Crockett et al (2010)

Procedure

- 30 healthy subjects volunteered and were recruited for the study with a mean age of 26 - Experiment followed a repeated measures design with 2 conditions: --Condition 1: participants were given a dose of citalopram (highly selective serotonin reuptake inhibitor, an SSRI, a chemical that blocks reuptake of serotonin from the synapse → boosts its concentration and prolongs its effects --Condition 2: (control) participants were given a placebo. - After taking the drugs, participants were given series of moral dilemmas that involved choosing btwn an utilitarian outcome (saving 5 lives) and aversive harmful actions (e.g. killing an innocent person) --2 types of aversive harmful actions in the scenarios: personal (e.g. pushing a man off a bridge to stop a train and prevent it from hitting 5 people) and impersonal (e.g. pressing a lever to divert a train off a track where it will hit 5 people to a track where it will hit 1)

Evaluate (method and ethics)

- Method: Citolopram intake induced slight nausea, which might have meant that the participants could know what condition they were in during the experiment. - Ethics: Participants were not at risk of physical harm, but some may have been caused some sort of emotional harm as a result of thinking of their answers to scenarios in which people would die as a result of their decisions. Researchers also would have had to receive informed consent from all participants (even the placebo group since they did not know who would get what) because they were given an SSRI

Method

- Repeated measures design with 2 conditions - Self-selected sampling - Double-blind study

Results

- Responses in the impersonal version were unaffected by citalopram - With citalopram, participants were less likely to push the man off the bridge in the personal scenario than the participants in the placebo condition

Conclusions

- Serotonin reduces acceptability of personal harm and in this way promotes prosocial behavior. It modulates reactions of the brain to emotionally salient solutions so that inflicting harm on other people is judged as less acceptable

Year of study

2010

Researchers

Crockett et al

Title/subject of research

Effect of serotonin on prosocial behavior

Aim

To answer how a person's free will can be affected by a biological factor (establish links between seemingly distant variables)