Previous research has revealed some mechanisms underlying the generalization of reward expectation of generalization stimuli, but little is known about the generalization of episodic memory for rewarding events, its consolidation, and how reward components such as expected value and reward uncertainty affect it. Participants underwent a Pavlovian reward-conditioning task to test whether reward conditioning would enhance episodic memory generalization and which reward components would directly affect it. Counterbalanced across participants, one semantic category was paired with a reward, while the other was never paired. Following a delay of either 5 min or 24 h, participants took a memory test consisting of old, highly similar, and new items. We found that participants were more likely to falsely recognize lure items as old in the reward-paired category after 5 min and 24 h delays. These results indicate that reward conditioning enhanced the generalization of episodic memory, but this effect was not necessarily dependent on consolidation. The composite score and raw data of generalization further showed that the uncertainty and expected value enhanced generalization. Together, these findings revealed an effect of reward conditioning on episodic memory generalization and supported the enhancement effects of expected value and uncertainty.

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Reward Uncertainty and Expected Value Enhance Generalization of Episodic Memory

Episodic memory consists of item memory and associative memory. Individual cognitive resources are typically allocated to more valuable information during encoding through metamemory, leading to competitive processing of item and associative information. Reward prediction error (RPE), defined as the difference between reward results and reward expectations, has two properties: valence (positive or negative) and salience (degree of difference). To examine the impact of reward prediction error valence and salience on item and associative memory, and how reward prediction error influences memory based on metamemory, three experiments were conducted. In the learning stage, participants were presented with indoor and outdoor scene pictures. They were asked to predict the score of each picture and then received feedback on the actual score. Through this reinforcement learning process, participants had to find out which type of pictures is more valuable, and 30% of the scores were accumulated into the total score. To induce the effect of reward motivation on memory, participants were introduced to the opportunity to choose between two pictures and receive the value of the selected picture, although the actual program did not include a decision-making stage. After the learning stage, participants were tested on item and reward associative memory. The findings of the study showed that: (1) There were advantages in associative memory performance for positive reward prediction error valence and low salience, with higher accuracy of JOCs at positive valence. In contrast, there were advantages in item memory performance for negative valence and high salience. (2) In the eye-tracking results during the encoding process, positive valence and low salience of reward prediction error resulted in increased mean and peak pupil dilation after feedback presentation, as well as longer value fixation duration and shorter picture fixation duration at low salience. (3) When the reward prediction error level was increased to reduce overlap between reward results and reward prediction error effects, the separation effect of reward prediction error on item and associative memory performance remained stable. The results of the study suggest that the effects of reward prediction error on item and associative memory are distinct. During the encoding stage, individuals use the valence and salience of reward prediction error as cues to allocate cognitive resources differently in item and associative memory encoding through metamemory control. In the retrieval stage, positive valence of reward prediction error enhances the metamemory monitoring level of associative memory retrieval.

Yang Yue

Papers

Reward Uncertainty and Expected Value Enhance Generalization of Episodic Memory

The distinct effects of reward prediction error on item and associative memory: The influence of metamemory