Effects of ecstasy on cooperative behaviour and perception of trustworthiness: A naturalistic study

This observational, longitudinal, repeated measures, between-subjects study (n=39) compared how ecstasy (unquantified MDMA) promotes empathy during its acute effects and three days after, among ecstasy users and control participants. Acute ecstasy use was associated with increased face trustworthiness ratings and increased cooperative behaviour on the dictator and ultimatum games, but there were no group differences three days after.

Abstract

“Background: Acute recreational use of 3,4-methylenedioxymethamphetamine (MDMA; ‘ecstasy’) can promote pro-social effects which may alter interpersonal perceptions.

Aims: To explore such effects, this study investigated whether acute recreational use of ecstasy was associated with changes in individual perception of trustworthiness of people’s faces and co-operative behaviours.

Method: An independent group, repeated measures design was used in which 17 ecstasy users were tested on the night of drug use (day 0) and again three days later (day 3); 22 controls were tested on parallel days. On each day, participants rated the trustworthiness of 66 faces, carried out three co-operative behaviour tasks (public good; dictator; ultimatum game) and completed mood self-ratings.

Results: Acute ecstasy use was associated with increased face trustworthiness ratings and increased cooperative behaviour on the dictator and ultimatum games; on day 3 there were no group differences on any task. Self-ratings showed the standard acute ecstasy effects (euphoria, energy, jaw clenching) with negative effects (less empathy, compassion, more distrust, hostility) emerging on day 3.

Conclusions: Our findings of increased perceived trustworthiness and co-operative behaviours following use of ecstasy suggest that a single dose of the drug enhances aspects of empathy. This may in turn contribute to its popularity as a recreational drug and potentially to its enhancement of the therapeutic alliance in psychotherapy.”

Authors: L. H. Stewart, B. Ferguson, C. J. A. Morgan, N. Swaboda, Loring Jones, R. Fenton, M. B. Wall & H. V. Curran

Summary

Introduction

3,4-methylenedioxymethamphetamine (MDMA; ‘ecstasy’) stimulates pro-social feelings, increasing subjective ratings of friendliness, closeness, openness and understanding towards others. These pro-social and empathic effects are also influential in recreational use of ecstasy, impacting upon interpersonal behaviours and potentially motivating subsequent drug use.

MDMA’s serotonergic effects are thought to produce its major neuropsychological consequences, including increased trust in humans, improved social behaviours in patients with high-functioning autism spectrum disorder, and improved perception of fear in faces and moral judgments.

MDMA, or ecstasy, promotes pro-social effects.

Ecstasy use was associated with changes in individual perception.

Faces show trustworthiness.

17 ecstasy users and 22 controls were tested on the night of drug use and again three days later. The results suggest that a single dose of ecstasy enhances aspects of empathy, which may contribute to its popularity as a recreational drug.

Studies have shown that serotonergic control of cooperative behaviour is in part under control by the prisoner’s dilemma (PD) task, and that oxytocin increases generosity towards others.

We used two tasks to investigate the effects of ecstasy on social-cognitive mediators. We hypothesized that ecstasy use would increase perceived trustworthiness of faces and lead to more co-operative behaviour acutely, but decrease trustworthiness ratings and co-operative behaviour sub-acutely.

Design and participants

A parallel group, repeated measures design was used to test ecstasy users and controls on the night of drug use and three days later. All participants gave written informed consent prior to testing and were compensated with £10 following the last testing session.

Procedure

Ecstasy participants were tested on a Friday or Saturday evening at their own or at their friends’ homes. Sub-acute testing occurred under the same conditions three days apart.

Assessments

Drug use and trait measures were assessed on Day 3 using a drug use history questionnaire, a shortened version of the Empathy Quotient scale, a hospital anxiety and depression scale, and a spot-the-word task.

Inquisit 3 software was used to present 66 emotionally neutral faces to participants and they rated the trustworthiness of each face on a seven-point scale.

The co-operative behaviour task involved four rounds, and participants were told that money won would be converted into points and entered into a prize draw.

Participants were told they had been awarded £5 and were asked to contribute to The Public Good or split £10 with an unknown person.

Participants were told they had been awarded £10 and had to decide how they would like to split this amount with the next participant. If accepted, both parties receive the amounts agreed; if rejected, both parties receive nothing.

Participants completed 12 VAS ratings to tap subjective effects of MDMA, and a modified Beck Depression Inventory to report their mood in the preceding three days.

Statistical analyses

Repeated measures analysis of variance was used to compare ecstasy and control group data on day 0 and 3. All post-hoc t-tests were subject to Bonferroni correction.

Drug use (Table 2)

The ecstasy group reported taking more ecstasy than the controls, and had smoked cigarettes and taken cocaine within the last two weeks. They had also consumed more alcohol on day 0 than the controls.

Trustworthiness ratings of facial stimuli

A two-way ANOVA with the between subjects factors drug and day revealed significant effects of drug and day.

Ecstasy users rated faces as more trustworthy on day 0 than on day 3, and overall trust ratings were higher on day 0 than on day 3.

Co-operative behaviour task (Table 3)

Round 2 – The dictator showed that ecstasy participants contributed more on day 0 than on day 3, and that they did not differ in their contributions on day 0 and 3 between the groups.

The ultimatum game was played by ecstasy users on day 0 and control participants on day 3. Ecstasy users had a greater difference between amount allocated and amount accepted on day 0 than day 3 for both groups.

Subjective ratings (Table 4)

Ecstasy users rated higher empathy on day 0 than day 3, but lower empathy on day 3 than day 0. Ecstasy users rated more desire to be with others on day 0 than did controls, although this reversed somewhat on day 3.

Correlations were found between empathy rating and amount contributed during the public good task on day 0 and between BDI scores and difference between amount allocated and amount accepted during the ultimatum game on day 3.

Discussion

Participants taking ecstasy showed increases in both ratings of trustworthiness of faces and levels of cooperative behaviour, compared to the control group. This effect was only seen on day 0, suggesting that the acute effects were due to the influence of the drug.

Ecstasy users were more generous on the night they took the drug, even though the individual they were helping was unknown. Oxytocin may be the common mediator in both studies.

Ecstasy use was associated with increased ratings of trustworthiness in faces, suggesting that the drug’s pro-social effects are mediated, at least in part, by increased levels of interpersonal trust.

Ecstasy use increased perceived trustworthiness of faces and led to more co-operative behaviour compared with non-using control participants, but three days later these effects were reversed and ecstasy users rated themselves as less trusting than controls.

This study had the strength of ecological validity alongside a weakness that the precise dose or purity of ecstasy was not measured. However, subjective ratings showed that participants experienced the standard profile of acute ecstasy effects and that ecstasy users scored higher on trait empathy than controls.

In a naturalistic study of recreational ecstasy users, increased perceived trustworthiness of faces and increased co-operative behaviours between people were found. This finding adds to evidence from controlled studies with healthy volunteers that a single dose of ecstasy enhances empathy and prosocial behaviour.