GCSE Psychology

Topic C Do TV and violent video games affect people’s behaviour?

Hormones & aggression

objectives By the end of the lesson you will be

able to…

• To understand how destroying the amygdala reduces aggression.

• Explain how testosterone leads to aggressive behaviour.

Key words

• testosterone

• Hormones• amygdala

The Role of Neural and Hormonal Mechanisms in Aggression

Phineas Gage• One of the best examples of how

brain injury can influence aggressive behaviour is the case of Phineas Gage.

• Working on a railway in 1848, he had an accident in which a tamping iron went up through his face , behind his left eye and out through the top of his head.

• He survived the accident, but his personality was changed, including a huge increase in aggression.

I’ve got a splitting

headache!

The Role of the Amygdala

• Taming effect found in rhesus monkeys by removing part of the temporal lobes and therefore destroying the amygdala.

• Narabyashi et al (1972) – 43 / 51 patients whose amygdala was destroyed through psychosurgery showed reduced aggression afterwards.

• King (1961) described a case study of a woman whose amygdala was electrically stimulated during an operation.

• She became threatening and verbally aggressive until the electrical current was turned off.

• Wong et al (1997) – criminals with violent tendencies have reduced size amygdala

.

The exact role of the amygdala in aggression is unclear, but it is certainly a significant one.

•In 1966 Charels Whitman killed 13 people from an observation tower at Texas University, after killing his wife and mother. •He left behind a note asking doctors to examine his brain as he was convinced that something was making him aggressive.• He was found to have a brain tumour pressing against his amygdala.

The Role of Neurotransmitters

• The neurotransmitter (chemicals which transmit signals from a neuron to a target cell across the synapse) serotonin influences aggressive behaviour.

• In research with vervet monkeys, reducing serotonin levels resulted in increased aggressive behaviour, whereas increasing serotonin decreased the aggressive occurrences.

• Drugs to raise serotonin levels, such as trytophan have been given to juvenile delinquents and unpredictable institutionalised patients.

So… the higher the serotonin level, the lower the aggression.

Hormones & agrression

• What is a hormone? • A hormone is a chemical produced by the body that

sends messages to organs of the body via the bloodstream.

• What is the role of testosterone in the body? • Testosterone is a male sex hormone produced in the

testes and secreted by the adrenal gland which is needed to produce sperm.

• Testosterone is also involved in the development of the male reproductive organs and produces male features, such as facial hair and a deep voice.

• It is also said to be involved in aggression.

Hormones & aggression

Hormones and Aggression - Testosterone

• Beeman (1947) castrated male mice and found that aggressiveness reduced.

• He later injected the mice with testosterone which re-established their aggressiveness.

• Castration has since been used as a method for making domestic and farm animals more manageable.

Aggression in animals

3) In animals, what happens when they are injected with testosterone or have their testes removed?

4) Define castration.

Read page 97.

5) Why is aggression in humans less instinctive than in animals?

Aggression in humans

• Psychologists can take blood from humans to see what levels of testosterone they have and compare this to how aggressive they feel or act.

• Some correlation studies (studies that see if there is a link between 2 variables) have found a relationship between high testosterone levels and questionnaire results showing greater reported aggression.

It is not certain though whether testosterone causes increased aggression or aggression

causes increased testosterone

• Testosterone is also clearly related to aggression in humans.

• Dabbs et al (1995) – measured testosterone in saliva of 692 adult male prisoners. Found higher levels in rapists and violent offenders than in burglars and thieves.

• Dabbs et al (1996) – looked at 12 fraternities (a social club for male undergraduates) in 2 universities. Members of fraternities with highest levels of testosterone were described as boisterous and macho, those with lowest were attentive and helpful.

Those frat boys at it again…

Male aggression and testosterone

Read page 96.• Why is it that males in almost every culture are

more aggressive than females?

2) What does testosterone do in the body?

• The same effects of testosterone are also found in women.

• Dabbs et al (1988) – female prisoners. Testosterone highest in cases of unprovoked violence but lowest where violence was defensive (eg. In domestic abuse cases)

Other research has found conflicting results, but this is to do with the operationalisation of ‘aggression’.

Aggression in humans

6) How can testosterone levels be measured?

7) What are correlation studies?

Task

• Read through evaluating the role of testosterone on aggression (Pg 97 in your text book)

• Using the information, create a table of evidence for and against hormones as the cause of human aggression

Review & reflect

Headbandz game

In groups of 4:• One person is to wear the

headband and the rest of the group have to write down a word associated with today’s lesson and place it on the headband.

• The person with headband on has to try and guess the answer with only yes or no