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
I’ve got a
splitting
headache!
• 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.
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
•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 exact role of the amygdala in
aggression is unclear, but it is
certainly a significant one.
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 &
Hormones
& agrression
aggression
• 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 and Aggression Testosterone
• Beeman (1947) castrated male mice and found that
aggressiveness reduced.
• He later injected the mice with testosterone which reestablished 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
•
•
•
Those frat boys at it again…
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.
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:
1.
2.
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