PSYB10 Lec 8 Aggression

Proactive vs reactive aggresion

Proactive means actively seeking aggresive acts

reactive is aggresive reactions

physical versus relational aggression

physical violence vs psychological

proximal vs distal aggression

target of aggression is nearby physically or distant

hostile vs instrumental aggresion

intent to cause harm vs intent is not to produce harm but a means to another event (like robbery)

three targets of aggression

between-groups, between-individuals, within-self

What is good for evolution

is not always good for wellbeing

Sexual size dimorphism and competitive mating

sexual sizes differ between males and females

since females are the choosier sex, the average size differences in males and females creates competition between males for mates

territorial aggression in chimps

killing neighboring chimp coalitions is adaptive to reduce opponent strengths and increase resource access

infanticide in langur monkeys and lions

sexual access in monopolized by competitive males

female lions enter sexual reproductivity sooner if cub is killed by adult males

Better nature of people over time

Violence/aggression decreasing over history

homicide rates declining in Europe, domestic violence, and against children

Aggression Genes

Genetic factors account for 50-60% of variability in aggression

Diathesis-Stress model

Genetic vulnerability interacts with environmental factors to produce psychological manifestations of disorders

High dispo + low stress = disorder vs low dispo + high stress = no disorder

MAOA gene and aggression

influences catabolism of neurotransmitters

animal studies link MAOA activity and aggression

Does MAOA gene interact with childhood maltreatment results

Severe childhood maltreatment strongly predicts aggression and antisocial behaviour, but only in individuals with low MAOA activity;

High MAOA activity are largely protected. This shows a clear gene–environment interaction.

Digit ratio, testosterone and aggression

Ratio of 2D (index) and 4D (ring finger) shows fetal testosterone level exposure (lower = higher)

Study showed Lower digit ratio correlated with higher physical aggression

Challenge Hypothesis

Testosterone rises among males in response to biologically valued challenges (competing for mates)

Increase in testosterone promotes aggression

Testosterone levels would decrease when males become fathers

Key regions involved in aggression

thalamus, hypothalamus, and amygdala

Kluver-Bucy Syndrome

lesion of amygdala through lobectomy or encephalitis

produces dramatically decreased aggression

Activation of amygdala

through electrical stimulation or epilepsy

produces sudden and unprovoked aggression

Frontal Lobe and aggression

Inhibition of aggressive impulses

Affective States and aggression study

Increased Nucleus Accumbens (NAc) activity when retaliatory loud noise against partner

after partner gives on to the individual first

evidence of pleasure of aggression

Boredom study results

Boredom proneness correlated findings to online trolling, sadism

Experimentally inducing boredom increased aggression towards killing worms

When behavioural alternatives are available, boredom only increases aggression in individuals high on sadism but with no other alternative, boredom increases aggression regardless of trait sadism

Alcohol and effect on aggression behaviour

Alcohol increases aggression more during ascending limb of BAc (compared to descending)

frustration-aggression theory

frustration triggers readiness to aggress

Frustration

block of goal directed behaviour

Displacement

redirection of aggression to a target other than source of frustration’ new target is safer or sociall acceptable target

Relative deprivation

Perception that one is less well of than other to whom one compares oneself

social learning theory

theory that we learn social behaviour by observing and imitating and by being rewarded and punished