Investigating the genetic basis of behaviour

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Investigating the genetic basis of behaviour

• Lesson 1 Objectives
• To know the difference between nature and nurture
• To know the terms genotype and phenotype
• To understand why psychologists debate genetic
  influences on behaviour

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Nature or Nurture?
Watch this
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Nature Nurture

• And the interaction
• between them
• Genes
  Environment

Influences that occur outside the individual
could be Pre-natal environment Diet Pollution Fami
ly/peers Media
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The Current view

• It is impossible to view human characteristics
  and behaviour as purely biological or
  environmental
• Each individual human has a genotype this is
  the genetic composition
• Each person has a phenotype which is what the
  individual becomes when their genes interact with
  the environment.
• http//www.youtube.com/watch?vqyqbnDjId7g

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Why is it a debate?

• It isnt really because there is wide acceptance
  that genes and the environment interact.
• Our environment can affect our genes
• Genes can affect our environment
• Psychologists disagree over the extent of genetic
  vs environmental influences e.g they may agree
  that IQ is down to both genes and environment but
  they disagree on how much of it genes and how
  much is environment.
• ESSAY TIP 1 Controversial Question
• How much of behaviour is determined by genes and
  how much by environment?

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Why is this a big question?

• A belief that intelligence is genetic could lead
  to practice of eugenics selective breeding of
  humans.
• Likewise a belief that behaviour is purely down
  to environment may lead to harsh regimes based on
  conditioning people.
• See textbook for examples!

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The Application of Psychological knowledge

• If we think a behaviour is mostly genetic, we
  would treat it differently than if we thought it
  was environmental (or learned)
• For example think about.
• Intelligence
• Criminality
• Homosexuality

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Plenary

• Complete gap fill and questions 1-3 on your
  handout.

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Objectives Lesson 2

• To be able to explain the term heritability
  estimate
• To describe and evaluate three pieces of research
  into the genetic influences on behaviour.

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The Role of Genes in Human Behaviour

• NO I said GENES
  
  
  

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Twin Studies, adoption studiesand correlation

• How they contribute to our understanding of the
  debate

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Twin and adoption studies look to see how much
of our INDIVIDUAL DIFFERENCES are due to genes

• For example they want to know the reason why I
  like oranges and you dont. Is it more nature
  than nurture or vice versa.
• The extent to which this DIFFERENCE is due to
  genetic make-up is called a
• Heritability Estimate.
• THIS IS A BIOLOGICAL APPROACH

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Comparing

• When we say we compare twins or children with
  parents we mean on a measurable variable and
  because we are psychologists this will be
  something to do with behaviour for example
• Intelligence
• Aggression
• Introversion/extroversion
• Sense of humour
• Mental illnesses such as depression or
  schizophrenia
• Whatever it is you need some kind of test to
  give both parties that will give a number
  representing a behaviour

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Twin studies

• With twin studies there are 2 methods
• 1.comparing Monozygotic twins with Dyzygotic
  twins
• Eg
• MZ 0.86
• DZ 0.46
• What does this indicate? .
• 2.Comparing Monozygotic twins reared together
  with monozygotic twins reared apart
• Eg
• Together 0.86
• Apart 0.74
• What does this indicate?

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Adoption studies

• With adoption studies we tend to compare the
  adopted child with the biological mother and the
  adoptive mother to see which correlation
  coefficient is highest
• Eg
• Child and adoptive mother 0.42
• Child and biological mother 0.72

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• Answer questions 4 and 5 on your handout

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• Mental Illness
• Joseph (2004) the concordance rates for
  Schizophrenia is 40 for MZ twins and 7 for DZ
  twins.
• However Tienari et al (1994) provide evidence of
  the diathesis stress model which encompasses both
  genes and environment.

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Further Evaluation

• Do twins, siblings and adopted and biological
  children always share the same environment?
• What do you think ??
• http//www.psychexchange.co.uk/videos/view/20460/

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So how do we explain the fact that MZ twins
reared together do not always show perfect
concordance rates ?
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The Human GenomeExamples of the effects of genes
on human behaviour

• Intelligence
• Chorney et al (1998) have identified individual
  genes associated with a high IQ through gene
  mapping.
• However Turkheimer (2003) states socio-economic
  status is more important when accounting for
  variance in IQ scores.

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• Mate preference
• Evolutionary studies like that of Buss (1989)
  suggests that adaptive behaviours are passed on
  in our genes e.g women preferring ambition and
  industriousness
• However, Buss also found cultural variances and
  exceptions 22 of women did not prefer ambition
  and industriousness.

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Plenary

• Answer questions 6-8 on your handout.

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Objectives Lesson 3

• To be able to describe and evaluate 3 pieces
  research into environmental influences on
  behaviour
• To understand the term neural plasticity

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• Aggression Social Learning Theory
• Banduras classic bobo doll study illustrates the
  importance of vicarious reinforcement and the
  environment on our behaviour
• THIS IS A BEHAVIOURIST APPROACH
• However Coccaro et al (1997) suggest 50 of
  variance in aggressive tendencies is due to genes.

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• Neural plasticity
• This is the ability of the brain (as in its
  physical structure) to change according to
  experiences and environmental factors
• For example in Maguire et al 2000 the hippocampi
  of London Taxi drivers were found to be larger.
• Evaluation ?

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Research Study

• Blakemore and Cooper (1970)
• See page 70 of textbook
• What is the key message of this study?
• THAT NURTURE CREATES NATURE !!
• Evaluation ??

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• Answer question 9-12 on your handout.

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Objectives Lesson 4

• To understand how genes and the environment can
  interact with each other.
• To prepare an essay plan for the question
• Discuss the influence of genetic factors on human
  behaviour (22)

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Nurture affects nature!

• Look at pg 72 of your textbook
• Look at the picture of identical twins separated
  at birth
• Environmental factors such as stress or poor diet
  can switch on certain genes which are then passed
  on to the next generation. This is called
  epigenetics

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Nature affects Nurture

• Do parents treat all their young children exactly
  the same way? Why? Why not?
• Reactive influence - Genetic factors like
  temperament can create a microenvironment.
• e.g an aggressive child may be treated with more
  aggression.

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Nature affects Nurture

• Passive Influence - Genetically determined
  behaviour of parents might influence environment.
  
• e.g mental disorder of parent may cause
  environment which triggers disorder in child.
• Active influence Genes may influence actively
  selected parts of unshared environments in
  siblings niche picking e.g Child with high IQ
  seeks challenging books, sporty child prefers
  outdoor activities this has the effect of
  increasing the genetic characteristic.

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Overall

• Many examples demonstrate the interaction between
  genes and environment.
• Another good example is Phenylketonuria- this
  prevents the amino acid phenylalanine being
  metabolised causing brain damage.
• However if this is detected at birth it can be
  prevented through diet. So is it due to nature or
  nurture?

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Plenary

• Complete the gap fill on your handout and then
  start work on your essay plan.

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Key word check

• Epigenetics
• Reactive influence
• Passive Influence
• Active influence
• Microenvironment
• Niche-picking

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• Watch this
• Bear in mind the debate!