ON THE DETECTION OF LETTERS WITHIN REDUNDANT ARRAYS

It has been reported (Johnson, 1977) that subjects can detect the presence or absence of a target letter (e.g., B) in a subsequent display more rapidly if the display consists of a single letter (e.g., B or L) than if it is redundant in the sense of containing several instances of the same letter (e.g., BBBBB or LLLLL). Unfortunately, Krueger and Shapiro (1980) reported a series of similar experiments in which that effect was not obtained. The present study reports two experiments in which the original effect was obtained. In the first experiment, the single-letter displays were presented in one block of trials, and multiletter displays were presented in another block of trials, but the latter blocks contained a mixture of redundant (BBBBB) and nonredundant (BQTRZ) displays. To rule out the possibility that the effect was caused by some strategic carryover from the handling of the nonredundant displays to that of the redundant displays, in the second experiment those multiletter items were divided into separate blocks of redundant and nonredundant displays. While the advantage of single-letter displays over redundant displays was reduced somewhat, it was not eliminated.