of these saccadic movements. It also allows
enough time for the brain stem to decide if the information is important enough to be
brought into consciousness—like the possibly pantless person.

ECHOIC SENSORY MEMORY Another type of sensory system is echoic memory, or the
brief memory of something a person has heard. A good example of echoic memory is
the “What?” phenomenon. You might be reading or concentrating on the television, and
your parent, roommate, or friend walks up and says something to you. You sit there for
a second or two and then say “What? Oh—yes, I’m ready to eat now,” or whatever
comment is appropriate. You didn’t really process the statement from the other person
as he or she said it. You heard it, but your brain didn’t interpret it immediately. Instead,
it took several seconds for you to realize that (1) something was said, (2) it may have
been important, and (3) you’d better try to remember what it was. If you realize all this
within about 4 seconds (the duration of echoic memory), you will more than likely be
able to “hear” an echo of the statement in your head, a kind of “instant replay.”

Using this technique, Sperling found that subjects could accurately report any of

the three rows. This meant that the entire grid was in iconic memory and available to

the subjects. The capacity of iconic memory is everything that can be seen at one time.

Sperling also found that if he delayed the tone for a brief period of time, after about

a second, subjects could no longer recall letters from the grid any better than they had

during the whole report procedure. The iconic information had completely faded out of

sensory memory in that brief time.

Questions for Further Discussion

1. How might the results of the partial report method be different for people from cultures
   in which text is read from right to left or top to bottom?


2. Would the results be different if more detailed pictures were used instead of letters?

eidetic imagery

the ability to access a visual memory

for 30 seconds or more.

Pablo Picasso was one of the most

creative artists of his time. Here he is

seen drawing an abstract of a woman

in the air with a flashlight, using multiple

exposures of the camera. What does his

ability to “hold” the light image in his head

long enough to complete the abstract tell

us about his visual memory?

echoic memory

auditory sensory memory, lasting only

2–4 seconds.