Explaining dual-task implicit learning deficits: the effect of within stimulus presentation

Abstract

Under typical between stimulus dual-task conditions, implicit sequence learning typically suffers, except under within stimulus conditions, where the stimuli for both tasks are the same. This finding is inconclusive, given that it has not been replicated and the study under which it was obtained was methodologically flawed. The finding also seemed to contradict the psychological refractory period finding that simultaneous presentation of the two task stimuli will result in performance decrements. Two experiments were conducted to test the effect of within stimulus presentation in a dual-task implicit learning task. In Experiment 1, within stimulus presentation resulted in improved sequence learning, relative to between stimulus presentation. The second experiment did not show an effect of response selection load under within stimulus presentation conditions. The findings suggest that implicit learning can occur under attentionally demanding conditions, but that the incidental task structure to be learned should be comprised of stimuli that are already attended during primary task processing.