1. Infants, Children, and Adolescents
Chapter 5
Physical Development in Infancy and Toddlerhood
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Body Growth
Gain 50% in height from birth to age 1; 75% by age 2
Grow in spurts
Gain “baby fat” until about 9 months, then get slimmer
Girls slightly shorter and lighter than boys, some ethnic differences
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Growth Trends
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
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4. Growth During First Two Years
Figure 5.1
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Epiphyses of the Bone
Figure 5.2
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The Skull at Birth
Figure 5.3
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Brain Development
Human brain has 100 to 200 billion neurons that store/transmit information
At birth, brain closest to adult size than any other physical structure
Neurons send messages by releasing chemicals called neurotransmitters.
Figure 5.4
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8. Major Milestones of Brain Development
Figure 5.5
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9. Methods for Measuring Brain Functioning
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Table 5.1

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Functional Magnetic Resonance Imaging (fMRI) and Near Infrared Spectroscopy (NIRS)
Figure 5.7
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11. Regions of the Cerebral Cortex
Figure 5.8
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12. Lateralization and Plasticity of the Cerebral Cortex
Specialization of the left and right hemispheres of the brain is called lateralization.
Left hemisphere: best at processing information in a sequential, analytic way
Right hemisphere: best at processing information in a holistic, integrative manner
In a highly plastic cerebral cortex, many areas are not yet committed to one function; consequently, the cortex has a high capacity for learning.
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13. Brain Plasticity Insights
With injuries to the cerebral cortex occurring before birth or in the first 6 months, language delays persisted to about 3½ years of age.
By age 5, the children caught up in grammatical and vocabulary skills; the undamaged area of the brain— either hemisphere—had taken over the language function.
Spatial skills showed more impairment after a brain injury, likely because spatial processing is more lateralized at birth.
Brain plasticity can occur later in adulthood (e.g., in stroke victims).
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14. Sensitive Periods in Brain Development
Early, extreme sensory deprivation results in permanent brain damage and loss of function.
Babies born with cataracts in both eyes who have corrective surgery within 4 to 6 months show rapid improvement in vision.
The longer the surgery is postponed, the less complete the recovery of visual skills.
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15. Brain Development in Orphanage Children
Children adopted from Romanian orphanages before age 6 months showed dramatic cognitive and physical gains.
Those adopted after 6 months showed serious intellectual deficits.
The chronic stress of early, deprived orphanage rearing disrupts the brain’s ability to manage stress, with long-term consequences.
Figure 5.9
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16. Appropriate Stimulation
Experience-expectant growth
Ordinary experiences “expected” by brain to grow normally
Occurs early and naturally
Experience-dependent growth
Specific experience, varies widely across cultures
Rushing early learning can overwhelm young brains.
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Sleep Patterns
Sleep moves to an adult-like night–day schedule during the first year.
Sleep needs decline from 18 to 12 hours a day by age 2.
Night wakings often increase between the ages of 1½ and 2 years, and then decline.
Affected by brain development and social environment
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18. Cultural Variations in Infant Sleeping Arrangements
Cosleeping is the norm for 90% of the world’s population.
Cultural values of collectivism versus individualism strongly influence infant sleeping arrangements.
Cosleeping is increasing in the United States, perhaps because more mothers are breastfeeding.
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19. Influences on Early Growth
Heredity
Nutrition
Breast v. bottle feeding
Malnutrition
Emotional well-being
Problems can cause failure to thrive.
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20. Benefits of Breastfeeding
Correct fat–protein balance
Nutritionally complete
Promotes healthy growth patterns
Disease protection
Better jaw and tooth development
Ensures digestibility
Easier transition to solid food
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21. Are Chubby Babies at Risk for Later Obesity?
Recent research shows a relationship between rapid weight gain in infancy and later obesity.
What to do?
Breastfeed for six months.
Avoid foods loaded with sugar, salt, and saturated fats.
Promote physical exercise.
Limit TV viewing time.
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Malnutrition
Types
Marasmus
Kwashiorkor
Iron-deficiency anemia
Food insecurity
Consequences
Physical symptoms
Growth and weight problems
Poor motor development
Learning, attention problems
Passivity, irritability, anxiety
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Emotional Well-Being
Affection is as vital as food for healthy physical growth.
Growth faltering applies to infants whose weight, height, and head circumference are substantially below age-related growth norms.
Infants are withdrawn and apathetic.
Often a result of disturbed parent–child relationship
Unhappy marriage or parental psychological disturbance may be at fault.
May cause lasting cognitive and emotional difficulties
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24. The Steps of Classical Conditioning
Figure 5.10
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25. Operant Conditioning Terms
Punishment
Reduces probability of behavior occurring again
Presenting unpleasant stimulus
Removing desirable stimulus
Reinforcer
Increases probability of behavior occurring again
Presenting desirable stimulus
Removing unpleasant stimulus
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26. Using Habituation to Study Infants
Figure 5.11
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Imitation
Imitation is a powerful method of learning.
It is more difficult to induce in babies 2 to 3 months old than right after birth.
Andrew Meltzoff: Newborns imitate as much as older children and adults.
Mirror neurons enable us to observe another person’s behavior while simulating that behavior in our own brain.
Meltzoff’s theory of newborn imitation as a voluntary capacity is controversial.
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28. Imitation by Human and Chimpanzee Newborns
Figure 5.12
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29. The Sequence of Motor Development
Gross-motor development
Crawling, standing, walking
Fine-motor development
Reaching and grasping
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30. Gross- and Fine-Motor Development in the First Two Years
Table 5.2
Sources: Bayley 1969, 1993, 2005
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31. Motor Skills as Dynamic Systems
Increasingly complex systems of action with each skill
Four factors in each new skill:
CNS development
Body’s movement capacity
Child’s goals
Environmental supports
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32. Cultural Variations in Motor Development
Home environments and infant rearing practices affect motor development.
Some cultures discourage rapid motor progress.
Kipsigis of Kenya and the West Indians of Jamaica teach early motor skills.
Western parents consider crawling and “tummy time” essential, but not all cultures do.
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33. Milestones of Reaching
Figure 5.14
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34. Bowel and Bladder Control
Toilet training is best delayed until the months following the second birthday.
Effective training techniques include
establishing regular toileting routines.
using gentle encouragement.
praising children for their effort .
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35. Developments in Hearing
4–7 months
Sense of musical phrasing
6–8 months
“Screen out” sounds from non-native languages
7–9 months
Divide the speech stream into word-like units
10 months
Can detect words that start with weak syllables
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36. Improvements in Vision
Brain development helps infants reach adult levels of vision skills.
2–4 months:
focus and color vision
6 months:
acuity, scanning, and tracking
6–7 months:
depth perception
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37. Steps in Depth Perception
Birth–
1 month
Sensitivity to motion cues
2–3 months
Sensitivity to binocular cues
6–7 months
Sensitivity to pictorial cues
Wariness of heights
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38. Steps in Pattern Perception
3 weeks
Poor contrast sensitivity
Prefer large simple patterns
2 months
Can detect fine-grained detail
Prefer complex patterns
4 months
Can detect patterns even if
boundaries are not really present
12 months
Can detect objects if two-thirds
of drawing is missing
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39. Appearance of Checkerboards to Very Young Infants
Figure 5.17
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40. Subjective Boundaries in Visual Patterns
Figure 5.18
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Early Face Perception
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Figure 5.19

42. Testing Infants’ Ability to Perceive Object Unity
Figure 5.20
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43. Intermodal Perception
World provides intermodal stimulation: simultaneous input from more than one modality, or sensory system
Intermodal perception: making sense of multisensory input as integrated wholes
Infants can detect amodal sensory properties even as newborns.
Abilities develop rapidly in first year.
Facilitates perception of physical world and understanding of social world
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44. Differentiation Theory of Infant Perception
Infants actively search for invariant, unchanging features of the environment.
Borders of stimuli, faces
They note stable relationships between features.
Complex visual patterns, intermodal relationships
Perception gets more and more sensitive: differentiation
Acting on the environment helps this process: affordances
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Acting on the Environment Plays a Major Role in Perceptual Differentiation
Figure 5.21
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