Parallel Response Selection in Dual -Tasks

154 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003.Why is it so difficult to do two things at once? Many accounts of dual-task performance have suggested that the answer lies in the concept of a central processing bottleneck---a stage of processing that can only be performed for one task at a time. Using variations of the Psychological Refractory Period (PRP) paradigm, most authors have converged on Pashler's Response Selection Bottleneck (RSB) theory. RSB theory relies on a discrete stage processing assumption in modeling PRP reaction time data using the locus-of-slack logic. This assumes that the processes involved in the bottleneck---canonically the response selection stage for both tasks in a PRP experiment---are discrete and serial. Specifically, RSB theory states that Task2 response selection cannot begin until Task1 response selection is complete. This study examined cross-task semantic and motor priming within a standard PRP paradigm. In a series of experiments, reaction times to the first and second stimuli were faster when the finger required for the Task1 response was the same as the finger required for the Task2 response, under conditions requiring strict serial Task1-then-Task2 performance. Such compatibility effects suggest that Task2 response information was generated prior to the completion of Task1 response selection---that is, that response selection processes for both tasks may operate in parallel. These data pose a potential challenge to the Response Selection Bottleneck theory of dual-task performance, as they may indicate a violation of the discrete-stage processing assumption of the underlying locus-of-slack logic. Accommodating these data while preserving the essential bottleneck character of RSB theory may be possible, but may alter the very nature of the bottleneck itself.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD