Biological and Social causes of Aggression

Aggression: Physical or Verbal Behavior intended to harm

Aggression can be either:

Inwardly directed (self-mutilation or suicide) Or Outwardly directed at another person.

Hostile: Anger based agression

Or Instrumental: Agression meant to achieve a goal

Agressive Direction

Inward Outward

Hostile Self-Mutilation due to self-hate Killing your spouse bc you believe they have been cheating


Instrumental self-mutilation Physical assaults

To gain sympathy such as mugging

From someone









Biological influences:

Certain brain areas, when electrically stimulated, can increase aggressive behavior in monkeys.

The amygdala in humans is the brain structure which has been linked to aggressive behavior.

Aggressive behavior is genetically influenced:

By selective breeding, aggressive and passive strains of mice can be created (Lagerspetz, 1979)

Blood chemistry can contribute to aggressive behavior.

Alcohol can contribute to aggressive behavior by

decreasing self-awareness (deindividuation factor), and decreasing the ability to accurately perceive the outcome of an aggressive act.

Low blood sugar levels can boost aggressiveness.


Males with high testosterone levels are more prone to delinquency, hard drug use, and aggressive responses when provoked.



Psychological Influences of Aggressive Behavior

Frustration: the blocking of goal-directed behavior.

The frustration-aggression theory (1939) : Frustration creates a motive for aggression. Fear of punishment or disapproval may cause the aggressive behavior to be displaced against some other target, or oneself.

However, the frustration-aggression theory overstated the link.

Frustration that arises from an understandable cause does not necessarily lead to aggressive behavior.

Burnstein & Worchel (1962): Had a research confederate disrupt a subject groupís problem solving task. If the disruption was blamed on a failing hearing aid, no aggression toward the confederate was observed.

Berkowitz (1978,1989) revised the frustration-aggression theory.

His revised theory stated that frustration led to anger, and anger can sometimes lead to aggressive behavior

Anger : An emotional readiness to perform an aggressive behavior

Anger arises when a person who frustrates us could have chosen to act otherwise.

Social Influences on aggression

Environmental cues can increase the likelihood or amplify aggressive behavior.

Berkowitz & LePage (1967): Subjects made angry by an insulting confederate gave more electric shocks when given the chance if a rifle and revolver were on a table nearby, than when badminton rackets were left on the table.

Berkowitz (1968): Children who had just played with toy guns were more likely to knock down another childís blocks than children who had been playing with non-aggressive toys.

Other Factors which can contribute to Aggression:











The Learning of Aggression

When people (especialy children)observe aggressive behavior which is rewarded, this can increase their own use of aggression.

A child whose aggressive acts intimidate other children will often become increasingly aggressive.

Aggressive Hockey players (as measured by penalty minutes) score more goals than non-aggressive players (McCarthy & Kelly, 1978).

Reinforcement: Canadien youth hockey players whose fathers applauded rough play show the most aggressive style of play.

Large scale riots can lead to changes in social and economic policies.

Observational Learning:

Bandura (1979) Social Learning Theory: We learn social behavior by observing and imitating the behavior of others, in particular observing the consequences of particular actions.

Had children watch a video of a confederate playing with a "BoBo" doll. The confederate either played aggressively (hitting BoBo with a hammer) or non-aggressively. Next, the children were frustrated by removing them from the first "toy-room", and put into a second "toy-room" which contained the BoBo doll


Results: When put into another room with the BoBo doll, children who had observed the confederate hitting the BoBo doll were much more likely to hit and punch BoBo than children who had observed the confederate playing in a non-aggressive manner.

In another experiment children saw a confederate either rewarded or not rewarded for abusing the BoBo doll. Those children who had seen the confederate being rewarded were much more likely to play aggressively with the BoBo doll.

Bandura believes that aggressive models appear in the

1. Family: Abusive parents were usually abused as children. Abused children are four times as likely to abuse their children than non-abused children.

2. Subculture: Cultural Stereotypes can enforce expectations of "Macho" behavior in men. Teen-age gangs provides younger members with aggressive models.

3. Mass Media : Viewing television violence can

A. Desensitize people to violent behavior

B. Increase aggressiveness

C. Wrongly shape peoples assumptions about Social Reality

Television watching and violent behavior:


Eron & Huesmann (1980,84, 85) Conducted a longitudinal study on 875 students from age 8 to age 30.

At age 8: Viewing violent television and aggressive behavior were shown to be positively correlated, even when potentially contaminating factors were removed from the analysis.

The amount of violent television viewed at age 8 modestly predicted amount of aggressive behavior at age 19.

However, aggressiveness at age 8 could not reliably predict how much violent television one watched at age 19.

The above two findings led to the conclusion that violent behavior followed from watching violent TV, and it wasnít simply the case that aggressive children liked to watch violent television.

Furthermore, at age 30, adults who had watched more violent television at age 8 were more likely to have been convicted of a serious crime.






Further fun T.V. facts : Between 1957 and 1974, homicide rates doubled in the U.S. and Canada.


A Canadien town which had never received television until the late 80's saw the incidence of playground aggression double within months. (Williams, 1986).


Susan Hearold (1986) did a meta-analysis of 230 Correlational and experimental research articles and concluded that viewing antisocial images on television is associated with antisocial behavior.

Can T.V. ever promote prosocial Behavior?

The Mister Rogers Study: Freidrich and Stein (1972) showed a preschool group Mister Rogers every weekday for four weeks.

During the viewing period, children from less educated homes became more cooperative, helpful, and more likely to state their feelings.









Pornography and Sexual Violence


21 Social Scientists and the Surgeon General issued a statement in 1987:

"Pornography that portrays sexual aggression as pleasurable for the victim increases the acceptance of the use of coercion in sexual relations."

Correlational studies indicate that pornography may contribute toward male aggressive behavior towards females.

Baron & Straus (1984) determined that the sales rate of magazines such as Hustler and Playboy within a state were positively correlated with each states rape rate.

For example, Alaska ranked first in sex magazine sales and first in rape.

Anecdotally, Ted Bundyís death row "confession" claimed that viewing pornography is what lead him to murder women.

In Denmark, a study done for 10 years after the introduction of legal pornography in the country showed a decrease in sexual assaults.