Chapter 4 – Infancy: Sensation, Perception, and Learning
Neonates: Newborn babies, their noses, ears and entire heads often bear the marks of the pressures
exerted on them as they passed through the birth canal. Their skin is often red, wrinkled, and blotchy,
partly as a result of floating for nine months in the amniotic fluid. Their heads are oversized in
proportion to their bodies, and their little legs appear weak, even useless, most of these
characteristics disappear even before the neonate period of three to four weeks is over.
A new baby's reflexes
Reflex: A human's involuntary response to external stimulation. Reflexes are some of the first
behaviours to appear in a new born, some of which are permanent , others disappear during
the first year of life, and in some cases these are replaced by voluntary behaviours that baby
learns early in life. Abnormalities in a baby's reflexes during the first days or weeks after can
be useful indicators for identifying visual and hearing problems.
Infant state: A recurring pattern of arousal in the newborn, ranging from alert, vigorous, wakeful
activity to quiet, regular sleep. Internal forces play a central role in infant states and their changes.
Sleep: The newborn on average sleeps about 70 percent of the time in a series of long and
short naps during the day and night. By 4 weeks a baby's period of sleep tend to be fewer but
longer and by 8 weeks the baby sleeps more during the night and less during the day. The
infant becomes less fussy as it gains control over its states of arousal.
Sudden infant death syndrome: SIDS refers to the sudden and unexpected death of an otherwise
apparently healthy infant under 1 year of age. The death usually remains unexplained after all known
and possible causes of death have been ruled out.
REM and non-REM sleep: Rapid-eye movement (REM) sleep is characterized by rapid, jerky
movements of eyes and, in adults, is often associated with dreaming; infants spend 50 percent of their
sleep in REM activity, whereas adults spend only about 20 percent. This activity is absent in the
remaining non-REM sleep. Even though infants have REM sleep there is no real way of knowing if
infants dream. If people are prevented from obtaining REM sleep they tend to be irritable and
disorganized during their later waking hours.
Autostimulation theory: The theory that during REM sleep the infant's brain stimulated itself and this
this, in turn, stimulates early development of the central nervous system. If this theory is right, the
speed with which infants reduce their percentage of REM sleep could depend on how much external
stimulation they receive.
Crying: Three different types of crying, reflective of the infant’s varying needs, have been
identified.Most mothers can distinguish between these types of cries but only when they are listening
to their own babies, men are less skilled than women and non-parents are less skilled than parents.
Basic: Linked to hunger, among other factors. Starts arrhythmically and at low intensity;
gradually becomes louder and more rhythmic; sequence is cry-rest-inhale-rest.
Angry: Same as basic pattern except that segments of crying, resting, and inhaling vary in length, and crying segments are longer. Causes include removal of a pacifier or toy.
Pain: Sudden in onset, loud from the start, and made up of a long cry followed by a series of
short, gasping inhalations. Causes include discomfort from soiled diaper, a pin prick, or
Colic: A prolonged period of unexplained crying in an infant, occurs in roughly 20 percent of infants,
usually begins between 2 and 4 weeks of age and its causes are not known. In most cases, it stops by
the time the baby is 3 or 4 months of age. Colic is usually harmless but in some cases it may indicate
an illness, such as a hernia or an ear infection.
How to soothe an infant
Infants soothe themselves: One way infants soothe themselves is by sucking, which the baby
routinely engages in, even while still in the utero. The soothing techniques that work change as
the infant develops. Sucking on a sweet liquid appears to be effective in calming a 2 week old
baby, but less effective for a 4 week old baby unless accompanied by eye contact with an adult.
Parents soothe their babies: A variety of techniques are effective in soothing, including rocking,
swaddling and massaging. In swaddling, a baby is wrapped tightly in a blanket or cloth, thus
keeping her arms and legs immobile. Swaddling has been used successfully in hospital
nurseries throughout North America and in may cultures around the world.
Evaluating the Newborn's Health and Capabilities
To find out about the health, maturity, and the capabilities of the newborn, tests of baby's reflexes
may be combined with other assessment techniques.
Brazelton Neonatal Assessment Scale: One of the most widely used tests for newborns. A
scale used to measure an infant’s sensory and perceptual capabilities, motor development,
range of states, and ability to regulate these states. The scale also indicates whether the brain
and the central nervous system are properly regulating autonomic responsivity. It is used to
identify infants at risk for developmental problems, and it can aid in diagnosing neurological
The infant's Sensory and Perceptual Capacities
Researchers have discovered that babies' sensory and perceptual capabilities are quite well developed
even at birth, allowing infants to begin adapting immediately to the environment.
Sensation: The detection of stimuli by the sensory receptors (eyes and ears).
Perception: The interpretation of sensations in order to make them meaningful.
Unlocking the Secrets of Babies' Sensory Capabilities
To study an infant's sensory capabilities researchers have relied on information from the autonomic
nervous system, which controls involuntary bodily function as heart rate and berthing. For instance, a
change in a baby's breathing following a change in the pitch of a sound suggest that the infants heart
the pitch change.
Violation-of-expectation: a technique used to study infants, it introduces an unusual or
impossible sight, such as an object floating in space. If, upon seeing this information, the baby
responds by altering his behaviour (by slowing down or stopping his rate of sucking), it
suggests that the baby knows something about objects normally work. Visual Preference Method: A method of studying infants; abilities to distinguish one stimulus
from another by measuring the length of time they spend attending to different stimuli. The
researcher presents an infant with two stimuli, if an infant looks longer at one stimuli than at
the other, we can assume that she can distinguish between the two stimuli.
Habituation: The process by which an individual reacts with less and less intensity to a
repeatedly presented stimulus, eventually responding only faintly or not at all. Habituation is
widely used to explore infants' sensory and perceptual capabilities.
Hearing: Babies Are Good Listeners
An infant's hearing can be tested shortly after birth and these tests show that newborn's hearing is
extremely well developed, although it is not as developed as adults. For a newborn, a sound must be
louder—about 10 to 17 decibels louder—than the sound that an adult can detect. Babies are less
sensitive to low pitched sounds; they are more likely to hear a sound that is high in pitch. Over the first
two years babies rapidly improve in their ability to discriminate sounds of different pitches, until they
eventually reach adult levels of d