Test delay and change awareness moderate retroactive and proactive memory effects.

Similar experiences can enhance or impair existing memories or newly encoded events. Such retroactive and proactive memory effects have been examined using A-B, A-D tasks in which pairs studied across two lists share cues but have changed responses. These tasks often show greater retroactive interference on immediate than delayed tests and greater proactive interference on delayed than immediate tests. Four experiments using A-B, A-D tasks characterized the role of change awareness in such effects. Retroactive interference from List 2 onto List 1 recall was observed on immediate but not delayed tests. When List 2 included measures of change awareness and List 1 recall, retroactive facilitation in List 1 recall was observed on a delayed test. Conversely, intrusions from List 1 onto List 2 recall, indicating proactive interference, were greater on delayed than immediate tests. Response interdependence on the final test showed that correct recall was associated with recollection of other list responses and that changes had occurred. These findings indicate that retrieval practice during List 2 both increased accessibility of earlier responses and promoted cross-episode integration. When the retrieved response was later the target, this accessibility produced retroactive facilitation; when it was the competitor, it increased proactive interference unless recollection of change preserved information about the responses' temporal relationship. The theoretical implications are that temporal changes in retroactive and proactive interference depend not only on differences in trace accessibility across lists but also on whether study-phase retrieval promotes integrative encoding and whether change information remains accessible at test.