322 CHAPTER 8
Infancy and Childhood Development
Infancy and early childhood are a time of rapid growth and development in the body,
motor skills, cognitive abilities, and sensory systems.Physical Development
- 6 Describe the physical and sensory changes that take place in infancy and
childhood.
Immediately after birth, several things start to happen. The respiratory system begins
to function, filling the lungs with air and putting oxygen into the blood. The blood now
circulates only within the infant’s system because the umbilical cord has been cut. Body
temperature is now regulated by the infant’s own activity and body fat (which acts as
insulation) rather than by the amniotic fluid. The digestive system probably takes the
longest to adjust to life outside the womb. This is another reason for the baby’s excess
body fat. It provides fuel until the infant is able to take in enough nourishment on its
own. That is why most babies lose a little weight in the first week after birth.
How much can babies really do? Aren’t they pretty much
unaware of what’s going on around them at first?Surprisingly, babies can do a lot more than researchers used to believe they could.
A lot of the early research on infants just after birth was done on babies who were still
very drowsy from the general anesthesia that was administered to their mothers during
the labor process. Drowsy babies don’t tend to respond well, as one might imagine. Since
those early days, researchers have developed ways of studying what infants cannot tell
us in words. Two common methods are the use of preferential looking and habituation. Pref-
erential looking assumes that the longer an infant spends looking at a stimulus, the more
the infant prefers that stimulus over others (Fantz, 1961). Habituation is the tendency for
infants (and adults) to stop paying attention to a stimulus that does not change.
to Learning Objective 3.3. By exposing the infant to an unchanging sound or picture, for
example, researchers can wait for the infant to habituate (look away) and then change the
stimulus. If the infant reacts (dishabituates), the infant is capable of detecting that change
(Columbo & Mitchell, 2009).
REFLEXES Babies come into this world able to interact with it. Infants have a set of
innate (existing from birth), involuntary behavior patterns called ref lexes. Until a baby
is capable of learning more complex means of interaction, reflexes help the infant sur-
vive. Figure 8. 4 shows five infant reflexes. Pediatricians use these and other reflexes to
determine whether a newborn’s nervous system is working properly.Practice Quiz How much do you remember?
Pick the best answer.
- The first 2 weeks of pregnancy are called the __ period.
a. fetal c. placental
b. embryonic d. germinal - Which of the following does NOT happen in the germinal period?
a. dividing mass of cells travels to the uterus
b. developing organs can be affected by toxins passing through the
placenta
c. mass of cells form a hollow ball
d. cells begin to differentiate
3. The period of pregnancy that contains the clearest examples of criti-
cal periods is the __ period.
a. germinal c. fetal
b. embryonic d. gestational
4. Intellectual disability and blindness are possible outcomes of the
effects of __ on the developing baby.
a. alcohol c. cocaine
b. caffeine d. mercury