Response-compatibility effects in focused-attention tasks: a same-hand advantage in response activation.

Abstract

Previous studies have shown that responses can be partially activated by irrelevant stimuli in focused-attention tasks. In two experiments, such response activation was used to investigate the organization of keypress responses. Stimuli were rows of three letters, with a relevant target letter in the middle of the row and irrelevant flanker letters on the outside. There were four target letters, and these were assigned to four keypress responses made with the index and middle fingers of the two hands. Irrelevant flankers were parentheses, a neutral letter, or one of the four target letters. Responses were fastest when flankers were identical to the target, indicating facilitation of a response activated by both relevant and irrelevant letters. When flankers were response-incompatible target letters, responses were faster if these were target letters assigned to a response finger on the same hand as the correct response than if they were target letters assigned to a response finger on the opposite hand. The latter result is consistent with the hypothesis that simultaneous activation of two response fingers on the same hand produces faster responses than simultaneous activation of two response fingers on different hands, as assumed by Miller (1982). In Experiment 2, flankers were presented slightly before targets, and flankers that were same-hand target letters sometimes facilitated responses relative to the neutral parentheses flankers.