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October 29 Class Notes (Week 10 Aggression, Anger) - Chapter 9 - PSYCH 3M03

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Denys Decatanzaro

WEEK 10 PSYCH 3M03 Chapter 9: Anger, Hate and Aggression October 24, 25, 2013  Threat – shows intention to follow through with aggression, could be bluffing  Rage – amygdala and hypothalamus o Baring of the teeth o Social animals do not have musculature to show certain facial expressions  Fear – most ancient in terms of evolutionary conservation; conserved neural circuits in hypothalamus, amygdala and autonomic responses  Aggression – fighting; beyond threat; same sort of fighting across mammals (use of the teeth, ramming of head, boxing) o Sexually dimorphic – rats, humans, vertebrates  more among males  Forms of Aggression o Predatory aggression – usually directed at other species to obtain food  Motivation – food; usually another species, cannibalism can occur o Intermale Aggression – within species, competing for limited resources (eg/ food, mates)  Related to territorial aggression – each have own dynamic, but interrelated with overlap  Polygyny common among mammals sets the stage for differential and reproductive success amongst males; differential is established by threat and aggression  Males being chased away from harems of females by another male (baboons, rhesus monkeys, gorillas etc)  Accounts for evolution of intermale aggression – aggression against other males leads to gains in reproduction and characteristic gets propagated o Territorial Aggression – protecting specific territory, chasing trespassers away, boundary marking  Same type of dynamic as intermale aggression – often males hold territories and fend off intruders o Defensive Aggression – defense of self, kin, territory  Females and males  If attacked by a male, female will show whole range of aggressive behaviour in defense  Will attack in defense of kin o Maternal Aggression – protection of young by mother o Irritable Aggression – induced by frustration or pain  At least anger will be shown by frustration (non-reward; reward expected but do not receive it) o Instrumental Aggression – dispassionate, learned, developed via conditioning, influenced by rewards  Neurologically, behaviorally complex; intelligent  Elicited by passion, occurs view calculated aggression  Eg/ if I kill, I will get a reward  Dominance and Subordination o Dominance is associated with controlling resources and/or hierarchal control within a group o Results from competitive interactions that are aggressive in nature or threatening o Threat and appeasement are more common than outright violence  Threat gestures – posture, angry facial expression, barking, “hate stares”, rushing, self maximizing postures (eg/ piloerection maximizes appearance)  Appeasement – self minimizing postures, withdrawal, female sexual postures, species-specific gestures (eg/ exposure of neck in wolves, smiling in humans)  Subordinate males may begin starting sexual postures (eg/ in baboons) o Alpha males that are polygynous – other keep respective distance or may give them things to appease them o Non-alpha males are usually excluded from the group o Eg/ Gorillas - ~3 males and 6-7 females; one alpha male who mates frequently, other males do not mate, waiting for alpha male to die; juvenile male and females; all other adult males have been excluded o Less stressful to be subordinate o Dominance is situation specific – alpha male may not always be alpha male  Sex Differences in Aggression o Males are usually more aggressive than females  Eg/ bulls vs. cows; stallions vs. mares  Seen in humans beings; seen in juveniles across species (developing boys demonstrate play fighting) o This is seen in mammalian species including humans o Reflected in rough and tumble play in children o Testosterone perinatally and at puberty correlated with higher levels of aggression in many species (eg/ red deer, elephants, cats, mice, rats etc) o Castration will reduce or even eliminate intermale aggression in many species (eg/ cats, rats, mice, horses, cattle) o Female mice injected with testosterone perinatally and given repeated doses through adulthood  male levels of aggression 1 WEEK 10 PSYCH 3M03  Humans o Connection between testosterone levels and human aggression is not clear o Aggression in boys does not consistently change at puberty o Individuals can have very high T but not be aggressive, or low levels and be aggressive o T related more to social dominance than aggression o Sex and Age of Homicide Victims  Canada  Victims of homicide ages and sex  More commonly male victims  Peak around most reproductive years – not including infants o Infants often killed by mother or other males (more often not the father; may be male with relations to the mother who is not the father)  Mexico  Differential between males and females Trend more stark than Canada  More commonly male victims  Illustrates male vs. male aggression Physiology and Aggression  Rage, fear, excitement – autonomic nervous system; intense activation of sympathetic NS; blood pressure, respiratory rate, flow of blood to the muscles and brain o Anger and fear have some differences – paleness in fear (blood draining from face), flushing in anger o Central catecholamine’s in aggression o Prepare for alertness and full body activation o Less so with sadness, embarrassment  Sex, Androgens and Aggression o Males generally more aggressive than females in many mammals, including humans  In human cultures, there are some pressures that take us away from evolutionary roots – eg/ bullies don’t always get ahead because it is not necessarily socially acceptable o Reflected in rough and tumble play in juveniles; boys vs. girls  NOT a simple case of more androgens more aggressive and sexual behaviour – threshold level is necessary for male sexuality and aggression to occur o T perinatally and adulthood related to aggression in many species (eg/ red deer, cats, mice, rats etc)  Critical period during perinatal development in which brain differentiates (preoptic areas particularly for sexuality and aggression; anterior hypothalamus) for behaviorally masculinity; surge in androgens as gonads develop that causes differentiation of critical areas of hypothalamus; endured throughout life  Give androgens to female mouse perinatally – morphologically female; reaches adulthood and regularly inject testosterone  more aggression o Castration will reduce or even eliminate intermale aggression in many species  Testosterone sustained above threshold is needed for aggression and sexual behaviour  Eg/ in cat, cattle, rats, mice, horses; less so in dogs  Castration inhibits post-pubertal aggression – androgen levels below threshold  Inject testosterone back into castrated male – can restore aggression to regular level o Female mice injected with T perinatally and throughout adulthood show male levels of aggression o 2 factors – presence of absence of perinatal surge and sustained levels above critical threshold post-pubertally  Eg/ Red Deer Intermale Aggression – reproduction is seasonal; gonads regress during non-reproductive seasons; males developing antlers and surge of testosterone above threshold (because of suppression the rest of the year) during rut, seeking to breed and competing with other males (polygynous species) o High correlation between testosterone levels, antler growth, aggressiveness  Aggression in House Mice o Best studied, typical results in other animals; confidence because primitive mammal o Males direct aggression vs. males o Females usually only fight in defense o Genetic o Perinatal development o Stereotyped patterns (FAP) – tail-rattle, flank and hind quarter bites o Spontaneous and without learning  Eg/ Mice – Raise in isolation, no exposure; put two mice together; will start fighting o Competition for females intensified intermale aggression  Competition for reproductive success – possibly the root of intermale aggression is reproductive success  Hormonal Response to Aggression in Mice o LH + T decline following defeat; increases in success (short term; within minutes, hours) 2 WEEK 10 PSYCH 3M03 o Defeated males show diminished gonadal and enhanced adrenal response (long term)  Depression o Central catecholamine’s dynamic in aggression become depleted following defeat and enhanced following victory  Increases in victorious – have not yet reached point of exhaustion  Social Status o Male Mice Winners Losers Aggression Increased Decreased Assertiveness Increased Decreased Sexual Activity Increased Decreased Catecholamine’s Increased Decreased Testes Increased Decreased Adrenals Decreased Increased  Victorious in aggression, become more aggressive; defeated individuals decrease in aggressiveness (become more cautious)  Ex/ even if no other male present, sexually defeated males may not even att
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