McDermott (2008)

Aim(s)

McDermott et al. aimed to study the underlying causes of aggression and punishment by studying if genetics predispose participants to carry out aggressive behaviour that is costly to the participant when they are environmentally provoked. They specifically aimed to investigate whether the MAOA gene affected aggression when environmentally provoked.

Procedure

Genetic samples were gained from 78 male participants. The participants were the divided into two groups, one group had high MAOA activity (MAOA-H) and one group had low MOAO activity (MAOA-L).

Aggression was measured by the amount of an unpleasant hot sauce participants would give to an opponent in a ‘power-to-take’ game when they knew the opponent did not like the taste of the hot sauce. The more of the hot sauce that was given, the more aggressive the participant was deemed to be.

Participants played a power-to-take game where they made earnings from a vocabulary task. A portion of these earnings were then taken by an anonymous person (who was in fact not real). Participants could then punish this anonymous person by giving the person some hot sauce.

The participants played four rounds of the game and they were told their opponent was a different person in each round. Participants were told they had a new supply of hot sauce in each of the four rounds, and they could use the hot sauce to punish their opponent or they could trade it in for money.

The amount of earnings that could be taken from the participants by their opponent was manipulated by the experimenters and was either ‘high take’ with 80% of the money being taken or ‘low take’ with 20% of the money being taken.

Results

It was found that high take participants were aggressive to their opponent more often than low take participants, and that they administered more hot sauce than low take participants.

66% of the participants gave some hot sauce to their opponent when 80% of their earnings were taken compared to 39% when only 20% of their earnings were taken.