On the ability to inhibit simple thoughts and actions: II. Stop-signal studies of repetition priming.

When a person inhibits a simple action that is based on a simple thought, does the thought stop with the action? Five experiments were conducted to address that question, attempting to determine the conditions under which simple thoughts could be inhibited. Subjects made speeded category and rhyme judgments about word pairs and were asked to inhibit their (overt) responses on 40 % of the trials. The word pairs were presented again, and priming from repetition was used to decide whether the original thoughts went on to completion when their overt responses were inhibited. The results suggested that thoughts could be inhibited by switching to a new task when the response was inhibited (Experiment 2) or by changing the display when the response was inhibited (Experiment 4) but not by simply inhibiting the response (Experiment 1). The results are compared with other studies that used recognition memory as the index of inhibited thought, and implications for the basis of repetition priming are discussed. Cognitive control depends to a large extent on the ability to inhibit courses of thought and action that are not relevant to current goals. Some thoughts and actions may never be relevant to current goals; others may have been relevant but are no longer so. This article reports an investigation of the inhibition of the latter type of thought and action. Subjects were shown pairs of words and were asked to make category and rhyme judgments about them (e.g., Is a FRIGATE a BOAT? Does SLEIGH rhyme with PLAY?), which they reported by pressing keys. Occasionally, they were given a stop signal (a tone) which told them to inhibit their keypress response on that trial. Previous studies showed that subjects can inhibit a variety of responses up to the point of executing them (see Logan & Cowan, 1984, for a review). The major question addressed in the present in-