Child Development - A Thematic Approach
, Fifth Edition
Basic Learning and Perception
Basic learning processes in infancy and childhood
Developmental psychologists have found evidence for a number of basic learning processes in early infancy and childhood.
Habituation is the gradual decline in responding following repeated occurrences of the
same stimulus. When a response reoccurs after a change in the familiarized stimulus, an individual is displaying recovery from habituation, or dishabituation. Nearly all infants demonstrate habituation, but premature, brain-damaged,
and younger infants show less rapid habituation and less rapid recovery from habituation than older, more mature infants.
In classical conditioning, a neutral stimulus, called the conditioned stimulus (CS), becomes associated with a stimulus that spontaneously elicits an inborn response. It is the unconditioned stimulus (UCS) that normally elicits the unconditioned response (UCR). Following a number of pairings of the CS with the UCS, the CS alone will
come to elicit a response similar to the UCR. The response that is elicited by the CS alone is called the conditioned response (CR). Infants as young as two hours have been shown to exhibit classical conditioning.
Newborn infants' limited behaviors, however, restrict the CRs they can learn. As infants become older classical conditioning occurs more rapidly and involves a broader
range of stimuli.
|Research Applied to Parenting: Reducing Sleep Disturbances Through Changes in Learned Behavior
Operant conditioning involves changes in a behavior as a result of the consequences
that follow the behavior. In general, behaviors increase in frequency when
followed by a positive reinforcement or by the removal of an aversive stimulus, or negative reinforcement. Behaviors decrease in frequency when they are followed by the removal of
rewards (negative punishment) or the presentation of an aversive event (positive punishment). Experimental evidence also exists for operant conditioning in newborns within a few hours after birth.
Sleep disorders and conditioning
. Principles of classical and operant conditioning may contribute to sleep
difficulties for infants and young children. Picking up, rocking, and other
attention provided by parents when infants are ill or upset can serve to maintain fussing, crying,
and other behaviors well after the problem is resolved. However, the principles
of learning can also be applied to reduce sleep disturbances. For example,
parents can provide regular positive routines before bedtime, encourage sleep within the child's crib, provide appropriate alternative cues such as a blanket or toy to
promote sleep, and eliminate reinforcers that might encourage the child's attention-getting efforts at bedtime. Parents may wish to initiate delayed responding, that is, implementing an increasingly
longer interval before checking to see that an older infant or young child
is all right if having difficulty falling to sleep.
Imitation is the process whereby an infant repeats a response that another
individual, the model, has made. Some researchers have reported that one-
or two-day-old newborns can imitate facial expressions. Other psychologists
have questioned whether the infants' behaviors are true imitations or biologically programmed responses to any
external stimulation. Even before one year of age, the infant demonstrates deferred imitation, the ability to imitate a model's behavior hours, days, or even weeks later. After a year of age, they also differentiate behaviors that are intentional
compared to those that are unintentional.
Implicit learning refers to abstract knowledge not available to conscious reflection. This knowledge is acquired incidentally from other
processing, and therefore the learning is unintentional. We are sensitive
to the regularities that are present in the physical and social world, and
therefore implicitly learn these regularities or patterns.
Sensory and perceptual capacities
Psychologists distinguish between sensation, the registration of basic information such as sights and sounds by the sensory
receptors and the brain, and perception, the organization and interpretation of sensations.
Measuring infant sensory and perceptual capacities
Most of the techniques that researchers have developed to study infant sensation and perception involve measures of attention. Infants often display preferential looking at some kinds of stimuli. Researchers
have found that infants prefer complex visual patterns such as faces or bull's-eye patterns over solid-colored circles. Habituation, when the infant pays less and less attention to a familiar object,
has also been used to examine sensory capacities. Operant conditioning procedures
have also been used to study infant perception. Infants are rewarded with
food or other pleasant outcomes for the production of a response, such as sucking or head turning,
in the presence of a particular stimulus. Physiological responses such as
heart rate or neurological brain activity have also been used to examine
the sensory and perceptual abilities of infants.
|Examining Research Methods: Habituation Procedures
The logic of the habituation procedure rests on the finding that infants
presented with the same stimulus over repeated trials will decrease their
attention to that stimulus. If the stimulus is then altered in certain ways and the infants interpret
the modification as a change, they may demonstrate recovery from habituation,
that is, renew their attention to the altered stimulus. To illustrate this
procedure, a study is described in which the results suggest that two month old infants could detect
the illusory shape of a black square with points of light on a surface appearing
much like starlight in a black sky. When the square moved along a path in
the center of the background, infants paid attention to it. However, with repeated trials, their
looking time decreased. Infants dehabituated when new test patterns were
The human infant is an active perceiver of the visual information in the environment. Visual accommodation is the process whereby the lens changes its shape so that objects at different
distances from the eye can be brought into focus on the retina. Newborns
have limited accommodation and best discriminate objects located approximately eight to twenty inches away. Saccades, rapid movements of the eye for inspection of objects or viewing in the periphery,
occur immediately after birth. However, the newborn's saccadic eye movements are slow and range over only small distances. By one month, infants' saccades are similar to those of adults. Smooth visual pursuit consists of following a slowly moving target with smooth, continuous movements
of the eyes. By six to eight months of age this capacity appears adultlike. Infants younger than two months do not show reliable vergence (rotation of the eyes to focus on withdrawing and approaching objects), but
by three months they demonstrate this skill more reliably.
How well an infant can see is determined by measures of visual acuity, the ability to make discriminations among contours, borders, and edges in
the visual array. Visual acuity improves rapidly in the first six months
after birth. The retina contains rods and cones, two types of receptor cells. Rods are sensitive to the intensity
of light, whereas cones are sensitive to wavelengths of light that are responsible
for color perception. By three months of age, and possibly before, infants
possess adultlike color vision.
Not all infants have normal visual development. Infants may be born with
cataracts or have amblyopia, or lazy eye. A child with amblyopia (which may
or may not be detectable by "cross-eyed" appearance) can lose vision and depth perception, unless care is taken early to allow the weaker eye to strengthen.
Visual information processing in infants under two months of age is governed
primarily by relatively simple elements such as contours, angles, and motion.
After two months of age, scanning becomes more systematic. The externality effect refers to the fact that infants less than two months old tend to look only
at the outer contours of a complex stimulus. Older infants, however, will
scan the internal features of a complex stimulus, thereby processing the entire pattern. The recognition of "subjective" contours is a source of evidence that by three to four months of age, infants
perceive patterns rather than isolated angles or features. The face is a
visual pattern that is obviously important to the infant and is preferred very early in infancy.
Kinetic cues are helpful in identifying objects. Three-month-olds (but not newborns) will
perceive a partially occluded object as a unified whole if the visible pieces
of the object are seen moving together. Kinetic cues are also used in the perception of biological motion. When a
pattern of lights simulates a person walking, five-month-olds (but not three-month-
olds) seem to give special meaning to this pattern.
The ability to perceive depth is partly a result of binocular vision, the reception of slightly different visual inputs
by the two eyes. The synthesis of these two images into a single, three-dimensional
percept is called stereopsis. Depth perception is also made possible by kinetic cues that come from eye movements, head or body movements, and movements of objects in the
environment. Studies using the visual cliff have found that infants who are able to crawl usually will not crawl to the
deep side of the cliff. At five to seven months, infants appear able to detect pictorial depth cues (which can be perceived by one eye)
such as relative size, shadows, interposition of surfaces, and linear perspective.
Babies begin responding to sound stimuli several weeks before birth. Remarkably, newborns prefer sounds they heard prenatally.
Prenatal familiarity helps to explain why newborns prefer to listen to a
recording of their mothers' voices rather than to a stranger's voice. Some expectant mothers expose the fetus to auditory and vibroacoustic events with the goal of stimulating
prenatal learning and development. However, the benefits of such experience
are unknown, and there is even concern about damaging delicate sensory organs.
Although infants can detect sound before birth, their hearing improves after birth. Newborns display sound localization, the ability to locate a sound by turning the head or eyes in the direction
of the sound; however, they are less precise in locating the position of
a noise than children or adults. Infants of two to three months begin to recognize changes
in sound patterns, such as the duration of intervals between bursts of sound.
Six-month-olds can distinguish more complex rhythms and melodies. The importance
of sound pattern perception applies not only to music appreciation but also to the phrasing
and perception of the sound rhythms that underlie speech.
Infants under six months have the perceptual capacities to discriminate the
basic distinctive speech sounds called phonemes in any of the hundreds of languages spoken around the world. Theoretical
accounts of these findings suggest that infants either are born with a "speech module," an innate capacity to detect and process speech sound, or make use of general
auditory capacities and quickly learn to use these abilities to process speech sounds. Evidence
for innate speech perception comes from studies on categorical perception. Categorical perception occurs, for example, when small changes in voice onset time (VOT) of a phoneme such as ba are not perceived but changes in VOT across a category boundary such as ba versus pa are detected. Infants as young as one month demonstrate categorical perception
for many speech sounds. However, by about one year of age, infants who have not heard certain phonemes in their language environment lose the ability to
|Controversy: Should the Fetus Undergo a Sensory Curriculum?
Many prospective parents are eager to help their child's development. Some parents extend this to the fetus, but exposing the fetus
to patterned sounds, music or even words and numbers. Controversy exists over whether or not there are lasting positive
effects from this experience, and some believe over-stimulation might actually
have negative effects.
Smell and taste
Newborns can detect many odors, as measured by their facial expressions in response to
odor stimuli. By five days of age, breast-fed infants prefer their own mothers' breast pads to other mothers' breast pads. Extended experience with a particular odor within forty-eight hours of birth leads to preferences for that odor. In addition, reliable
sex differences have been observed; at all ages, females are more sensitive
to odors than males.
Infants respond differentially to taste stimuli shortly after birth, making
relaxed facial responses to sweet, lip pursings to sour, and mouth openings to bitter.
Innate taste preferences may help infants meet nutritional needs and avoid
Sensitivity to pain
Traditionally, newborns and very young infants have seldom received medication to reduce
pain. Infants were thought not to experience pain or to remember it if experienced.
Furthermore, the consequences of exposure to pain-reducing medication for
the infant have been a concern. Research indicates, however, that the neurological mechanisms for
detecting pain develop early, and behavioral responses suggest sensitivity
to pain, and even some memory of it, in young infants. The use of pain-reducing
medications or alternative methods of reducing distress when exposing infants to painful procedures
is now recommended.
F. Intermodal perception
The coordination of information from multiple sensory systems is called intermodal perception. According to James and Eleanor Gibson, infants are amodal at birth; that
is, they may be unable to differentiate stimulation from the different sense
organs. As they gain experience, infants and children learn perceptual differentiation. Alternative theoretical perspectives posit that infants can identify separate sensory inputs
but must learn (through enrichment, for example) to coordinate the relationships
among them. Research has revealed that infants as young as three-and-a-half
months demonstrate intermodal perception. Infants also appear able to coordinate vision and touch
information. Six-month-olds who manipulate an object with their hands can
then recognize the object by visual inspection alone. However, even one-month-olds
can coordinate visual information with objects they have mouthed. The evidence is not conclusive
regarding the innate or learned coordination of sensory information; there
may be some truth to both perspectives.
Examples of intermodal perception
To determine whether infants link visual and auditory events, Elizabeth
Spelke presented infants with the option to view two films. A soundtrack
playing in the background matched one of the films, and four month old infants
preferred to watch the film that matched the soundtrack. Other research shows coordination
between sight and touch. For instance, infants seem to recognize (by sight)
the difference between hard and soft objects that they had been given the
opportunity to mouth.
Perceptual development throughout childhood
Although infants show remarkable perceptual abilities at birth or shortly
thereafter, perception does change with further development. Children become
faster and more efficient at perceptual discrimination as their attention to features of the environment
becomes more focused and organized.
Eleanor Gibson's theory of perceptual learning emphasizes three developmental changes: increasing specificity in perception,
improved attention, and more economical and efficient acquisition of perceptual
Preschoolers' perception is frequently influenced by the whole; that is, they have difficulty
analyzing objects according to specific features and attributes. They may
be able to detect the parts or features, but this ability may depend on the
complexity of the stimuli. The simpler the stimuli, the more likely younger children will be able to report
seeing both parts as well as the integrated whole.
Experience and perceptual development
Research with animals and humans has revealed that experience is very important
for maintaining perceptual capacities. Sensory deprivation, for example,
has serious detrimental consequences for the developing infant. Infants born with cataracts
show a gradual and permanent loss in their ability to discriminate objects
over time. There are also sensitive periods, such as that for binocular vision,
during which perceptual capacities may be lost if specific external stimulation is limited. Perception
also appears to be influenced by the child's sociocultural experiences.