Chapter 5 Perceptual and Physical Development in Infancy Physical Growth First 2 years Average weight is 7 5lb and 20 inches as a newborn Birth weight doubles by 5 months and triples by 1 yr Height increases by 50 in the first year and additional 5 6 inches are added by 2nd year Change in Body Proportion Cephalocaudal Principle head and upper boy grow more than lower body o 8 wks head is half of body length o Birth head is 25 of length Proximodistal Principle grow from the center outward Childproofing collective set of precautions to ensure safety i e covering light sockets stairs baby gates Nutrition in Infancy Infants needs can be met by breast milk or formula Breast feeding promotes early development of infant s brain and has positive long term effects on cognitive intellectual development This offers immunological benefits that formula doesn t have Colostrum Breast fed babies are 72 less likely to have respiratory illness and 64 less likely a thin yellow fluid secreted by breast that contains antibodies for GI illness There is a 36 reduction in sudden death and Type 1 diabetes Development of the Brain Structure of the Brain Synapse where never cells meet Dendrite and axon terminal Neurotransmitter chemical transmitted Myelination happens in 28th week of gestation Insulating fatty coating that speeds up action potential and nerve impulse transmission Synaptogenesis density is when we are 3 years old 50 more of the adult brain synapses developing in first 3 years of life Highest synaptic Plasticity of the Brain other part of brain adapting when a certain part of the brain can t Plasticity perform Use it or Lose it disappear This levels off the number of synapses This is why we want to diversify stimuli and provide repetition to strengthen synapses when 2 10yrs old pathways that are used survive those that are unused Pruning removing of synapses cells that are not used occurs during adolescence Children who experience more varied more patterned more organized and more repetitious and challenging interaction will have better developed brains Typical interaction b n attentive and sensitive parents and infants provides everything a baby needs for healthy brain development Perceptual Development 1 Methods of Study a Sensation 2 Visual Development b Perception ability to passively receive and register information concerning internal an external events to transmit that to the CNS infants active searching for information and the processing of that sensory information by the brain seeking stimulation Mechanism of function that helps stimulate brain so it can grow c Electroencephalography measurement and interpretation of electrical d Habituation Dishabituation a particular stimulus is repeated over and over activity in the brain at same intensity Infants habituate response to stimulus steadily decreases A small change is applied no altered behavior no perception A small change is applied Changed response dishabituates discriminate change in stimulus a Structure of the Eye Light waves reflect off objects and enter the eye through the lens and land on the retina a complex layered tissue on the back surface of eye composed of light sensitive and nerve cells Discriminates detail densely packed set of highly sensitive cells at the center of the retina b Fovea c Visual acuity at birth is low as retina and fovea are not mature Becomes normal at around 6 months d Visual Perception and the Brain i Visual function in the newborn is regulated at subcortical brain levels 1 Deals with where the object is 2 Deals with who what the object is 3 Attempt to interact with the object ii Tracking moving objects at 4th month the eyes can locate objects in a visual field and focus on the individual objects at varying distances Piaget demonstrates that after 4 months infants began to engage in active search enabling them to follow an object when it was briefly blocked iii At 1 month can focus on internal contour if there is movement complexity Saccadic eye movement iv At 2 months scan mostly internal features Smooth tracking starts here instead of saccadic eye movement Infants best make out objects they see frequently and that move in relation to the background v Face is a preferred object associated with positive reinforcement and reduction of aversive stimuli i e hunger pain vi Ciliary muscles stretch lens allowing for focus By about 4 weeks baby can make out detail vii Visually initiated preemption reaching Visually directed preemption e Depth Perception Objects in 3D Space i Binocular Information different locations of eye produce different retinal images We need to blend these images and that s done around 4 5 months ii Kinetic Information differentiating and distinguishing objects when moving head side to side Image of near object moves more rapidly across the retina than does a distant object iii Occlusion blocking object is closer iv Visual Cliff lab tasks involving testing visual kinetic depth cues Propelling oneself through space is essential to learn to recognize depth cues v Pictorial Information provides distance cues that provide 3D perspective and super imposition Process to develop this depth is about 5 7 months of age a Auditory Processing begins as early as 28 weeks 7 8 months in womb a 6 month olds hearing auditory systems have the ability to detect different intensities of sound and variation in pitch Discriminate between loudness pitch and duration b Newborn response to noise is a reflex reflex weakens replaced with Voluntary response c Babies prefer to listen to speech sounds as compared to non speech sounds d Auditory system develops faster than visual 3 Auditory Development 4 Other Sensory Development a Taste Smell i Babies like sweet tastes Infants who experience greater variety of foods developed more diverse food preferences than those who had less variety ii Able to recognize scent of mother b Motor Control i Motor control increases with age ii Nature vs Nurture Myrtle B McGraw iii Reflexes iv first observable organized behaviors of newborns Involuntary stimulus response pattern I e rooting stepping moro Babinski grasping tonic neck sucking eye blink Startle reflex arms flail out and back arches Reflexes provide survival value v Involuntary reflexes at birth may be related to voluntary counterparts in later development Reflexes depend on circuitry in CNS good for neurological testing c Spontaneous Movement i Rhythmical Movement Stereotypes repetitious movement patterns that are
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