| Abstract: | It is commonly assumed that memories contribute to value-based decisions. Nevertheless, most theories of value-based decision-making do not account for memory influences on choice. Recently, new interest has emerged in the interactions between these two fundamental processes, mainly using reinforcement-based paradigms. Here, we aimed to study the role memory processes play in preference change following the nonreinforced cue-approach training (CAT) paradigm. In CAT, the mere association of cued items with a speeded motor response influences choices. Previous studies with this paradigm showed that a single training session induces a long-lasting effect of enhanced preferences for high-value trained stimuli, that is maintained for several months. We hypothesized that CAT increases memory of trained items, leading to enhanced accessibility of their positive associative memories and in turn to preference changes. In two preregistered experiments, we found evidence that memory is enhanced for trained items and that better memory is correlated with enhanced preferences at the individual item level, both immediately and 1 mo following CAT. Our findings suggest that memory plays a central role in value-based decision-making following CAT, even in the absence of external reinforcements. These findings contribute to new theories relating memory and value-based decision-making and set the groundwork for the implementation of novel nonreinforced behavioral interventions that lead to long-lasting behavioral change.Value-based decision-making and memory are both extensively studied processes in cognitive psychology and cognitive neuroscience (Fellows 2017). Most theories of value-based decision-making have focused on processes related to the incremental learning of value following external reinforcement, but have not explicitly addressed the role of memory per se. Thus, fundamental questions remain regarding interactions between memory and value-based decisions, which have been gaining attention in recent years.Several recent empirical studies have demonstrated interactions between episodic memory and value-based decision-making. For example, memory for past events has been shown to bias value-based decisions (Duncan and Shohamy 2016), differently for choices of novel versus choices of familiar options (Duncan et al. 2019), and choice behavior and fMRI signals during value-based decision-making were better explained by episodic memory for individual past choices than by a standard reinforcement learning model (Bornstein et al. 2017). Another study has found that during sampling of episodic memories of previous choices, the retrieved context influenced present choices, deviating from the predictions of standard reinforcement learning models (Bornstein and Norman 2017). Other studies have demonstrated that the long time known effect of choices on future preferences is related to memory processes (Chammat et al. 2017; DuBrow et al. 2019; Luettgau et al. 2020). At the neural level, the ventromedial prefrontal cortex (vmPFC) and the hippocampus both have been shown to play a role in memory processes and value-based decisions (Weilbächer and Gluth 2017) and recent studies have been further emphasizing that the hippocampus bridges between past experience and future decisions (Bakkour et al. 2019; Biderman et al. 2020).All these studies, and many others, highlighted the interaction between memory and value-based decision-making involving external reinforcements. However, everyday life involves decisions and associations that are not directly reinforced. Thus, it remains unclear whether memory plays a general role in value-based decision-making even without external reinforcements.To better understand the role of memory processes in shaping preferences independently of external reinforcements, we used a novel behavioral change paradigm, named cue-approach training (CAT). In this paradigm, associating images of items with a neutral cue and a speeded motor response results in a consistent preference enhancement without external reinforcement, which is maintained for months (Schonberg et al. 2014; Bakkour et al. 2018; Salomon et al. 2018, 2019; Botvinik-Nezer et al. 2020). During CAT, images of items are consistently paired with a neutral cue and a speeded motor response (“Go items”), while other items are presented without the cue or the response (“NoGo items”). One training session with several presentations of all items leads to long-lasting preference changes, measured as the likelihood of choosing Go over NoGo items that had similar initial subjective values (Schonberg et al. 2014). Results from over 30 samples with this paradigm have demonstrated a replicable effect on various types of stimuli, including snack food items, fruits and vegetables, unfamiliar faces, fractal art images, and positive affective images (Bakkour et al. 2016, 2017; Veling et al. 2017; Zoltak et al. 2017; Bakkour et al. 2018; Salomon et al. 2018, 2019; Botvinik-Nezer et al. 2020), revealing the potential of the CAT paradigm as an experimental platform for value-based decision-making without external reinforcements (Schonberg and Katz 2020).The underlying mechanisms of the change of preferences following CAT are not yet fully understood (Schonberg et al. 2014; Bakkour et al. 2017; Salomon et al. 2019; Botvinik-Nezer et al. 2020; Schonberg and Katz 2020). The long-lasting nature of the effect, which has been shown to last for up to 6 mo following a single training session (Schonberg et al. 2014; Salomon et al. 2018, 2019; Botvinik-Nezer et al. 2020), raises the hypothesis that memory processes are involved in its maintenance. Furthermore, previous studies have found enhanced memory for Go compared with NoGo items with other types of Go–NoGo tasks (Chiu and Egner 2015a,b; Yebra et al. 2019) and for items for which participants have a sense of agency (Murty et al. 2015). One recent study provided preliminary evidence suggesting that memory is involved in preference change following a similar nonreinforced Go/NoGo training task (Chen et al. 2021).We hypothesized that CAT enhances memory of Go items, which in turn leads to preferring these items over NoGo items. Previous neuroimaging findings with CAT that suggested possible interactions between hippocampal fMRI activity and subsequent preferences 1 mo following CAT, provide additional evidence in support of this hypothesis (Botvinik-Nezer et al. 2020). Therefore, here we set out to test the role memory processes play in the behavioral change of preferences following CAT, in the short and in the long term.We propose an underlying mechanism for the CAT effect, in which preference change following CAT results from a boost in memory encoding of positive Go items, which in itself is a consequence of enhanced perceptual processing of Go items (Schonberg et al. 2014; Botvinik-Nezer et al. 2020). We hypothesize that the enhanced encoding of Go items, as well as the greater perceptual activation in response to them, increases accessibility of attributes and associations of these specific Go items (Anderson 1983; Bhatia 2013). Furthermore, we hypothesized that preference changes, reflected in the binary choice phase, are due to the enhanced accessibility of memory associations of the Go items, which tips the scales in favor of the Go items when the associations are positive.In order to test memory for individual items, in the current work we introduced a memory recognition task following CAT. In two independent preregistered experiments and one pilot experiment, memory was evaluated following a long (16 repetitions) or short (a single exposure) CAT training session, before the probe phase that evaluated post-training preferences. We then tested our predictions that (1) memory will be stronger for Go compared with NoGo items following CAT (more accurate and faster responses in the recognition task) and (2) that memory will be related to choices (better remembered Go items will be chosen over worse remembered NoGo items). Since the link between better memory and enhanced choices is hypothesized to be related to positive associated memories, we tested the relationship between memory and choices separately for choices between low-value and choices between high-value items. These hypotheses were tested both in the short term (immediately or a few days after CAT) and in a 1-mo follow-up. |
