Serial Killers Serial Killers are a study in the psychopathic perversion - usually a man with a sexual dysfunction The US has 5% of the world’s population and 75% of its serial killers • Buffalo Bill is the serial killer in The Silence of the Lambs • Dr. Lecter says that Buffalo Bill was not born, but made through years of child abuse • Buffalo Bill dresses like a woman, wears makeup, hides his penis = gay lifestyles? • Film perpetuates the idea that if you are gay and a man you really want to be a woman • Film links homosexuality, transsexuals, and female impersonation directly to killing
General Serial Killer ProfileDemographics • Male (88.3%) • White • 80% of all serial killers • 73% of male serial killers • 93% of female serial killers • Average intelligence • 107 in our data base • n = 71 • Often a police groupie • Seldom involved with groups
General Serial Killer ProfileDemographics – Average age is 28 • Males • 27.5 is average age at first kill • 9 is the youngest (Clarence Hill) • 72 is the oldest (Ray Copeland) • Jesse Pomeroy (Boston in the 1870s) • Killed 28 people by the age of 14 • Spent 58 years in solitary confinement until he died • Females (Kelleher & Kelleher, 1998) • 30 is average age at first kill • 14 is youngest (Caril Ann Fugate) • 55 is oldest (Marie Becker) • Angels of death, revenge killers, and team killers tend to be younger
General Serial Killer ProfileChildhood • Unstable home (37%) • Absence of loving and nurturing relationship • Physical ailments and disabilities • Head injuries • Triad • bed wetting • fire starting • animal torture
General Serial Killer ProfileForensic History • Triad • Most have a criminal history (80%) • 75% spent time in jail/prison prior to their serial killing • Many received psychiatric treatment • 33% spent time in a forensic unit • Many murdered well before their serial killing
Methods 1. Firearms mainly(41%) 2. Suffocation (37%) 3. Stabbing (34%) 4. Bludgeoning (26%) 5. Firearms only (19%) 6. Poison (11%) 7. Drowning (3%) 8. Other (2%) Motives 1. Sex (55%) 2. Control (29%) 3. Money (19%) 4. Enjoyment (16%) 5. Racism and hatred (11%) 6. Mental problems (6%) 7. Cult-inspired (5%) 8. Attention (2%) Male Serial Killers(399):
Methods 1. Poison (80%) 2. Shooting (20%) 3. Bludgeoning (16%) 4. Suffocation (16%) 5. Stabbing (11%) 6. Drowning (5%) Motives 1. Money (74%) 2. Control (13%) 3. Enjoyment (11%) 4. Sex (10%) 5. Drugs, cultinvolvement, cover up, or feelings of inadequacy (24%) Female Serial Killers (62):
III. Female Serial Killers & their victims • Female serial killers tend to be "black widows" who kill a succession of husbands, lovers, or other family members. • They can also be nurses or other medical professionals who become self-appointed "angels of death" murdering babies, elderly, or the desperately ill in a misguided effort to relieve their suffering.
Aggression Statistics • 15,533 murders in the U.S. in 1999 • 15,586 murders in the U.S. in 2000 • 16,037 murders in the U.S. in 2001 • 16,204 murders in the U.S. in 2002 • Expand definition to violent crime (murder, non-negligent manslaughter, rape, robbery, and aggravated assault): • 1,430,693 in 1999 • 1,425,486 in 2000 • 1,439,480 in 2001 • 1,426,325 in 2002
What did Freud say? • Eros: Life force • Drive-thwarted • Instinct • Catharsis • Thantos: death force
What did Freud say? • "The existence of this inclination to aggression, which we can detect in ourselves and justly assume to be present in others, is the factor which disturbs our relations with our neighbors and which forces civilization into such high expenditure [of energy]. In consequence of this primary mutual hostility of human beings, civilized society is perpetually threatened with disintegration.
What did Freud say? • Civilization has to use its utmost efforts in order to set limits to man's aggressive instincts and to hold the manifestations of them in check by psychical reaction-formations. Hence, therefore, the use of methods intended to incite people into identifications and aim-inhibited relations of love, hence the restrictions upon sexual life, and hence too the ideal's commandment to love one's neighbor as oneself-a commandment which is really justified by the fact that nothing else runs so strongly counter to the original nature of man."
Is Aggression Instinctual? • Hobbes, Freud, and Lorenz say yes. • Freud and Lorenz in particular believe that aggressive energy builds up and must be released. • Catharsis theory. • Unfortunately, aggressive catharsis frequently leads to more aggression. • One problem with instinctual explanations is that they tend to be descriptive and circular.
Theories of Aggression Leading Proponent: Konrad Lorenz (ethology) He says we have a biological need for aggression. It gets stronger as time passes since the last aggressive act (like hunger increases hours after a meal). This causes our energy level (drive level) to increase. This energy must somehow be released (“catharsis”). Instinct Theory: Through evolution, humans have inherited a fighting instinct similar to that found in many species of animals.
Theories of Aggression Instinct Theory says that humans learn their own individual ways of expressing aggressive motivation. Nonhuman species behave in ways that are genetically programmed and characteristic of all members of the species. Fixed Action Pattern: complex behavior that is largely unlearned and found in all members of a species (or subgroup), and that is triggered by a very simple stimulus in the environment (“releaser”).
Hydraulic Theory predicts: 1. Aggression is inevitable - the accumulating energy must find an outlet • 2. Humans & animals will actively 'look for fights'. • 3. After an attack an animal / human will become less aggressive. • 4. Animals reared in isolation will show aggressive behaviour.
Roots of Violence • Instinct- innate (unlearned) behavior pattern • Freud- redirecting the “death instinct” (thanatos) to others • Lorenz- inherited “fighting instinct” developed through the course of evolution (strongest survive) Not supported because: • Human aggression takes many forms • Frequency of violence varies across cultures • Engaging in potentially lethal behavior makes little sense in evolutionary terms
If not instinctual, can aggression still be biological? • Evolutionary psychologists argue yes. • Buss and Shackleford propose that our ancestors found aggression to be adaptive. • Lore and Schultz agree to a point. They also point out that most species have developed inhibitory mechanisms. • Thus, aggression is an optional strategy.
Neurological and Chemical Influences • Amygdala (located in the forebrain). • Testosterone – leads to an increase in aggression, but also increases during aggression • If testosterone is linked to aggression, does this mean that men are more aggressive than women? • Maccoby and Jacklin research suggests yes. • Across cultures, women demonstrate less violence • Further, during era of womens’ liberation, non-violent crime rate relative to male rate has increased, but not violent crime rate.
Research on Humans • General Research Question: Do men show reactive increases in testosterone after exposure to potential mates? • Are hormonal responses related to behavioral measures of courtship? • Previous research on hormonal responses to sexual stimuli: • A number of studies have found increased LH or testosterone levels in men within 10-20 minutes of the onset of exposure to erotic or sexually explicit films • However, no published studies have demonstrated increases in testosterone after more ecologically realistic social interactions with potential mates
Study Design • Male subjects (mean age = 21.36) were randomly assigned to a “male” (n=18) or “female” (n=21) condition • Subjects engaged in a 5-minute conversation with a male or female confederate • Saliva samples were taken before and 15 minutes after the interaction • Confederates rated the subjects’ behavior during the interaction.
Female condition: paired t (18) = 2.10, p = .05, d = .99 Male condition: paired t (17) = 0.90, p = .38, d = .44 Change scores did not differ significantly across conditions
Change in Testosterone by Courtship-Like Behavior r (19) = .52, p < .05 Roney et al., 2003
Courtship Behaviors (immediate) Activation of Limbic-Hypothalamic Structures Cues from Females r = .52 Testosterone Increase (post 20 minutes)
Violence in Hunter-Gatherer Society • Yanomamo group of hunter-gatherers in Amazon studies over last 25 years (Napolean Chagnon) • Inter-tribe violence very common with cycles of killings and retaliations – Chagnon estimated that about 70% of individuals over age 40 had lost at least one close genetic kin to homicide • “…kinship groups that retaliate swiftly and demonstrate their resolve to avenge deaths acquire reputations for ferocity that deter the violent designs of their neighbors. … a group with a reputation for swift retaliation is attacked less frequently and thus suffers a lower rate of mortality. … Aggressive groups coerce nubile females from less aggressive groups whenever the opportunity arises. Many appear to calculate the costs and benefits of forcibly appropriating or coercing females from groups that are perceived to be weak.”
Yanomamo men who have killed someone undergo a purification ritual that gives them the status of “unokai” • Women almost never unokai • Chagnon computed that unokai on average had more offspring than non-unokai – 4.91 vs. 1.59 on avg., collapsed across adult age groups • Men who had killed also had more wives: 1.63 vs. 0.63 on average • He speculates that men who have killed are both considered more valuable to the group (avenge and deter attacks from other groups) and thus are more attractive as mates, and they are able to forcibly acquire resources/women from other men in the group
Roots of Violence (cont.) • Biological Factors • High testosterone linked to higher aggression and less helping behavior in both males and females • Low levels of serotonin inhibit ability to restrain aggressive urges • Drive theories—externally elicited drives arouses motive to harm others • Frustration-aggression theory not well-supported because: • Frustration may lead to sadness, depression • People may aggress for other reasons (boxers, soldiers)
XYY- Super Male Syndrome Criminal Chromosomes?
Supermale? Or supercriminal? • Early work with karyotyping showed that normal men have an X and a Y sex chromosome, unlike women who have two X chromosomes. In 1961, Sandberg et al. found a man with an extra Y Chromosome (XYY). Since the Y chromosome codes for ‘maleness’ these individuals were dubbed ‘super-males’. [Ritter, 1993] • In 1965 a well-respected geneticist, Patricia Jacobs, stated that the incidence of XYY condition among the prison population was 20 times greater than normal. Her study linked the XYY condition with subnormal IQ and tendencies for violent crime.[Jacobs et.al. 1965]. • The Jacobs study led to sensationalized trials in which lawyers tried to exonerate the actions of the accused by blaming it on XYY syndrome. • A belief that XYY males were genetically predisposed to criminal behaviour encouraged public leaders to call for genetic screening of newborns and the imposition of interventions to prevent criminal behaviors from occurring.
Personal Determinants • Type A behavior pattern • Type A’s (highly competitive, time-urgent, hostile) tend to be more aggressive • Hostile attributional style • Tend to perceive malice in other’s ambiguous acts • Narcissism (inflated self-esteem) • Tend to lash out if grandiosity is threatened • Gender (higher in males) • Males tend to use direct forms (push, shove, coercion) • Females tend to use indirect (gossip, spread rumors) Note: Gender differences disappear under provocation
Is Aggression Learned? • Does aggression pay? Are people reinforced for aggression? • If so, operant conditional suggests that they are more likely to aggress in the future. • Social Learning Theory • Vicarious reinforcement • Bandura’s famous study with the Bobo doll.
Regional Differences in Aggression and Social Models • Homicide rates for White southern males are substantially higher than for White northern males (especially in rural areas) • However, they do not endorse violence in general, only as a tool for protection of property and in response to insults: “Culture of honor” based upon history as herding society • Nisbett research on southerners reaction to being bumped and cursed at • More upset (cortisol increase), primed for aggression (testosterone increase), more likely to engage in aggression after the incident.
Frustration-Aggression Theory • Dollard’s original definition: Frustration leads to (hostile) aggression. • Frustration is defined as having one’s goal attainment blocked. • Is this always true? • Berkowitz revises theory to state • Frustration produces anger, which provides a readiness to agress – but does not guarantee it. • Important concepts include expectations and relative deprivation. • American society “creates” frustration.
Theories of Aggression Negative Affect Theory: Proposed by Leonard Berkowitz, it states that negative feelings and experiences are the main cause of anger and angry aggression. Sources of anger include: pain, frustration, loud noise, foul odors, crowding, sadness, and depression. The likelihood that an angry person will act aggressively depends on his or her interpretation of the motives of the people involved.
Situational Determinants • Temperature (curvilinear relationship) • As temp. increases, assaults increase, but only up to a point (around 90 degrees) • Hotter years (and summers) increased rates of violent crimes, but not property or rape crimes • Alcohol • Intoxicated participants behave more aggressively and respond to provocations more strongly • Alcohol myopia—the more alcohol, the more accepting of sexual aggression to woman acting friendly (see Figure) • Low aggressors became more aggressive when intoxicated, whereas high aggressors did not
Heat and Aggression • Heat and Aggression • Heat and the Bean Ball • U-shaped Curve • Reliable but not very strong pattern
Alcohol • Strong correlation between • alcohol use and violent crimes
Did they believe they were drinking alcohol Yes No Did they actually drink alcohol Yes 25% 25% No 25% 25% Typical Experimental Design cp