Distinguishing Between Long-Term Memory and Short-Term Memory • 151Serial Position
the meaning of words from LTM, which helps him understand the meaning of each of
the words that make up the sentence.
Tony’s LTM also contains a great deal of additional information about movies,
James Bond, and Cindy. Although Tony might not consciously think about all of this
information (after all, he has to pay attention to the next thing that Cindy is going to
tell him), it is all there in his LTM and adds to his understanding of what he is hearing
and his interpretation of what it might mean. LTM therefore provides both an archive
that we can refer to when we want to remember events from the past, and a wealth of
background information that we are constantly consulting as we use working memory
to make contact with what is happening at a particular moment.
The interplay between what is happening in the present and information from
the past, which we described in the interaction between Tony and Cindy, is based on
the distinction between STM/WM and LTM. Beginning in the 1960s, a great deal of
research was conducted that was designed to distinguish between short-term and long-
term processes. In describing these experiments, we will identify the short-term process
as short-term memory (STM) for the early experiments that used that term, and as
working memory for more recent experiments that focused on working memory.
The distinction between STM and LTM was studied in a classic experiment by
B. B. Murdoch, Jr. (1962), which is illustrated by the following demonstration.DEMONSTRATION Serial Position
Read the stimulus list below (omitting the numbers) to another person at a rate of about one word
every 2 seconds. At the end of the list, tell the person to write down all of the words he or she
can remember, in any order. This is the recall procedure we introduced in Chapter 5 (page 123).- barricade
- children
- diet
- gourd
- folio
- meter
- journey
- mohair
9. phoenix
10. crossbow
11. doorbell
12. muffler
13. mouse
14. menu
15. airplane
Analyze your results by noting how many words the person remembered from the
fi rst fi ve entries on the list, the middle fi ve, and the last fi ve. Did they remember more
words from the fi rst or last fi ve than from the middle? Individual results vary widely,
but when Murdoch did this experiment on a large number of participants and plotted
the percentage recall for each word against the word’s position on the list, he obtained
a function called the serial position curve.SERIAL POSITION CURVE
Murdoch’s serial position curve, shown in ● Figure 6.3, indicates that memory is
better for words at the beginning of the list and at the end of the list than for words
in the middle. Superior memory for stimuli presented at the beginning of a sequence
is called the primacy effect. A possible explanation of the primacy effect is that
participants had time to rehearse these words and transfer them to LTM. According
to this idea, participants begin rehearsing the fi rst word right after it is presented;
because no other words have been presented, it receives 100 percent of the person’s
attention. When the second word is presented, attention becomes spread over two
words, and so on; as additional words are presented, less rehearsal is possible for
later words.Copyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.