Imagination inflation for action events: repeated imaginings lead to illusory recollections.

In two experiments, subjects heard simple action statements (e.g., "Break the toothpick"), and, in some conditions, they also performed the action or imagined performing the action. In a second session that occurred at a later point (10 min, 24 h, 1 week, or 2 weeks later), subjects imagined performing actions one, three, or five times. Some imagined actions represented statements heard, imagined, or performed in the first session, whereas other statements were new in the second session. During a third (test) phase, subjects were instructed to recognize statements only if they had occurred during the first session and, if recognized, to tell whether the action statement had been carried out, imagined, or merely heard. The primary finding was that increasing the number of imaginings during the second session caused subjects to remember later that they had performed an action during the first session when in fact they had not (imagination inflation). This outcome occurred both for statements that subjects had heard but not performed during the first session and for statements that had never been heard during the first session. The results are generally consistent with Johnson, Hashtroudi, and Lindsay's (1993) source monitoring framework and reveal a powerful memory illusion: Imagining performance of an action can cause its recollection as actually having been carried out.