Aggression: Sibling and Peer
Relationships
Pro-social and anti-social influences
through adolescence
Evolution of responses to
(un)fairness
Sarah Brosnan & Frans de Waal
https://www.youtube.com/watch?v=meiU6Txys
Cg
Will M.
Problem of cooperation
Cooperation yields higher benefits than
could be attained alone, but reaping the
benefits without paying the cost would be
even better
Examples
- Tragedy of the commons
- Bystander effect
- Stinginess

Will M.
Ultimatum Game
Why not accept any positive offer, no
matter how low?
Puzzling when the game is only played
once.
Will M.
Problem of cooperation
Yet we know that humans cooperate with nonkin, as do primates (a bit)
How can cooperative behavior among nonkin evolve if it is more beneficial to cheat?
Inequity aversion may stabilize cooperation
(it should be called inequality aversion in the
context of the Ultimatum Game)
Will M.
Why aversion to inequity?


First-order IA: take stance against personal exploitation
Second-order IA: attract cooperative partners
These are present in humans and some apes. More developed in
humans because of language, enhanced self-control, etc.
Amount of partner choice influences adaptive value of IA.
(Also true in humans: collectivist societies will tolerate more
inequality)
Punishment is more effective when there is less partner choice.
Will M.
Genuine second-order IA?
The evidence is strong for kin and allies, but
not for strangers
Chimps don’t reduce advantageous inequality
even at no cost to self
In humans, there is aversion to inequality with
strangers when reputation is at stake, but not
otherwise.
Will M.
Relational model. aggressive behavior is one of several
ways in which conflicts of interest can be settled.
Other possible ways are tolerance (e.g., sharing of
resources), or avoidance of confrontation (e.g., by
subordinates to dominants).
Kiss to make-up
Fig. 2. Chimpanzees
typically seal a
postconflict reunion,
or reconciliation, with
a mouth-to-mouth
kiss, as here by a
female (right) to the
dominant male.
Aggression
De Waal, F. B. M. (2000).
Primates--a natural
heritage of conflict
resolution. Science,
289(5479), 586-590.
Most primates show a dramatic increase in body contact between
former opponents during post conflict (PC) as compared with
matched-control (MC) observations
The cumulative
percentage of opponentpairs seeking friendly
contact during a 10-min
time window after
670 spontaneous
aggressive incidents in a
zoo group of stumptail
macaques
Reconciliations allow rhesus monkeys to maintain tight
kinship bonds despite frequent intrafamilial squabbles.
Shortly after two adult
sisters bit each other, they
reunite sitting on the left
and right of their mother,
the alpha female of the
troop, each female holding
her own infant. The sisters
smack their lips while the
matriarch loudly grunts.
Reconciliation
The nature of the social relationship determines whether repair
attempts will be made, or not.
If there is a strong mutual interest in maintenance of the
relationship, reconciliation is most likely.
Parties negotiate the terms of their relationship by going through
cycles of conflict and reconciliation.
Weaning
A weaning compromise
has been arrived at
between a mother
chimpanzee and her 4year-old son. After
repeated nursing
conflicts, the son is
permitted to suck on a
part of the mother's body
other than the nipple.
Human aggression
Types
 Reactive and proactive aggression
 Overt and covert anti-social behavior

Processes

Under-socialized aggressive conduct
disorder associated with weak inhibition
system (BIS)
–

Impulsivity a key (Quay)
Information Processing
–
Real-time processes
 Somebody
bumps into you at a party
Stability of aggression
The earlier a person start, the more intense
the form of aggression and the longer it
lasts
 Stability of aggression can be as high as .76

–
–

Remarkably stable over up to 10 years
The aggressive remain so
One of the more stable psychological
characteristics
Behavior genetics

One inherits a propensity toward antisociality which interacts with an
environment in its (non)emergence
–
–
Genetic effects greater for self-reported than
adjudicated measures of aggression
Environmental, genetic, and interactive effects
evident in petty crime (806)
Real-time coercion



A parent–child dyad with
two main interaction
patterns:
A cooperative, mutually
positive pattern and a
hostile–withdrawn pattern
in which the parent berates
the child and the child
ignores the parent.
As mutual positivity
declines in early
adolescence, existing
habits of withdrawal will
constrain the interactions
that emerge next.
(Granic & Patterson, 2006).
Granic & Patterson, 2006
Relational aggression
Relational aggression


“Attempts to harm the victim through the
manipulation of relationships, threat of damage to
them, or both” (Crick et al, ’02 p.98)
Associated with internalizing/externalizing
problems and later peer rejection
Preschool
• Direct, face-to face behaviors
• Exclusion from party
Middle
Childhood
• More sophisticated, direct and indirect behaviors
• Direct: refuse to choose as a team member
• Indirect: spread a rumor
Adolescence
• Sophisticated and focused on opposite-sex relationships
• Stealing a boyfriend
Provocation  aggression

Physically aggressive children exhibited hostile
attributional biases and reported relatively greater
distress for instrumental provocation situations
–

Getting pushed into the mud
Relationally aggressive children exhibited hostile
attributional biases and reported relatively greater
distress for relational provocation contexts
–
Not getting invited to a birthday party.
–
662 third- to sixth-grade children

Crick et al., 2002. CD.
Aggression type and gender






Boys more physically victimized by their friends.
Girls more relationally victimized.
Friend physical victimization was particularly
related to boys adjustment difficulties
Friend relational victimization particularly related
to girls’ adjustment difficulties.
Is relational aggression a cause for concern or part
of everyday life?
Are some people more impacted by relational
aggression?
•
Crick & Nelson, 2002.
Disentangle forms and functions of
aggression in early childhood

Forms
–

physical, relational
Functions
–

A Longitudinal Study of
Forms and Functions of
Aggressive Behavior in
Early Childhood
Murray-Close & Ostrov, 2009
proactive, reactive
Potential predictors of
aggression subtypes
–
Gender, age, social
dominance, exclusion
Gangi
Measures
Observer Ratings


Observations of
Aggression
Ratings of Aggression
–

Preschool Social Behavior
Scale- Observer Form
Ratings of Form and
Function of Aggression
–
Preschool Proactive and
Reactive AggressionObserver Report
Teacher report

Report of Exclusion
–

Child Behavior Scale
Report of Social
Dominance and
Resource Control
Latent aggression factors
Forms stable, functions unstable, over time
 Proactive  increase in physical

Prediction
Findings


Support for distinction between aggression forms
and functions by early childhood
Forms were stable over time, functions were not
–

May use distinct forms to meet variety of needs
Predictors of aggression:
–
–
–
–
Females more relationally aggressive
Older children less likely to use physical aggression
Dominance associated with concurrent relational
aggression, decreases in physical aggression over time
Exclusion related to increases in relational aggression
over time
Gangi
Conclusions

Results from both studies support the pathway
from PV in elementary school to DPA in middle
school
–
Early externalizing behavior likely sets this process
in motion and eventually leads to DPA
PV has negative long-term social consequences
 Early behavior problems are a risk factor for
experiencing PV and eventually associating with
deviant peer groups

–
Role of internalizing symptoms is less clear
Peer victimization (PV)—a
stressor for youth

However, little is known about PV’s longterm impact on social relationships
–
Specifically, authors were interested in predictors
of deviant peer affiliation (DPA; e.g., antisocial
behaviors, getting into fights, stealing, cheating)
Rudolph, K. D., Lansford, J. E., Agoston, A. M., Sugimura, N., Schwartz,
D., Dodge, K. A., Pettit, G. S., & Bates, J. E. (2014). Peer Victimization
and Social Alienation: Predicting Deviant Peer Affiliation in Middle
School. Child Development, 85(1), 124-139. doi: 10.1111/cdev.12112
Peer victimization in elementary
school  deviant peer affiliation
(DPA) in middle school
Early externalizing behavior likely sets this
process in motion and eventually leads to DPA
 PV has negative long-term social consequences
 Early behavior problems are a risk factor for
experiencing PV and eventually associating with
deviant peer groups

–
Role of internalizing symptoms is less clear