CHAPTER 5
INFANCY
LEARNING OUTCOMES
1. UNDERSTAND THE TOPIC OF INFANCY;
2. DESCRIBE THE STAGES OF INFANT'S PHYSICAL
DEVELOPMENT, INCLUDING MOTOR SKILLS, SIGHT,
HEARING, TASTE AND SMELL;
3 . D I S C U S S I N FA N T F E E D I N G , I N C L U D I N G T H E
IMPORTANCE OF BREASTFEEDING.
Developmentalists are careful to distinguish between
sensation and perception. Sensation is the process by
which sensory receptor neurons detect information and
transmit it to the brain. Clearly, neonates “sense” the
environment. They gaze at interesting sights, react to
sounds, tastes, and odors, and are likely to cry up a storm
when poked by a needle for a blood test. But do they “make
sense” of these sensations?
The Newborn’s Readiness for Life
In the past, newborns were often characterized as fragile
and helpless little organisms who were simply not prepared
for life outside the womb. This view may once have been
highly adaptive, helping to ease parents’ grief in earlier eras
when medical procedures were rather primitive and a fair
percentage of newborns died. Even today, in cultures where
many newborns die because of poor health and medical
care, parents often do not name their newborns until they
are 3 months old and have passed the critical age for
newborn death (Brazelton, 1979).
Newborn Reflexes
One of the neonate’s greatest strengths is a full set of
useful reflexes. A reflex is an involuntary and automatic
response to a stimulus, as when the eye automatically
blinks in response to a puff of air. It describes some reflexes
that healthy newborns display. Some of these graceful and
complex patterns of behavior are called survival reflexes
because they have clear adaptive value (Berne, 2003).
Infant States
Newborns also display organized patterns of daily activity
that are predictable and foster healthy developmental
outcomes. In a typical day (or night), a neonate moves in
and out of six infant states, or levels of arousal, that are
described in Table 5.2.
During the first month, a baby may move rapidly from one
state to another, as mothers observe when their wideawake babies suddenly nod off to sleep in the middle of a
feeding.
Developmental Changes in Infant States
• Two of the states—sleeping and crying—show regular
patterns of change over the fi rst year and provide
important information about the developmental progress a
baby is making.
Changes in Sleep
As infants develop, they spend less time sleeping and more
time awake, alert, and attending to their surroundings. By
age 2 to 6 weeks, babies sleep only 14 to 16 hours a day;
and somewhere between 3 and 7 months of age, many
infants reach a milestone that parents truly appreciate—
they begin to sleep through the night and require but two or
three shorter naps during the day (Berg & Berg, 1987; St.
James-Roberts & Plewis, 1996).
The Functions and Course of Crying
A baby’s earliest cries are unlearned and involuntary
responses to discomfort—distress signals by which the
infant makes caregivers aware of his needs. Most of a
newborn’s early cries are provoked by such physical
discomforts as hunger, pain, or a wet diaper, although chills,
loud noises, and even sudden changes in illumination (as
when the light over a crib goes off ) are often enough to
make a baby cry. An infant’s cry is a complex vocal signal
that may vary from a soft whimper to piercing shrieks and
wails.
Philip Zeskind and his associates (1985) discovered that
adults find the intense cries of hungry babies just as
arousing and urgent as equally intense “pain” cries. So
crying probably conveys only one very general message—
“Hey, I’m distressed”—and the effectiveness of this signal at
eliciting attention depends more on the amount of distress it
implies than on the kind of distress that the baby is
experiencing (Green, Gustafson, & McGhie, 1998; Zeskind
et al., 1992).
Developmental Changes in Crying
Babies around the world cry most often during their first 3
months of life (St. James-Roberts & Plewis, 1996). In fact,
the declines we see early in life in both crying and REM
sleep suggest that both these changes are meaningfully
related to the maturation of a baby’s brain and central
nervous system (Halpern,
MacLean, & Baumeister, 1995).
Pediatricians and nurses are trained to listen carefully to the
vocalizations of a newborn infant because congenital
problems are sometimes detectable by the way an infant
cries. Preterm babies, for example, and those who are
malnourished, brain-damaged, sudden infant death
syndrome (SIDS) the unexplained death of a sleeping infant
who suddenly stops breathing (also called crib death).
Sudden Infant Death Syndrome
Young infant from becoming aroused when oxygen intake is
inadequate (Franco et al., 1998; Frick, 1999). So when
babies with abnormalities in the lower brain centers are
sleeping prone, are heavily bundled, or have a respiratory
infection that may restrict breathing, they may not struggle
suffi ciently to breathe and thus may succumb to SIDS
(Iyasu et al., 2002; Ozawa et al., 2003; Sawaguchi et al.,
2003a–d, g–n). Nevertheless, it is important to note that (1)
not all SIDS victims have identifi able brain abnormalities,
and (2) researchers, as yet, have no foolproof screening
tests to predict which babies are at highest risk of SIDS.
Methods of Soothing a Fussy Babyto be soothed (Korner, 1996).
Even in the first few days of life, some infants are easily
distressed and diffi cult to soothe, whereas others are rarely
perturbed and will calm easily should they become
overstimulated. One in ten infants experience colic, which is
an inability to be soothed and intense, high-pitched, and
irritable crying despite every physical need being met. For
parents of these infants there is little consolation because
the crying may continue for hours without relief. The one
positive note is that colic usually ends by the third month.
Other Soothing Techniques
When feeding or diaper changing doesn’t work, rocking,
stroking, singing lullabies, and other forms of continuous,
rhythmic stimulation will often quiet restless babies
(Campos, 1989; Rock & Trainor, 1999). Swaddling
(wrapping the infant snugly in a blanket) is also comforting
because the wraps provide continuous tactile sensation all
over the baby’s body.
APPLYING RESEARCH TO YOUR LIFE
In many cultures, babies are kept quite contented through
swaddling and having ample close contact with their
mothers, who stand ready to nurse at the baby’s first
whimper.
Preference Method
The preference method is a simple procedure in which at
least two stimuli are presented simultaneously to see
whether infants will attend more to one of them than the
other(s) (Houston-Price & Nakai, 2004). This approach
became popular during the early 1960s after Robert Fantz
used it to determine whether very young infants could
discriminate visual patterns (e.g., faces, concentric circles,
newsprint, and unpatterned disks). Babies were placed on
their backs in a looking chamber and shown two or more
stimuli.
The Habituation Method
Perhaps the most popular strategy for measuring infant
sensory and perceptual capabilities is the habituation method.
Habituation is the process in which a repeated stimulus
becomes so familiar that responses initially associated with it
(e.g., head or eye movements, changes in respiration or heart
rate) no longer occur. Thus, habituation is a simple form of
learning. As the infant stops responding to the familiar
stimulus, he or she is telling us that they recognize it as
something that they have experienced before (Bertenthal &
Longo, 2002). For this reason, the habituation method is also
referred to as a “familiarization-novelty” procedure (Brookes
et al., 2001; Houston-Price & Nakai, 2004).
The Method of Evoked Potentials
Yet another way of determining what infants can sense or
perceive is to present them with a stimulus and record their
brain waves. Electrodes are placed on the infant’s scalp
above those brain centers that process the kind of sensory
information that the investigator is presenting This means,
for example, that responses to visual stimuli are recorded
from the back of the head, at a site above the occipital lobe.
If the infant senses the particular stimulus presented, she
will show a change in the patterning of her brain waves, or
evoked potential.
The High-Amplitude
Sucking Method
Finally, most infants can exert enough control over their
sucking behavior to use it to show us what they can sense
and to give us some idea of their likes and dislikes. After the
researcher establishes an infant’s baseline sucking rate, the
procedure begins. Whenever the infant sucks faster or
harder than she did during the baseline observations (highamplitude sucking), she trips the electrical circuit in the
pacifier, thereby activating a slide projector or tape recorder
that introduces some kind of sensory stimulation.
Infant Sensory Capabilities
Hearing
Soft sounds that adults hear must be made noticeably
louder before a neonate can detect them (Aslin, Pisoni, &
Jusczyk, 1983). In the fi rst few hours of life, infants may
hear about as well as an adult with a head cold. Their
insensitivity to softer sounds could be due, in part, to fl uids
that have seeped into the inner ear during the birth process.
Despite this minor limitation, neonates are capable of
discriminating sounds that differ in loudness, duration,
direction, and frequency (Bower, 1982). They hear rather
well indeed.
Reactions to Voices
Young infants are particularly attentive to voices, especially
high-pitched feminine voices (Ecklund-Flores & Turkewitz,
1996). But can they recognize their mother’s voices?
Research by Anthony DeCasper and his associates
(DeCasper & Fifer, 1980; DeCasper & Spence, 1986, 1991)
reveals that newborns suck faster on a nipple to hear a
recording of their mother’s voice than a recording of another
woman.
Reactions to Language
Not only do babies listen closely to voices, but they are also
a b l e t o d i s c r i mi n a t e b a s i c s p e e c h s o u n d s — c a l l e d
phonemes—very early in life. Peter Eimas (1975b, 1985)
pioneered research in this area by demonstrating that
infants 2 to 3 months old could distinguish consonant
sounds that are very similar (e.g., ba and pa). In fact,
infants less than 1 week old can tell the difference between
the vowels a and i (Clarkson & Berg, 1983), and can even
segment words into discrete syllables (Bijeljac-Babic,
Bertoncini, & Mehler, 1993).
Causes and Consequences of Hearing Loss
Youngsters with recurring infections may have diffi culties
understanding others’ speech, which could hamper their
language development as well as other cognitive and social
skills that normally emerge early in childhood. And there is
reason for concern. Children who have had recurring ear
infections early in life do show delays in language
development and poorer academic performance early in
elementary school than peers whose bouts with the disease
were less prolonged (Friel-Patti & Finitzo, 1990; Teele, Klein,
& Chase et al., 1990). They also exhibit impaired auditory
attention skills (Asbjornsen et al., 2005).
Visual Perception in Infancy
Perception of Patterns and Forms
Recall Robert Fantz’s observations of infants in his looking
chamber: babies only 2 days old could easily discriminate
visual patterns.
Early Pattern Perception (0 to 2 Months)
Apparently not. When Fantz (1961) presented young infants
with a face, a stimulus consisting of scrambled facial
features, and a simpler stimulus that contained the same
amount of light and dark shading as the facelike and
scrambled face drawings, the infants were just as interested
in the scrambled face as the normal one.
Later Form Perception (2 Months to 1 Year)
Between 2 and 12 months of age, the infant’s visual system
is rapidly maturing. She now sees better and is capable of
making increasingly complex visual discriminations,
eventually even including temporal movement sequencing
into her discriminations (Kirkham, Slemmer, Richardson, &
Johnson, 2007). She is also organizing what she sees to
perceive visual forms and sets of separate forms (Cordes &
Brannon, 2008).
Explaining Form Perception
Newborns are biologically prepared to seek visual
stimulation and make visual discriminations. These early
visual experiences are important, for they keep the visual
neurons firing and contribute to the maturation of the visual
centers of the brain (Nelson, 1995).
By about 2 to 3 months of age, maturation has progressed
to the point of allowing an infant to see more detail, scan
more systematically, and begin to construct visual forms,
including one for faces in general, as well as more specifi c
confi gurations that represent the faces of familiar
companions.
Perception of Three-Dimensional Space
Because we adults easily perceive depth and the third
dimension, it is tempting to conclude that newborns can too.
But when are infants capable of perceiving depth and
making reasonably accurate inferences about size and
spatial relations? We’ll briefly consider research designed
to answer these questions.
Size Constancy
Very young infants have shown some intriguing abilities to
interpret movement across the third dimension. For
example, a 1-month-old reacts defensively by blinking his
eyes as a looming object approaches his face (Nanez &
Yonas, 1994). Three- to fi ve-montholds react differently to
looming objects than to looming openings. Along with
pressing the head backward and throwing the arms outward,
infants’ heightened blinking response has been interpreted
as anticipation of an impending collision (Schmuckler &
Li, 1998).
Use of Pictorial Cues
Albert Yonas and his associates have studied infants’
reactions to monocular depth cues—the tricks artists and
photographers use to portray depth and distance on a twodimensional surface. In the earliest of these studies (Yonas,
Cleaves, & Pettersen, 1978), infants were exposed to a
photograph of a bank of windows taken at a 45-degree
angle.
Development of Depth Perception
Eleanor Gibson and Richard Walk (1960) developed an
apparatus they called the visual cliff to determine whether
infants can perceive depth.
The visual cliff (see Figure) consists of an elevated glass
platform divided into two sections by a center board.
On the “shallow” side, a checkerboard pattern is placed
directly under the glass. On the “deep” side, the pattern is
placed several feet below the glass, creating the illusion of
a sharp drop-off, or a “visual cliff.” The investigator tests an
infant for depth perception by placing him on the center
board and then asking the child’s mother to try to coax the
infant to cross both the “shallow” and the “deep” sides.
Motor Development and Depth Perception.
One reason that many 6- to 7-montholds come to fear drop-offs
is that they are more sensitive to kinetic, binocular, and
monocular depth cues than younger infants are. Yet, this fear
also depends very heavily on the experiences infants have
creeping and crawling about and perhaps falling now and then.
Joseph Campos and his associates (1992) found that infants
who have crawled for a couple of weeks are much more afraid
of drop-offs than infants of the same age who are not yet
crawling. In fact, precrawlers quickly develop a healthy fear of
heights when given special walkers that allow them to move
about on their own. So motor development provides
experiences that change infants’ interpretation of the meaning
of depth.
Intermodal perception
• the ability to use one sensory modality to identify a
stimulus or pattern of stimuli that is already familiar
through another modality.
Are the Senses Integrated at Birth?
It would obviously be useful for an infant who is attempting
to understand the world to be able to integrate information
gained by viewing, fi ngering, sniffi ng, or otherwise
exploring objects. Do the senses function in an integrative
way early in life?
Suppose that you captured a baby’s attention by fl oating a
soap bubble in front of her face. Would she reach for it? If
she did, how do you think she would react when the
bubble pops at her slightest touch?
Thomas Bower and his associates (1970) exposed
neonates to a situation similar to the soap-bubble scenario.
The subjects were 8- to 31-day-old infants who could see
an object well within reaching distance while they were
wearing special goggles. Actually, this virtual object was an
illusion created by a shadow caster. If the infant reached for
it, his or her hand would feel nothing at all. Bower and his
associates found that the infants did reach for the virtual
object and that they often became frustrated to tears when
they failed to touch it.
Development of Intermodal Perception
Although intermodal perception has never been observed in
newborns, it seems that babies only 1 month old have the
ability to recognize by sight at least some of the objects
they have previously sucked. In one study, Eleanor Gibson
and Arlene Walker (1984) allowed 1-month-old infants to
suck either a rigid cylinder or a spongy, pliable one. Then
the two objects were displayed visually to illustrate that the
spongy cylinder would bend
and the rigid one would not.
Explaining Intermodal Perception
The intersensory redundancy hypothesis suggests that the
amodal detection of a stimulus aids in the development and
differentiation of individual senses (Bahrick & Lickliter,
2000). That is, the multiple sensory modalities of a stimulus
object draw an infant’s attention, and as the infant attends
to and interacts with that object, the infant gathers
comparative input that refi nes individual sensory modalities.
Basic Learning Processes in Infancy
■ The individual now thinks, perceives, or reacts to the environment in a new
way.
■ This change is clearly the result of a person’s experiences—that is,
attributable to
repetition, study, practice, or the observations the person has made, rather than
to hereditary or maturational processes or to physiological damage resulting
from injury.
■ The change is relatively permanent. Facts, thoughts, and behaviors that are
acquired and immediately forgotten have not really been learned, and
temporary
changes due to fatigue, illness, or drugs do not qualify as learned responses.
■ Let’s now consider four fundamental ways in which infants learn: habituation,
classical conditioning, operant conditioning, and observational learning.
Habituation: Early Evidence of Information
Processing and Memory
Earlier, we touched on one very simple and oftenoverlooked form of
learning called habituation—the process by which we stop attending
or responding to a stimulus repeated over and over (Streri, Lemoine,
& Devouche, 2008). Habituation can be thought of as learning to
become disinterested in stimuli that are recognized as familiar and
nothing to get excited about. It can occur even before a baby is
born: 27- to 36-week-old fetuses initially become quite active when a
vibrator is placed on the mother’s abdomen, but soon stop moving
(i.e., habituate), as if they process these vibrations as a familiar
sensation that is no longer worthy of attention (Madison, Madison, &
Adubato, 1986).
Individual Differences
Infants reliably differ in the rate at which they habituate.
Some are highly effi cient information processors: they
quickly recognize repetitive sensory inputs and are very
slow to forget what they have experienced. Others are less
effi cient: they require longer exposures to brand a stimulus
as “familiar” and may soon forget what they have learned.
Classical Conditioning
A second way that infants learn is through classical
conditioning. In classical conditioning, a neutral stimulus
(the conditioned stimulus, or CS) that initially has no effect
on the infant eventually elicits a response (the conditioned
response, or CR) of some sort by virtue of its association
with a second stimulus (the unconditioned stimulus, or
UCS)that always elicits the response.
Operant Conditioning in Infancy
Even babies born prematurely are susceptible to operant
conditioning (Thoman & Ingersoll, 1993). However,
successful conditioning in very young infants is generally
limited to the few biologically signifi cant behaviors (i.e.,
sucking, head-turning) that they can control (Rovee-Collier,
1997). Newborns are also very ineffi cient information
processors who learn very slowly. So if you hoped to teach
2-day-old infants to turn their heads to the right and offered
them a nippleful of milk every time they did, you would fi nd
that they took about 200 trials, on average, to acquire this
simple habit (Papousek, 1967).
Can Infants Remember What They Have Learned?
Earlier, we noted that very young infants seem to have very
short memories. Minutes after they have habituated to a
stimulus, they may begin to respond once again to that
stimulus, as if they no longer recognize it as familiar. Yet,
the simple act of recognizing a stimulus as “familiar” may
not be terribly meaningful to a neonate, or even a 2-monthold. Might young infants be better at remembering
behaviors they have performed and that have proved to be
reinforcing?
Newborn Imitation or Observational Learning
The last form of basic learning we will consider is
observational learning, which results from observing the
behavior of other people. Almost anything can be learned
by watching (or listening to) others. For example, a child
may learn how to speak a language and tackle math
problems, as well as how to swear, snack between meals,
and smoke by imitating his parents.
Newborn Imitation
Researchers once believed that infants were unable to
imitate the actions of another person until the latter half of
the first year (Piaget, 1951). But beginning in the late 1970s,
a number of studies began to report that babies less than 7
days old were apparently able to imitate a number of adult
facial gestures, including sticking out their tongues, opening
and closing their mouths, protruding their lower lips (as if
they were sad), and even displays of happiness (Field et al.,
1982; Meltzoff & Moore, 1977)
Advances in Imitation and Observational Learning
An infant’s capacity to imitate novel responses that are not
a part of her behavioral repertoire becomes much more
obvious and more reliable between 8 and 12 months of age
(Piaget, 1951).