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

2. In This Chapter

3. Physical Changes
The Brain and Nervous System
Brain
 Rapid development during the first 2 years
 Midbrain and medulla most fully developed
at birth
 The cortex is the least developed.

4. Figure 4.1 Parts of the Brain

5. The Brain and Nervous System
Physical Changes: Synaptic Development

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

7. The Brain and the Nervous System
Myelinization
Myelin: Insulating layer of proteins and fatty
substances
 Description
 Timing

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.

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.

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.

11. Most infants move through these states in the same
sequence every 2 hours
Reflexes and Behavioral States
Five States of Sleep and Wakefulness

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.

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.  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.
Growth, Motor Skills, and Developing
Body Systems
Growth and Motor Skills: Overview

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.

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.

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

19. Experience influences motor development!
African motor development
 The pattern of traditional cultural
practices promotes motor development.
 Precocity does not persist into early
childhood.
Developing Body Systems
and Motor Skills
Cross-Cultural Research

20. 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?
Questions To PonderQuestions To PonderQuestions To PonderQuestions To Ponder

21. Health and Wellness
Nutrition: Breastfeeding and Bottle feeding
Breastfeeding
 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
Bottle feeding
 May be needed
supplement for preterm
babies
 Special-needs formulas
available
 Can be high quality
 Allows more father
participation

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

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.

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

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.

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

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

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

33. Taste Responses in Newborns
What responses do you see?

34. Taste Responses in Newborns

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.

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?

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.

39. Visual
attention:
guided by
search for
meaningful
pattern
Perceptual Skills
What Babies Look At: Scanning

40. What Babies Look At
What Babies Look At: Faces
Face NOT
uniquely
interesting
to infants
Before 2
months:
Scan edges
(hairline,
chin)
2–3 months:
Scan internal
facial
features,
especially
eyes
Attractive
faces and
mother’s
face
preferred

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

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

43. Perceptual Systems
Explaining Perceptual Development
Nativists
 Most perceptual abilities
inborn
 Many of these abilities
present at birth
Empiricists
 Most perceptual abilities
learned
 Experience needed to
develop perceptual
systems
A compromise position: Perceptual skill
development is the result of interaction between
inborn and experiential factors.