Transcript 03&04Psych315Biology&Behavior

Psych 315: Childhood and
Adolescence
Biology and Behavior
Physical, Perceptual, and Motor
Development
Announcements:
Teaching Assistants:
• Jeremy Frimer (Section 002)
• Office: Kenny Bldg. Room 1101 (corner of West Mall and University)
• Office hours: Tuesdays 3:30-4:30pm or by appointment
• E-mail: [email protected]
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Kathryn Dewar (Section 001)
Office: Kenny Bldg. Room 1101 (corner of West Mall and University)
Office hours: TBA or by appointment
E-mail: [email protected]
• Text ( on reserve),
• additional readings will be assigned the week
before.
Genetic and Environmental Forces
Model Components:
• Genotype: The genetic material we inherit from our
parents.
• Phenotype: The observable expression of the
genotype, including bodily characteristics and
behavior.
• Environment: Every aspect of an individual’s
surroundings other than the genes themselves.
Development
Development is a joint function of genetic and environmental factors. The four
numbered relations are discussed in detail in the text.
Parents’ Genotype
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Child’s Genotype
Every cell has 46 chromosomes (23 pairs), except germ
cells (23 chromosomes)
½ of genetic inheritance comes from mom and the other ½
from dad
Sex Determination by Sex Chromosomes
 Females XX
 Males XY—presence of the Y chromosome determines male sex
Diversity
1. Mutations—random spontaneous errors
2. Random assortment of chromosomes in egg and sperm (over 8
million possible combinations)
3. Crossing over—chromosomes swap some DNA sections
Child’s Genotype = ~100% Nature (+ mutations which can
sometimes be the result of environment)
Child’s Genotype
Child’s Phenotype
• A child will not express every characteristic in its
genetic makeup.
• E.g. some traits, such as straight hair, require matching
“recessive” alleles, others, such as curly hair, require only one
“dominant” allele which overrides recessive from other parent.
Mendelian inheritance
patterns
GenotypePhenotype
• Few patterns are as simple as Mendelian inheritance
• Regulator genes control the activity of other genes.
• Most traits and behaviors of interest to behavioral
scientists (e.g. shyness, aggression, risk-taking
behavior, and empathy) involve contributions by
several genes = polygenic.
Child’s Environment
Child’s Phenotype
•Depending on the environment–genotype
relationship, numerous phenotypes may result
•Genotypes are expressed differently in varying
environments. The norm of reaction is the range of all
possible phenotypes in relation to all possible
environments. (e.g. revisit oak tree analogy)
e.g. intelligence
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Parents’ role—highly literate parents may have more books in
the home, exposing children to more literature
Child’s Phenotype
Child’s Environment
1. They actively select surroundings and
experiences conducive to their interests, talents,
and personality characteristics (increasing
influence with age).
2. They evoke certain responses from others
(e.g. temperament, appearance).
Phenotype  Environment
E.g. Appearance
• Humans (adults and children alike) behave
differently toward more attractive individuals
– E.g. halo effect
• Even newborns prefer to look at attractive faces
• Attractive mask study = more pleasure, more
active and involved in play, less withdrawal than
less attractive mask.
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*What makes a face attractive?
To us, and to a baby
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Symmetry?
Smooth/blemish-free complexion?
Darker skin?
Baby-facedness?
Contrast?
Average-ness?
Why might infants be predisposed to attend to (prefer)
attractive faces?
How might such a preference influence their development?
N&N Interactions
• The influence is bi-directional.
• Transactional Model = continuous interaction between
N&N
– e.g. Temperament = risk or protective factor (starts a
chain of events)
• Direct vs. Indirect Effects
– Direct: (e.g. fearful/inhibited leads to social withdrawal)
– Indirect: (e.g. fearful/inhibited leads to social withdrawal
which leads to poor social understanding)
• Most people get a “double whammy” (share both their
genes and their environment with parents)
– (e.g. parents that like to read)
Behavioral Genetics
• area of psychology concerned with how variation
in behavior and development results from the
combo of genetic and environmental factors.
• Heritability = an estimate of the proportion of measurable
difference/variability on a given trait (e.g. intelligence), in a
given population (living in a particular environment at a
particular period of time), is due to genetic differences
• All behavioral traits are heritable to some extent
– Substantial heritability: infant activity level, antisocial
behavior, reading disabilities, divorce, tv viewing
• Note: genes do not code specifically for behavior patterns but
they can affect underlying processes that predispose us to
attend to certain things more, find some things more
interesting/stimulating than others etc. (e.g. novelty
seeking/easily habituated increase chances of divorce)
Behavioral Genetics
• 3 types of designs:
– 1. Twin Studies
– 2. Adoption Studies
– 3. Twin Adoption Studies (Rare)
Environmental Effects
• Shared Genetic Effects: Heritability
estimates rarely exceed 50%, indicating the large
contribution of environmental factors.
• Shared Environmental Effects: can be
tested among adoptive siblings/biologically
unrelated people who grew up together.
• Nonshared Environmental Effects: (those
unique to the individual) can be measured by
identical twins who grew up together.
Brain Imaging
•Positron Emission Tomography (PET scan)
Radioactive sugar is traced
Functional Magnetic Resonance Imaging (fMRI)
iron in blood is traced
Not typically done until the child is 6 years old
Brain Imaging
Electrophysiological Recording (EEG) or Eventrelated Potentials (ERPs)
 electrical impulses/activity, Popular method to
use on children
ERPs (Video clip!)
The Neuron
The human cerebral cortex
Oversimplification:
Occipital ~ Vision
Temporal ~ Auditory, Emotions, Visual recognition, memory?
Parietal ~ Spatial processing, sensory integration from PSC
Frontal ~ “executive” tasks (e.g. planning, organizing, working
memory, inhibition),
--last to fully develop
Frontal Lobe Dev./Inhibition Video
The human cerebral cortex
• Contralateral processing
• Left ~ Linear/sequential
• Right ~ Holistic/global
Severed Corpus Collosum (lateralization) Video!
Developmental Processes
Neurogenesis—proliferation of neurons through cell division
Occurs from the 3rd/4th week to the 18th week
Myelination—insulation around the axon
Occurs prenatally through late adolescence
Synaptogenesis—each neuron forms 1000s of connections
Occurs prenatally, with rapid development right before
and after birth
Synapse Elimination— “pruning” of excess synapses
Occurs prenatally through adolescence
The Brain and Experience
• Plasticity: The capacity of the brain to be
affected by experience.
• Critical/sensitive periods (time window where
input can organize the brain, when the sensitive period
ends, neural organization is typically irreversible)
– E.g. near vs. far–sightedness
– E.g. Strabismus—“lazy eye”
– E.g. Signers (auditory cortex
is put to a better purpose)
– E.g. cellists/violinists
(extra cortical representation of fingers)
– E.g. Ability to hear all phonemes of the world’s
languages
Pruning and Conditioned Head
Turn Procedure (Werker video)
Brain Plasticity and Braille Study Video
Brain Damage and Recovery
• “worst time” to suffer brain damage =
very early stages of prenatal development
and first year after birth (neurogenesis is
occurring).
• “best time” = early childhood when
synapse generation and pruning are
occurring (Plasticity is highest)
Brain Damage and Recovery
Perceptual, Physical, and Motor
Development:
The Basics
The Body—Physical Growth and
Development
• humans undergo a long period of growth and
development.
• Growth spurts are steep in first two years of life and in
early adolescence.
• Adolescent girls experience growth burst earlier than
boys.
• Body composition (the proportion of fat and of muscle)
changes with age (gender dependent).
• Failure to thrive (FTT): infants become malnourished and fail
to grow or gain weight for no obvious medical reason;
associated with disturbances in mother–child
interactions/emotional bond (e.g. orphans).
Importance of Proper Nutrition
• 40% of world’s young children
under/malnurished (result of poverty or poor education)
• Proper Nutrition is vital to proper physical and
cognitive development
– direct (e.g. illness, brain damage)
– Indirect (e.g. low energy lack of exploration of
environment, underdeveloped appearance 
treated as ‘younger’ by peers/adults)
• Breast-feeding provides antibodies against
infectious agents
Prenatal Perception
Sensory structures are present relatively early in prenatal
development
Hearing - last trimester fetus’ heart rate responds to external
noises (e.g. voices)
Taste - preference for sweet flavors (e.g. DeSnoo treatment for
women with excess amniotic fluid)
- at 5 months preferred carrot juice if Mom drank carrot
juice frequently near end of pregnancy
Touch - some tactile stimulation in womb
Smell - can likely smell coffee, curry etc in amniotic fluid, at
birth prefer the familiar scent of Mom’s amniotic fluid
Vision - limited visibility, but will orient to external light
Visual Perception
• Infants prefer high contrast (e.g Black and white
checkerboard)
• poor color vision for the first 3 months
• ~8 months = adult’s vision
• Role of environment (e.g. Genie, college students)
Depth Perception: The Visual Cliff
Depth Perception and Fear
• 1 month olds lowered over the cliff have
decelerated heart rates over the deep side
indicating they perceive the difference but are
interested -- not afraid!
• New crawlers will cross the deep side of the cliff
• Experienced crawlers won’t cross the “visual
cliff”
• Role of active experience with depth.
Sound, Smell, and Touch
Sound
Auditory localization = the ability to identify the location of
a sound source (e.g 10 mins after birth)
Children are slightly “deaf” compared to adults until age 5-8
Smell
• 2 week-old infants prefer own mother’s breast milk scent to
another mother’s.
Touch
• Oral exploration dominates in the first 4 months
Putting it all together:
Intermodal Perception
• Intermodal perception = combining info from two or
more sensory systems (modalities)
• Important skill for integrating sensory info (e.g. looking
at a soft thing and knowing how it will feel, or feeling
something and knowing how it will look)
• 29-day old infants were given either a round pacifier or a nubby pacifier and
did not see it. Later, when they were shown both pacifiers they looked longer
at the one they had sucked on
Intermodal Perception
Intermodal Counting
Perception & Motor
Development
• At each new locomotor “stage” they have to
learn to integrate their perceptual info with
their new motor skills
• (e.g. “gap” experiments)
Aspects Involved in Motor Development
• Brain maturation and body proportion
changes (Nature)
• Physical strength, posture, and balance
(both Nature and Nuture)
• Perceptual skills (both N&N)
• Motivation (both N&N)
• Cultural and Environmental Factors (back vs
belly sleepers, e.g. Malian babies) (Nurture)
Malian Baby Exercises Facilitate Motor Development
“To Walk” Video