Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Randomized Controlled Trial
. 2018 May 29;8(1):8236.
doi: 10.1038/s41598-018-26656-2.

Psilocybin and MDMA reduce costly punishment in the Ultimatum Game

Anthony S Gabay  1 , Robin L Carhart-Harris  2 , Ndaba Mazibuko  3 , Matthew J Kempton  3   4 , Paul D Morrison  4 , David J Nutt  2 , Mitul A Mehta  3
Affiliations
Randomized Controlled Trial

Psilocybin and MDMA reduce costly punishment in the Ultimatum Game

Anthony S Gabay et al. Sci Rep. .

Abstract

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 (R2 = 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.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Boxplot displaying rejection rates of unfair offers in the Ultimatum Game across conditions in the psilocybin study. OR: odds ratio. Note that while the figure displays rejection rates, the statistics are based on GEE analysis which incorporates trial-by-trial data.
Figure 2
Figure 2
Boxplot displaying rejection rates for unfair offers in the MDMA study. White dots represent the placebo session, orange dots the MDMA session. Note that while the figure displays rejection rates, the statistics are based on GEE analysis which incorporates trial-by-trial data.
See this image and copyright information in PMC

References

    1. Brothers, L. The social brain: a project for integrating primate behavior and neurophysiology in a new domain. In Foundations in social neuroscience 367–385 (MIT Press, 2002).
    1. Dunbar R. Psychology. Evolution of the social brain. Science. 2003;302:1160–1161. doi: 10.1126/science.1092116. - DOI - PubMed
    1. Polgár P, Fogd D, Unoka Z, Sirály E, Csukly G. Altered social decision making in borderline personality disorder: an Ultimatum Game study. J. Personal. Disord. 2014;28:841–852. doi: 10.1521/pedi_2014_28_142. - DOI - PubMed
    1. Radke S, Schäfer IC, Müller BW, de Bruijn ERA. Do different fairness contexts and facial emotions motivate ‘irrational’ social decision-making in major depression? An exploratory patient study. Psychiatry Res. 2013;210:438–443. doi: 10.1016/j.psychres.2013.07.017. - DOI - PubMed
    1. Carhart-Harris RL, et al. Psilocybin with psychological support for treatment-resistant depression: an open-label feasibility study. Lancet Psychiatry. 2016;3:619–627. doi: 10.1016/S2215-0366(16)30065-7. - DOI - PubMed

Publication types

Substances