Lecture: Unit 2
Dr. Neil Schwartz
Psych 353
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Variability
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Survival
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Reproduction
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Phenotype
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Genotype
Biston betularia f. carbonaria,
the black-bodied peppered moth.
Biston betularia f. typica, the
white-bodied
DNA Transcription
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The emergence of new structures and
functions during the course of development.
Development is characterized by an increase
of complexity of organization.
Reflects a biderectional relationship between
all levels of biological and experiential
variables, such that genetic activity both
influences and is influenced by structural
maturation, which is bidirectionally related to
function and activity.
Genetic activity (DNA
RNA
proteins)
structural maturation
function, activity
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Developmental Systems Approach
suggests that development occurs as a
function of the interaction between multiple
layers of an organism and its environment.
Epigenesis suggests that a human, at any
given developmental level, will be
qualitatively different—both in terms of
structure (what they look like/what they know)
and function (what they can do). These
changes occur at all levels of an organism
because of bi-directional relationships with all
of these levels.
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There are constrains ( genetics and
environment)
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EX. Breast milk and IQ
Right and left hemispheres are not
symmetrical
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Environment
Behavior
Neural Activity
Genetic Activity
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There are no simple genetic or experiential
causes of behavior. Instead, the two interact
to increase or decrease the probability of
behavior based on the interaction of genetic
predisposition and experience.
But, remember… experience is not just
experience generically defined. Rather it is
species-typical environmental experience—
both prenatally and postnatally.
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Critical periods are the time in
development when infants/children are
“ripe” for the influence of environmental
experiences. (when a specific skill or ability
is most easily acquired)
Humans are prepared neurologically for
certain experiences and not others. When
the time is right, the experiences exert
their most effective and efficient effect on
development.
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Neurological preparedness suggests that
there are undifferentiated neurons that
become specialized for various functions as a
result of their location in the brain and
experience. When these neurons are made
available for differentiation, the nature of
experience can and will have a clear effect on
them, and hence on all of development.
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Genes direct biochemical production (proteins,
for example).
Bio-chemicals determine structural development
(like various tissues—nerves, muscles, bones).
Use or disuse of these structures (nerve cells or
muscle cells, for example) can turn genes on or
off —which in turn can create or allow to atrophy
nerve or muscle cells.
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Behavior Genetics — studies genetic effects
on behavior and complex psychological
characteristics, such as intelligence and
personality.
So, is biology truly destiny?
No… remember, all genetic effects are
moderated by environmental effects.
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A person’s genetic makeup influences which
environments one encounters
and the type of experiences one has.
Genes drive experience and determine how
we organize our world and how our
experiences are perceived.
Child’s
Genotype
Environment
sought out and
established by
the Child
Child’s
Phenotype
Genotype of
the Parents
Genotype of
the Child
Phenotype of
the Child
Rearing
Environment of the
Child
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Passive Genotype — The environmental
influences that parents provide for their kids
exert a gradually decreasing effect on the
children as the children get older.
Environmental effects decrease with age.
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Evocative Genotype — Temperamental
characteristics of children that elicit
responses from others.
Environmental effects remain constant with
age.
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Active Genotype — As children get older,
they have more and more ability to select
environments that suit their own particular
needs.
Environmental effects increase with age.
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Biologically primary abilities: Abilities which are
selected in evolution, acquired universally, and that
draw high motivation from children to perform
tasks involving them. Ex: language
Biologically secondary abilities: Culturally invented
skills built atop primary abilities. Repetition and
external pressure are used to learn such skills. Ex:
reading
Possible reasons for extended period of
immaturity:
◦ Children need a good deal of time and practice to “master
the complexities of human societies and technologies;”
◦ Humans live with a variety of social and physical
environments, and as such, they need much cognitive
flexibility to adapt to such differences;
◦ We need “a long period of apprenticeship, as well as a large
brain capable of flexible learning and cognition.”
Biological functions of the brain are important to
touch on, because talking about cognition and
cognitive functions is relatively unexciting without
knowledge of the way the brain works. So much
more is known about the brain today that validates
theories of cognition.
Unmyelinated
Neuron
Myelinated
Neuron
PET Scan
fMRI Scan
Therefore, characteristics of the child, as well
as the rearing environment and genetic
contributions of the parents, influence the
course of development.
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Domain-specific modules
David Geary’s model of domain-specific
modules:
◦ Social
 Individual
 Group
◦ Ecological
 Biological
 Physical
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Central idea: Cognitive and behavioral
variability within an individual are subject to
environmental selection. Adaptive cognitions
or behaviors increase in frequency and nonadaptive ones decrease or cease.
Seemingly a process of trying out strategies
in order to find those that are most effective.
Brain development: Neurons produced in
great variability and numbers; adaptive ones
survive and others do not.