Serial Position Effect and Rehearsal

Figure 1. Serial position effect. Immediate recall of a list of items (such as words) is best from the end of the list and worst in the middle.

One example of the role of rehearsal comes from the serial position effect. If participants hear a list of words and recall them immediately, they recall more words from the beginning and from the end of the list than from the middle. Figure 2-3k shows the serial position effect for a list of 20 words.

Figure 2 Serial position effect. Immediate recall of a list of items (such as words) is best from the end of the list and worst in the middle.

The better recall of the first few words, called the primacy effect, reflects the extra maintenance rehearsal they receive. The first word gets the most extra rehearsal, because it's the only one the participants have. The second word in the list shares rehearsal time with the first, the third word shares with the first two, and so on. To test this explanation, participants are asked to equate rehearsal time for all words on the list by repeating each word three times. Equal rehearsal wipes out the primacy effect. Figure 3-3k shows this from the difference (labeled PRIMACY) between the red, solid and blue, dashed lines.

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