STIMULUS-RESPONSE COMPATIBILITY AND POSITION OF THE HANDS - NONADDITIVE EFFECTS

An experiment was conducted using a two-choice stimulus-response compa tibility task factorially combined with position of the hands. Subject s responded to a visual target word (Left or Right) by pressing on the left or the right key depending on the compatible or incompatible ass ignment and performed the task with the hands uncrossed or crossed. Th e effects of Stimulus-response compatibility and Position of hands wer e not additive. Moreover, no effect of compatibility occurred in the c rossed-hand condition. These findings are consistent with the predicti ons derived from a recent hypothesis assuming that in some particular experimental conditions the presentation of the stimulus will activate two automatic responses. The two stimulus-response compatibility mapp ings related to these two automatic responses have been shown to be po sitively or negatively correlated depending on the factorial combinati on of Stimulus-Response Compatibility and Position of Hands. As a cons equence the effects of the two factors theoretically cannot be additiv e. This assumption accounts for the present results.