Neural and Hormonal Mechanisms Flashcards
Aggression
An act carried out with the intention to harm another person.
Limbic system
A neural network of structures including the hippocampus, hypothalamus and amygdala. Help to coordinate behaviours that satisfy emotional urges (e.g. aggression).
Amygdala
This plays a key role in humans and animals and how they respond to their environment (threats and challenges).
Responsible for quickly evaluating the emotional importance of sensory information and prompting an appropriate response.
The stimulation of the amygdala can increase the likelihood of an aggression response, hence it is an important predictor of aggressive behaviour.
Heightened activity in amygdala = increased aggression.
Hippocampus
The hippocampus is involved with the formation of long-term memories, and so allows one to compare a current threat with similar past experiences.
Impaired hippocampal function prevents the nervous system from putting things into a relevant and meaningful context, and may cause the amygdala to respond inappropriately to sensory stimuli, resulting in aggressive behaviour.
Serotonin
Serotonin is a neurotransmitter which has an inhibitory effect on the brain; it slows down neural activity.
Normal levels of serotonin in the orbitofrontal cortex (OFC) and the amygdala are linked to reduced firing of neurons. This, in turn, is associated with a greater degree of behavioural self-control.
Decreased (low levels of) serotonin disturbs this mechanism = lower self-control = aggression.
Testosterone
Testosterone is an androgen (male sex hormone) that is linked to aggression in males due to its mediating role in areas of the brain linked to aggression (e.g. amygdala and OFC).
Testosterone is produced in spurts, so levels can rise suddenly and have an effect within minutes.
Castration studies of animals show that removing the testes reduces aggression, and injecting testosterone in the same animals will restore aggression (Giammanco et al).
Positive correlation found in high levels of testosterone and prisoners (Dolan et al).
Progesterone
Progesterone plays a role in aggression of women.
Levels of progesterone vary during ovulation cycle and are the lowest after menstruation.
Zimokiewicz found a negative correlation between progesterone levels and self-reported aggression (low levels of progesterone are linked to increased aggression in women).
- P - Reductionist approach
E - This means that the complexity of human behaviour has been reduced down to only biological mechanisms.
E - Other factors may have an influence on aggression, such as through social learning in the environment, e.g. Bandura’s study using Bobo dolls.
L - This suggests that the neural and hormonal explanation of aggression fails to consider other factors affecting aggression, making the explanation invalid.
+ P - Research support for testosterone
E - Dabbs et al measured salivary testosterone levels were measured in violent and non-violent criminals.
E - They found that those with the highest testosterone levels had a history of primarily violent acts, and only non-violent criminals had the lowest levels.
L - This suggests that there is a relationship between high levels of testosterone and aggression.
- P - Gender bias
E - Most of the research concerned with testosterone and aggression has been conducted using male participants, meaning that there may be a gender bias in the findings and conclusions drawn.
E - Baucom et al found that women with higher testosterone levels had higher occupational status, possibly a result of being more assertive.
L - This suggests that women may also respond to challenging social situations with increased testosterone and display aggression and dominance.
