1. Physical, Sensory, and Perceptual Development In Infancy
Chapter 4:
Physical, Sensory, and Perceptual Development In Infancy

2. In This Chapter Physical Changes Health and Wellness Infant Mortality
Sensory Skills
Perceptual Skills

3. Physical Changes The Brain and Nervous System
Rapid development during the first 2 years
Midbrain and medulla most fully developed at birth
The cortex is the least developed.
The medulla regulates vital functions such as heartbeat and respiration, attention, sleeping, waking, elimination, and movement of the head and neck.
The cortex is responsible for perception, body movement, thinking, and language.

4. Figure 4.1 Parts of the Brain
The medulla regulates vital functions such as heartbeat and respiration, attention, sleeping, waking, elimination, and movement of the head and neck.
The cortex is responsible for perception, body movement, thinking, and language.
Figure 4.1 Parts of the Brain

5. The Brain and Nervous System Physical Changes: Synaptic Development
Synaptogenesis
Creation of synapses or connections between neurons
Synaptic pruning
Elimination of unused neural pathways and connections
Early in development, each muscle cell seems to develop synaptic connections with several motor neurons in the spinal cord. But after the pruning process has occurred, each muscle fiber is connected to only one neuron. Some neurophysiologists have suggested that the initial surge of synapse formation follows a built-in pattern (Greenough et al., 1987). The organism seems to be programmed to create certain kinds of neural connections and does so in abundance, creating redundant pathways. According to this argument, the pruning that takes place beginning at around eighteen months is a response to experience, resulting in selective retention of the most efficient pathways.

6. The Brain and Nervous System Plasticity
Neural plasticity: Brain’s ability to change in response to experience
Use it or lose it
Changes in psychological functioning
Rat infants reared in a highly stimulating environment have a denser network of neurons, dendrites, and synaptic connections.
Young infants need sufficient stimulation and order in their environments to maximize the early period of rapid growth and plasticity.
Use it or lose it
An intellectually challenging environment creates a more complex network of synapses.
Changes in psychological functioning
Developmental changes in brain across lifespan
Infant brains have greater plasticity but more vulnerability to major deficits.

7. The Brain and the Nervous System Myelinization
Myelin: Insulating layer of proteins and fatty substances
Description
Timing
Myelin: Insulating layer of proteins and fatty substances
Description
Forms myelin sheath covering individual axons
Provides insulation and speeds up neuronal processes
Follows cephalocaudal and proximodistal patterns
Timing
Most rapid during first two years
Continues at slower pace throughout childhood and adolescence
Cephalocaudal: head to toe
Proximodistal: near to far

8. Reflexes and Behavioral States Adaptive Reflexes
Adaptive reflexes: Reflexes that help survival
Warn of possible neuronal development problems when weak or absent
Some persist throughout life.
Help survival
Sucking
Withdrawal from pain
Opening and closing of pupil
Warn of possible neuronal development problems when weak or absent
Some reflexes, such as sucking, will be replaced by voluntary behaviors, while others are available throughout the lifespan.

9. Reflexes and Behavioral States Primitive Reflexes
Primitive reflexes: Reflexes controlled by less sophisticated parts of brain
Should appear at birth and disappear by 6 to 8 months.
May indicate neurological problems if persistent.
Controlled by less sophisticated parts of brain
Moro (or “startle”) reflex
Babinski reflex (curled toes)
Should disappear by six to eight months.
May indicate neurological problems if persistent.
Less sophisticated parts of the brain include the medulla and midbrain.

10. Reflexes and Behavioral States States of Consciousness
Sleep, Baby, sleep
Patterns of sleep and wakefulness stabilize with age.
Neonates sleep 80 percent of the time.
By 8 weeks, babies begin to sleep through the night.
By 6 months, babies average 14 hours of sleep per day.
Sleep patterns are individualized and some babies may not develop nighttime patterns until one year of age.
Patterns of sleep and wakefulness stabilize with age.
Neonates sleep 80 percent of the time.
By eight weeks, babies begin to sleep through the night.
By six months, babies average fourteen hours of sleep per day.
Clear nighttime patterns and daytime naps are established.

11. Reflexes and Behavioral States Five States of Sleep and Wakefulness
Deep sleep
Light sleep
Alert wakefulness
Fussing
Drowsy
Sleep patterns are individualized and some babies may not develop nighttime patterns until one year of age.
Patterns of sleep and wakefulness stabilize with age.
Neonates sleep 80 percent of the time.
By eight weeks, babies begin to sleep through the night.
By six months, babies average fourteen hours of sleep per day.
Clear nighttime patterns and daytime naps are established.
Most infants move through these states in the same sequence every 2 hours

12. Reflexes and Behavioral States Crying Baby, Not Crybaby!
Cries differ by need.
Cross-cultural studies suggest crying increases until 6 weeks then tapers off.
Prompt attention to crying in the first 3 months leads to less crying later.
Cries differ by need.
Basic cry signals hunger: rhythmic pattern
Anger cry: louder and more intense
Pain cry: very abrupt onset
Colic: a pattern involving intense bouts of crying for no immediately apparent reason, as much as three hours a day. Appears at about two weeks then disappears by three to four months of age.

13. Growth, Motor Skills, and Developing Body Systems Physical Changes: Growth
By age one
10 to 12 inches of growth
Infants triple body weight
Around age two
Toddlers reach half their adult height.
Proportionately much larger heads than adults

14. Growth, Motor Skills, and Developing Body Systems Growth and Motor Skills: Overview
Inborn timetable of motor skills interacts with other aspects of physical development (Thelen).
Muscles, bones, weight—all work together.
Opportunities to practice motor skills are important.

15. Stop and Think!
Researchers suggest there is a difference in the rate but similarity in the sequence of motor skill development. Using this information as a base, what advice would you give to parents of toddlers?

16. Developing Body Systems and Motor Skills Bones
Ossification: Process of hardening of bones
Begins during prenatal development
Continues through puberty
Motor development depends to a large extent on ossification.
Changes in number and density of bones are responsible for improved coordination.
At birth, wrist is cartilage; by one to three years of age, it is separate bones: by adolescence, nine separate bones. This improves manipulative skills.
Standing is impossible without ossification.

17. Developing Body Systems and Motor Skills Muscles
Full complement of muscle fibers present at birth
Decline in muscle tissue to fat ratio occurs by age 1.
Change in muscle composition leads to increase in strength.
Stamina: ability to maintain activity
Gross motor skills exhibit predictable changes over time.
Fine motor skills, such as palmar grasp and pincer grasp, take longer to develop.
Motor skills follows cephalocaudal and proximodistal development.
Gallaway and Thelen (2004): infants can reach for objects more efficiently with their legs—just the opposite of cephalocaudal development.

18. Developing Body Systems and Motor Skills Lungs and Heart
Rapid growth during the first 2 years leads to stamina.
Ability to sustain motor activity without rest by end of infancy
Stamina: ability to maintain activity
Gross motor skills exhibit predictable changes over time.
Fine motor skills, such as palmar grasp and pincer grasp, take longer to develop.
Motor skills follow cephalocaudal and proximodistal development.
Gallaway and Thelen (2004): infants can reach for objects more efficiently with their legs—just the opposite of cephalocaudal development.

19. Cross-Cultural Research
Developing Body Systems
and Motor Skills
Cross-Cultural Research
Experience influences motor development!
African motor development
The pattern of traditional cultural practices promotes motor development.
Precocity does not persist into early childhood.
Stamina: ability to maintain activity
Gross motor skills exhibit predictable changes over time.
Fine motor skills, such as palmar grasp and pincer grasp, take longer to develop.
Motor skills follow cephalocaudal and proximodistal development.
Gallaway and Thelen(2004): infants can reach for objects more efficiently with their legs—just the opposite of cephalocaudal development.

20. ? ?
Questions To Ponder
Do you or your spouse plan on breastfeeding? What factors would make you want to breastfeed? What factors would cause you not to breastfeed? What are the 3 most important factors that influence physical growth? Why are they important?

21. Health and Wellness Nutrition: Breastfeeding and Bottle feeding
Nutritionally superior: More rapid weight gain and size
Early health benefits
Only nutrition needed for first 4 to 6 months of life
May not be possible for all mothers
May be needed supplement for preterm babies
Special-needs formulas available
Can be high quality
Allows more father participation
Common illnesses: diarrhea, gastroenteritis, bronchitis, ear infections, and colic, as well as infant death
Mothers should not breastfeed if using drugs, if they are substance abusers, or if they have AIDS.

22. Health and Wellness Nutrition: Solid Food
Solid Foods
Early introduction can interfere with nutrition.
Do not help babies to sleep through the night
Should start between 4–6 months
Baby is ready for solid foods when he or she can:
Hold head in steady, upright position
Sit with support
Show interest in what you are eating

23. Health and Wellness Malnutrition
Macronutrient malnutrition
Marasmus
Kwashiorkor
Micro-nutrient malnutrition
Macronutrient malnutrition
Diet containing too few calories
Leading worldwide cause of death in children under five
Marasmus
Severe calorie deficit
Extremely small
Can cause permanent brain damage
Kwashiorkor
Diet too low in protein
Micronutrient malnutrition
Deficiency of certain vitamins and/or minerals
Marasmus and Kwashiorkor are found in many developing countries.
Industrial societies suffer more from micronutrient malnutrition—a deficiency of certain vitamins or minerals. Iron deficiency leads to anemia, which may impede both social and language development.

24. Health and Wellness Health Care and Immunization
Health Care and Immunizations
Routine health professional visits are important.
Overall health and motor skills are assessed during visits
Vaccinations are given to prevent diseases.
Vaccinations: three for hepatitis, four for diphtheria/tetanus/pertussis, three for influenza, one for measles
U.S. vaccination rates are high, but declining.
Continued education efforts and government support are needed.
Daycare babies have twice as many respiratory illnesses as stay-at-home babies.

25. Health and Wellness Health Care and Illness
Illnesses in first 2 years
Respiratory illnesses common
Higher in children participating in childcare programs
Chronic ear infections
Daycare babies have twice as many respiratory illnesses as stay-at-home babies.

26. Health and Wellness Infant Mortality
Death within the first year of life
7 babies per 1000 in the U.S.
Related to prenatal care
Varies widely among U.S. ethnic groups
Let’s look at Figure 4.3 to examine group differences in infant mortality.
Racial differences occur in infant mortality (Figure 4.2): lowest among Asian-American infants; African-American infants have the highest.
7 babies per 1000 in the U.S.
Has declined steadily for several decades
Higher in U. S. than in other industrialized countries
Poverty is still a leading cause of infant mortality regardless of race.

27. Figure 4.2 Group Differences in Infant Mortality

28. Next Let’s Look at Early Prenatal Care and Ethnicity
See if you can identify disparities across ethnic groups with regard to access to prenatal care. Do you see any correspondence to these disparities and infant mortality?

29. Figure 4.3 Early Prenatal Care and Ethnicity

30. Health and Wellness Sudden Infant Death Syndrome (SIDS)
Incidence: Leading cause of death in U.S. in infants 1–12 months
Relationships:
Apnea
Sleeping on stomach
Maternal smoking
More common in babies with apnea (brief cessations in breathing)
Racial differences occur in infant mortality (Figure 4.2): lowest among Asian-American infants; African-American infants have the highest.
Poverty is still a leading cause of infant mortality regardless of race.

31. Sensory Skills Vision Rapid development of visual acuity
20/200 at birth; 20/20 at 2 years
Color vision
Red, blue, green at 1 month
Tracking
Tracking slow-moving object before 2 months and skilled at 6–10 weeks
Infants younger than two months show some tracking ability for brief periods; by 6–10 weeks, babies become skillful at tracking.
20/200 at birth
20/20 by 2 years
Color vision
Red, green, and blue present by one month
Color sense almost identical to an adult’s
Tracking
Process of following moving object
Initially inefficient but improves rapidly
Tracks for short period of time when younger than two months (slow-moving target)
By ten weeks, skillful

32. Sensory Skills Hearing
Adult voices heard well and some directional loud-sound location
Smelling and tasting
Newborns react differently to each basic taste as early as birth.
Touch and motion
Best developed of all senses
Hearing
Adult voices heard well
High-pitched noises must be loud to be heard.
Some directional sound location
Smelling and tasting are intricately related.
Four basic tastes: sweet, sour, bitter, and salty
Sensitive to touches on the mouth, hands, soles of feet, and abdomen

33. Taste Responses in Newborns What responses do you see?
Ask: What responses do you see? Sour, sweet, bitter?

34. Taste Responses in Newborns
Ask: How many did you correctly identify?

35. Stop and Think!
In what ways do babies’ sensory skills contribute to the development of the parent–infant relationship?

36. Perceptual Skills Studying Perceptual Development
Preference technique
Study how long baby attends to a particular stimulus.
Habituation/dishabituation
Study loss of interest in particular stimulus after repeated exposures.
Operant conditioning
Vary the stimulus and study the learned responses.
How does a baby interpret or combine sensory experience? The process is called perception.
Preference technique: baby is shown 2 pictures and researchers keep track of how long the baby looks at each one.
Habituation: show a baby something over and over until the baby stops looking at it.
Dishabituation: renewed interest in something that is slightly different than the original stimulus

37. Looking Skills Depth Perception
Depth perception can be judged by:
Binocular cues
Monocular cues
Kinetic cues
Do you know the differences among
these cues?
Binocular cues
Involve both eyes
The closer an object, the more the views from the two eyes differ.
Information from eye muscles tells about distance.
Monocular cues
Input from one eye
Interposition
Linear perspective
Kinetic cues
Motion from objects or the eyes

38. Depth Perception A Walk on the Wild Side—Almost
Visual Cliff: Gibson and Walk (1960)
Initial findings: 6-month-old babies would not cross the visual cliff.
Recent findings: 3-month-olds have some depth perception.
Recent findings:
Babies use kinetic information as early as three months.
Binocular cues are used at four months.
Linear perspective cues are used last, at five to seven months.

39. Perceptual Skills What Babies Look At: Scanning
Initially scan for sharp, light/dark contrasts and then scan edges
2 months: scan entire object and look for patterns
2-3 months: shift from where to what object
3-4 months: attention to patterns, not just specific stimuli
Visual attention: guided by search for meaningful pattern
Babies demonstrate a preference for light/dark contrasts.
Albert Caron and Rose Caron used habituation (Figure 4.5); small over big.

40. What Babies Look At What Babies Look At: Faces
Face NOT uniquely interesting to infants
Attractive faces and mother’s face preferred
Before 2 months: Scan edges (hairline, chin)
2–3 months: Scan internal facial features, especially eyes
Research by Gail Walton (1992), using the preference technique, compared sucking rates of babies only a day or two old when looking at either a picture of their mothers or someone else. The babies clearly preferred to look at their moms.
Walton’s subjects spent at least an hour with their mothers immediately after birth—even when the birth was by cesarean section.

41. Listening What Babies Hear: Discriminating Speech Sounds
1 month: discriminate between “pa” and “ba”
3 months: respond to male, female, and children’s voices similarly
6 months: discriminate between 2-syllable words
6 months: distinguish sound contrasts in any language; fades by 1 year
Prefer the mother’s voice above all others
Very young infants make fine discriminations among individual sounds and pay attention to patterns.

42. Perceptual Systems Combining Information from Several Senses
Intermodal perception: Formation of single perception of stimulus that is based on information from 2 or more senses
Possible by 1 month
Common by 6 months
Important in infant learning
Gibson and Gibson argue that cross-modal transfer is an inborn set of skills.
Learn in one sense modality, transfer information to another modality
Intersensory integration is essential to infant learning.

43. Perceptual Systems Explaining Perceptual Development
Nativists
Empiricists
Most perceptual abilities inborn
Many of these abilities present at birth
Most perceptual abilities learned
Experience needed to develop perceptual systems
Gibson and Gibson argue that cross-modal transfer is an inborn set of skills.
Intersensory integration is essential to infant learning.
A compromise position: Perceptual skill development is the result of interaction between inborn and experiential factors.