Coordination of Component Mental Operations in Sequences of Discrete Responses

In daily life we often perform sequences of actions, which with practice are accomplished by overlapping mental operations for successive actions. Is it possible to derive performance predictions for such sequences from a characterization of the mental operations for a single stimulus-response pair? We explore this by examining the joint timing of eye movements and manual responses in a typing-like task following Pashler (1994). Participants made separate choice responses to a series of five stimuli spread over a wide viewing area. Replicating Pashler’s results, responses to the first stimulus (RT1) were elevated, with inter-response intervals (IRI) for subsequent items rapid and flat across items. The eyes moved toward the next letter about 800 ms before the corresponding manual response (eye-hand span). Analyses of manual responses show multiple components to the RT1 elevation. Analyses of dwell times show that the eyes move to the next stimulus before the completion of all central processing.