Four Central Questions
• Nature or nurture?
– What are the contributions of genetics and
environment to development?
• Continuous or discontinuous?
Human Development
Chapter 4
– Is development gradual process or are there
periods of rapid change?
• One course or many?
– Does everyone develop the same or are there
individual or cultural differences?
• Active or passive?
– What role does child play in own development?
Periods of Development
• Zygote/germinal
• Embryo
• Fetus
Zygote
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fertilized egg/ovum
conception to 2 weeks
multiplies from 1 cell to ~ 100
moves from Fallopian tube near ovary
to uterus
• implants in uterine wall & forms
umbilical cord & placenta
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Fetus
Embryo
• 3 weeks to 8 weeks
• cell multiplication & organ
differentiation
• heart beats, beginnings of CNS
(neural tube), some features (e.g.,
eyes)
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8 weeks to birth
growth is rapid, slow, rapid
existing organs grow & are refined
protective structures develop (bones,
skin)
• physical response to environment
• practice independent functions
(breathing)
Prenatal development and sensitive periods
Environmental hazards: Teratogens
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Growth trends
• Double weight by 4-6mo
• Triple weight by 12mo
• From 2 to puberty:
– 2-3 inch/year
– 6-7 lbs/year
• Cephalocaudal
– top-down
– Head develops first
• Proximodistal:
– center - outward
– Internal organs
– Trunk faster than arms & legs
Gross Motor development
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Reaching for objects (2mo)
Roll over (3mo)
Sit without support (5mo)
Creeping and crawling (7-10mo)
Pull to a stand (8mo)
Standing, squatting, cruising (10mo)
Walking with help (11mo)
Walking (12mo)
Walking
• Nature or nurture?
• Continuous or
discontinuous?
• One course or many?
• Active or passive?
• What do you think?
• What are Ester
Thelen’s findings?
• How would she answer
the above questions?
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Movement Possibilities of the
Body
• Physical Growth and The Stepping Reflex
– Ester Thelen and colleagues research
• Induced stepping for infants (2 - 6 weeks)
1. “Chubby” babies = Fewer steps
2. Leg-weights = Fewer steps
3. Legs in water = More steps
• “Stepping Reflex” disappears only because
of infants’ asynchronous physical growth
Thelen’s Dynamic Systems Theory
of Motor Development
• All parts of Dynamic System work together
to help child master new skill…
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Central nervous system development
Physical growth
Goals of the child
Environmental supports
Fine Motor Development
• Newborns: grasping/palmar reflex
• 1-2 months: visually-guided reaching
• 4 months: reach inward to body midline
– use 2 hands simultaneously
• 7-8 months: sequence of behaviors
• 8-10 years - skills close to adults
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