The response-cued completion hypothesis and the nature of residual cost in regular switch

Three experiments are presented that compare the residual cost found when shifting from one task to another under different extra-response conditions, to test whether the response is the main factor to complete mental set reconfiguration. We investigated whether residual costs can be eliminated if participants carry out a response prior to completing switch trials. In all experiments, participants were required to press an extra key during the inter-trial interval (ITI) to proceed. In experiment 1, this extra response consisted of pressing the space bar. In experiment 2, the response consisted of pressing one of the two possible keys that belonged to the alternating tasks response set. In experiment 3, the interpolated response involved pressing one of the two possible keys, not belonging to the response set of the alternating tasks. We found no residual cost in the second or the third experiments. To explain the nature of residual cost we discuss the data in the context of a response cued completion hypothesis.