Lecture notes
A level psychology aqa aggression
- Module
- Aggression
- Institution
- AQA
In depth well splitted in contexts, detailed notes on aggression. Usually paper 3 of aqa a level psychology exam.
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A-level PsychologyPAPER 1 PAPER 2 PAPER 3
a. Social influence a. Approaches a. Issues and debates
b. memory b. Biopsychology b. Relationships
c. Attachment c. Research methods c. Schizophrenia
d. Psychopathology d. Aggression
AGGRESSION
WHAT IS AGGRESSION? Any physical or non-physical behaviour that is threatening or
intends to harm humans or objects.
Neural and Hormonal Mechanisms in Aggression
(Biological Explanation)
THE LIMBIC SYSTEM
Together, the hippocampus, amygdala and
hypothalamus are called the limbic
system, the system of the brain regions
which produce aggression.
Frontal Cortex
(prevents The main part of the brain involved in
aggression when storing long-term memories is the
it’s Hippocampus hippocampus, which sends information
inappropriate)
Hypothalamus (uses information stored in our memory to the amygdala, to
from the memory to
(produces aggressive
interpret events) help determine the emotional meaning of
behaviour)
Amygdala the events in the environment.
(determines the emotional meaning of The Amygdala, located deep inside the
events)
brain, determines the emotional meaning
of the events in the environment, if the event is perceived as scary or dangerous then nerve
impulses are sent to the hypothalamus causing it to produce aggressive behaviour.
The hypothalamus is a part of the brain that is involved in activating the sympathetic
nervous system and controlling the fight or flight response, but also in producing
aggressive behaviour. The fight or flight response increases pupil size, sweating, heart
rate, muscle tension, and breathing rate, whereas, decreases salivation and digestion. When
the hypothalamus detects a potential threat or danger it also triggers the production of
aggressive behaviour.
The frontal cortex stops individuals from displaying aggressive behaviour in inappropriate
situations, by sending electrical signals that inhibit neurons in the amygdala. This
causes neurons in the amygdala to generate fewer nerve impulses and to stop sending
nerve impulses to the hypothalamus stopping the production of aggressive behaviour. If a
person’s frontal cortex is damaged, the neurons can’t generate electrical signals then their
amygdala will not be inhibited and signals will continue to be sent to the hypothalamus, so
the person will be more likely to display aggression.
,EVALUATION OF THE ROLE OF THE AMYGDALA IN AGGRESSION
✔️ Evidence for the role of the amygdala comes from MRI (Magnetic Resonance Imaging, a
brain imaging method that produces an image of the structure of the brain) studies.
Sumer et al. (2007) conducted a case study about a 14-year-old girl who started to display
excessive anger even in unprovoked situations, through an MRI scan it was found a tumour
pressing her amygdala, Sumer et al. concluded that the tumour was causing her abnormal
aggression. More activity in the amygdala leads to high levels of aggression, when the
tumour presses a part of the brain it can cause to produce more nerve impulses than normal,
in the case of the 14-years-old, her tumour was causing more activity in her amygdala,
meaning that more nerve impulses were sent to her hypothalamus, which increased her
aggression.
✔️ Further support for the role of the amygdala comes from a review conducted by
Mpakopoulou, who reviewed 13 studies that investigated patients with really bad
seizures, due to abnormal activity in their amygdala. To treat their seizures, patients had
brain surgeries to disconnect their amygdala from the rest of their brain - known as
Amygdalotomy. The studies looked at the patients' aggression before and after their
amygdalotomy. Before the surgery, the patients had too much activity in the neurons in their
amygdala, meaning they displayed higher levels of aggression. After their surgeries, their
amygdala was disconnected from the rest of their brain, so neurons in the amygdala could
no longer send nerve impulses to the hypothalamus, meaning that the patients’ levels of
aggression decreased. When Mpakopoulou reviewed all the studies, investigating the effects
of Amygdalotomy she found that amygdalotomy causes a decrease in aggressive behaviour,
which ranges from 33% to 100%. This means that for some patients the amygdalotomy
totally prevented the aggressive behaviour, which provides strong evidence for the role of
the amygdala in producing aggression.
❌There are a lot of studies in humans and animals, which looked at the damage
to the amygdala and it was found that the damage leads to changes in
aggression. However, there are some limitations to the study investigating the
role of the amygdala in aggression. One limitation of the study support for the role
of the amygdala in aggression is that the results of the studies haven’t all been consistent,
as the results are not all the same. While some studies have found that a damaged
amygdala is associated with a decrease in aggression, others have reported an increase in
aggression. This suggests that the amygdala may be more complicated than first thought
and that its role might differ depending on the sub-regions of the amygdala.
THE ROLE OF NEUROTRANSMITTERS: SEROTONIN
Other brain mechanisms can also help control aggression. By increasing or decreasing
aggressive behaviour. When neurons send electrical signals to other neurons at the
synapse, they release neurotransmitters (GABA, dopamine, acetylcholine, serotonin) that
bind to receptors on the postsynaptic membrane.
GABA - the main inhibitory neurotransmitter used in the brain.
Dopamine - is involved in processing reward and attention.
Acetylcholine - is involved in muscle movement.
Serotonin (plays a role in controlling our mood and how we feel about things) - is involved in
controlling the level of aggression. Serotonin is one of the main neurotransmitters released
in the limbic system.
When serotonin is released in the synapses in the amygdala it causes negative electrical
charges to flow into neurons meaning that the neurons are inhibited and are less likely to
, generate nerve impulses. Since serotonin inhibits neurons in the amygdala, this means that
the amygdala sends fewer nerve impulses to the hypothalamus. Therefore serotonin
reduces aggressive behaviour. The more serotonin we have, the less likely we are to be
aggressive. The less serotonin we have, the more likely we are to be aggressive.
EVALUATION OF THE ROLE OF SEROTONIN IN AGGRESSION
✔️ Serotonin is released at synapses in the limbic system, where it inhibits neural activity,
leading to a decrease in aggression. A neuron scientist, Molly Crockett investigated the
effects of manipulating serotonin on participants' level of aggression in a social decision-
making game, participants were given a drug that either increased their levels of serotonin or
decreased the serotonin. Participants then were matched with an opponent and took turns in
deciding how to split a sum of money between them. Crockett found that participants who
were given a drug to increase their serotonin behaved less aggressively when their
opponent behaved unfairly. When participants were given drugs to decrease their serotonin
they behaved more aggressively when their opponents behaved unfairly. According to the
biological approach, we should expect participants with increased serotonin levels to
become less aggressive, and participants with decreased serotonin levels to become
more aggressive.
THE ROLE OF HORMONES: TESTOSTERONE
(also involved in controlling level of aggression) Hormones are chemical messengers
released by glands into the bloodstream. Testosterone increases the tendency to be
aggressive. The more testosterone that is released, the more aggressive we are.
Testosterone is produced and released by the adrenal glands and sex glands (testes and
ovaries). As men produce more testosterone than women they are more likely to display
aggression than women.
✔️ Dabbs et al. (1987), conducted a correlational study by measuring the levels of
testosterone in 89 prison inmates and looked at the relationship between their levels of
testosterone and the levels of violent crimes committed. Research has found that Increased
testosterone level was associated with more violence, meaning there was a positive
correlation between the level of testosterone and the level of violence. Further support
for the role of testosterone in aggression comes from studies showing that men, who have
higher levels of testosterone, display more aggression and violence than women.
❌One limitation of the support for the role of testosterone in aggression is that
the studies are correlational (Dabbs et al. 1987), therefore it can’t establish a
cause-and-effect relationship, so just because there is a correlation between the level of
testosterone and the level of aggression displayed by prison inmates, it doesn’t mean that
higher levels of testosterone cause the higher levels of aggression seen in some inmates.
(2) Another limitation is that research hasn’t been always consistent, for instance, some
studies show correlation between testosterone and aggression in prison inmates, while
others have reported no correlation between testosterone and aggression in prison inmates.
Therefore the results haven’t always replicated across studies.
LIMITATIONS OF THE NEURAL AND HORMONAL EXPLANATIONS OF AGGRESSION:
IGNORES OTHER FACTORS
❌There are some limitations for the neural and hormonal explanations of aggression. One
major limitation is that they ignore non-biological factors that contribute to aggression.
Such as environmental and social factors that cause men to be more violent than women.
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