UC Irvine

When an organism experiences a salient event, such as when a reward or punishment is received, it is crucial that the information pertaining to that stimulus is encoded and consolidated into memory. The memory of the salient event then allows the organism to continue seeking or avoiding that stimulus. However, it is essential that the organism is also able to recognize the events leading up to encountering the salient stimuli. Theoretically, this requires retroactive enhancement of memory. Retroactive enhancement of memory occurs when previously seemingly irrelevant memories are enhanced at a later time point due to a salient event. While there is theoretical support for the possibility of retroactive enhancement of memories, the empirical evidence in human participants has largely been mixed primarily due to methodological differences and conflation of learning paradigms. Furthermore, as prior studies that have attempted to elicit retroactive enhancement of memory using rewards have only used monetary rewards, it is unclear if social rewards could elicit the effect as well. The effect of retroactive enhancement of memory using rewards on false memories is also unclear. To address the inconsistencies and ambiguities in the literature, this dissertation examined the effects of monetary and social rewards on retroactive enhancement of memory and false memories using an operant conditioning paradigm in Study 1 and a classical conditioning paradigm in Study 2. First, while the data in Study 1 provided evidence of retroactive enhancement of memory for both monetary and social rewards, the data in Study 2 did not support retroactive enhancement of memory. Second, using a two-step conditioning process, results from Study 1 suggest that monetary and social rewards can exert comparable influence on memory in an operant conditioning paradigm. However, results from Study 2 demonstrated that recall in the conditioning phase of the social reward condition was significantly higher than that of the monetary reward condition using a classical conditioning paradigm. Third, in examining rates of false alarms, the data revealed no significant differences between the reward category images in Study 1. The findings of this dissertation not only add to the extant literature but also provide clarity regarding mixed findings in previous studies. Across these two studies, this dissertation provides important insights regarding one facet of memory, retroactive enhancement of memory, especially in the presence of rewards.