Paradoxical effects of testing: repeated retrieval attempts enhance the likelihood of later accurate and false recall.

The testing effect is the finding that taking an initial test enhances the likelihood of later recall. The present report examines the extent to which this benefit of testing comes with a cost: an enhanced likelihood of erroneously recalling incorrect information. Subjects were given short lists of semantic associates (e.g., hill, valley, climb); each list converged upon a related nonpresented word (e.g., mountain). After presentation of some lists, the subjects received no initial test; after others, one initial free recall test; and after others, three successive free recall tests. The probabilities of final free recall (and the probability of reporting vivid recollection of the moment of encoding) of both studied and related, nonstudied words (e.g., mountain) were highest when three initial tests had been taken, intermediate following one initial test, and lowest when no initial test had occurred. The beneficial effects of testing carry the cost of increases in erroneous memory for related information.