1. Infants, Children, and Adolescents
Eighth Edition
Chapter 5
Physical Development in Infancy and Toddlerhood

2. Learning Objectives (1 of 2)
5.1 Discuss major changes in body size, muscle–fat make-up, body proportions, and variations in rate of physical growth over the first two years.
5.2 Describe brain development during infancy and toddlerhood, current methods of measuring brain functioning, and appropriate stimulation to support the brain’s potential.
5.3 How does organization of sleep and wakefulness change over the first two years?
5.4 Cite evidence indicating that heredity, nutrition, and parental affection contribute to early physical growth.

3. Learning Objectives (2 of 2)
5.5 Describe infant learning capacities, the conditions under which they occur, and the unique value of each.
5.6 Discuss the general course of motor development during the first two years, along with factors that influence it.
5.7 What changes in hearing and in depth, pattern, object, and intermodal perception take place during infancy?
5.8 Explain differentiation theory of perceptual development.

4. Body Growth Typical gain in height is 50% by age 1, 75% by age 2.
“Baby fat” peaks at about 9 months.
Muscle tissue increases slowly, peaking in adolescence.

5. Physical Growth Trends
Cephalocaudal trend
“Head to tail”
Head develops more rapidly than lower part of the body.
Proximodistal trend
“Near to far”
Head, chest, and trunk grow ahead of extremities.

6. Differences in Growth
Girls are slightly smaller than boys, with higher ratio of fat to muscle.
Ethnic differences are apparent.
Skeletal age is the best estimate of physical maturity.

7. Brain Development
At birth, the brain is nearer to adult size than any other physical structure.
Human brain has 100 to 200 billion neurons that store/transmit information.
Synapses are tiny gaps between neurons.
Neurons send messages by releasing chemicals called neurotransmitters.

8. Major Milestones of Brain Development
Figure 5.3: Major milestones in brain development
Figure 5.3
(Based on Thompson & Nelson, 2001.)

9. Major Measures of Brain Functioning
Electroencephalogram (EEG)
Event-related potentials (ERPs)
Functional magnetic resonance imaging (fMRI)
Positron emission tomography (PET)
Near-infrared spectroscopy (NIRS)

10. Regions of the Cerebral Cortex
Figure 5.6: The left side of the human brain, showing the cerebral cortex
Figure 5.6

11. Lateralization of the Cerebral Cortex
Lateralization: specialization of the two hemispheres
Left hemisphere
Better at sequential, analytic processing
Good approach for communicative information
Right hemisphere
Specialized for holistic, integrative processing
Good for spatial abilities and regulating negative emotion

12. Brain Plasticity
Brain plasticity: If part of the cerebral cortex is damaged, other parts can take over tasks it would have handled.
Brain is highly plastic during the first few years.
In one study, after early brain injury, language skills recovered by age 5; spatial skills were more impaired.
Despite recovery, a “crowding effect” hindered cognitive progress: Complex abilities suffered.
Plasticity can occur at later ages but is far more limited.

13. Sensitive Periods in Brain Development: Romanian Orphans
Children adopted before age 6 months displayed impressive cognitive catch-up.
Those adopted after 6 months showed serious intellectual deficits.
Factors:
Decreased activity in the cerebral cortex
Disruption of capacity to manage stress
Disrupted response to pleasurable social interaction

14. Influence of Age of Adoption on Mental Test Scores of British and Romanian Adoptees
Figure 5.7: Relationship of age at adoption to mental test scores at ages 6 and 11 among British and Romanian adoptees
Figure 5.7
(Adapted from Beckett et al., 2006.)

15. Appropriate Stimulation
Experience-expectant brain growth
Depends on ordinary experiences “expected” by brain for normal growth
Occurs early and naturally
Experience-dependent brain growth
Results from specific learning experiences
Varies widely across individuals and cultures
Rushing early learning overwhelms the brain’s neural circuits.

16. Sleep and Wakefulness
Organization of sleep and wakefulness changes as a result of
brain development.
cultural beliefs and practices.
parents’ needs.
Total sleep time declines from 18 to 13 hours a day by age 2.
Night wakings often increase at 6 months and again between 1½ and 2 years, and then decline.

17. Cultural Variation in Infant Sleeping Arrangements
Parent–infant cosleeping is the norm for 90% of the world’s population.
Cultural emphasis on independent vs. interdependent self strongly influences infant sleeping arrangements.
Cosleeping is increasing in Western nations, perhaps because of a rise in breastfeeding.

18. Influences on Early Physical Growth
Heredity
Nutrition
Breastfeeding vs. bottle-feeding
Risk of overweight/obesity for chubby babies
Malnutrition: marasmus and kwashiorkor
Emotional well-being

19. Reasons to Breastfeed Provides correct fat–protein balance.
Ensures nutritional completeness.
Promotes healthy physical growth.
Protects against many diseases.
Protects against faulty jaw development and tooth decay.
Ensures digestibility.
Smooths transition to solid food.

20. Are Chubby Babies at Risk for Later Obesity?
Recent evidence shows a relationship between rapid weight gain in infancy and later obesity.
Recommendations for parents:
Breastfeed for the first six months.
Avoid giving babies foods loaded with sugar, salt, and saturated fats.
Provide opportunities for energetic play.
Limit TV viewing time.

21. U.S. Public Policies and Infant Feeding Practices
2009 WIC policy changes:
Stronger breastfeeding counseling and educational materials
Food package enhancements that promote breastfeeding
Changes have led to increased rates of breastfeeding, and longer breastfeeding, among low-income mothers.

22. U.S. Public Policy Changes and Infant Feeding Practices
Figure 5.8: Rates of breastfeeding by new mothers at WIC enrollment, as indicated by food package choice, before and after WIC policy changes
Figure 5.8
(Based on Whaley et al., 2012.)

23. Malnutrition Types Marasmus Kwashiorkor Iron-deficiency anemia
Food insecurity
Consequences
Growth and weight problems
Poor fine-motor coordination
Learning and attention problems
More intense stress response
Passivity and irritability

24. Emotional Well-Being
Affection is as vital as food for healthy physical growth.
Growth faltering:
Weight, height, and head circumference are substantially below age-related growth norms.
Infants are withdrawn and apathetic.
A disturbed parent–child relationship often contributes.
Unhappy marriage and parental psychological disturbance are often involved.
Lasting cognitive and emotional difficulties may result.

25. The Steps of Classical Conditioning
Figure 5.9: The steps of classical conditioning
Figure 5.9

26. Operant Conditioning Terms
Reinforcer increases occurrence of a response.
Presenting desirable stimulus
Removing unpleasant stimulus
Punishment decreases occurrence of a response.
Presenting unpleasant stimulus
Removing desirable stimulus

27. Using Habituation to Study Infant Perception and Cognition
Figure 5.10: Using habituation to study infant perception and cognition
Figure 5.10
(Photo © Prashant Zi/Fotolia)

28. Imitation
Newborns have primitive ability to learn by copying another person’s behavior.
Neural mirroring systems may underlie early imitative capacities.
View of newborn imitation as a flexible, voluntary capacity remains controversial.
Capacity to imitate expands greatly over first two years.

29. The Sequence of Motor Development
Gross-motor development:
Crawling
Standing
Walking
Fine-motor development:
Reaching
Grasping

30. Gross- and Fine-Motor Development in the First Two Years
Motor Skill
Average Age Achieved
Holds head erect, steady
6 weeks
Lifts self by arms
Rolls from side to back
2 months
Grasps cube
3–4 months
Sits alone
Crawls
7 months
Pulls to stand
8 months
Stands alone
11 months
Walks alone
Builds two-cube tower
11–12 months
Scribbles vigorously
14 months
Jumps in place
23–24 months
Walks on tiptoe
25 months

31. Motor Skills as Dynamic Systems
Acquisition of increasingly complex systems of action
Each new skill is a joint product of four factors:
Central nervous system development
The body’s movement capacities
The child’s goals
Environmental supports for the skill

32. Cultural Variations in Motor Development
Home environment and infant rearing practices affect motor development.
Some cultures discourage rapid motor progress; others actively encourage it.
Western practice of having babies sleep on their backs to protect them from SIDS delays motor milestones.

33. Some Milestones of Reaching and Grasping
Figure 5.14: Some milestones of reaching and grasping
Figure 5.14
(Ages from Bayley, 1969; Rochat, 1989.)

34. Developments in Hearing
4–7 months
Sense of musical phrasing
6–8 months
“Screen out” sounds from nonnative languages
7–9 months
Divide the speech stream into wordlike units
10 months
Detect words that start with
weak syllables

35. A Sensitive Period for Culture-Specific Learning
Perceptual sensitivity becomes attuned to information most often encountered:
Faces
Musical rhythms
Language
Babies are biologically prepared to “zero in” on socially meaningful perceptual distinctions.

36. Improvements in Vision
Visual Ability
Age of Maturation to Adultlike Levels
Focus
2 months
Color vision
4 months
Visual acuity
4 years
Scanning
Tracking objects
Improves over first 6 months, as other abilities improve

37. Emergence of Depth Perception
Birth–1 month
Sensitivity to motion
2–3 months
Sensitivity to binocular depth cues
3–7 months
Sensitivity to pictorial depth cues

38. Development of Pattern Perception
3 weeks
Poor contrast sensitivity
Prefers large, simple patterns
2 months
Detects fine-grained detail
Prefers complex patterns
4 months
Detects subjective boundaries that are not really present
12 months
Detects familiar objects when two-thirds of drawing is missing

39. Appearance of Checkerboards to Very Young Infants
Figure 5.18: The way two checkerboards differing in complexity look to infants in the first few weeks of life
Figure 5.18
(Adapted from M. S. Banks & P. Salapatek, 1983, “Infant Visual Perception,” in M. M. Haith & J. J. Campos (Eds.), Handbook of Child Psychology: Vol. 2. Infancy and Developmental Psychobiology [4th ed.], New York: John Wiley & Sons, p Copyright © 1983 by John Wiley & Sons, Inc. Reproduced with permission of John Wiley & Sons, Inc.)

40. Subjective Boundaries in Visual Patterns
Figure 5.19: Subjective boundaries in visual patterns
Figure 5.19
(Adapted from Ghim, 1990; Rose, Jankowski, & Senior, 1997.)

41. Early Face Perception
Newborns respond to facelike structures but cannot discriminate a complex facial pattern from other complex patterns.
Around 3 months, infants make fine distinctions among features of different faces.
At 5 months, infants perceive emotional expressions as meaningful wholes, a capacity that expands by 7 months.
Early experience promotes perceptual narrowing with respect to gender and racial information.

42. Testing Infants’ Ability to Perceive Object Identity
Size and shape constancy are present in the first week of life.
Perception of object unity develops around 2 months.
At 5 months, infants can track objects traveling on a curvilinear course at varying speeds.
Experience enhances infants’ predictive eye tracking.

43. Testing Infants’ Ability to Perceive Object Unity
Figure 5.21: Testing infants’ ability to perceive object unity
Figure 5.21
(Based on Johnson, 1997.)

44. Intermodal Perception
Intermodal stimulation: simultaneous input from more than one modality or sensory system
Intermodal perception: capacity to perceive streams of multisensory input as integrated wholes
Newborns can detect amodal sensory properties.
Intermodal perception
develops rapidly in first year.
facilitates processing of both physical and social world.

45. Differentiation Theory of Infant Perception
Infants actively search for invariant features of the environment—those that remain stable.
As a result, babies detect patterns such as complex designs, individual faces.
Over time, baby differentiates among increasingly fine invariant features.
Perception is guided by discovery of affordances: the action possibilities offered by a situation.

46. Acting on the Environment Plays a Major Role in Perceptual Differentiation
Figure 5.22: Acting on the environment plays a major role in perceptual development
Figure 5.22

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