Violence
•	Important in today’s world
•	Inherently multidisciplinary
•	Many areas of psychology
•	Across social and biological sciences
Use here to illustrate major points
•	Questions
•	Theoretical approaches
•	Methodologies
Definitions I
•	Important first step in any scientific inquiry
•	What definitions do for us
•	Capture the right exemplars
•	And exclude irrelevant ones
•	But what constitutes right and wrong is driven by theory
•	And hence definitions embody theories
Definitions II
•	The scope of violent behavior
•	Individual
•	Collective (wars)
•	Types of behavior
•	Uncountable
•	Also verbal and nonverbal?
Definitions III
•	Types of causes
•	Anger and emotion
•	Strategic and instrumental
•	Collective 
•	Ideological
Definitions IV
•	Often and most productively defined as behavior that is primarily intended to hurt another person
•	Very broad
•	Includes many types of behaviors
•	Collective as well as individual
•	Instrumental as well as emotional and ideological
•	The “dentist” example
•	The “hurts me more than you” example
•	The regress of intentions
The important questions
•	Most obvious is why are people violent?
•	But “why” questions are often not productive
•	Too many causal factors
•	Like any complex behavior has multiple causes
•	So the answer depends on one’s perspective
•	No right or wrong questions
•	Some more productive than others
•	And no rule for which is the most productive
A first important question
•	How much violence is there?
•	Actually not all that much
•	Low “base-rate”
•	When is it observed?
•	Some people seem more prone to be violent
•	Some situations seem more prone to produce it
•	Some cultures seem more likely to have more than their share
•	These are the basic “facts” of violence – how much, who, when, and where
Individual differences –who is violent?
•	Four general ways to answer that question
•	Demographics
•	Personality, motivation, and emotion
•	Cognitions
•	Biological
•	Freudian motivation not a good approach
The demographics of violence
•	Gender – men about 9 times more likely
•	Race – black males about 5-8 times more likely
•	Age – young men 18-25 about 5 times more likely
•	Socioeconomic class – not a strong predictor
  Gender and Murder
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 lower with income corrections
•	Usual explanations
•	Alienation
•	Discrimination
•	But also plays into other variables
Murder Circumstances
Murder Weapons
Personality differences
•	Anger and frustration
•	Violent men get angrier quicker
•	More often
•	More likely to act on basis of anger
•	Low IQ
•	Impulsive
•	Blame others
•	Oppositional temperament
•	Low self-esteem
Are violent people mentally ill?
•	Not by definition
•	Mentally ill people are more likely to be violent but only if
•	Experiencing hallucinations
•	Drug related problems
•	Previous violence
•	Most mentally ill people not violent
Cognitive differences
•	More likely to view situations as threatening
•	More likely to view ambiguous behavior as threatening
A social learning account of cognitive differences
•	Rewards of violence
•	Costs of violence
•	Different for different people
•	Affected by culture
•	And learning environment
•	The special role of the mass media
•	The Toch studies of violent offenders – a case study
The biology of violence
•	Hormones
•	Neurotransmitters
•	Brain structures
Biological differences – testosterone
•	Correlated with aggression
•	Accounts for some basic “facts”
•	Accounts for male –female difference
•	Perhaps age
•	But not a simple causal process
•	Experimental induction of testosterone does not cause aggression
•	Mostly affects dominance seeking
•	And affected by dominance success
•	Thus may influence aggression as a means to dominance – parsing of behavior
Biological differences – serotonin
•	A neurotransmitter involved with depression and other affective reactions
•	Low levels are correlated with aggression
•	Probably because of increases of responsivity to aversive and frustrating stimuli
•	So affects aggression for different reasons
The Integrated model
•	Important lesson– the biology of thought and behavior does not necessarily map directly onto how we parse it
The neurology of violence
•	Most emotions involve interplay between
•	Amygdala
•	Frontal cortex
The fast reaction pattern
•	Information processed by thalamus 
•	Sent to amygdala 
•	And to sensory cortex for better processing
•	From amygdala 
•	Messages to hypothalamus which initiates bodily reactions
•	And to the frontal cortex
•	This produces a fast rage responses
The slow reaction pattern
•	The frontal cortex gets information from three sources
•	Sensory cortex providing abstract conceptions
•	Feedback from the body leading to an experience of emotion or anger
•	Information from the amygdala saying in effect I am about to explode
The frontal cortex as a brake
•	“Seat” of consciousness, planning, working memory
•	Analyzes and assesses appropriateness of reactions
•	Usually then tells the amygdala and hypothalamus to calm down 
•	 Inhibits the initial rage response
•	And calms the body down some
The neurological explanation I
•	Overzealous amygdala 
•	Pathways respond to minimal stimulation
•	Epileptic seizures often begin in this region
•	And may inhibit signals reaching the frontal cortex
•	This accounts for blackouts reported by many murderers
The neurological explanation II
•	Underzealous frontal lobes
•	Connections from amygdala to frontal areas not present at birth and take time (and experience) to develop
•	Not fully mature until early 20s
•	Violent criminals almost all have frontal lobe disorders
What situations produce violence?
•	Instrumental violence to accomplish some goal
•	Emotional violence
•	Frustration
•	Threat
•	Anger
Heat as an example situational variable
•	Correlational studies
•	People are more violent in hotter areas of the country – the South
•	More murders in hotter months and years
•	More murders on hotter days
•	Control and third variable issues
•	Experimental studies
•	Less clear but generally people in hot rooms are more hostile
Cultural factors
•	Some cultures value violence as a sign of masculinity
•	Yanamomo 
•	The ecology of violence
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 are 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
The basic question of universality
•	Given the specificity I just claimed, this may seem an odd question
•	But the situational part may give us pause
•	If some situations seem to produce more violence
•	Then perhaps most of us could be violent in those situations
•	Seems clear this could happen
•	War
•	Self-defense
What would it mean to say violence is universal?
•	Would seem to implicate genetics and evolution
•	But be careful
•	Common environmental  pressures
•	Competition for scarce resources
•	Still would make sense from an evolutionary point of view
What would an evolutionary account look like
•	Three necessary features
•	Specify the functions of violence
•	But also the limitations
•	Be consistent with known biological factors – will cover later in lecture
•	Evidence
•	Universality among human species
•	Continuities with other primates
•	Solves some known problem
The evolutionary program
•	Roughly people are programmed to ensure that their genes are passed along
•	Implications for sexual behavior to be discussed later
Evolution and violence
•	Should protect genetic kin in proportion to genetic overlap
•	Should behave in an efficient manner for gene preservation
•	Not waste time raising non-biological children
•	Priorities in protecting children on
Limitations on violence
•	Not kill kin who have some % of your genes
•	Careful, efficient and graded
•	Violence uses energy
•	And exposes one to counter-violence
•	Therefore, people should be sensitive to contingencies
•	Situational
•	Nature of victim
•	Cognitive and moral concerns
Evidence for an evolutionary account – cross cultural infanticide 
•	More common with twins 
•	More common when older children
•	More common with unhealthy or deformed
•	More common with female children
•	More common with lack of parental or spousal support
•	More common with younger mothers
Evidence from murder statistics
•	Within families men much more likely to kill stepchildren – stepchildren about 70 times more likely to be killed
•	Children are 100 times more likely to be abused when living with a step parent
Evidence for evolution – cross cultural
•	In all cultures males are more violent
•	And about 90% of violence is male against male
•	Across species related to sex fitness variance differences
•	Fitness variance refers to the variability of children produced. 
•	In most human societies the variance is much larger for males than for females
•	Also related to size differences between males and females
Competition for reproduction
•	Thus males need to compete for breeding partners
•	Shows of strength are important 
•	Females prefer stronger males
•	Stronger males beat up weaker ones
•	Thus violence (or threats) is a kind of display used to acquire breeding partners
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
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 split 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