Psyc311: Developmental Psychology

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Psyc311 Developmental Psychology

• Chapter 2
• Biological and Environmental Foundations

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exercise

• What are some traits that you share with your
  family members?
• What are some traits that make you different from
  your family members?
• What factors (genes vs. environment) would you
  hold responsible for each of these traits?
• Which are most likely genetic?
• Which are most likely environmental?

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nature vs. nurture

• How do we explain the tremendous variability in
  human traits and behaviors?
• It must be environment!
• Humans have only 3x more genes than fruit flies.
• Genes cant explain behavioral flexibility
• Plasticity argues against innate wiring
• It must be genes!
• Genes have tremendous combitorial power
• Slight differences lead to large changes in
  behavior
• Cascades of change
• Innateness ? pre-wiring
• Plasticity ? re-wiring

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nature vs. nurture

• Individual level the extent to which any given
  childs development the product of his/her
  genetic vs. environmental influences.
• Population level the degree to which observed
  variation in particular traits (in a given
  population) is due to environmental or to genetic
  factors.

Why does it matter?
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nature vs. nurture

• The observable characteristics of a person,
  including appearance, personality, intelligence,
  and all other traits.

phenotype
?

• An organisms entire genetic inheritance or
  genetic potential.

genotype
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View 1

• genotype

phenotype
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• Not all variation in phenotypes can be explained
  by variation in genotypes.
• Scientists have studied thousands of twins, both
  monozygotic and dizygotic, raised together in the
  same home and raised separately in different homes

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• Notice that identical twins are not identical,
  (there is clear evidence for the effect of
  environment).

Notice that DZ twins and regular siblings look
the same. Why isnt this surprising? Why is this
surprising?
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View 2

• genotype
• environment

phenotype
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which contributes more?
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which contributes more?

• ?Trait B
• High heritability (genes)
• High shared environmental variance
• High unshared (unique) environmental variance

• ?Trait A
• High heritability (genes)
• High shared environmental variance
• High unshared (unique) environmental variance

• 
  Trait C ?
• High heritability (genes)
• High shared environmental variance
• High unshared (unique) environmental variance

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asking wrong question?

• Asking which (genes or environment) contributes
  more to childs phenotype.
• Is like asking which (length or width)
  contributes more to the area of a rectangle?
• The correct question to ask is which contributes
  more to variation within a given group (of
  children and rectangles)?

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range of reaction
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environments influence genes

• Lots of genes are carried in a persons genotype,
  but do not get expressed in their phenotype.
• "The phenotype is the unique consequence of a
  particular genotype developing in a particular
  environment"
• (Lewontin, 1982, pp. 2223).
• So environment can influence
• Which genes get expressed
• How they get expressed

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genes influence environment

• Passive genotype-environment correlation.
• Evocative genotype-environment correlation.
• Each childs genes elicit other peoples
  responses, and these responses shape development.
  
• In other words, a childs environment is partly
  the result of his or her genes.
• Active genotype-environment correlation.
• Children, adolescents, and especially adults
  choose environments that are compatible with
  their genes (called niche-picking),
• thus genetic influences in adulthood increase.

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iclicker

• A child is exposed to music because her parents
  enjoy music and frequently have it playing in the
  background.
• A) passive
• B) evocative
• C) active

• A child is exposed to music because she has colic
  and will only quiet down and fall asleep when her
  parents put on music, so they frequently have
  music playing in the background.
• A) passive
• B) evocative
• C) active

A child is exposed to music because she asks her
parents if she can go to music camp for the
summer. A) passive B) evocative C) active
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View 3

• genotype
• environment

phenotype
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epigenetic framework
Can you think of protective and risk factors in
your own life?
neighborhood
family
SES
culture

• Each layer can serve as either a protective or a
  risk factor for the developing child (and, at
  times, vice versa).

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two important concepts

• Phenotypic plasticity the degree to which an
  organism's phenotype is determined by its
  genotype.
• A phenotype is plastic if changes in the
  environment noticeably affect the physical
  properties of the organism.
• Low plasticity the phenotype can be reliably
  predicted from the genotype
• The phenotype will express regardless of
  environmental variation.

• Genetic canalization the extent to which an
  organism's phenotype allows conclusions about its
  genotype.
• A phenotype is canalized if changes in the genome
  do not noticeably affect the physical properties
  of the organism.
• High canalization the genotype cannot be
  reliably predicted from the phenotype
• The phenotype will express regardless of genetic
  variation.

• Examples
• Language is low in plasticity and high in
  canalization.
• Eye color is low in canalization.
• Reading ability is high in plasticity.

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exercise

• Name traits with low and high phenotypic
  plasticity

Sensitivity to environment
High sensitivity High plasticity
Low sensitivity Low plasticity

• Name traits with low and high genetic canalization

Sensitivity to genetic variation
Low sensitivity High canalization
High sensitivity Low canalization
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announcements

• Gattaca showing
• 9/15 (Weds) 7-9pm, ECTR 118
• First debate Friday 9/17
• Ask Yourself Qs due Monday 9/20
• Meeting of the Psychology Majors Minors
• 9/16 310pm Physicians Auditorium
• Psychology Club needs you!!
• Psi Chi applications due 9/24/10
• Sign up for ECDC observations!!

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ADHD

• Genes
• Commonly found in boys who have male relatives
  with the same problem
• Heritability rate 60-91
• Generates overactivity across environmental
  contexts
• Home as well as school
• Typically calmed by stimulants
• Ritalin, Adderall, and even coffee
• Environment
• The rapid increase in ADHD
• from 1 to 5 of all U.S. children in the past 50
  years
• Many environmental factors correlated with ADHD
• crowded homes, television, lead, food additives,
  rigid teaching, lack of sleep

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ADHD
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alcohol and drug addiction

• Genes
• Inherited biochemistry makes people vulnerable to
  various additions
• Fewer dopamine receptors
• People with high anxiety or quick tempers more
  likely to drink
• Environment
• Environments contribute to the likelihood that an
  addiction will form
• College
• Culture
• Gender genetic or environmental?

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nearsightedness

• Nearsightedness is a symptom in more than 150
  genetic syndromes
• Commonly inherited trait
• Environment also influences nearsightedness
• diet is deficient of vitamin A
• large quantities of close-in vision (reading
  books/computer screens)

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Type 2 diabetes

• Rapid increase due to environmental changes
• What are some of these changes?
• Also a genetic pre-disposition
• Only some people vulnerable to the risk factors

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IQ

• Interesting gene-environment interaction
• Fatty acids DHA and ARA promote neuronal
  growth/connectivity
• Breast milk is rich in DHA and ARA
• Absence of breast milk may negatively effect IQ
• Certain genes play crucial role in metabolism of
  these fatty acids
• Babies that have these genes benefit from breast
  milk others dont.

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political orientation

• How could political orientation be genetic?!
• Liberal vs. conservative ideology
• Instinctive emotional response