Chapter 5 Perceptual and Physical Development in infancy Physical Growth in the first two years The average newborn weighs 7 lbs and measures about 20 in Birth weight typically doubles by 5 months to 15 lbs and triples by first birthday 22 lbs Breastfeeding and formula are both nutritionally acceptable breastfeeding offers several important health advantages such as Changes as your baby grows Easier to digest Fights disease The Development of the Brain Central nervous system includes the brain most complicated physical structure in the body Nerve cell production stops just before birth but structure of brain continues to evolve through first ten years of life Synapse structured to allow impulses to be conducted from cell to cell by chemicals known as neurotransmitters Plasticity of the brain the ability for other parts of the brain to take over and function I e hemispherectomy removal of half a child s brain By second year synapses begin to disappear pathways hat get used repeatedly Pruning process of the nervous system eliminating senates and cells that have no survive those they get unused disappear Use it or loose it function or purpose Occurs mostly during adolescence Until further research it is recommended to parents and practitioners for early brain stimulation to remain speculative Sensory and Perceptual development in infancy How infant perception is studied Sensation refers to the ability to register information concerning internal and external events and to transmit that information to the central nervous system Perception refers to the processing of sensory information by the brain Visual preference method researchers present pairs of stimuli to baby then observes the infant from hidden vantage point between two stimuli then detects which stimulus baby is looking at Method of event related potentials electrodes attached to infants scalp to measure changes in electrical activity in the brain in response to changing stimuli presented to the infant Habituation Dishabituation procedure Habituation intensity of responses steadily decrease become less interested Dishabituation Infants changes response and notices the change in stimulus High amplitude sucking technique internal sensing device that indicates when infants rate or intensity of sucking increases visual or auditory stimulus The development of visual perception Retina a complex layered tissue on the back surface of the eye made up of light sensitive cells and nerve cells Fovea a densely packed set of highly sensitive cells at the center of the retina detail Visual acuity sharpness of vision Newborn vary 20 500 distances toward the fovea Tracking moving objects in space Ciliary muscles bend or focus light waves reflected off objects at varying Smooth pursuit movements enable infants to track movement of objects in space By the fourth month infants visual acuity can discriminate considerable detail Separating figure from ground Differentiating objects as separate entities Infants are best able to make out objects they see frequently and that move in relation to other objects and backgrounds Depth perception Objects in 3 dimensional space Infants learn to process three types of visual information 1 Binocular information the different locations of the two eyes in the head o Reasonably developed by about 4 months 2 Kinetic information when infants head moves side to side the image of near objects moves more rapidly across retinal surface than image of more distant object Visual cliff measure depth perception crawling infants placed on sheet of plate glass that creates illusion of a drop off as infant crawls across it 3 Pictorial information perspective objects of equal size are judged closer or farther away by their relative size in picture and superimposition objects that block out the view of other object are judged to be closer o Develops between 5 and 7 months Auditory Perception The ear is developed several weeks before birth By 6 months the auditory system s ability to detect different intensities of sound and variations in pitch is highly mature Newborns can locate sounds to the left or right of the head but that ability declines over next two months about comes back around 4 months Perception of speech sounds between sounds High amplitude sucking technique demonstrates neonates notices difference Scientists now believe that newborns possess innate perceptual mechanisms that facilitate the development of language Websource Babies start to develop language at birth Hearing loss can be found early You can promote your baby s ability to localize sound by providing an environment that is rich in sounds that come from easily identifiable sources Other Sensory Developments Taste and Smell Sensitivity to taste is present soon after birth Display slight smile when sucking movements to sweet substances purse the lips and wrinkly the nose and blink to sour substances spit up and choke on bitter substances Newborns sense of smell develops rapidly during the neonatal period Sense of smell may play important role in bonding breastfeeding mothers to infants Study showed that mothers recognized the smell of their 1 2 day old babies Websource Experiments were done to prove that babies do in fact feel pain it is not just a reflex Developing Motor Control Reflex Behaviors Reflexes involuntary stimulus response patters turns hear opens mouth and suck when check is stroked steps when feet contact surface sudden arching of the back and grasping motions of arms to loud noise Innate reflexes in human infants Rooting Stepping Moro of loss of support Babinski Grasping Tonic neck Sucking Eye blink toes fan out and foot curls when sole of foot is stroked grasp in response to pressure in plam head to one side and body in fencer position sucking to oral stimulation rapid closing of eye to sudden light or air puff Cerebral cortex has very little effect on behavior of newborn Reflexes are controlled by clusters of cells within the brainstem Brain stem is most highly developed component of central nervous system at birth purpose is to receive impulses from sensory receptors and transmit second input to musculature for specific motor response Disappearance of reflexes reflects increasing role of cerebral cortex A reflex that fails so appear or persists past its time may indicate neurological problem Early Spontaneous Movement Waving of the arms kicking their legs and open and closing their hands are patterned movements that emerge gradually
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