Two routes to the same action: an action repetition priming study.

Action selection can be influenced by preceding movements. The authors investigated how retrospective factors may interact with plan- versus rule-based action selection. Participants completed 2 tasks, both of which involved selecting a pronated or supinated posture. In the plan task, they chose the most comfortable hand orientation. In the rule task, they followed a learned prescription. Trials in both tasks comprised prime-probe pairs that were identical, or differed in the visual stimulus or required motor response. Both tasks showed a response-time advantage for probes that were preceded by identical primes. This effect was greater for the plan task suggesting that plan-based action selection is especially susceptible to recent history, fortifying the idea that differential mechanisms underlie a rule- versus plan-based approach to the same action.