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Abstract:
Abstract: We studied the performance of highly practiced
individuals in a situation where they had to perform two concurrent
tasks. For the spatial discrimination task, manual keypresses were
used to indicate the position of a spatial stimulus. For the pitch
discrimination task, vocal responses were used to indicate the
pitch of a tone. On single-task trials, either a visual or auditory
stimulus was presented; on dual-task trials, two stimuli were
presented simultaneously. There were three possible values for each
dimension. During initial training, only six of the possible nine
stimulus combinations were presented. After extended practice,
performance on dual-task trials was nearly identical to that
observed on single-task trials, replicating recent findings of
Schumacher and colleagues. Moreover, novel pairings of stimuli for
the two tasks were performed as well as those that had been
presented during training, indicating that participants had not
learned to process combinations of stimuli as a single, complex
task. Changing the stimulus properties (Experiment 2) or the
stimulus-response compatibility (Experiment 3) for one of the tasks
dramatically affected reaction times on that task but had little
effect on the performance of the other. These data suggest that the
two tasks were performed independently and challenge the hypothesis
that a central bottleneck associated with response selection
constitutes a fundamental constraint on multitask
performance.
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