Automatic processing, code dissimilarity, and the efficiency of successive memory searches.

Two experiments examined the effects of automatic processing and code dissimilarity on the performance of successive memory searches through a single memory set having the same or different kinds of information (i.e., verbal and spatial). The results of both experiments showed that the total time to complete the successive searches was less when automatic processing was involved compared with when both searches required controlled processing. Performance of the successive searches improved substantially with practice. Both experiments also showed an asymmetrical temporal interference between the two searches. Aspects of the to-be-performed second search did not affect first-search reaction times (RTs), but performing the first search did affect the second-search RTs. The interfering effect of the first search was greatest when controlled processes that used the same code were required for both searches, whether the code was verbal or spatial. Several interpretations are offered for the interference generated by the first search. The joint effects of automatic processing and code dissimilarity are also discussed.