Overlapping Mental Operations in Serial Performance with Preview: Typing. A Reply to Pashler

Abstract

Pashler (this issue) concluded that the rate of responding in serial choice reaction tasks was controlled by a limit on simultaneous response selection rather than on simultaneous response execution. Film of a skilled typist shows that each finger movement starts as a key earlier in the sequence to be typed is struck (three earlier with words, two with orthographically legal non-words). Thus, her rate of responding is controlled by a limit on the number of responses that can be executed simultaneously, not by a limit on response selection. Preventing simultaneous response selection is one possible strategy for maintaining correct response order in serial tasks. It is suitable for tasks such as those studied by Pashler, where response selection is relatively slow and response execution is quick. Other strategies are more suitable for tasks where response selection is quick and response execution relatively slow and variable.