Recognition-induced forgetting of temporally related visual long-term memories

Abstract

Long-term storage of visual object representations is neither veridical nor stable. For instance, recognition-induced forgetting shows that an object becomes more prone to forgetting when a semantically related object is practiced. Here, we ask whether relating to the practiced object by virtue of temporal grouping, rather than semantic grouping, leads to forgetting. To impose temporal grouping, we employed a modified recognition-induced forgetting paradigm in which sequentially presented objects were grouped into triplets. To elicit forgetting, we had participants practice the second object in the triplet. We later tested if memory became impaired for the first/third items in these triplets, compared to control objects. In preliminary experiments, we found this forgetting effect only for objects presented in the third position (i.e., right after the practiced objects). These results may have been weak due to relatively little experience with each triplet. To bolster memory for temporal associations, participants initially studied each triplet multiple times. Participants then returned within 1–4 days for the second session. In the initial study phase of the second session, participants studied some of the trained triplets from the first session. Next, in the recognition-practice phase, participants made source recognition judgments, reporting if they had seen each presented object during the study phase of the current day’s session. Correct hits were middle objects from half of the triplets presented from the initial study phase on the second day. In the final test phase, source memory for all studied objects was tested. We found a robust forgetting effect for objects in the same triplets as practiced objects, relative to a baseline comprised of objects in the same serial positions of non-practiced triplets. These results induced via visual episodic source memory suggest that recognition-induced forgetting is a more ubiquitous effect than previously believed.