The persistence of false memories in list recall

Roediger and McDermott (1995) recently re-introduced a paradigm to study the creation of false memories. Subjects hear short lists of related words (e.g., thread, pin, eye, sewing, etc.), all of which are associates of a critical nonpresented word (e.g., needle); on a free recall test given immediately after list presentation, subjects often erroneously recall the critical nonpresented word. The experiments reported here explore (a) the effect of test delay on false recall and (b) whether multiple study/test opportunities reduce the proportion of critical items erroneously recalled. In Experiment 1, introduction of a 2-day delay between study and test produced probabilities of false recall that exceeded those of veridical recall. In addition, prior testing of the list enhanced false recall, much like testing enhances later recall of studied items (the testing effect). In Experiment 2, an attempt was made to reduce or eliminate the false recall effect by using a multitrial study/test procedure. Although subjects were able to reduce the proportion of critical nonpresented words erroneously recalled, they were unable to eliminate the false recall effect, even after 5 study-test trials. An interaction occurred between accurate and false recall as a function of retention interval: after a one-day delay, false recall levels rose, whereas accurate recall decreased. Results of both experiments demonstrate the persistence of this memory illusion.