152 • CHAPTER 6 Long-Term Memory: Structure
The idea that the primacy effect occurs because participants have more time
to rehearse earlier words on the list was tested by Dewey Rundus (1971). Rundus
derived a serial position curve by presenting a list of 20 words at a rate of 1 word
every 5 seconds and then asking his participants to write down all of the words
they could remember. The resulting serial position curve, which is the red curve in
● Figure 6.4, demonstrates the same primacy and recency effects as Murdoch’s curve
in Figure 6.3. But Rundus added a further twist to his experiment by asking his● (^) FIGURE 6.3 Serial position curve (Murdoch, 1962). Notice that memory is better
for words presented at the beginning of the list (primacy eff ect) and at the end
(recency eff ect). (Source: B. B. Murdoch, Jr., “The Serial Position Eff ect in Free Recall,” Journal of
Experimental Psychology, 64, 482–488.)
5101520
Serial position
20
0
40
60
80
100
Percent recalled
Serial-position curve
Recency
effect
Primacy
effect
●FIGURE 6.4 Results of Rundus’s (1971) experiment. The solid red line is the usual serial
position curve. The dashed blue line indicates how many times the participant rehearsed
(said out loud) each word on the list. Note how closely the rehearsal curve matches the
initial part of the serial position curve. (Source: D. Rundus, “Analysis of Rehearsal Processes in Free
Recall,” Journal of Experimental Psychology, 89, 63–77, Figure 1, p. 66. Copyright © 1971 by the American
Psychological Association. Reprinted by permission.)
0
100
80
60
40
0
11
15
7
3
Percent recalled
Mean number of rehearsals
1 3 5 7 9 1113151719
Serial position
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