PSYC20009 Lecture Notes - Lecture 11: La Trobe University, Twin, Pollination Syndrome
14 Jun 2018
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Lecture 11 - Monday 9 October 2017
ANAT20006 - HUMAN STRUCTURE & FUNCTION
LECTURE 11
NATURE vs NURTURE
TODAY
•The role of the genes and the environmenT
•Guest lecture on evolutionary approaches
•Dr Beatrice Alba (La Trobe University / Monash University)
PERSONALITY EXPLANATION
•(1) Description = how, i.e., the way in which people differ
•Traits
•Characteristic Adaptations
•Life Narratives
•Explanation = why, i.e., the ‘reasons’ there are differences
•What gives rise to individual differences in personality?
•(2) How can we explain personality?
•Distal influences:
•Social context and culture?
•Upbringing, parenting?
•Genetics and evolutionary
history
•Proximal processes:
•Cognitive processes?
•Brain structure and function?
•(4) From last week...
•“Personality is an individual’s
unique variation on the general
evolutionary design for human
nature, expressed as a developing
pattern of dispositional traits,
characteristic adaptations, and
integrative life stories, complexly and
differentially situated in culture.”
•- McAdams & Pals, 2006
•(5) diagram right.
NATURE-NURTURE DEBATE
•(6) “The evolved general design...”
•Refers to role of genetics and
evolutionary forces
•Personality as a product of ‘nature’
•“Culture...Social ecology of daily life...”
•Refers to the role of the
environment (esp. social
environment)
•Personality as a product of ‘nurture’!
!
Lecture 11 - Monday 9 October 2017
ANAT20006 - HUMAN STRUCTURE & FUNCTION
•“Nature is all that a man brings with himself into the world; nurture is every influence that affects
him after birth” (Sir Francis Galton, 1874).
•(7) Radical behaviourism (Watson/Skinner):
•‘Blank slates’ at birth
•All behaviour results from our learning histories
•“Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in
and I ’ll guarantee to take any at random and train him to become any type of specialist I might
select—doctor, lawyer, artist, merchant-chief, and yes, even beggar-man and thief... There is no
such thing as an inheritance of capacity, talent, temperament, mental constitution, and
characteristics.”
•(James B. Watson, 1925)
•(8) For much of the 20th century – a socio-political debate:
•Proponents of nurture accused of:
•Social engineering
•Parental blame
•Proponents of nature accused of:
•Justification of inequality
•Eugenic ideals
•Throughout the 1960s-1970s, the socio-political climate increasingly favoured ‘nurture’.
•Eg. ‘refrigerator mothers’ theory of autism: cold/aloof mothers caused autism. This is
obviously not believed anymore.
•(9) Behavioural (Quantitative) Genetics:
•A set of statistical methods to partition variation in traits into:
•1. Genetic variance or ‘heritability’ (i.e., ‘nature’): influence of genes inherited from biological
parents
•2. Environmental variance (i.e., ‘nurture’): influence of experiences
•Shared variance: environmental influences that are common to the individuals being
studied
•Non-shared variance: environmental influences that differ across the individuals being
studied
•Plomin et al., 2001
•(10) Methods assess the strength of association between genetic relatedness and phenotypic
relatedness.
•Basically: “to what extent can we predict how similar people will be in terms of a personality
trait by knowing how similar they are in terms of their genetic makeup?”
•Designs:
•Family studies: siblings vs. more distant relatives
•Twin studies: identical vs. fraternal twins
•Adoption studies: siblings raised together vs. apart
•Combination designs: e.g., twin-adoptions; twins raised together vs. apart
•Genome-wide complex-trait analysis (GCTA): unrelated individuals varying in genetic
similarity. Scan the entire genome of Eg. lecture theatre.
•(11) diagram page below. (half of the variation could be contributed to genetic and half to
environmental factors.
•(13) → Turkheimer, 2000:
•“The nature-nurture debate is over”
•All personality traits and many other characteristics are the result of both genetic and
environmental influences (1st law of behavioural genetics)
Lecture 11 - Monday 9 October 2017
ANAT20006 - HUMAN STRUCTURE & FUNCTION
•The next challenge:
•Which genes influence
personality formation,
and how do they do so?
•Which environmental
factors (parenting,
experiences, social and
cultural context) shape
personality?
GENES ‘FOR’
PERSONALITY?
•(14) You have some
hypothesis about the
candidate gene.
•Candidate gene approach:
•Identify a gene that is of theoretical relevance to a trait of interest.
•Eg. genes involved in social bonding may have relevance to agreeableness
•Challenge: low replicability.
•Not very popular; each gene identified has a very very small effect.
→ Chabris et al., 2015
•Genome-wide association approach:
•Explore the entire genome for any empirical associations with a trait of interest
•Challenge : very large samples required (tens of thousands)
SOCIAL CONTEXT & CULTURE
•(15) Social norms
•Socially sanctioned rules for behaviour
•Descriptive norms: perceptions of what is typical
•Injunctive norms: perceptions of what is desirable
•Examples...
•Speech Accompanying Gestures (Italians vs. British)
•Silence: undesirable in individualist cultures, desirable in collectivist cultures.
•Display rules: norms concerning emotion expression.
•Research comparing display rules between the US and Japan. Similar emotional
physiological responses to evocative film clips but the physical expression of them (Eg.
facial expressions) are more obvious in US participants.
•Eg., happiness in public (Japanese vs. North Americans) Graham & Argyle, 1975; Iwao
1993; Matsumoto, 1990)
•(16) Social norms and dishonesty
•Study of country-level institutional practices. General prevalence of rule violations.
•How might levels of corruption and rule violations throughout one’s society influence traits
associated with honesty?
•159 nations assessed in terms of a ‘Prevalence of Rule Violations’ (PRV) index, reflecting 3 things:
•Ratings of (un)democratic practices
•Institutional level tax evasion
•World Bank’s Control of Corruption Index
•....all in 2003
•Gächter & Schulz, 2016
Document Summary
Today: the role of the genes and the environment, guest lecture on evolutionary approaches, dr beatrice alba (la trobe university / monash university) Nature-nurture debate: (6) the evolved general design , refers to role of genetics and evolutionary forces, personality as a product of nature", culturesocial ecology of daily life , refers to the role of the environment (esp. social environment, personality as a product of nurture". Refrigerator mothers" theory of autism: cold/aloof mothers caused autism. This is obviously not believed anymore: (9) behavioural (quantitative) genetics, a set of statistical methods to partition variation in traits into, 1. Genetic variance or heritability" (i. e. , nature"): influence of genes inherited from biological parents: 2. Chabris et al. , 2015: genome-wide association approach, explore the entire genome for any empirical associations with a trait of interest, challenge : very large samples required (tens of thousands)
