The source of dual-task limitations: serial or parallel processing of multiple response selections? Attent. Percept. Psychophys. 75, 1395–1405. doi

Abstract Although it is generally recognized that the con-current performance of two tasks incurs costs, the sources of these dual-task costs remain controversial. The serial bottle-neck model suggests that serial postponement of task perfor-mance in dual-task conditions results from a central stage of response selection that can only process one task at a time. Cognitive-control models, by contrast, propose that multiple response selections can proceed in parallel, but that serial processing of task performance is predominantly adopted because its processing efficiency is higher than that of par-allel processing. In the present study, we empirically tested this proposition by examining whether parallel processing would occur when it was more efficient and financially rewarded. The results indicated that even when parallel pro-cessing was more efficient and was incentivized by financial reward, participants still failed to process tasks in parallel. We conclude that central information processing is limited by a serial bottleneck