Psilocybin and MDMA reduce costly punishment in the Ultimatum Game

Disruptions in social decision-making are becoming evident in many psychiatric conditions. These are studied using paradigms investigating the psychological mechanisms underlying interpersonal interactions, such as the Ultimatum Game (UG). Rejection behaviour in the UG represents altruistic punishme...

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Bibliographic Details
Published in:Scientific reports 2018-05, Vol.8 (1), p.8236-9, Article 8236
Main Authors: Gabay, Anthony S., Carhart-Harris, Robin L., Mazibuko, Ndaba, Kempton, Matthew J., Morrison, Paul D., Nutt, David J., Mehta, Mitul A.
Format: Article
Language:English
Subjects:
631/378/2645/2646
631/378/2649/1409
631/378/3919
631/477/2811
Decision making
Ecstasy
Humanities and Social Sciences
MDMA
multidisciplinary
Psilocybin
Psychotherapy
Punishment
Reinforcement
Science
Science (multidisciplinary)
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Summary:Disruptions in social decision-making are becoming evident in many psychiatric conditions. These are studied using paradigms investigating the psychological mechanisms underlying interpersonal interactions, such as the Ultimatum Game (UG). Rejection behaviour in the UG represents altruistic punishment – the costly punishment of norm violators – but the mechanisms underlying it require clarification. To investigate the psychopharmacology of UG behaviour, we carried out two studies with healthy participants, employing serotonergic agonists: psilocybin (open-label, within-participant design, N = 19) and 3,4-methylenedioxymethamphetamine (MDMA; placebo-controlled, double-blind, crossover design, N = 20). We found that both MDMA and psilocybin reduced rejection of unfair offers (odds ratio: 0.57 and 0.42, respectively). The reduction in rejection rate following MDMA was associated with increased prosociality (R 2  = 0.26, p  = 0.025). In the MDMA study, we investigated third-party decision-making and proposer behaviour. MDMA did not reduce rejection in the third-party condition, but produced an increase in the amount offered to others (Cohen’s d  = 0.82). We argue that these compounds altered participants’ conceptualisation of ‘social reward’, placing more emphasis on the direct relationship with interacting partners. With these compounds showing efficacy in drug-assisted psychotherapy, these studies are an important step in the further characterisation of their psychological effects.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-018-26656-2