Does the previous trial affect lateralized lexical decision?

Abstract

We investigated the effect of previous trial variables on performance in the current trial in a lexical decision task with unilateral presentation of one letter string or bilateral simultaneous presentation of two different letter strings, one cued to be processed (target) and the other uncued, to be ignored (distractor). The variables included correctness of the previous trial, visual hemifield and wordness of the previous trial, and presentation mode of the previous trial (unilateral or bilateral). An incorrect response on the previous trial enhanced the accuracy in the current trial only in the left visual field (LVF). A previous LVF target produced faster correct responses to LVF targets in the current trial and LVF word recognition was more accurate when the previous LVF target was a word rather than a nonword. Target processing in the current trial was not inhibited or facilitated if the target belonged to the same response category as the unattended stimulus in the previous trial (absence of ‘negative priming’). Taken together, our data suggest that previous trial effects in lateralized lexical decision are stronger for word decisions in the LVF, and may account for the inconsistency of the wordness effect in the LVF across different lateralized lexical decision experiments. Our data also suggest that behavioral laterality experiments are well advised to use random sequences that change across subjects in order to minimize previous trial effects.