Positive autobiographical memory recall does not influence temporal discounting: an internal meta-analysis of experimental studies

People tend to discount the value of future rewards as the delay to receiving them increases. This phenomenon, known as temporal discounting, has been proposed to underlie many impulsive behaviors, such as drug abuse and overeating. Furthermore, steep temporal discounting has been observed in people with addiction and other impulsive disorders. Given the potential role of temporal discounting in maladaptive behaviors, there have been many efforts to find experimental manipulations that reduce temporal discounting, with the hope that these manipulations can be adapted into interventions with clinical utility. One class of manipulations that has held some promise involves recalling positive autobiographical memories prior to making intertemporal choices. Just as imagining positive personal events in the future has been shown to reduce temporal discounting, a few studies have shown that recalling positive events from the past reduces temporal discounting, especially if memory retrieval evokes positive affective states, such as gratitude and nostalgia. However, we failed to replicate these findings. Here we present a meta-analysis combining data from 14 studies done by the authors (n = 603) that involved within-subjects positive memory recall-based manipulations. In each study, temporal discounting was assessed using a monetary intertemporal choice task. The average effect size was small and not significantly different from zero. This finding helps elucidate the neurocognitive mechanisms of temporal discounting; whereas engaging the episodic memory system to imagine future events might promote more patience, engaging the episodic memory system to imagine past events does not.