Attentional selection and word processing in Stroop and word search tasks: the role of selection for action

The time course of visual word processing was investigated in two tasks differing in whether words were "selected for action" (Allport, 1989). Using identical displays in which a square color patch appeared at fixation with either 2, 4, or 8 flanking words appearing at any of the 8 sides and corners, subjects performed either a Stroop color-naming task or a word search task requiring detection of a color name among the flanking words by either a manual presence/absence response (Experiment 1) or a vocal naming response (Experiment 2). The color-naming task produced Stroop effects indicating parallel word processing in multiword displays, whereas the word search task produced evidence consistent with serial, self-terminating search requiring allocation of spatial attention. The differences in word processing across tasks are reconciled using Allport's concept of selection for action and extended to neuropsychological evidence on attention.