1. Chapter 4: Physical Development in Infancy
Life-Span Development
Twelfth Edition
Chapter 4:
Physical Development in Infancy
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Patterns of Growth:
Cephalocaudal Pattern: sequence in which the earliest growth always occurs from the top downward
Also applies to gains in motor development
Proximodistal Pattern: sequence in which growth starts in the center of the body and moves toward the extremities
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Forebrain: portion of the brain farthest from the spinal cord; includes cerebral cortex
Cerebral Cortex: folded surface covering the forebrain
Cerebral cortex is divided into 2 hemispheres, each with 4 lobes
Frontal lobe: voluntary movement, thinking, personality, and intentionality
Occipital lobe: vision functions
Temporal lobe: hearing, language processing, and memory
Parietal lobe: spatial location, attention, and motor control
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Lateralization: specialization of function in one hemisphere of the cerebral cortex or the other
Some functions are lateralized, some are not
Complex functions involve communication between both hemispheres
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Neurons: brain nerve cells that communicate through electrical and chemical signals
Axons carry signals away from the cell body
Dendrites carry signals toward the cell body
Myelin sheath is a layer of fat cells that insulate axons
Helps electrical signals travel faster
Terminal buttons release chemicals (neurotransmitters) into synapses
Synapses: tiny gaps between neurons
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Changes in Neurons:
Myelination: the process of encasing axons with fat cells
Begins prenatally and continues into adolescence
Connectivity among neurons increases
New dendrites grow
Connections among dendrites increase
Synaptic connections increase
More synaptic connections are created than will ever be used
Leads to a “pruning” of unused connections
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Changes in regions of the brain:
“Blooming and pruning” of synapses varies by brain region
Pace of myelination varies as well
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Depressed brain activity has been found in children who grow up in a deprived environment
Enriched environments promote faster brain development than deprived ones
After birth: sights, sounds, smells, touches, language, and eye contact help shape the brain’s neural connections
Repeated experience wires (and rewires) the brain
Brain is both flexible and resilient
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Dynamic Systems View:
Infants assemble motor skills for perceiving and acting
Motor skills represent solutions to goals
Development is an active process in which nature and nurture work together
Development of nervous system
Body’s physical properties and possibilities for movement
Goal the child is motivated to reach
Environmental support for the skill
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Development in the 2nd Year:
Toddlers become more skilled and mobile
Motor activity is vital to the child’s development of competence and independence
By months, toddlers can:
Walk quickly or run stiffly
Balance on their feet in a squat position
Walk backward
Stand and kick a ball without falling
Jump in place
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Cultural Variations: mothers in developing countries tend to stimulate their infants’ motor skills more than mothers in more modern countries
Infants can reach motor milestones slightly earlier if provided with physical guidance or given opportunities for exercise
Even when activity is restricted, many infants still reach milestones at a normal age
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Fine Motor Skills: involve finely tuned movements
Reaching and grasping is a significant milestone for infants
Palmer grasp: grasping with the whole hand
Pincer grip: grasping with the thumb and forefinger
Perceptual-motor coupling is necessary for infants to coordinate grasping
Experienced infants look at objects longer, reach for them more, and are more likely to mouth the objects
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Visual Preference Method: infants look at different things for different lengths of time
They look at preferred objects longer
Habituation: decreased responsiveness to a stimulus after repeated presentations
Dishabituation: recovery of a habituated response after a change in stimulation
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Habituation and Dishabituation Studies:
High-amplitude sucking
Orienting response
Tracking
Videotaping
Recording heart rate, respiration, body movement, sucking behavior, visual fixation
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Newborn’s vision is about 20/600 (an object 20 feet away appears as if it were 600 feet away)
By the age of 6 months, vision is 20/100 or better
Vision approximates that of an adult by the infant’s first birthday
Infants show an interest in human faces soon after birth
The way they gather information about the visual world changes rapidly with age
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Eleanor Gibson and Richard Walk studied development of depth perception using a “visual cliff”
Infants 6-12 months old can distinguish depth
Infants 2-4 months old show heart rate difference when placed on deep side of cliff
Infants develop binocular depth cues by about 3-4 months of age
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Fetuses can hear and learn sounds during the last two months of pregnancy and can recognize their mother’s voice at birth
Newborns:
Cannot hear soft sounds as well as adults
Are less sensitive to pitch
Are fairly good at determining the location of a sound
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Touch and Pain: newborns respond to touch and can feel pain
Smell: newborns can differentiate odors
Preference for mother’s smell by 6 days
Taste: sensitivity to taste may be present before birth
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Intermodal Perception: the ability to integrate information from two or more sensory modalities
Babies are born with some innate abilities to perceive relations among senses
Their abilities improve considerably through experience
Perceptual–Motor Coupling: action guides perception, and perception guides action
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