A PSY 203 Lecture 4: Reflexes and perception
13 Jun 2018
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Day 4: The Emergence of Action
Reflexes:
• Patellar reflex → Knee Jerk
• Rooting reflex → Newborn’s mouth moves
toward brush on cheek
• Grasp reflex → Newborns grab on to anything
in their hand
• Stepping reflex → Baby will walk when lowered
on surface
• Moro Reflex → arms move to side when baby is
unsupported
• Most reflexes disappear with the 1st few months
o Hypothesis → Frontal cortex growth
▪ Ability to inhibit motor action!
Maturational Account
• Motor development depends on the development of the brain’s motor program!
• Twins participated in Gesell’s 1929 stair study. One twin was given 6 weeks of stair training,
while the other was given no training. At age 52 weeks both were given the opportunity to walk
upstairs, and they both performed equally well.
• Motor deprivation →
o Doesn’t lead to motor impairment
▪ Babies with less motor experience develop normally!
▪ Only extreme motor deprivation causes motor impairment, and this is often
reversible.
▪ Hopi infant’s studies!
• Evidence that infants who spent most of their day in crib, still met motor
milestones on time!
Dynamic system’s theory
• Emergence of complex behaviors
o Complex interactions of necessary behaviors
▪ Complex interactions of necessary components
• Brain maturation
• Sensation and perception
• Properties of the environment
• Imitation
• Physical features
The Emergence of walking
• The step reflexes
o Babies are born with a stepping reflex that disappears within weeks of birth!
o 1-month old infants (who don’t have that step reflex) will step in water
o Thelen
▪ Kicks reflex similar to stepping reflex
▪ Physical changes affect development
Integrating Perception and Action
• Perceptual- motor development
o Development of the ability to guide voluntary action on the basis of perceived stimuli
o Cyclical → see something, react, perceive your own reaction, and adjust your own
performance!
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