In for a penny, in for a pound: Examining motivated memory through the lens of retrieved context models

Abstract

When people encounter items that they believe will help them gain reward, they later remember them better than those that do not. While it is adaptive to preferentially remember experiences that will be useful later, it is unknown how the competition for memory resources is implemented in time, through the processes of encoding, consolidation, and retrieval. In two experiments we promised participants £1 for remembering some pictures, but only 10 pence for remembering others. Their ability to describe the pictures was tested after one minute and after 24 hours. Memory at immediate test showed effects of list composition, suggesting local competition at encoding and/or retrieval. These results are consistent with our recently-proposed emotional Context Maintenance and Retrieval model, supporting it as a general account of motivated memory. In contrast, relative to this baseline, more valuable memories were not preferentially retained following delay, suggesting no detectable role of competition for consolidation.

Can neural correlates of encoding explain the context dependence of reward-enhanced memory?

“…Reward-enhanced memory was dependent on list context, meaning that recall of items that predicted reward was increased in mixed lists, but not in pure lists, replicating a recent study from our group (Talmi et al, 2021). The finding that reward did not enhance recall in pure lists places an important constraint on any explanation of reward-enhanced memory as solely a function of automatic encoding processes.…”

“…Findings from the mixed list condition agreed with the recall dynamics that this computational model predicted. In agreement with the prediction that the high reward items are more tightly bound to the encoding context and therefore will be more likely to be recalled first (Talmi, Lohnas, et al, 2019; Talmi et al, 2021), participants recalled high-reward items earlier than low-reward items. While in previous studies of recall of mixed lists of ‘strong’ and ‘weak’ items the propensity to recall ‘stronger’ items early was confounded with the increased average recall of such items, here we observed that high-reward items were recalled earlier than low-reward items while controlling for this confound.…”

“…The effect is present when the items are studied together in mixed lists, but is decreased or disappear altogether in pure lists where negative and neutral items do not compete during encoding and retrieval (Barnacle et al, 2016, 2018; Talmi et al, 2007; Talmi & McGarry, 2012). Of relevance for the present study, we recently provided initial evidence that reward -enhanced memory also is context dependent (Talmi et al, 2021). In the forementioned study, we found that reward increased memory performance in mixed lists, where high and low reward items were encoded together, but not in pure lists where they were encoded separately.…”

“…On the other hand, the list composition effect could be explained by competition during retrieval . One cognitive computational model that formalizes how list-composition effects could occur is the emotional Context Maintenance and Retrieval Model (eCMR, Talmi, Lohnas, et al, 2019) which has successfully modelled list-composition effects both in the context of emotion (Talmi, Lohnas, et al, 2019) and reward (Talmi et al, 2021). Similarly to previous computational models of list-composition effects (Shiffrin & Steyvers, 1997), this model explains emotion and reward-enhanced memory effects as the consequence of an interaction between encoding and retrieval processes.…”

Episodic retrieval for model-based evaluation in sequential decision tasks

“…Given that emotional salience modulates episodic memory, it follows that it should also modulate action evaluation in TCM-SR. We examine this issue below. For present purposes, we gloss over the many differences between emotional stimuli, prioritized stimuli, and rewards and punishments with varied magnitude, referring to all of them as 'emotionally salient' or 'important' states, and speak generally about 'emotional modulation' to refer to their effect on memory (Talmi, Kavaliauskaite, & Daw, 2018).…”