On the ability to inhibit simple thoughts and actions: I. Stop-signal studies of decision and memory.

In six experiments, subjects made speeded category and rhyme judgments about pairs of words and were occasionally asked to inhibit their responses. At issue was whether thoughts stop when the corresponding actions are inhibited. The extent to which thoughts were completed was assessed from memory for the words presented in the orienting tasks. Experiments 1 and 2 suggested that thoughts were not inhibited with their corresponding actions: Memory for words whose responses were inhibited was not different from memory for words whose responses were not inhibited, and memory performance did not vary,with stop-signal delay (i.e., the time between the onset of the. word pair and the onset of the stop signal). The same results were obtained in Experiments 3 and 4, though subjects made an overt response to the stop signal (tone) when it occurred. In Experiments 5 and 6, the display changed when the stop signal sounded, and the data suggested that thoughts were inhibited with their actions: Memory for words whose responses were inhibited was much worse than memory for words whose responses were not inhibited, and memory performance improved substantially as stop-signal delay increased. It was concluded that simple thoughts run on to completion whether or not the corresponding action is inhibited, provided that the stimuli that drive the thoughts are not disrupted before the thoughts finish.