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Physical Development in Infancy
Chapter Review
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Four principles of growth in infancy are the cephalocaudal principle, the proximodistal principle, the principle of hierarchical integration, and the principle of the independence of systems.
The nervous system comprises the brain and the nerves that extend throughout the body.
Neurons are the basic cells of the nervous system, which can communicate with other cells using dendrites, axons, and synapses.
In the first two years after birth, a baby's brain will establish billions of new connections between neurons. Later, the brain prunes down unnecessary neurons and connections as a result of the infant's experiences.
Plasticity, the degree to which a developing structure or behavior is modifiable due to experience, is relatively great for the brain. An infant's sensory experience affects both the size of the individual neurons and the structure of their interconnections.
A sensitive period is a specific, but limited, time, usually early in an organism's life, during which the organism is particularly susceptible to environmental influences relating to some particular facet of development.
One of the most important ways behavior becomes integrated is through the development of various body rhythms. One of the major body rhythms is that of an infant's state, the degree of awareness it displays to both internal and external stimulation.
At the beginning of infancy, sleep is the major state that occupies a baby's time. At first, REM-like sleep takes up around one-half of an infant's sleep and some researchers think that this type of sleep provides a means for the brain to stimulate itself.
Reflexes are unlearned, organized involuntary responses that occur automatically in the presence of certain stimuli.
Reflexes have survival value, form a foundation for future, more complex behaviors, stimulate the brain and can signal problems in development.
Infants are able to accomplish different types of gross motor movement including lifting their heads, propelling themselves, crawling, and eventually walking. Fine motor skills also develop throughout infancy through the coordination of limbs, reaching, and grasping.
Both gross and fine motor skills follow a sequential developmental pattern in which simple skills are combined into more complex ones.
Norms represent the average performance of a large sample of children of a given age.
The Brazelton Neonatal Behavior Assessment Scale is one measure used to determine infants' neurological and behavioral responses to the environment.
Because norms are averages, they mask large individual differences among infants and also hide the fact that the sequence of attainment of certain behaviors may differ from infant to infant. In addition, many of the norms that are used were based on samples of middle and upper class Caucasian youth.
Variations in the timing of motor skills seem to depend in part on parental expectations of what is the appropriate schedule for the emergence of particular skills. Activities that are an intrinsic part of a culture are apt to be taught purposely leading to the likelihood that the skill will emerge earlier.
Without proper nutrition, infants cannot reach their physical, cognitive, or social potentials.
Breast milk contains all the nutrients necessary for growth, offers some degree of immunity to a variety of childhood diseases, is more easily digested than cow's milk or formula, and is sterile, warm, and convenient for the mother to dispense.
There is evidence that breast milk may enhance cognitive growth, mothers report that breast-feeding brings about feelings of well-being and intimacy with their infants, and breast-feeding may hold health-related advantages for mothers.
Educational, social, and cultural support for breast-feeding is particularly important.
The processes that underlie infants' understanding of the world are sensation, the stimulation of the sense organs, and perception, the sorting out, interpretation, analysis, and integration of stimuli involving the sense organs and the brain.
A newborn's distance vision ranges from 20/200 to 20/600 but this vision grows increasingly acute. Binocular vision is achieved at around 14 weeks. Infants prefer to look at stimuli with patterns and are genetically pre-programmed to prefer particular types of stimuli.
Infants hear from the time of birth and even before and are born with a preference for certain sound combinations. Infants are more sensitive to certain high and low frequencies than adults. Sound localization abilities and discrimination of groups of different sounds are fairly good at birth. Infants are able to discriminate certain characteristics that differentiate one language from another and show a clear preference for some voices over others.
The sense of smell in infants is so well developed that young infants can distinguish their mothers based on smell alone. In addition, taste is sophisticated during infancy.
Infants are born with the capacity to experience pain.
Touch is one of the most highly developed sensory systems in newborns and it is one of the ways children gain information about the world.
The multimodal approach to perception considers how information that is collected by various individual sensory systems is integrated and coordinated.
Parents can ensure that their infants receive sufficient physical sensory stimulation by carrying their baby in different positions, letting infants explore their environment, engaging in rough-and-tumble play, letting babies touch and play with their food, and providing toys that stimulate the senses.
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