Concerning the role of perceptual factors in the serial position effect

The experiment described here addresses itself to the serial position effect of recall, and in particular to the cause of primacy. Two of the three theories discussed here (selective rehearsal and proactive interference) postulate competition between items during the storage interval as a cause of primacy, acquisition being assumed to be equal for all items. The third theory (differential perceptual processing) places the locus of the effect prior to the storage stage, and does not hold interactions between items to be essential to the effect after encoding. The experiment used this distinction between the two classes of theories, storage of the whole presentation (and hence interactions during storage) not being required. Only one word from each list was recalled, and this item was indicated to S on presentation, thereby eliminating the necessity to attempt to encode all items. The storage-interaction theories predict no primacy for the recall of individual items in this experiment, but the initial member of the list was recalled more often than the third member. This example of primacy lends support to the argument that the trace strengths of items are not always equal immediately after presentation.