Neural and hormonal explanations Aggression Neural and hormonal explanations

Learning Objectives To outline and evaluate the role of testosterone in aggression using research evidence To outline and evaluate the role of serotonin in aggression using research evidence

The role of testosterone Testosterone is a type of androgen which are male sex hormones Testosterone is produced by the Leydig cells in the male testes It is also found in females (produced by the ovaries) but in a much smaller quantity – converted to female sex hormones Testosterone is thought to be linked to aggression as aggression increases during puberty when testosterone levels are higher.

Research evidence (use page 132 of books to outline) Wagner et al (1979) Mice – castrated mice showed less aggression Pillay (2006) More testosterone in more aggressive sports people Harrison et al (2000) Increase testosterone increase aggression when playing frustrated computer game EVALUATION – Consider issues with experiments as well as key issues and debates

The role of serotonin Serotonin is a neurotransmitter - chemicals that allow impulses from one area of the brain to be transmitted to another area Low levels of serotonin are thought to be associated with higher levels of aggression Where serotonin receptors are not functioning, there tends to be an increase in aggressive behaviour If serotonin levels are increased, aggression levels decrease

Mann et al (1990) Gave 35 healthy participants a drug (dexfenfluramine) which is known to deplete serotonin. They used a questionnaire to measure hostility and aggression After taking the drug: Males increased in aggression and hostility scores Females scores didn’t change ADD YOUR OWN EVALUATION POINTS FOR THIS STUDY

Raleigh et al (1991) – Vervet monkeys They were kept in two conditions: One group were fed on a diet high in tryptophan (a type of amino acid, normally in meats) One group were fed on a diet low in tryptophan. Tryptophan increases serotonin in the brain. Those who had a low-tryptophan diet exhibited higher aggression than the other group. ADD YOUR OWN EVALUATION POINTS FOR THIS STUDY

Evaluation of serotonin explanation Use GRENADE to evaluate the neural explanation of aggression G – gender bias R – reductionism E – ethical issues N – nature vs nurture A – application D – determinism vs free will E – ethnocentrism