“The Real Nature” of impulsive choice: Recent exposure to natural environments, not images depicting nature, reduces delay discounting in a systematic replication of Berry et al. (2014)

Delay discounting (DD) has been widely studied as a behavioral process relevant to unhealthy behavior and psychiatric disorders. As a result, DD has been proposed as an underlying trans-disease process of several maladaptive behaviors, such as smoking and risky sexual behaviors, and there is a growing interest in identifying factors that reduce it. Among the interventions examined in humans, exposure to nature cues has appeared especially promising. Berry et al. (2014, 2015, 2019) reported that brief exposure to images depicting nature scenes, such as forests and mountains, reduces impulsive choice in hypothetical monetary DD tasks. Despite these promising findings, subsequent replication attempts in other laboratories have failed to reproduce this effect consistently. One possible reason is that the mechanism through which nature images may reduce DD remain unclear. Although attention has been proposed as a candidate mechanism, it has not been directly tested. The present study extended prior replication efforts by examining whether increased observing responses moderated the effects of exposure to images of nature versus built environments on DD of college students (n = 148). We replicated Berry et al. (2014) as closely as possible and incorporated a matching-to-sample task developed by Hurtado-Parrado et al. (2023) to manipulate participants’ observing responses. We found that delay discounting rates were not affected by the attentional manipulation (matching photographs or not), image content (natural or built environments), sex, or employment status, and rates in our sample were significantly higher than those reported in the participants exposed to the Natural condition in Berry et al.’s (2014) original study. In contrast, self-reported exposure to actual natural environments during the week prior to participation was associated with lower delay-discounting rates, attenuating the discounting of participants with higher exposure to nature. Further, higher exposure to natural environments was associated with reduced discounting only among participants who also reported greater exposure to built environments and working indoors. Overall, our findings do not support the notion that attention may be responsible for the inconsistencies in previously reported reduction of DD by brief exposure to nature images. Instead, they suggest that recent real contact with natural environments may be more relevant to impulsive choice than exposure to depictions of nature.