Physical Growth and Development in Infancy by fjzhangweiyun


									Chapter 3     Physical and Cognitive Development in Infancy

                         Physical Growth and Development in Infancy

       large relative to the rest of the body
       flops around uncontrollably
Infant becomes capable of

 usually walking
                        Cephalocaudal and Proximodistal Patterns
Cephalocaudal -- sequence in which the earliest growth always occurs at the top, beginning with
the head

       physical growth and differentiation of features gradually works down from top to
Proximodistal -- sequence in which growth starts at the center of the body and moves toward the

       infants control the muscles ofThe First Year arms before they control their hands
                                       their trunk and

Average North American newborn -- 20 inches long; 7½ pounds
Most newborns lose 5 to 7 percent of their body weight adjusting to feeding
They double their birth weight by the age of 4 months; nearly triple it by their first birthday
Infants grow about 1 inch per month during the first year

                                    From Age 1 to 2 Years
     At 2 years of age, children weigh approximately 26 to 32 pounds

       gaining a quarter to half a pound per month
       the average child is 32of theirinches tall--nearly half of their eventual adult height
At 2 years,
            attain about one-fifth
                                   to 35
                                         adult weight

                                            The Brain
Cerebral cortex covers the forebrain like a wrinkled cap
Two halves, or hemispheres, based on ridges and valleys in the cortex
Four main areas, lobes, in each hemisphere
        frontal lobes, occipitalfunctiontemporalhemisphere or the other
Lateralization -- specialization of
                                           in one
                                                  lobes, parietal lobes

     Parts of the neuron

       Axon carries signals away from the cell body
       Dendrites carry signals toward it
       Myelinfaster downa the axonfat cells -- provides insulation and helps electrical signals
                sheath -- layer of

       At the end of the axon synapses buttons, which release chemicals called
        neurotransmitters into
                                are terminal

       Synapses -- tiny gaps between neurons' fibers
                                         Changes in Neurons
Chemical interactions in synapses connect axons and dendrites, allowing information to pass
from neuron to neuron
The pace of myelination also varies in different areas of the brain
The infant’s brain is literally waiting for experiences to determine how connections are made

                                  Changes in Regions of the Brain
      Both heredity and environment influence synaptic overproduction and subsequent
“Blooming (development) and pruning” vary considerably by brain region
      Pruning -- unused connections are replaced by other pathways or disappear
Prefrontal cortex -- the area of the brain where higher-level thinking and self-regulation occur

     Considerable individual variation in how much infants sleep

        typical newborn sleeps 16 to 17 hours a day
        preferred times and patterns of sleep also vary
Infants spend a greater amount of time in REM (rapid eye movement) sleep

        by 3 months of age, the percentage of time in REM sleep decreases
     Sudden infant death syndrome (SIDS) -- condition that occurs when infants stop breathing,
     usually during the night, and die suddenly without an apparent cause
     SIDS is the highest cause of infant death in the United States

       Risk of SIDS is highest at 2 to 4 months of age
                                      Risk Factors for SIDS
     SIDS decreases when infants sleep on their backs
     More common in low birth weight infants
     Infants who are passively exposed to cigarette smoke are at higher risk
     More frequent in infants who sleep in
     soft bedding
     Less likely in infants who use a pacifier when they go to sleep
                                   Benefits of Breast Feeding
Appropriate weight gain a
     d lowered risk of childhood obesity
     Fewer allergies
Prevention or reduction of diarrhea, respiratory infections, bacterial and urinary tract infections,
and otitis media
     Denser bones in childhood and adulthood
     Reduced childhood cancer and reduced incidence of breast cancer in mothers and their
     female offspring
     Lower incidence of SIDS

                             When Mother Should Not Breast Feed
     If she is infected with AIDS or any other infectious disease that can be transmitted through
     her milk
     If she has active tuberculosis
     If she is taking any drug that may not be safe for the infant

                                        Nutritional Needs
Nutritionists recommend that infants consume approximately 50 calories per day for each pound
they weigh
      This is more than twice an adult’s requirement per pound
      Many U.S. parents are feeding their 4- to 24-month-old babies too few fruits and
      vegetables, and too much junk food

                                  Dynamic Systems Theory
     Infants assemble motor skills for perceiving and acting, which are coupled together

       When infants are motivated to do something, they might create a new motor

       Mastering a motor skill requires the infant’s active efforts to coordinate several
        components of the skill

                                     Mastering a New Skill
     The infant is motivated by a new challenge
     Partially accomplishes the task
     “Fine tunes” movements to make them smoother and more effective
     “Tuning” is achieved through repeated cycles of action and perception of the consequences
     of that action
Reflexes -- built-in reactions to stimuli
     Genetically carried survival mechanisms

Allow infants to respond adaptively to their environment
     Example reflexes

       Rooting and sucking, Moro or startle reflex, coughing, sneezing, blinking, shivering,
        and yawning
                                       Gross Motor Skills
     Skills that involve large-muscle activities

       Sitting with support -- 2 months
       Sitting upright without support -- 6 to 7 months of age
       Pull themselves up and hold on to a chair -- 8 months
       Stand alone – 10 to 12 months
With experience, babies learn to avoid risky situations, integrating perceptual information with
the development of a new motor behavior

                     Gross Motor Development in the Second Year
Toddlers become more mobile
     13–18 months

        can pull a toy attached to a string
        use their hands and legs to climb up a number of steps
18–24 months

        toddlers can walk quickly or run stiffly
        walk backwards without losing their balance
        stand and kick a ball without falling and stand and throw a ball
        jump in place
                                        Fine Motor Skills
Finely tuned movements

            anything that requires finger dexterity
At birth, infants have very little control over fine motor skills
      During the first two years of life, infants refine how they reach and grasp

       Perceptual-motor coupling is necessary for the infant to coordinate grasping
       Experience plays a role in reaching and grasping
                              Sensory and Perceptual Development
Sensation occurs when information interacts with sensory receptors -- the eyes, ears, tongue,
nostrils, and skin
      Perception is the interpretation of what is sensed
      Ecological View -- Gibsons

       Our perceptual system can select from the rich information that the environment

       We directly perceive information that exists in the world around us
                                Studying the Infant’s Perception
Perception brings us into contact with the environment in order to interact with and adapt to it
Visual Preference Method -- Infants look at different things for different lengths of time
     Orienting response -- to determine if an infant can see or hear a stimulus
Habituation -- decreased responsiveness to a stimulus after repeated presentations of the stimulus
     Dishabituation -- is the recovery of a habituated response after a change in stimulation

                                    Visual Acuity and Color
     Newborn’s vision is estimated to be 20/600 on the well-known Snellan eye examination
By 6 months of age -- vision is 20/40 or better
     By about the first birthday, the infant’s vision approximates that of an adult
By 8 weeks, possibly even by 4 weeks, infants can discriminate among some colors

                                 Perception of Pattern and Depth
     Infants prefer to look at a normal human face rather than one with scrambled features
     They prefer to look at a bull’s-eye target or black-and-white stripes rather than a plain
     Depth perception -- visual cliff

       Infants develop the ability to use binocular (two-eyed) cues to depth by about 3 to 4
        months of age

                                   Hearing, Touch, and Pain
     Prenatally at 7 months, infants can hear sounds such as mother’s voice and music
     Immediately after birth, infants cannot hear soft sounds or pitch as well as adults do
     Newborns respond to touch and feel pain
     Infants also display amazing resiliency

       Within several minutes afterand interact in a normal manner withperformed without
        anesthesia), they can nurse
                                     the circumcision surgery (which is
                                                                         their mothers

                                         Smell and Taste
     Newborns can differentiate among odors
     Sensitivity to taste might be present even before birth
     At only 2 hours of age, babies made different facial expressions when they tasted sweet,
     sour, and bitter solutions
     At about 4 months of age, infants begin to prefer salty tastes, which as newborns they had
     found to be aversive

                         Piaget’s Theory of Cognitive Development
     Piaget thought we build mental structures that help us to adapt to the world
     Adaptation involves adjusting to new environmental demands

                                 Processes of Development
     Developing brain creates schemes, which are actions or mental representations that
     organize knowledge

     Assimilation -- children use their existing schemes to deal with new information or

     Accommodation -- children adjust their schemes to take new information and experiences
     into account

     Organization -- is the grouping of isolated behaviors and thoughts into a higher-order
                                Equilibrium and Disequilibrium
     Cognitive conflict -- disequilibrium

        the child is constantly faced with inconsistencies and counterexamples to existing
     An internal search for equilibrium creates motivation for change

        the child assimilates and accommodates, develops new schemes, and organizes and
            reorganizes old and new schemes
Equilibration -- mechanism by which children shift from one stage of thought to the next

Cognition is qualitatively different in one stage compared with another

                                          Sensorimotor Stage
     Infants construct an understanding of the world by coordinating sensory experiences (such
     as seeing and hearing) with physical actions
     Lasts from birth to 2 years
     At the end of this stage, 2-year-olds can produce complex sensorimotor patterns and use
     primitive symbols
                                          Object Permanence
     Object permanence -- understanding that objects continue to exist even when they cannot
     be seen, heard, or touched
     One of the infant’s most important accomplishments
     Watch an infant’s reaction when an interesting object disappears. If the infant searches for
     the object, it is inferred that the baby knows it continues to exist

                   Evaluating and Modifying Piaget’s Sensorimotor Stage
The infant’s cognitive world is not as neatly packaged as Piaget portrayed it
     Some of Piaget’s explanations for the cause of change are debated
     Piaget's view of sensorimotor development needs to be modified
     Some researchers conclude that infants’ perceptual abilities are highly developed very early
     in development
     A-not-B error is the term used to describe the tendency of infants to reach where an object
     was located earlier rather than where the object was last hidden
     The core knowledge approach states that infants are born with domain-specific innate
     knowledge systems

                         Learning, Remembering, and Conceptualizing
Infants can learn through operant conditioning
Attention is the focusing of mental resources on select information and improves cognitive
processing on many tasks
      Joint attention involves individuals focusing on the same object or event and involves:

      The ability to track another’s behavior
      One person directing another’s attention
      Reciprocal interaction don’t blindly imitate everything they see and often make
Meltzoff (2007) concludes that infants
creative errors
      He argues that beginning at birth there is an interplay between learning by observing and
      learning by doing
      Critics say the newborns simply engage in automatic responses to a stimulus
      Memory involves the retention of information over time
      Some infants as young as 2 to 6 months can remember some experiences through 1½ to 2
      years of age
      Infantile or childhood amnesia -- few memories before age 3

                           Concept Formation and Categorization
Concepts -- ideas about what categories represent

        indispensable to competent cognitive development
Categories -- a way to group objects, events, and characteristics on the basis of common
By about 7 to 9 months of age, infants are able to form conceptual categories rather than just
making perceptual discriminations between different categories

                                 Language Development
Language -- a form of communication—whether spoken, written, or signed—that is based on a
system of symbols
     All human languages have some common characteristics

       Rules describe the way the language works
       Infinite generativity -- the ability to produce an endless number of meaningful
        sentences using a finite set of words and rules

                         Key Milestones in Language Development
Babies' sounds and gestures go through this sequence during the first year
       Crying: can signal distress, but there are different types of cries that signal different

       Cooing: about 1 to 2 months, gurgling sounds that arewith theincaregiver of the
        throat and usually express pleasure during interaction
                                                                 made the back

       Babbling: In thecombinations, first year, babiesba, ba” -- strings of
                           middle of the
                                         such as “ba, ba,

       Gestures: of age start using gestures, such as showing and pointing, at about 8 to
        12 months

                                Recognizing Language Sounds
    Phonemes -- the basic sound units of a language
    First words occur between 10 to 15 months (average is 13 months)
    Overextension -- the tendency to apply a word to objects that are inappropriate for the
    word’s meaning
Underextension -- the tendency to apply a word too narrowly

                                     Two-Word Utterances
Occurs by the time children are 18 to 24 months of age

       “Big car”
       “Whereisball?”use of short, precise words without grammatical markers such as
Telegraphic speech the
articles, auxiliary verbs, and other connectives

       “Mommy give ice cream”
                                      Biological Influences
The ability to use language requires vocal apparatus as well as nervous system capabilities
     Brain regions predisposed for language

       Broca’s area -- an area in the left frontal lobe of the brain involved in producing

       Wernicke’s area -- a region of the brain’s left hemisphere involved in language
Aphasia -- a loss or impairment of language processing as a result of damage to brain

                                      Biological Influences
Language Acquisition Device (LAD) -- Humans are biologically prewired to learn language at a
certain time and in a certain way and to detect the various features and rules of language

                                Environmental Influences
Behaviorists opposed Chomsky's LAD hypothesis

        Stated that language was nothing more than chains of responses acquired through
The behavioral view is no longer considered a viable explanation of how children acquire
Language is not learned in a social vacuum

  Most children learn at a very early age
Vocabulary development is linked to the family’s socioeconomic status and the type of talk
that parents direct to the child
Compared to professional parents, parents on welfare:
     Talked much less to young children
     Talked less about past events
     Provided less elaboration
Child-directed speech is language spoken in a higher pitch than normal, using simple words
and sentences
Other strategies include recasting, expanding, labeling

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