1. Chapter 4 Physical Development in Infancy and Toddlerhood

2. Body Growth Height increases 50% by age 1, 75% by age 2
Weight doubles by 5 months, triples by 1 year
Growth occurs in spurts
Individual and group differences in size and rate of growth
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3. Body Growth During First Two Years
Figure 4.1 Body growth during the first two years
Figure 4.1

4. Individual and Group Differences in Growth
male/female
ethnic
Individual differences
Skeletal age: best estimate of physical maturity
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5. Changes in Body Proportions
Growth Trends
Changes in Body Proportions
Cephalocaudal
“Head to tail”
Lower part of body grows later than the head
Proximodistal
“Near to far”
Extremities grow later than head, chest, and trunk

6. Neurons and Their Connective Fibers
Nerve cells that store and transmit information
Synapses
Tiny gaps where fibers from different neurons come together but do not touch
Neurotransmitters
Chemicals that are released by neurons and cross the synapse
Figure 4.2

7. Major Milestones of Brain Development
Figure 4.3 Major milestones of brain development
Figure 4.3
(Adapted from Thompson & Nelson, 2001.)

8. Methods for Measuring Brain Functioning
Electroencephalogram (EEG)
Event-related potentials (ERPs)
Functional magnetic resonance imaging (fMRI)
Positron emission tomography (PET)
Near-infrared spectroscopy (NIRS)

9. Regions of the Cerebral Cortex
Figure 4.5 The left side of the human brain, showing the cerebral cortex
Figure 4.5

10. Prefrontal Cortex
Region of the cerebral cortex responsible for thought, especially:
consciousness
inhibition of impulses
integration of information
use of memory, reasoning, planning, and problem-solving strategies
Undergoes rapid growth in the preschool and school years, and in adolescence

11. Lateralization of the Cerebral Cortex
Left Hemisphere
Verbal abilities
Positive emotion
Sequential, analytic processing
Right Hemisphere
Spatial abilities
Negative emotion
Holistic, integrative processing

12. Brain Plasticity At birth, hemispheres have begun to specialize
Highly plastic cerebral cortex has high capacity for learning
If part of cortex is damaged, other areas can take over its tasks
Older children and adults retain some plasticity, but less than in young children

13. Sensitive Periods in Brain Development
Appropriate stimulation is vital for brain growth
Experience-expectant growth: depends on ordinary experiences
Experience-dependent growth: additional growth resulting from specific learning experiences
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14. Changing States of Arousal
Sleep–wake pattern moves to night–day schedule during first year
By age 2, total sleep time declines from 18 to 12 hours per day
Sleep patterns are affected by social environment, cultural values
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15. Influences on Early Growth
Heredity
Nutrition:
breastfeeding vs. bottle-feeding
risks of overfeeding
Malnutrition
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16. Benefits of Breastfeeding
Correct balance of fat and protein
Ensures nutritional completeness
Helps ensure healthy physical growth
Protects against disease
Protects against faulty jaw and tooth development
Ensures digestibility
Smooths transition to solid food

17. Malnutrition Type Consequences
Marasmus (diet low in all essential nutrients)
Lasting physical damage; learning and behavioral effects; risk of death
Kwashiorkor (diet very low in protein)
Lasting physical damage; learning and behavioral effects
Food insecurity
Effects on physical growth; learning problems

18. The Steps of Classical Conditioning
Figure 4.7 The steps of classical conditioning
Figure 4.7

19. Operant Conditioning Reinforcer Punishment
Increases probability that behavior will occur again by
presenting desirable stimulus
removing unpleasant stimulus
Punishment
Reduces probability that behavior will occur again by
presenting unpleasant stimulus
removing desirable stimulus

20. Using Habituation to Study Infant Memory and Knowledge
Figure 4.8 Using habituation to study infant perception and cognition
Figure 4.8

21. Imitation Infants are born with primitive ability to imitate
Mirror neurons provide biological explanation
Powerful means of learning
Helps facilitate positive relationships
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22. Motor Development Sequence and Trends
Gross-motor development: crawling, standing, walking
Fine-motor development: reaching, grasping
Sequence is fairly uniform
Large individual differences in rate of motor progress
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23. Motor Skills as Dynamic Systems
Mastery involves acquiring increasingly complex systems of action with each skill
Each new skill is joint product of
central nervous system development
the body’s movement capacity
the child’s goals
environmental supports for the skill

24. Cultural Variations in Motor Development
Rates and patterns of development affected by
early movement opportunities
environmental stimulation
child-rearing practices
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25. Milestones of Reaching and Grasping
Prereaching
Ulnar grasp
Transferring object from hand to hand
Pincer grasp
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26. Developments in Hearing
4–7 months
Sense of musical phrasing
6–7 months
Distinguishes musical tunes based on variations in rhythmic patterns
6–8 months
“Screens out” sounds not used in native language
6–12 months
Detects sound regularities in human speech
7–9 months
Begins to divide speech stream into wordlike units

27. Visual Development
Supported by rapid maturation of eyes and visual centers in brain
Improvements:
2 months: focus
4 months: color vision
6 months: acuity, scanning, and tracking
6–7 months: depth perception
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28. Milestones in Depth Perception
3–4 weeks
Sensitivity to motion cues
2–3 months
Sensitivity to binocular depth cues
5–7 months
Sensitivity to pictorial depth cues

29. The Visual Cliff Reveals link between crawling and depth perception
Figure The visual cliff
Figure 4.13

30. Milestones in Pattern Perception
2 months
Becomes sensitive to contrast in complex patterns; prefers them to simple patterns
2–3 months
Thoroughly explores a pattern’s features, pausing briefly to look at each part
4 months
Detects pattern organization; can perceive subjective boundaries not really present
12 months
Detects familiar objects represented by incomplete drawings

31. Subjective Boundaries in Visual Patterns
Figure Subjective boundaries in visual patterns
Figure 4.15
(Adapted from Ghim, 1990; Rose, Jankowski, & Senior, 1997.)

32. Milestones in Face Perception
Birth– 1 month
Prefers simple facelike pattern to other stimuli
Prefers photos of faces with eyes open and direct gaze
2–4 months
Prefers complex facial pattern to other complex stimulus arrangements
Prefers mother’s detailed facial features to another woman’s
3 months
Distinguishes features of different faces
5–12 months
Perceives emotional expressions on faces as meaningful wholes

33. Early Face Perception Figure 4.16 Early face perception Figure 4.16
(From Cassia, Turati, & Simion, 2004; Johnson, 1999; Mondloch et al., 1999.)

34. Milestones in Intermodal Perception
Birth
Perceives amodal sensory properties
3–4 months
Matches faces with voices on basis of lip–voice synchrony, emotional expression, and speaker’s age and gender
4–6 months
Perceives and remembers unique face–voice pairings of unfamiliar adults

35. Differentiation Theory
Infants
actively search for invariant features of the environment
notice stable relationships among features of a stimulus, detecting patterns such as individual faces
gradually detect finer and finer features

36. Environment and Perceptual Differentiation
Figure Acting on the environment plays a major role in perceptual differentiation
Figure 4.17

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