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Chapter 4 Physical Development in Infancy and Toddlerhood

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Title: Chapter 4 Physical Development in Infancy and Toddlerhood


1
Chapter 4Physical Development in Infancy and
Toddlerhood
  • Development Through the Lifespan
  • 2nd edition Berk

2
BODY GROWTH
  • Changes in Body Size and Muscle Fat
  • (0 to 2 years)
  • Physical growth is rapid.
  • Length increases 50 percent by first year, 75
    percent by second.
  • Weight doubles at 5 months, triples by first
    year, and quadruples by the second.
  • Gains occur in growth spurts.
  • Early rise in baby fat until 9 months
  • Helps keep a constant body temperature
  • Toddlers become more slender.

3
Individual and Group Differences
  • Skeletal age
  • Measure of bone development
  • Best way to measure physical development
  • Girls are slightly shorter and lighter and have a
    higher ratio of fat to muscle.
  • Ethnic differences in size and rate of growth
  • Developmental problems and mortality rates vary
    by gender and race.

Figure 4.1
4
BRAIN DEVELOPMENT
Birth
  • Neurons
  • At birth, the brain is nearer its adult size than
    any other physical structure.
  • 100 to 200 billion neurons
  • Synapses
  • Tiny gaps between neurons
  • Neurons release chemicals that send messages
  • Synaptic pruning
  • Unused neurons die off.
  • Myelinization
  • Neural fibers are coated with fatty insulation.
  • Glial cells myelinate.

Six months
Two years
Figure 4.3
5
The Cerebral Cortex
  • 85 percent of brain weight, and last to stop
    growing
  • Different regions have specific functions.
  • Frontal lobes (thought) develop later.
  • Lateralization
  • Specialization of hemispheres in cortex
  • Brain plasticity
  • Ability of part of brain to take over function of
    damaged part

Figure 4.4
6
Sensitive Periods of Development
  • Stimulation is vital during growth spurts, which
    occur from infancy to early adulthood.
  • Experience "wires" a child's brain growth.
  • Understimulation impairs development.
  • Possible to overwhelm children
  • Note new brain research

7
INFLUENCES ON PHYSICAL GROWTH
  • Heredity largely determines height and rate of
    physical growth.
  • Catch-up growth
  • Heredity and nutrition determine weight.
  • Emotional well being as a factor
  • Non-organic failure to thrive related to small
    size and cognitive or emotional problems

8
Nutrition
  • Babys energy needs twice those of an adult.
  • 25 percent of infant's calories are devoted to
    growth.
  • Breast- versus bottle-feeding
  • Correlation between fatness in infancy and
    obesity at older ages.
  • Malnutrition impedes growth and brain development
    ( 40-60 of worlds children)

9
LEARNING CAPACITIES
  • Classical Conditioning
  • Reflexes allow classical conditioning in young
    infants.
  • Extinction is a decline in the CR as a result of
    presenting the CS without the UCS.

Figure 4.5
10
LEARNING CAPACITIES
  • Operant Conditioning
  • Spontaneous behavior is followed by a reinforcer.
  • Changes the probability that the behavior will
    occur again
  • Punishment
  • Removing a desirable stimulus or presenting of an
    unpleasant one to decrease the occurrence of a
    response
  • Young babies are active learners.

11
LEARNING CAPACITIES
  • Habituation
  • Gradual reduction in the strength of a response
    due to repetitive stimulation
  • Dishabituation
  • Recovery of responsiveness after stimulation
    changes
  • Imitation
  • Copying the behavior of another person
  • Newborns can imitate facial expressions and head
    movements.

Figure 4.6
12
MOTOR DEVELOPMENT
  • Gross motor development
  • Crawling, standing, and walking
  • Fine motor development
  • Reaching and grasping
  • Individual differences in rate of motor progress
  • Cephalocaudal trend
  • Proximodistal trend

Table 4.1
13
Motor Skills as Dynamic Systems
  • Mastery of motor skills involves acquiring
    increasingly complex dynamic systems of action.
  • New skills are a joint product of
  • Central nervous system development.
  • Movement possibilities of the body.
  • Environmental supports for the skill.
  • Motivation of the child.
  • Note Cultural variations in environment

14
Fine Gross Motor Development
  • Voluntary reaching and cognitive progress
  • Role of perception (e.g. visual)
  • Gross motor progression - lifting head,sitting,
    standing, cruising, walking
  • Body balance, motor control and refinement of
    fundamental movement patterns

15
Fine Motor Development
  • Motor skills go from gross to finer movements.
  • Prereaching
  • Uncoordinated, primitive
  • Ulnar grasp
  • Clumsy, fingers close against palm
  • Tripod pincer grasps
  • Coordinated use of forefinger and thumb

16
PERCEPTUAL DEVELOPMENT
  • Hearing
  • Sound supports visual and tactile exploration.
  • Ability to identify location of sound improves
    over the first 6 months.
  • By 6 months, babies "screen out" sounds not used
    in their language.
  • By 6 to 12 months, infants focus on larger speech
    units critical for meaning.

17
Vision
  • By 2 months, infants focus on objects and
    discriminate colours well.
  • By 11 months, visual acuity reaches a near-adult
    level.
  • Independent movement promotes depth perception
    -new level of brain organisation

18
Vision
  • Depth Perception
  • Crawling infants distinguish deep and shallow
    surfaces and avoid dangerous-looking drop-offs.
  • Emergence of depth perception
  • Motion is the first depth cue.
  • Binocular sensitivity (2 to 3 months)
  • Pictorial depth perception ( 6 months)

19
Vision
  • . Pattern and Face Perception
  • Newborns prefer patterned to plain stimuli.
  • Contrast sensitivity
  • Babies prefer more contrast.
  • Face perception becomes more refined by 3 mths

Figure 4.10
20
Intermodal Perception
  • Intermodal perception combines information from
    more than one modality.
  • Babies perceive the world in an intermodal method.

21
UNDERSTANDING PERCEPTUAL DEVELOPMENT
  • Differentiation Theory (Eleanor and James Gibson)
  • Perceptual development involves detection of
    fine-grained, invariant features in the
    environment.
  • Other researchers believe babies impose meaning
    on what they perceive, constructing categories of
    objects and events.
  • Many researchers combine the two viewpoints.
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