Seeing the bigger picture: Endorphins mediate attentional broadening after reward receipt (PREPRINT)

Contemporary society faces significant challenges, that can lead to stress-induced tunnel vision. Research has shown that positive affect can counteract these effects by expanding humans' attentional scope, potentially promoting resilience and innovative thinking. However, the neurochemical mechanism underlying these effects remains unknown. This pre-registered triple-blind study investigated the role of beta-endorphins, neuropeptides released during pleasurable experiences, in mediating attentional broadening following reward receipt. Using a placebo-controlled cross-over design, forty volunteers underwent two sessions separated by at least 1 week, receiving either 50 mg naltrexone or a placebo. Participants completed a Navon letters task known to elicit contrasting effects of post-goal versus pre-goal positive affect on attentional scope. Our results show that attentional broadening observed after reward receipt under placebo was eliminated when opioid receptors were blocked, supporting our primary hypothesis. Interestingly, naltrexone did not impact attentional narrowing during reward anticipation, suggesting distinct neurochemical pathways governing the attentional effects of reward receipt versus anticipation. This study highlights the specific role of endogenous opioids in attentional breadth, emphasizing their potential in enhancing cognitive flexibility and resilience through natural positive experiences, with potential implications for mental health and stress management. Hypotheses, methods, and analyses were preregistered (https://osf.io/tbv8d) and all data and analysis scripts are publicly available (https://osf.io/kufts/).