Preparatory strategies in overlapping-task performance.

In four experiments, we tested whether perceptual identification is impeded by temporal overlap with another task. The results demonstrate that temporal overlap with an auditory task consistently impaired the identification of the highest digit in a briefly presented and masked array of digits. The impairment was especially pronounced when we emphasized speed on the auditory task, thus counteracting the normal tendency to focus advance preparation on the more challenging visual task. The data also indicate that previous findings of minimal effects of temporal overlap may have been due to the use of a restricted range of stimulus onset asynchronies. The present results demonstrate the important role of preparatory strategies in overlapping-task performance, and show that perceptual identification is impeded by the overlapping performance of another task.