Reliable retrieval is intrinsically rewarding: Recency, item difficulty, study session memory, and subjective confidence predict satisfaction in word-pair recall.

The recall of a distant memory may appear satisfying and suggest successful retrieval is inherently rewarding. If the brain incentivizes retrieval attempts on the prospect of an internal retrieval reward, then the desire for that reward might natively reinforce declarative memory access. But what determines the level of retrieval satisfaction? We tested the idea that retrieval attempt uncertainty drives retrieval satisfaction. For instance, the more distant the memory, the more satisfying should it be to successfully retrieve it. Alternatively, the brain issues rewards based on the level of confidence in recall independent of the recall achievement. If so, then more confident retrieval is also more satisfying. In an online experiment containing five Swahili-English word pair study sessions spaced across one week, we tested 30 English-speaking participants' recall satisfaction and memory confidence during learning as well as in a final cued recall test. We hypothesized that retrieval satisfaction should either increase or decrease with retrieval uncertainty as indicated by time since encoding, and how little in overall they recalled from the session. We found that retrieval satisfaction decreased with time since encoding and with study session retrieval performance. Moreover, we found that retrieval confidence and satisfaction ratings were highly related in the experiment. We also found a reliable interaction between confidence and word difficulty indicating that confidently recalled difficult items induced more satisfaction. Thus, the brain appears to reward both retrieval confidence and to a lesser extent, fruitful retrieval effort. Our findings may explain seemingly irrational self-regulated study behavior such as avoiding learning-efficient but difficult training protocols, as effects of a system rationally seeking to accrue intrinsic cognitive reward.