CHD EXAM 2 Chapters 5 7 2 Chapter 5 The Perceptual and Physical Development In Infancy PHYSICAL GROWTH IN THE FIRST TWO YEARS o Changes in weight The avg newborn weighs 7 5 lbs and measures about 20 inch from head to toe Birth weight typically doubles by 5 months to 15 lbs Birth weight triples by first birthday to 22 lbs Baby gains only 5 to 6 pounds in second year 4 to 5 in third o Changes in height Increases by about half in first year to 30 inch 5 6 inches in second year Tapers off from the first to the second year Babies tend to grow in spurts rather than in an even progression o To ensure child s safety as he or she grows must childproof your home NUTRITION IN INFANCY o Breast milk contains all of the required nutrients for infant s needs during the first 3 4 months Offers several important health advantages over formula Mothers who breast feed are less likely to develop diabetes and same thing for their kids Lower level of pancreas and breast cancer in women Colostrum fluid that the breast will produce when the baby sucks at the breast Helps with o Formula made of modified cow s milk is nutritionally acceptable for babies of mothers who cannot o Parents should not rely on their own intuition or on unreliable sources in establishing good nutrition immunity for baby breastfeed for their infants THE DEVELOPMENT OF THE BRAIN o No greater risk to development than endangering the CNS o Brain begins to form days after conception o Early prenatal 250 00 new cells minute 100 billion cells in newborn o Synapse is structured to allow impulses to be conducted from cell to cell by neurotransmitters Begin to develop in very large numbers prenatally Increase in large numbers through first 3 years of life Process called synaptogenesis At highest density neuron 15 000 synapses brain 1 000 trillion 5 more than adult brain End of second year rate of new synapses levels decrease and synapses begin to appear Pathways that get used survive unused disappear pruning o The greater the variation and organization of incoming stimuli the greater the number of pathways that survive Leveling off from age 2 10 Apoptosis cell suicide Cells engage in a series of processes where they destroy themselves o Ex In womb when hand is developing apoptosis creates the creases that separate the fingers Manage storage and transfer of all info necessary to function Evolving system of circuits if one part damaged another can take over o CNS Plasticity o Examining the brain PET scan measuring metabolic change Neuroimaging MRI measuring oxygen utilization Cannot be used effectively with infants and young children SENSORY AND PERCEPTUAL DEVELOPMENT IN INFANCY o Sensation ability to register info and transmit to CNS o Perception processing sensory info by the brain o How infant perception is studied Visual preference method Researcher presents pairs of stimuli to the brain Detects which stimulus the infant is looking at by reflection on the pupil of the infant s eye Showed that 2 day old infants discriminate among visual stimuli and preferred patterned stimuli like faces and circles to disorganized lines Method of event related potentials Electrodes attached to scalp of infant Measures changes in electoral activity in response to changing stimuli presented to the infant Brain wave patterns indicate infant perceived stimuli as different Habituation dishabituation procedure Stimulus repeated over and over at same intensity cause infant to habituate to the stimulus o Intensity of response decreases When response at rate of original level subtle change to stimulus introduced o If the infant does not alter its behavior the change was not perceived o If change dishabituation child discriminated change in stimulus High amplitude sucking technique Special pacifier with internal sensing device o Indicates sucking rate or intensity Increase sucking activates visual or auditory stimulus If infant likes the stimulus will keep sucking o infants increased the intensity of sucking to maintain a recording of their mothers voices THE DEVELOPMENT OF VISUAL PERCEPTION o The eye Light waves enter the eye through the lends and land on the retina Retina layered tissue on back of eye light sensitive nerve cells o Transforms visual info into neural impulses Optic nerve carries impulse The fovea center of retina densely packed cells discriminates detail necessary to perceive objects Infant visual acuity sharpness is low because retina and fovea not mature at birth a newborn can see at 20 feet approximately what an individual with perfect vision could see at 500 feet Acuity improves during first months of life adult like by 6 months Eye uses ciliary muscles to bend light waves toward fovea Develops gradually over few weeks of life Adult like at 3 months o Tracking moving objects in space Cannot perform reliably until end of second month Not efficient until 3 4 months By end of 4th month eyes can locate objects in visual field focus at varying distances move Smooth pursuit movements enable tracking of movement of objects in space from object to object and track their motion Newborns have no knowledge of objects or boundaries o Object perception o Scanning object contours Infants have no familiarity with images that come into their view Neonates fixate on external contours By second month infants switch to scanning mostly interior features o Separating figure from ground Differentiating objects from its background separating the figure from the ground Infants are best able to make out objects they see frequently and that move in relation to other objects and backgrounds No object meets this better than the primary caregiver s face o The face as a preferred object Scientists have confirmed that the human face takes on special significance for the young infant but this preference for faces does not appear to be innate some learning is involved Plays role in infant s emerging facial expressions o Depth perception Infants must learn to process 3 types of visual information Binocular information o Estimate distance of an object o Well developed by 4 months Kinetic information object o Emerges during the first month of life Pictorial information o Near object moves more rapidly across retinal surface than a more distant the first two years AUDITORY PERCEPTION o Perspective objects are judged closer or farther by their relative size in a picture o Superimposition objects that block the view of others are closer o Develops between 5 7 months Visual cliff
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