Attentional control of response selection in task switching.

Modulation of cognitive control was investigated by using a proportion congruent manipulation to change response congruency effects in task switching. In an experiment that involved cued switching between semantic categorization tasks, targets were either congruent or incongruent (mapped to the same or different responses across tasks, respectively), and the proportion of congruent targets was manipulated between subjects. Response congruency effects (worse performance for incongruent than for congruent targets) were observed, and they increased with proportion congruent for both response time and error rate. A sequential congruency effect (a smaller response congruency effect following an incongruent than a congruent trial) was observed for error rate, but only for task repetitions. The results suggested top-down control of attention rather than bottom-up control based on item-specific learning, because targets were never repeated during the experiment. Implications for understanding attentional control of response selection in conflict situations are discussed.