difference between reactive and proactive aggression
reactive: Impulsive, angry aggression that happens in response to a perceived threat or provocation. Example: hitting someone because they insulted you.
proactive: Deliberate, planned aggression used to achieve a goal or reward. Example: bullying someone to gain status or stealing through intimidation.
neural and hormonal mechanisms: Role of the limbic system
- The limbic system (amygdala, hypothalamus, hippocampus, cingulate gyrus) is the main neural explanation for reactive aggression in response to perceived threat.
- The amygdala assigns emotional significance to sensory information; overactivity leads to exaggerated aggressive responses.
- The hypothalamus controls the autonomic nervous system, so damage can produce inappropriate aggression to emotional situations.
- The hippocampus forms emotional memories; dysfunction can cause misinterpretation of events as threatening, increasing aggression.
- The cingulate gyrus focuses attention on emotionally important stimuli, helping determine whether aggression is triggered.
- The limbic system connects to the prefrontal cortex, which inhibits impulsive behaviour; reduced PFC activity leads to poor control of the amygdala and higher aggression.
neural and hormonal mechanisms: Role of the neurotransmitter serotonin
- Serotonin normally inhibits the firing of the amygdala, which controls fear, anger and emotional responses.
- Because of this inhibitory effect, serotonin has a calming influence on behaviour.
- Low serotonin levels reduce this inhibition, making aggressive and impulsive behaviour more likely.
- Serotonin also helps regulate activity in the prefrontal cortex, which is involved in decision-making and behavioural control.
- Low serotonin impairs the ability to respond appropriately to external stimuli and increases emotional reactivity.
- As a result, individuals with low serotonin struggle to anticipate risk, lose control more easily, and show impulsive aggression.
neural and hormonal mechanisms: Role of the hormone testosterone
- Testosterone influences aggression by increasing activity in the amygdala and reducing the inhibitory control of the prefrontal cortex, making aggressive responses more likely
- Aggression is generally found to be higher in males than females in both human and non-human species.
- Animal research suggests that male hormones play a key role in producing aggressive behaviour.
- Testosterone is the primary hormone involved in determining whether an embryo develops as male or female.
- Testosterone levels peak during adolescence in males and then slowly decline with age.
- The hormone also influences muscle development and sex drive, showing its wide biological effects.
- Higher levels of testosterone are linked to increased aggression, making it a key hormonal explanation for aggressive behaviour.
neural and hormonal mechanisms ao3 points
- animal research supports role of limbic system (Kluver and Bucy)
- brain scans for the role of the amygdala (wong et al)
- serotonin (ferarri et al)
- testosterone (wagner)
neural and hormonal mechanisms ao3: animal research supports role of limbic system
P: One strength of the limbic system explanation of aggression is that it is supported by early animal research, such as the work of Kluver and Bucy (1939).
E: They removed key limbic structures—including the amygdala and hippocampus—from Rhesus monkeys and found that the animals showed a loss of normal emotional, motor, and vocal reactions linked to fear and anger. The monkeys also failed to recognise social hierarchies and even attempted to fight larger, dominant group members.
E: These findings demonstrate that damage to the limbic system disrupts normal emotional processing and increases inappropriate aggression, providing strong biological evidence for the system’s role in regulating aggressive responses.
D: However, a major limitation is that these findings come from animal studies, raising concerns about extrapolation to humans. Human and monkey physiology differ, and although they share similar neural structures, we cannot be certain that aggression is mediated in the same way in humans, reducing the extent to which these results can be generalised.
neural and hormonal mechanisms ao3: brain scans for the role of the amygdala
P: A strength of the limbic system explanation of aggression is that it is supported by modern neuroimaging research, such as Wong et al. (1997).
E: Wong et al. used MRI scans to compare the amygdala volume of 19 violent male criminals with 20 non-violent control participants and found that the violent individuals had a significantly smaller amygdala.
E: This supports the idea that the amygdala and limbic system are involved in regulating aggression, providing contemporary biological evidence consistent with earlier animal studies.
D: However, the study has limitations, including low population validity due to the small sample size and beta gender bias, as only males were studied. This means caution is needed when generalising these findings to females or the wider population.
neural and hormonal mechanisms ao3: serotonin
P: Ferrari et al. (2003) provide support for the role of serotonin in aggressive behaviour.
E: They allowed adult male rats to fight daily for ten days and found that on the eleventh day, when a rat was not allowed to fight, its dopamine levels increased by 65% and serotonin levels decreased by 35%, showing that fighting affected brain chemistry.
E: This demonstrates that serotonin is linked to aggression, as lower levels are associated with heightened aggressive tendencies, highlighting the biological basis of aggression.
D: However, the study raises a cause-and-effect issue: it is unclear whether low serotonin causes aggression or if aggression reduces serotonin levels. This limits the validity of the explanation, although it shows the complexity of serotonin’s role in aggressive behaviour.
neural and hormonal mechanisms ao3: testosterone
P: Research on testosterone supports its role in aggression.
E: Wagner (1979) castrated mice, removing their testes, and found that aggression levels decreased, supporting the idea that testosterone is linked to aggressive behaviour.
E: This suggests that testosterone plays a crucial role in regulating aggressive responses.
D: However, the study only shows a correlation between lowered testosterone and reduced aggression, so it does not establish a causal relationship, limiting the strength of the explanation.
Ethodological explanation of aggression
- Ethology studies innate behaviour in animals (including humans) in their natural environment to understand its adaptive value.
- Ethologists believe that studying animal behaviour can help explain human behaviour (e.g., Lorenz used geese to study attachment).
- Aggression is considered an innate behaviour that occurs in all animal species and has an adaptive function.
- Aggression can protect resources (e.g., land, food) and establish dominance hierarchies, which improves access to resources such as mates.
- Lorenz (1966) proposed that aggression is often ritualistic or symbolic, which is more adaptive than direct aggression.
- Ritualistic aggression (e.g., teeth baring) deters opponents without causing injury, preserving the organism’s ability to survive and reproduce.
Ethodological explanation of aggression: Innate Releasing Mechanisms and Fixed Action Patterns
- Ethological theory proposes that aggression can result from an evolved, automatic biological response in the brain.
- Animals have built-in neural structures that respond to specific sign stimuli or releasers (e.g., facial expressions) by triggering aggressive behaviour.
- This inbuilt structure is called the Innate Releasing Mechanism (IRM), which activates aggression automatically.
- The resulting aggressive behaviour follows a Fixed Action Pattern (FAP), a sequence of instinctive actions triggered by the IRM.
- FAPs are stereotyped, species-specific, and automatic, occurring once the IRM is activated (e.g., a dog chasing a running cat).
- The ethological approach highlights that aggression is instinctual and adaptive, ensuring survival and appropriate responses to environmental stimuli.
characteristics of FAPs
- stereotyped (FAP behaviours can happen in the same way)
- universal (behaviours follow same patterns for all members)
- innate (born with the ability to perform the behaviour)
- ballistic (once started, cant be stopped)
- specific triggers (sign stimulus)
ethological explanation ao3:
P: Research provides strong support for the ethological explanation of aggression, particularly the concepts of innate releasing mechanisms and fixed action patterns.
E: Tinbergen studied male stickleback fish, which become territorial during mating season and develop a distinctive red spot on their underside. He observed that males would instinctively attack any other male entering their territory that displayed this red spot.
E: To test this, Tinbergen presented sticklebacks with wooden models. Models with a red spot triggered aggressive attacks, while models without the red spot produced no aggression, demonstrating that the red spot acts as an innate releasing mechanism that triggers a fixed action pattern of aggression.
D: However, because this research is based on animals, the extent to which such instinctive mechanisms operate in humans is questionable. Human aggression is influenced by cognition, learning, and social norms, meaning these findings may have limited generalisability to human behaviour.
ethodolgical explanation ao3:
cultural differences.
P: A limitation of the ethological explanation is that it assumes aggression is innate and universal, yet research shows clear cultural differences.
E: Nisbett (1996) found that when insulted in a laboratory setting, South American white males responded with significantly more aggression than North American white males exposed to the same provocation.
E: These findings demonstrate that aggression levels can vary greatly between cultures, indicating that social and cultural factors influence aggressive behaviour.
D: This challenges the ethological view, as an innate behaviour should appear consistently across cultures; the observed variation suggests that aggression cannot be fully explained by instinct alone, reducing the explanatory power of the ethological approach.
ethodological explanation ao3: cannot account for all forms of animal aggression
P: A further limitation of the ethological explanation is that it cannot account for all forms of animal aggression, particularly when the behaviour is not ritualistic.
E: Goodall (2010) observed chimpanzees over a fifty-year period and documented cases where groups engaged in prolonged, violent conflict—essentially a “war”—against neighbouring groups, resulting in the systematic killing of all group members.
E: This behaviour involved extreme physical aggression with a high risk of injury to the attacking chimpanzees, which contradicts the ethological claim that aggression is usually ritualistic to avoid harm and preserve survival.
D: Such findings undermine the ethological explanation because aggression that endangers the attacker is not adaptive and does not fit the model of instinctive, ritualised behaviour. This suggests that aggression is more complex than the ethological view proposes and may be influenced by contextual or social factors.
ethodological explanation ao3: fixed action patterns (FAPs) are not always truly fixed
P: Another limitation of the ethological explanation is that fixed action patterns (FAPs) are not always truly fixed, reducing the validity of the theory.
E: Evidence shows that learning and environmental experiences can create variation in behaviours that were originally thought to be completely innate and automatic across a species.
E: For example, while dogs have an instinctual prey drive to chase (a supposed FAP), not all dogs chase cats—some do and some don’t. These differences can be explained by training, individual experience, or even selective breeding, suggesting that these behaviours are better described as modal action patterns, which vary between individuals.
D: This challenges the ethological explanation, as it shows that instinctual behaviours are not uniform or purely innate; instead, they are shaped by the environment. This weakens the idea of fixed action patterns and reduces the overall credibility of the ethological account of aggression.
evolutionary explanation ao1: sexual competition
- refers to intra sexual selection. the male strategy where males compete with each other for access to female partners
- this competition usually took the form of aggression where the successful male would be able to pass on their genes and increase their gene pool
evolutionary explanation ao1: sexual jealousy, mate retention and adaptivity
- it would’ve been adaptive for human males to display aggression as a way of deterring other males frok trying to steal their females
- sexual jealousy is more likely in males as males cant always be sure of paternity
- males have paternity uncertainty and are at risk of cuckoldry (consequences are that men might invest time and resources into offspring thats not their own, inflicting a reproductive cost)
- Daly and Wilson (1966) have proposed that men have evolved mate-retention strategies to deter their mate from leaving or cheating: 1. Aggressive direct guarding – restricting her freedom to prevent males gaining
access.
2. Intersexual negative inducements – issuing threats of physical violence to the female if they were interested in other males.
evolutionary explanation ao3: Shakleford et al
P: Research support for mate retention strategies being used by men
E: For example, Shakleford et al studied 107 married couples using a questionnaire to ask about their views on the use of mate retention strategies in their own relationships. It was found there was a positive correlation between the use of mate retention strategies and the use of violence.
E: This is a strength because this demonstrates that the more mate retention strategues were used, thr more violence those males also used towards their partner, just as the evolutionary explanation suggested.
D: Furthermore, this research included the self report views of both partners which demonstrates high reliability in the research results, providing inter-rater reliability.
evolutionary explanation ao3: issues with a correlational research like Shaklefords
P: Issues with correlational research
E: For example, Shakleford’s research is purely correlational and we dont know that the violent aggression was a result of the mate retention strategies and not another third variable. We also dont know for sure that mate retention strategies are innate or if theyve been learnt. Individuals demonstrating aggressive mate retention strategies may have observed this behaviour from others and social learning theory could be an explanation.
E: Difficult to separate effects of nature nurture when examining aggression and mating behaviours
D: Additionally, Shakleford’s research as based on self report measures, therefore there could be issues of social desirability as the couples could have reported low violence to seem as happy, although they experience high levels of violence. This lowers the validity.
evolutionary explanation ao3: research support from Dobash and Dobash
P: Research support fro aggression being used due to sexual jealousy and mate retention
E: For example, Dobash and Dobash completed a case study of 95 women who suffered from violent abuse from their male partners, finding that the main source of conflict leading to violence was the men’s sexual jealousy and their possessiveness
E: This is a strength because it demonstrates the main reason that males were using violence is just as stated in the evolutionary explanation; this is to restrict their female partners from interacting with other men, preventing any possibility of infidelity.
D: However, evolutionary explanations can be criticised for being post hoc—they attempt to explain behaviours thousands of years after they may have been adaptive. Human evolution spans over 10,000 years, and we cannot directly observe whether aggressive sexual jealousy was truly adaptive.
