奖赏预测误差对项目和联结记忆影响的分离:元记忆的作用

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

选取奖赏预测误差(reward prediction error,RPE)效价和凸显性为自变量,通过3个实验考察RPE对项目和联结记忆影响的差异及其元记忆机制。被试在对图片的奖赏猜测-奖赏反馈中形成RPE,且需要同时记忆图片(项目)以及图片-奖赏联结,最后进行记忆测试。结果表明,(1)联结记忆成绩存在RPE正效价和低凸显性优势,其信心判断准确性在RPE正效价时更高,而项目记忆成绩存在RPE负效价和高凸显性优势;(2)在编码过程中,RPE正效价和低凸显性提高了个体的瞳孔变化均值和峰值;RPE低凸显性增加了分值注视时间,缩短了图片注视时间;(3)增加RPE水平后,RPE对项目和联结记忆成绩的分离影响仍稳定存在。这些结果表明,RPE对项目和联结记忆的影响存在分离:编码阶段中,个体以RPE效价和凸显性为线索,通过元记忆控制对项目和联结记忆加工中的认知资源进行差异性分配;提取阶段中,RPE正效价提高了对联结记忆提取的元记忆监测水平。

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.