Transcript What is Evolutionary Psychology?

Evolutionary Psychology, Workshop 3:
Altruism and Cooperation.
Aims of the Workshop.
 1. Review the Burnstein et al., (1994) study on helping
behaviour.
 2. Collate and interpret results from the 'who shall I
save/help?' tasks in light of the Burnstein et al., (1994)
report.
 3. Observe a demonstration of 'prisoner's dilemma' to
assess cooperative and competitive behaviours and discuss
the outcomes.
 4. Watch a clip from the TV series 'Shafted' and discuss the
behaviour of the contestants in the context of the
'prisoner's dilemma'.
Background.
 Burnstein et al., (1994) pointed out that during natural
disasters people's uppermost concern is with their families.
 The idea that concern for others should be dependent upon
relatedness has been predicted by evolutionary biologists in
their discussions of 'inclusive fitness’.
 Burnstein et al., (1994) argued that social psychologists
could perhaps take into account inclusive fitness as it may
provide explanations for certain human social behaviours
involving
cooperation,
exchange,
competition
and
attraction.
Hypotheses.
 A key hypothesis to be addressed in this session is that
natural selection may favour a tendency to discriminate
amongst others who require help according to their degree
of relatedness.
 People should be able to weigh up the costs/benefits of the
outcomes of certain social situations, especially those
situations involving a decision as to whether to help
someone or not.
 We are very interested in who is related to who, who is
having a relationship with who as such information may
well influence our behaviour to that person.
Burnstein et al., (1994) Study.
 They argued that our decisions to help or assist another
individual should be influenced by the perceived degree of
relatedness we share with an individual.
 For example we should be more likely to assist another
when they are close relatives (e.g. a sister) than when they
are more distantly related (e.g. a cousin) or indeed if they
are unrelated.
 Other factors may also contribute to this decision making
process.
 For example age, sex, wealth, and health can influence
inclusive fitness.
Decision Rules for Altruism.
 Burnstein et al., (1994) presented 158 American and
Japanese undergraduates with a series of social dilemmas in
which the person had to rank-order individuals differing in
their degree of relatedness in terms of help or assistance.
 They found the following:
Tendency to help kin under life or death
versus everyday situations.
Tendency to help as a function of age, under
life or death versus everyday situations.
Tendency to help as a function of sex and
age, under life or death conditions.
Tendency to help as a function of sex and
age, under everyday conditions.
Tendency to help as a function of health
under life or death or everyday conditions.
The Task.
 You have 4 sheets, each with two versions of the 'who shall
I save/help' task.
 Test 4 participants and record their ratings in the spaces
provided.
 In the data record insert the raw data and calculate the
mean rankings.
 We can then draw a graph of the group data which plots
mean help ranking against degree of relatedness:
Our Data.
Mean Rank (1 = help
first)
Tendency to Help, N = 245
4
3
everyday
life/death
2
1
Relatedness
f ri
en
d
co
us
in
gm
ot
h/
fa
th
br
ot
h/
s
is
0
‘Prisoner’s Dilemma’ Demonstration.
 The aim is to win as many points as you can against your
opponent.
 On each trial you have to hold up one of the markers.
 If both of you hold up a blue marker you each win 3 points.
 If both hold up a red marker you each win 1 point.
 If one holds up a blue marker but the other holds up a red
marker, the the blue marker holder wins nothing, but the red
marker holder wins 5 points.
 You cannot speak during the game. The judge will announce
each person's choice of marker after you have both made
your choices, and they will tell you how many points you
have each won.
Prisoner’s Dilemma Payoff Matrix
Player B
Co-operates
(blue)
Player B
Defects (red)
Player A
Co-operates
(blue)
3 points each.
Reward for mutual
cooperation
0 points for A,
5 points for B.
Sucker's payoff
Player A
defects (red)
0 points for B,
5 points for A
Temptation to
defect
1 point each.
Punishment for
mutual defection
Increased Co-operation in Twins.
 In light of kin selection theories we may expect that in such
encounters, people who are related to one another may be
more likely to cooperate than unrelated individuals.
 Segal & Hershberger (1999) tested the hypothesis that
higher levels of co-operation would be associated with
increased genetic relatedness.
 59 MZ twins and 37 DZ pairs played ‘Prisoner’s Dilemma’ in
which each was encouraged to win as much money as
possible at the expense of the other.
 The game was played for 100 trials (participants were not
told this) and earnings were continually announced.
 The number of points collectively earned by MZ twins
significantly exceeded those won by DZ twins, and the MZ
twins displayed significantly more co-operative acts that
increased over time.
References.
 Burnstein, E., Crandell, C., & Kitayama, S. (1994). Some neodarwinian decision rules for altruism: weighing cues for inclusive
fitness as a function of the biological importance of the decision.
Journal of Personality and Social Psychology, 67: 773-789.
 Segal, N.L., & Hershberger, S.L. (1999). Cooperation and
competition between twins: findings from a Prisoner’s Dilemma
game. Evolution and Human Behaviour, 20: 29-51.