Hormonal And Neural Mechanisms Flashcards
Wagner and Hutchinson: castrated mice
-Found if male mice were castrated, overall levels of aggression tended to v and when castrated mice then received T, agg^. -Strong support for link between levels of T and agg as mice are unlikely to show demand characteristics; animals act more instinctively than humans.
Testosterone explanation
-Androgenic hormone T (both sexes) acts on areas of brain ctrl agg. -Adult M produce 10x more than adult F. M: testes produce T from birth. R = that T linked to ^ agg at points in life when hormone is plentiful i.e. puberty (^ ages 15-25) -Mazur + Booth found T; Sig role in dominance, competition and antisocial beh, // nature of link between T and agg beh not a simple ‘cause and effect’ mechanism. -^ levels of T rather than causing aggression, make it ^ likely that particular Agg beh will be expressed. Possibly; impaired control. -Role of T in agg is further complicated by cortisol. ^C levels inhibit T thus inhibiting aggression, whereas vC levels associated with ^agg as T is uninhibited. -Studies show habitually violent offenders have vC levels sugg link.
Rats aren’t humans!!
-// area of research relies heavily on non-human animal models. For ethical reasons, androgens not normally given to people to see if changes in aggression occur. -Raises argument that we should GWC from animals to humans. -Humans are not mice, AT we share many mammalian features including basic brain design, cannot be assumed that T works in same way in mouse brain as it will in more complex human brain. -Regardless of strong evidence that ^ T linked to ^ agg it is likely there will be differences in how aggressive behaviour is expressed.
Dabs et al: Link to offenders
-Studied salivary T of 692 criminals, found sig correlatory link between T and aggression in offenders. -^T = history of violent crime | vT = non-violent crime. -^V also had vC too. -//correlational so CandE can’t be established. Can’t be stated that ^T/vC directly cause agg as multitude of other bio-psychosocial
Harrison: determinism (56 frustrated men)
-Hormonal exp = all males will display agg bc ^T levels. -DT as suggest P can’t exercise FW to control agg beh bc bio mech -Individuals may have agg impulses but do not have to act on em. -Harrison: 56 men given T whilst playing frustrating computer game. -Agg towards game sig^ = causal link. // effect not seen across sample as many showed little psych change in agg towards CG. -individual differences and free will in ^T exp.
Gender bias: Women understudied
-Male focused maybe bc easier to to measure T levels. -Not enough R on link between T, dominance and agg in Females. -R shows F with ^T has higher occupational status maybe as a result of being assertive. -^T expressed differently depending on gender. More R needed for full understanding.
Neural explanation: amygdala + serotonin
-Agg = interaction between a system of brain structures. -Agg impulses = amygdala response to perceived env ‘threat’. -Involved in stress response; activates process of fight or flight, ^chemicals (noradrenaline and corticosteroids) -FM pre-frontal cortex, is also stimulated. -ICT primitive emotional amygdala, pre-frontal cortex = rational part -Involved in impulse control over agg urges created in amygdala. -// strength of inhibitory effect mediated by level of the NT Sr. -Normal Sr = calming inhibitory effect v aggression. // v Sr in PFC remove Inhibitory effect leaving individuals
Crockett et al: Sr levels (MRI faces)
-Altered participants Sr levels via diet; effect on brain region comm -Shown number of faces with neutral/sad/angry expressions. -Using fMRI, found comm between A and PFC weaker compared to when the individual had normal levels of Sr. -v levels of Sr affected ppts neural response to facial expressions. -TF when vSr more difficult for PFC to ctrl emotional responses. -“individuals predisposed to agg > sensitive to vSr. TF indicating ID must be considered when exp agg. R highlights powerful but complex role played by Sr in agg behaviour. -Epitome of scientific research bc of use of various RM
Mann: weight loss drug which vSr
-Administered dexfenfluramine; WLD which vSr. -Used questionnaire to asses hostility and aggression levels. -Found M but not F; hostility^ and Agg^ after trx with drug. -TF theory that vSr increases aggression appears applicable to males but not to females.
Psychology as science
-R on Sr-Agg use lab experiments analysing Bbio objectively: fMRI to measure Sr activity in PFC -Rigorous ctrl - process meets criteria of Psy as a science. -removes many ev and subjectivity inherent measuring emotions. -Creates ^IV that vSr ^agg
Badaway: RWA (alcohol)
-R = RWA dealing with relationship between alcoholism and agg. -Found acute alcohol intake = maj disturbances in metabolism of brain Sr for normal individuals. -In susceptible individuals Sr depletion may induce aggression. -application to limit alcohol consumption for naturally agg people
Reductionism (MAOA)
-Agg is very complex phenomenon, hence OS it to vSr in PFC/T = R -R’s believe gene responsible for producing MAOA may be responsible for agg beh. -MAOA = break down noradrenaline, dopamine and Sr after they carry the nerve impulses from cell to cell around the brain. -TF may be interaction between genes and NT/env factors exp agg
