Reward eliminates retrieval-induced forgetting

Abstract

Although it is well known that reward enhances learning and memory, how extensively such enhancement occurs remains unclear. To address this question, we examined how reward influences retrieval-induced forgetting (RIF) in which the retrieval of a nonpracticed item under the same category as a practiced item is worse than the retrieval of a nonpracticed item outside the category. Subjects were asked to try to encode category-exemplar pairs (e.g., FISH-salmon). Then, they were presented with a category name and a two-letter word stem (e.g., FISH-sa) and were asked to complete an encoded word (retrieval practice). For a correct response, apple juice was given as a reward in the reward condition and a beeping sound was presented in the no-reward condition. Finally, subjects were asked to report whether each exemplar had been presented in the first phase. RIF was replicated in the no-reward condition. However, in the reward condition, RIF was eliminated. These results suggest that reward enhances processing of retrieval of unpracticed members by mechanisms such as spreading activation within the same category, irrespective of whether items were practiced or not.reward | retrieval-induced forgetting | learning | memory A lthough it has been found that reward significantly enhances learning and memory (1-8), how extensively reward influences learning and memory processing has yet to be explored. It has been recently found that a subthreshold stimulus which was merely exposed in a visual field was learned if paired with reward, but was not if paired with no reward (5). These results suggest that in contrast to the role of attention which is to enhance only processing relevant to a given task, reward enhances learning of a presented item, irrespective of whether the item is task-relevant or not. An important question is how extensively reward influences learning and memory. To address this question, we examined how reward influences retrieval-induced forgetting (RIF) in which the retrieval of a nonpracticed item under the same category as a practiced item is worse than the retrieval of a nonpracticed item beyond the category (9). If reward completely unselectively enhances memory of any item, then it should enhance the retrieval of unpracticed items both within and beyond the category to which the practiced items belong. If reward selectively enhances only practiced items, it should not influence the retrieval of a nonpracticed item irrespective of whether it is within or beyond the category. In both cases, RIF should be observed because reward should not differentially influence the retrieval of nonpracticed items within and beyond the category. In contrast, if reward enhances items only within the category, irrespective of whether it was practiced or not, the degree of RIF should be significantly reduced or abolished.In the present study, when no reward was given on each trial of the practice session, RIF was observed. However, when reward was given, there was no significant performance difference between recalls of n...

Sharing a Context with Other Rewarding Events Increases the Probability that Neutral Events will be Recollected

“…If the rewarding and neutral objects were indeed representationally linked in this context-mediated manner, reward-related mechanisms that support enhanced consolidation of rewarding events (e.g., dopamine release and synaptic tagging) may then have led to stabilization of the entire hippocampal engram, resulting in improved memory for the neutral objects as well. Spreading of reward-related memory enhancements to non-rewarded but associatively linked exemplars have been noted in the literature ( Imai et al, 2014 ), and the findings reported here may be similar to such previous reports, pointing toward a similar phenomenon in which reward-related memory effects may spread to neutral objects that via indirect associative links.…”

“…One possibility is that the extent of cross-stimulus memory enhancement may rely on the associative links between the rewarding and neutral event, rather than strict temporal co-occurrence. Consistent with this hypothesis, reward has been shown to selectively benefit memory for neutral stimuli that are in the same semantic category (e.g., fish) as other rewarded stimuli, despite presentation of the rewarding and neutral stimuli being temporally spread out over the course of the experimental session ( Imai et al, 2014 ). Similar effects have been demonstrated in the domain of decision making, wherein choices between two neutral options is influenced by each options’ indirect (i.e., via other intervening stimuli) associations with reward ( Wimmer and Shohamy, 2012 ).…”

A retrieval-specific mechanism of adaptive forgetting in the mammalian brain

“…This work did not, however, rule out interference mechanisms as we have, nor did it establish functional parallels with retrieval-induced forgetting in humans. Moreover, its reliance on appetitive conditioning 52 and repeated training complicates comparisons to the human episodic memory phenomenon. As such, the case for active inhibition of competing episodic memories is less clear.…”

Retrieval-Induced Forgetting as Motivated Cognition

“…In line with this latter idea are two recent papers showing that non-specific motivations (i.e., rewards, mastery approach goals, and performance approach goals) influence the cognitive processes underlying the RIF on neutral stimuli. More specifically, rewards (i.e., apple juice during retrieval-practice), and mastery approach goals (i.e., developing one’s own skills) eliminate RIF, while performance approach goals (i.e., performing better than others) promote RIF ( Imai et al, 2014 ; Ikeda et al, 2015 ). The lack of RIF under (1) reward and (2) mastery approach goals is due to the fact that these motivations promote connections (and thus integration and spreading of activation) among the items within a category.…”