The role of response set overlap for flexibility and cognitive control in auditory multitasking

We developed a new variant of auditory task-switching in order to systematically investigate shifting and cognitive control in auditory task-switching and their relation to motor response overlap in a comprehensive way. In two experiments, participants classified either pitch or loudness of a simple tone as either low or high, hence, both tasks were constructed around a common underlying dimension ranging from low to high. In Experiment 1, response sets overlapped in both category and motor modality (both manual), whereas each task was related to a specific response category and motor response modality (manual vs. vocal) in Experiment 2. The data revealed reliable switch costs that were, contrary to our expectations, not reduced with reduced response set overlap. In addition, we found reliable congruency effects and their sequential modulation in both experiments with manual as well as vocal responses, and in the absence of competing motor activation (i.e., without motor response overlap). Congruency effects after auditory task switches were smaller when response sets did not overlap. Our data thus provides an important empirical generalization of known effects to auditory stimuli as well as with both manual and vocal responses. In addition, we demonstrated that reduced congruency effects after switches for non-overlapping response sets were due to the extent of overlap between different response sets in task-switching.