Violence
•	Levels of Analysis
•	Some basic facts
•	The Biology of Violence
•	Psychological Considerations
•	Cultural Factors
The Hobbes Perspective
•	People want power
•	Glory and vain glory (pride)
•	People essentially equal
•	Power a zero sum game 
•	Eternal competition and violence
•	Hobbes basically got it right except…
Limitations on a Hobbesian analysis
•	Failure to appreciate altruism and cooperation as natural
•	Focus on males rather than people
Important facts About Violence
•	Low base-rate
•	Universal and seen among all primates and mammals
•	Overwhelmingly male
•	Overwhelmingly young
Violence has Low Base-Rate (Rare)
•	Rare even among violent people and cultures
•	Implications
•	Hard to observe and easy to miss
•	Multiple causes
•	Biological 
•	Psychological
•	Cultural (broadly – learned, institutional)
Violence Data
•	UCR by FBI 
•	Reports by police departments
•	Problems
•	Crimes unreported
•	Often don’t know the perpetrator
•	Murder most reliable
•	Victimization Surveys
•	Find much higher crimes rates (100-200%)
•	But almost certainly over-estimates
Murder Rates by Year
  
Why Is Gender So Predictive?
•	One answer might be cultural
•	But males are more physically violent in all cultures
•	Also true of all primates
•	Shows up early in development
•	Suggests biological involvement
•	But does not mean culture is unimportant – stay tuned
Murder by Age US 2003
Why is Age So Predictive?
•	Culture and social pressures?
•	Alienation
•	Less family involvement
•	Low income and education
•	But again this pattern is universal
•	Suggesting biological involvement
•	And a more basic explanation underlying the above social factors
Murder by Race
Why is Race Predictive?
•	Not about race per se
•	In all cultures with status differences lower classes are more violent
•	Correlated with poverty -- race effects are often lower with income corrections
•	Usual explanations
•	Alienation
•	Discrimination
•	But also plays into other variables to be discussed
Poverty
•	Hard to assess exact effects
•	New Orleans ~1980

The Poverty Connection
•	Controversial
•	Most find substantial results
•	But not all with various corrections
•	Income itself not crucial
•	Some underlying causes
•	Mobility and disintegration of community
•	Social ecology
•	Attitudes toward violence
•	Parenting
Murder Circumstances
Murder Weapons
A Model of Violence
•	Biological Underpinnings
•	Psychological Considerations
•	Cultural Factors
The Biology of Violence
•	Several levels
•	Evolutionary considerations
•	Genetics
•	Neurotransmitters and hormones
•	Brain bits
•	Biology is not destiny – multiple causes
•	Mother nature does not necessarily parse phenomena as psychologists do
Evolutionary Considerations
•	Every known culture exhibits some violence
•	All primates exhibit intra-species violence
•	Found among early humans

Human Violence Is Universal
•	Exists in all human cultures
•	Both within
•	And often without as war and raiding
•	Western cultures extremely non-violence by comparison
Cultures and Violence
The Primate Connection
•	Most primates are violent from time to time – especially apes
•	Male fighting
•	Infant killing by males
•	Violence toward females by males including rape
•	Chimps have raiding parties
•	But exceptions -- Bonobos

Explanations for Primate Behavior
•	Most violence associated with
•	Breeding access
•	Or protecting parental investment
•	Protect own young
•	But not invest time in young of other fathers
•	Tends to produce sexual dimorphism
Chimps 
•	Males fight
•	Only species besides humans that regularly kills adult con-specifics
•	Raiding parties and wars 
•	Male dominance behaviors toward females at adolescence
•	Rape
Gorillas
•	Males often kills infants
•	Usually when take over a harem
•	But about 15% of infants killed in this way
•	Male-male violence over breeding
•	Rarely rape
•	Dominance behaviors toward females but rarely violence
Orangutans
•	Large males fight over territory and breeding
•	Smaller males rape
•	Cannot compete with larger males
•	About 40% of all copulations are rape
Bonobos
•	Males fight but not fiercely
•	Females cooperate with one another and have equal status with males
•	Sex used as a bonding ritual
Do Primate Data Count?
•	Variable evidence but probably
•	Males likely to be competitive with one another
•	Originally perhaps for breeding privileges
•	But once physiological mechanisms set up this can become autonomous
But Some Cautions
•	Evolution has has had plenty to time to create differences since spilt with primates
•	No violence imperative or instinct as Lorenz and Freud suggested
•	Individual differences
•	Situational interactions
•	At best primate evidence suggests we have the potential to be violent
Evolutionary Psychology
•	Males are more prone to violence
•	Especially against other males
•	And when young
•	Group status and pride will be important to males
•	Dominance and power 
•	Jealousy important cause
•	Males spend time impressing other males
•	Males more likely to kill non-relatives than relatives

Genetic Evidence
•	Not much direct evidence 
•	But clues
•	Violence does “run in” families
•	Also more closely related to biological than adoptive parents
•	Genetic abnormalities related to neurotransmitters related to violence
•	Temperament, impulse control, etc partially genetic
•	No gene for aggression 
•	Gene-environment interactions
•	Most likely neurotransmitters and hormones
Neurotransmitters and Hormones
•	Testosterone
•	Serotonin
The Testosterone Connection
•	Two major effects
•	Determines biological sex during gestation & puberty
•	Hormone 
•	Both males and females produce
•	Essentially same until adolescence
•	Then males more
Testosterone Production by Age
Levels of Testosterone
•	General levels genetic
•	But also subject to situational and health
•	People who win have elevated levels
•	Losers have lowered levels
•	Poor health can lower
•	Large amounts injury the immune system
Nature of Testosterone
•	Generally affects both men and women similarly – but males have more
•	Effects not straightforward 
•	Affects sexual interest and ability 
•	Not an aggression hormone per se
•	More related to dominance and status seeking
Testosterone and Crime

Testosterone and Misbehavior
Testosterone and Marriage
Effects of High Testosterone
•	More sexual partners and marriages
•	More dominant and masculine faces
•	Smile less often
•	More rambunctious and reckless
•	More “preening 
•	Occupations
•	More likely blue collar and unemployed
•	Actors and pro football players especially high
•	Ministers low
•	High dominance professions high
The Serotonin Connection
•	Implicated in many emotional features – depression
•	A strong component of depression is irritability
•	People low in serotonin are highly irritable and aggressive
•	Easily frustrated
•	Especially impulsive violence
•	May promote “fast track” anger
•	Serotonin levels partially genetic
•	But can be affected by extreme environments -- abuse
Testosterone and Serotonin Combined
•	Testosterone
•	Status seeking
•	Dominance
•	Promotes status challenges
•	Serotonin 
•	Frustration and anger
•	Short-circuiting impulse control
Testosterone and Serotonin Combined
Cultural/Environmental Influences 
•	Affect both dominance and irritability
•	Definitions of status and dominance
•	What is seen as irritating
•	Heat and violence
•	Social teasing and “egging” on 
•	Affect how channeled
Brain Pathways
•	Many likely involved in violence
•	Recognition and definition of threat
•	Arousal
•	Action
•	Inhibition
•	Also various neurotransmitters 
The Neurology of Violence – One Example 
•	Most emotional behaviors involve interplay between
•	Amygdala
•	Frontal cortex
•	Fast vs. slow
Violent Men
•	Tend to have larger fast track responses
•	This will show up as irritability
•	Less tolerance for frustration
•	And to lack inhibitions – frontal lobe damage 
•	Battering – Lonny Athens
•	Nutrition, chemicals
•	Genetic
•	Underdeveloped in adolescents (who also have more testosterone)
Biology and Culture
•	Biology of violence is complex and not by and large determining
•	Cultures
•	Can amplify or inhibit
•	Usually “go with the flow” in terms of biology
•	Rather than inhibiting
•	Channeling -- define appropriate responses to biologically driven events
•	Produce extreme versions of culturally valued
Psychological Issues
•	Social Learning Theory
•	Personality Correlates
•	Cognitive Correlates
•	Child Rearing
Cognitive Social Learning Theory
•	Albert Bandura
•	Learning from others
•	Payoffs
•	Techniques and strategies
•	Observational learning -- media crucial
•	People act to maximize rewards and avoid costs
•	Rational choice theory
•	Not necessarily conscious 
•	Nor rational by some larger definition
Rewards for Violence
•	Different for different people
•	Money
•	Revenge
•	Image and pride
•	Especially important when people have little else to fall back on
•	Hans Toch and violent prisoners
Costs for Violence
•	Different for different people
•	Legal
•	Guilt
•	Shame
•	Situational -- punishment
Personality Correlates of Violence
•	Low impulse control
•	Low intelligence and poor school performance
•	Irritability – emotional susceptibility
•	Low self-esteem
•	Oppositional temperament and blaming others
Cognitive Correlates
•	Tend to see more situations as threatening
•	Tend to think that proper response to threat is aggression
•	Learned at home or peers – dysfunctional environments
Stability and Incidence of Violence
•	Aggression is stable from early childhood on
•	Incidence
•	Most violent offences are sporadic and not repeated 
•	A few career violent offenders
Child Rearing and Violence
•	Aggression stable from childhood on
•	Abusive parenting
•	 Authoritarian and inconsistent (not authoritative) parenting
•	 Unrealistic expectations
•	Father absent
•	Lack of monitoring of child
•	Support for violence and deviance
A Model of Parental Effects
The Genetics of the Dysfunctional Family
•	Parent-child correlations largely genetic
•	Passive genetic model – no influence
•	Common genes influence both parents and child
•	Child has violent temper (or irritability) and so does parent 
•	Evocative models
•	Child acts up when irritated
•	Parent is easily irritated – responds aggressively
•	Typically find self-sustaining patterns
A Possible Genetic-Environment Interaction
•	Genes affect choices of environments
•	Boys who have “genetic propensity” for violence may pick peers who reinforce this tendency
•	Parents sharing genetic predisposition with sons
•	Encourage violent behavior
•	And have sons all too happy to be violent
Another Genetic-Environment Interaction
•	Caspi et al (2002)
•	MAOA gene on X regulates neurotransmitters including serotonin
•	Boys with low MAOA activity show considerable effects of abuse on antisocial
•	Boys with high MAOA are barely affected. 
Peer Effects Crucial
•	Americans too focused on parents rather than peers
•	Peers exert enormous influence from childhood on
•	Peer rewards and scorn important for violence
Cultural Factors
•	Cultures differ 
•	How much violence they allow or encourage
•	How they define precipitating events
•	How channeled
•	Some cultures especially value violence as a sign of masculinity
•	Amplify biological tendencies
•	Yanamomo 
•	The ecology of violence
Murder Rates for Countries 1987
US vs Other Western Countries
American Culture
•	High rates of violence
•	Valued for males
•	Role of media
•	TV
•	Video games
Regional Differences
•	The South is Violent

The Culture of Violence (Nisbett & Cohen)
•	Basic argument
•	Herding economies allow stealing of livestock
•	Hence honesty and honor valued
•	Culture of honor
•	Punishments for violations severe
•	Southern US settled by Scotch-Irish who brought this culture with them
Culture of Honor Predictions
•	Southern whites should be more violence prone
•	But only males
•	Only whites
•	Only those living in smaller communities with fewer Northern imports
•	And only for violations of honor
•	Attitudes toward violence should be based o culture of honor
Data for Violence by Region and City Size
Data for Violence Type
Attitude Data I
Attitude Data II
Attitude Data III
•	Southerners are more likely to
•	Own guns
•	Support their use in self-defense
•	Spank and approve of spanking of children
•	Encourage boys to fight back when insulted
Legal Differences
•	Capital punishment
•	Southern states more likely to have capital punishment
•	Punish a higher % of convictions with execution
•	Less likely to prohibit corporal punishment
•	Less likely to have laws mandating arrest for domestic violence
•	Less likely to mandate retreat in attacks before using weapon
•	Less strict gun control laws
•	Representatives more likely to support strong national defense
Experimental Studies I
•	U Michigan students from South or North
•	Insulted or not insulted during experiment by confederate
•	Bumps into subject
•	Calls him an asshole
•	Dependent variables
•	Walking down hallway and meet football lineman – point at which S moves out of the way
•	Handshake
•	Rated general demeanor
Data for Study
Data for Hormones
•	Different experiment but same manipulations
Ecological Factors -- Hobbes Redivicus
•	Most dangerous aspect of violence
•	Creates self-perpetuating spirals
•	Living in a violent environment means you must be violent
Violence Summary Model
•	Violent behavior = rewards - costs
Model of Violence -- Rewards
•	(Dominance + Irritability+ Goals) x Situation =  Rewards
•	Factors
•	Peers increase rewards of dominance and retaliation
•	Pride for physical important for violent men
•	Few other rewards
•	Perceived to be attractive to women
•	Other culturally determined rewards
Model of Violence – Costs 
•	External Situations + Personality (Conscience) = Costs 
•	Factors
•	Alienation from community reduces shame
•	Family ties increase inhibitions
•	Inconsistent parenting reduces conscience
•	Frontal lobe dysfunction
•	Low IQ and impulse control reduces consideration of costs
•	Alcohol and drugs reduce concern with costs
•	Prison not a big deterrent
Model of Violence – Biological Influences
•	Dominance & Irritability
•	Inhibition
•	Personality
•	Probably multiplier from family 
Model of Violence – Cultural Influences
•	Dominance & how expressed
•	Irritability & how expressed
•	Interpretations of situations & threats
•	Inhibitions
•	General goals and rewards