Aggression

Which subcortical structure of the limbic system, when electrically stimulated in Bard and Mountcastle's animal work, is most strongly associated with reactive aggression?

• AThe cerebellum
• BThe amygdala✓
• CThe corpus callosum
• DThe substantia nigra

Answer: The amygdala is the limbic structure central to evaluating sensory information and generating an aggressive/threat response; stimulation tends to increase aggression and damage tends to reduce it. The cerebellum coordinates movement, the corpus callosum links the hemispheres, and the substantia nigra is involved in dopamine and motor control.

How does the neurotransmitter serotonin most plausibly relate to aggression according to the neural explanation?

• AHigh serotonin causes aggression by over-exciting the limbic system
• BSerotonin only affects aggression in females, not males
• CSerotonin raises testosterone, which directly triggers attack behaviour
• DLow serotonin reduces inhibitory control of the orbitofrontal cortex, increasing impulsive aggression✓

Answer: Serotonin normally exerts an inhibitory, calming effect via the prefrontal/orbitofrontal cortex. Low serotonin activity reduces this top-down inhibition, so impulses are less controlled and impulsive aggression rises. The other options reverse the direction or invent unsupported mechanisms.

Studies such as those reviewed by Dabbs report that prison inmates with the highest testosterone levels are more likely to have committed violent crimes. What is the main limitation in concluding that testosterone causes aggression here?

• ATestosterone cannot be measured reliably in saliva
• BTestosterone has no known effect on any behaviour
• CThe data are correlational, so aggression or social dominance could raise testosterone rather than the reverse✓
• DOnly adolescents were tested, so the findings do not generalise

Answer: Such studies are correlational; a relationship between testosterone and violence does not establish causal direction. Aggressive or dominant behaviour may itself elevate testosterone (reciprocal influence), so cause and effect cannot be separated.

Brunner et al. (1993) studied a large Dutch family in which several males showed impulsive aggression. What genetic feature did the affected men share?

• AA point mutation producing a low-activity (deficient) variant of the MAOA gene✓
• BAn extra Y chromosome (XYY syndrome)
• CA duplication of the serotonin transporter gene
• DComplete absence of the amygdala from birth

Answer: Brunner identified a point mutation in the MAOA gene leading to MAOA deficiency (the low-activity, MAOA-L form) in affected males. MAOA breaks down neurotransmitters such as serotonin; low activity is linked to impulsive aggression. This low-activity variant later became popularly known as the warrior gene.

The MAOA gene is often described as the 'warrior gene'. Which finding best captures why a purely genetic account of aggression is considered incomplete?

• AMAOA is found only in women, so it cannot explain male violence
• BCaspi et al. (2002) found the low-activity MAOA variant predicted antisocial behaviour mainly in those who had also been maltreated in childhood✓
• CIdentical twins never share aggressive tendencies
• DThe MAOA gene has no effect on neurotransmitter levels

Answer: Caspi et al. (2002) showed a gene-environment interaction: the low-activity MAOA genotype predicted later antisocial/aggressive behaviour largely in men who had been maltreated as children. This diathesis-stress pattern shows genes act in concert with environment, not alone.

In the ethological explanation of aggression, what is a 'fixed action pattern' (FAP)?

• AA stereotyped, innate behaviour sequence that, once triggered by a sign stimulus, runs to completion✓
• BA learned sequence of behaviour acquired through reinforcement
• CA conscious decision to attack a rival
• DA temporary increase in testosterone before a fight

Answer: Lorenz described FAPs as innate, stereotyped, universal behaviour sequences released by a specific sign stimulus via the innate releasing mechanism; once started they typically run to completion (ballistic). They are not learned and are not conscious choices.

Tinbergen's classic study of the male three-spined stickleback supports the ethological account because the fish attacked any model showing a red underside, regardless of shape. What does the red belly act as?

• AA fixed action pattern
• BAn unconditioned response
• CA sign stimulus (releaser) that triggers the innate releasing mechanism✓
• DA form of displacement activity

Answer: The red underside of a rival male is the sign stimulus (releaser) that activates the innate releasing mechanism, triggering the aggressive fixed action pattern. Even crude models with a red belly were attacked, whereas accurate models without red were not.

According to evolutionary explanations, why might male sexual jealousy have evolved as a driver of aggression?

• AIt increases the number of offspring a female can produce
• BIt reliably reduces conflict between rival males
• CIt is a by-product of low serotonin with no adaptive value
• DIt functions as a mate-retention strategy guarding against cuckoldry and the resulting loss of paternal investment✓

Answer: Because paternity is uncertain, a man risks investing in offspring that are not his (cuckoldry). Sexual jealousy and associated mate-retention behaviours (including aggression and mate-guarding, as studied by Wilson and Daly) are argued to have been adaptive in reducing this risk.

The original frustration-aggression hypothesis (Dollard et al., 1939) was reformulated by Berkowitz (1989). What was Berkowitz's key modification?

• AFrustration creates only a readiness for aggression (negative affect), which becomes actual aggression in the presence of aggressive cues✓
• BFrustration always and inevitably leads to aggression
• CAggression is entirely innate and unrelated to frustration
• DOnly physical, not psychological, frustration produces aggression

Answer: Berkowitz argued frustration produces negative affect, creating a readiness to aggress rather than guaranteed aggression. Whether aggression occurs depends on environmental cues (e.g. the weapon effect, Berkowitz and LePage 1967). This addressed the original claim's over-determinism.

Deindividuation theory explains aggression in crowds primarily through which mechanism?

• AA reduced sense of individual identity and lowered self-awareness, weakening normal restraints on behaviour✓
• BIncreased private self-awareness and personal accountability
• CA surge in serotonin caused by being in a group
• DClassical conditioning of fear responses

Answer: Deindividuation involves a loss of personal identity and reduced public/private self-awareness in situations such as crowds or anonymity, which loosens the internal restraints that normally inhibit antisocial behaviour. Zimbardo and the Stanford prison study are often cited in support.