Exceptions to the PRP effect? A comparison of prepared and unconditioned reflexes

Psychological research has documented again and again marked performance decrements whenever humans perform 2 or more tasks at the same time. In fact, the available evidence seems to suggest that any type of behavior is subject to such limitations. The present experiments employed the psychological refractory period (PRP) paradigm to identify a clear exception to this rule: Unconditioned reflexes do escape dual-task interference, whereas intended simple responses, so called "prepared reflexes," do not. Beyond this empirical novelty, we discuss the findings in broader terms of human action control. In particular, we suggest that the (non)susceptibility to dual-task interference may provide a clear empirical delineation between goal-directed behavior (i.e., actions) and other, not goal-directed behavior.