Evolutionary psychology: the new science of the mind. Boston: Allyn & Bacon,
2nd edition, Chapters 1, 2 & 13. • Barrett L., Dunbar, R. & Lycett, J. (2002).
Human ...
Essential reading •
Buss D. (2004). Evolutionary psychology: the new science of the mind. Boston: Allyn & Bacon, 2nd edition, Chapters 1, 2 & 13
•
Barrett L., Dunbar, R. & Lycett, J. (2002). Human evolutionary psychology. London: Palgrave, Chapters 1, 2, 10 & 11
PS1014 Approaches to Psychology Carlo De Lillo Evolutionary Psychology
Evolutionary Psychology
Suggested reading •
Buss, M.D., Haselton, M.G., Shackelford, T.K., Bleske, A.L., Wakefield, J.C. (1998). Adaptations, Exaptations & Spandrels. American Psychologist 55(5): 533548.
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Cosmides, L. and Tooby, J. Evolutionary Psychology: A primer. Online document available at: http://www.psych.ucsb.edu/research/cep/primer.html
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Gould, S. J. (1997, October 9). Evolutionary Psychology: An exchange. New York Review of Books, XLIV: 53-58
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Gould, S. J. (2002). The Structure of Evolutionary Theory. Cambridge, Mass.: Harvard University Press
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Lewontin, R.C. (1993). Biology as Ideology: The Doctrine of DNA. HarperPerennial.
Evolutionary Psychology What is it?
• Definitions and Background • Altruism • Parental investment • Sexual conflict
• “Identifies selection pressures that have shaped the human psyche over the course of evolutionary time and test whether our psychological mechanisms were designed to solve these particular adaptive problems” (Barrett , Dunbar & Lycett p. 10)
• Cognition & Social Cognition
Historical Background • Behaviourism – Little role for instinct – General Learning Mechanisms – Limits of behaviourism • Harlow’s surrogate mothers • The Garcia effect
Historical Background • Ethology – Reaction to environmentalism and behaviourism – Imprinting (Lorenz 1965) – Fixed Action Patterns (Tinbergen 1951) – More description than explanation of behaviour
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Historical Background • The cognitive revolution – Chomsky’s “language organ” (1957) – Human Information Processing • Domain general • Domain specific
Background: Evolutionary Theory Darwin “On the Origin of Species” (1859):
Background: Evolutionary Theory Useful Terms: •
Phenotype = set of behaviours and physical traits of adult individual
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Gene = single, unbroken unit of inheritance
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Genotype = genetic make-up of individual
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Fitness = measure of relative reproductive success
Background: Evolutionary Theory Darwin “The Descent of Man, and Selection in Relation to Sex” (1871):
Natural selection: – – – –
Principle of variation refers to phenotype Principle of inheritance does not need to be DNA based (Barrett et al. 2002, p. 3) Principle of adaptation population growth and competition for scarce resources Principle of evolution rests on fitness
Levels of explanation Different types of behavioural causation (Tinbergen 1963): - Proximate immediate motives for behaviour e.g. mother breast feeds baby because baby crying
- Ontogenetic (developmental) how behaviour is acquired during lifespan e.g. in her lifetime mother learned by observation that crying babies are breast fed
- Phylogenetic (historical) how behaviour is acquired in natural history of species e.g. changes from egg lying ancestors to mammalian species
- Ultimate (functional) how behaviour contributes to individual’s fitness
Sexual selection - Some behaviours evolved not because have good survival function in general - But give more access to mates Intra-sexual selection competition with rivals
Inter-sexual selection preferential mate choice
Evolutionary Psychology 3 main products of Evolution: (David Buss, 2004) • Adaptations = inherited characteristics that developed through evolution to help survival or reproduction • By-products = characteristics that do not solve survival problems but are carried along as are coupled with adaptive factors (side effects) • Noise = random effects and chance mutations when sudden environment changes cause chance effects with no specific function
e.g. mother increases survival chances of child carrying her genes
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Evolutionary Psychology
Evolutionary Psychology How to identify an adaptive trait?
Environment of Evolutionary Adaptedness (EEA)= selection pressures occurring when an adaptation emerged
• Williams (1966) gives three criteria for identifying whether a behaviour or trait is likely to be an adaptation to the environment:
Human behavioural ecology EEA = current environment
– Reliability – Efficiency – Economy
Evolutionary psychology EEA = pleistocene
• If all of these satisfied, then behaviour unlikely have developed by chance and more likely to be an evolutionary adaptation
Altruism • • •
Kin Selection Theory •
Inclusive fitness (Hamilton 1964)/Kin selection (MayanardSmith 1964)
Helping behaviour may be a problem for evolutionary theory Altruism by definition means being selfless but evolution theory is about being selfish Are we altruistic by nature or by mistake?
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Shift from organism to gene as unit of selection
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Direct + indirect fitness
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Hamilton’s rule •
2 ideas of how to fit altruism into evolution context: – Either through kin selection (i.e. helps gene survival) – Or through reciprocal altruism (i.e. helper benefits long term)
Altruism gene evolves whenever r B > C 1
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C = costs
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B = benefits
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r = coefficient of relatedness
1
0.75 0.5
0.5
0.5 0.25 0.25 0.25
0.25
0.125 0.0625
0 In de nt ic al tw Pa in re nt /c hi ld S G pa ibli n re nt g \G ch U ild nc le /n ie ce 1/ 2 si bl in 1s g tc ou si 2n n d co us in
•
- up to 2.5 mllion years ago - before agriculture (10,000 year ago) - psychological mechanisms not always producing adaptive behaviour in modern society
Reciprocal Altruism Theory
Reciprocal Altruism Theory •
• Reciprocal altruism among non-kin (Trivers,1971) • Explains when we help people not related to us • Short-term loss to helper means are owed a favour in return! • Seen in other species where help now for benefit later • Requires ability to tell people apart and remember who owes you what
“Prisoners dilemma” game: – much of game theory based on issues of cooperation and trust versus cheating – In this game if you cheat and other person cooperates you are better off at cost to other player, – If you both cheat then both lose out – if you both cooperate both get an average pay-off – studies find which option choose depends on how much will be interacting with other player Pay-off matrix for Prisoner’s dilemma game
• BUT means risk of trust as if get cheated on will lose entirely
Opponent’s decision
• Therefore we have also evolved mechanisms to identify and stop cheating
Co-operate
Player’s decision
Defect
Co-operate
3
0
Defect
5
1
3
Parental Investment/Parent offspring conflict •
Trivers (1974) “Investment of parent…which increases offspring survival at the expense of investment in other offspring”
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Special case of kin selection
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In parents interest to end investment soon so can invest in another/new offspring
• •
Gets into conflict with offspring interests especially at weaning Child manipulation of parent: –
Use psychological techniques to gain more resources and attention from parents •
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e.g. Temper Tantrums: – child reverts to earlier age behaviours to get more attention – or is pretending may harm itself to threaten parent
Sexual Conflict •
Trivers (1974)
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Women can only have limited number of offspring and is very energy costly so go for quality But men can go for quantity
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More variability in males’ reproductive success (Bateman’s principle) –
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increases intra-sexual selection
Sex differences and complementary strategies exacerbated in promiscuous/polygamous societies
Sibling rivalry
Cognition
Cognition: cheater detection
• Modularity
Wason’s selection task (Wason 1966, 1983)
– Fodor (1983)
people presented with sets of cards with symbols
• Modular perceptual systems – Innate, Mandatory, Encapsulated
A
• Higher cognition – Domain general
– Karmiloff-Smith (1996) • Developmental model – Progressive modularisation, then representational redescription (RR) makes modules more domain general
H
4
7
Given a rule: “A card showing a vowel on the front has an even number on the reverse”, corresponding to logical statement: if P, then Q
– Tooby and Cosmides (2000) • Evolutionary perspective – Massive modularity/”Swiss Army Knife” model of cognition – Modularity applies to all cognition including higher functions
People have to decide which card to turn over to see if rule has been violated Logical response = A (P) & 7 (not-Q) People typically chose A (P) and 4 (Q) which is a logical mistake as the rule does not state what an even number should have on the back
Cognition: cheater detection Social contract version (e.g. Cosmides & Tooby 1992) symbols replaced with social contract rules
Coke
Beer
16
21
• Given the rule if you drink beer, then you are over 18 (if P, then Q) • People easily behave according to logical principles – I.e. correctly check that 16 year old is not drinking beer (not Q) • Even thought is domain specific • We have evolved a specialised module for detecting cheaters
Cognitive Psychology –
Cognitive psychology would look for general info processing mechanisms
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But Evolutionary Psychology says these mechanisms have developed specific to context and environment
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Therefore need to study them within context of real-world situations
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Cognitive psychology assumes can study the mechanisms without reference to their inherent function (not really!)
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Evolutionary Cognitive Psychology therefore looks at these info processing mechanisms in terms of their evolved function
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Social cognition
Summary
• Theory of Mind – Ability to attribute mental states in others – Develops by age 4-5 in children – False belief task • Object displaced in absence of a tester • Child asked whether absent tester will be aware of the new location of object
– Possible candidate for modularity as autistic children are selectively impaired in TOM tasks – However, viable alternative theories
Background Example of EP theories and evidence 1. 2. 3. 4. 5.
Altruism Parental investment Sexual conflict Cognition Social Cognition
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