Early Infancy
Physical Development andBody Growth • Norms • Wide variability • Rates of Development • Cephadocaudal (head to toe) • Proximodistal (inside out) • Muscle, slow peaking at adolescence • Fat tissue fast, peaking at 9 mo • Racial and gender difference
Physical DevelopmentBrain • Neurons • Full Complement by 6 mos, possibility of regeneration later, best recovery for <1yr • Connections throughout life, pruning • Glial • Supporting brain tissue peaking at 2 yrs • Myelin • Complete by 3 years
Physical DevelopmentBrain, cont’d • Cortex • Functionality emerges as cortical areas mature • Cephadocaudal trend • Lateralization evident at birth • Right body advantage for reflexes • Increased electrical activity on left hemisphere for speech sounds, and on right for nonspeech sounds • Plasticity in first year, reduced following
Factors Affecting Growth • Heredity • Evidence from twin studies • Nutrition • Needs twice adults in infancy due to rapid growth • Breastmilk perfect food • Balance of fat/protein • Complete food if mom nourished • Immunity • Digestible
Malnutrition • Not just a developing world problem • 12%NA, 40% worldwide, 4-7%severe (20 mill) • Marasmus • Appears 1st year, diet low in all nutrients, tied to malnourished moms • Kwashiorkor • Between 1-3 yrs after weaning, low protein levels, body breaks down own protein sources • Non Organic Failure to Thrive • Lack of affection, occurs at all se levels, can have lasting emotional, physical effects, intervention possible
Motor Development • Coordination of simple motor acts into complex systems • E.g., Voluntary Reaching • Opens up new way of exploring the world, having cognitive implications • Birth - Prereaching: swipes or swings usually unsuccessful, drop out at 7 weeks • 3 mos - Voluntary reaching, as effective reaching in dark as light, thus not visually guided • 5 mos - will adjust posture for out-of-reach items • 9 mos - can change course to reach for moving item
Motor Development • E.g., grasping • Grasp reflex gives way to ulnar grasp (fingers closing against palm of hand) • 4-5 mos both hands used to explore objects • 8-11 mos reaching and grasping become very smooth and release cognitive load for processing information about the explored objects • 1 yr pincer grasp employed (opposing thumb and forefinger)
Maturation or Experience? • Denis (1940) • Hopi babies swaddled but walk at same age • Iranian orphanage study • Restricted motor experience led to delays in motor milestones like crawling/walking • Scooting preferred, doesn’t lead to standing/walking • Super (1976) • Kenyan babies sit earlier after training in scooped out holes in mud (baby seat idea) • Kaplan & Dove (1987) • Paraguayan babies walk later as kept in close contact with moms, later very skilled climbers • Stimulation can accelerate, limited by growth patterns
Learning Mechanisms:Classical Conditioning • CS paired with US to produce CR • Needs to have ecological significance (does it make sense for survival?) • Blass et al (1984) show cond of sucking (CR) by stroking forehead (CS) in nursing situation (US) • Watson and Little Albert conditioning of fear, strong between 8-12 mos, when they are mobile enough to escape unpleasant events
Learning Mechanisms:Operant Conditioning • Stimuli that follow acts either increase (reinforcer) or decrease (punisher) • 2 behaviors: sucking and head turning • Used to determine the variety of sensory/perceptual distinctions that can be made by infants and preferences • DeCasper recognition of mom’s voice • Eimas, Werker categorical speech perception
Habituation • Habituation is the gradual reduction of responding when an item is repeatedly presented • Dishabituation is increase in responding when novel stimulus is presented • Subtype is the surprise technique for presenting event that contradicts expectations to test for knowledge that infant has • A powerful method for determining what infant discriminates • Baillargeon studies of object concept
Imitation • Experimenter models simple actions (e.g., tongue protrusion, head turn) in burst-pause sequence, looks for evidence of imitation in infant • Find imitation in newborn of tongue protrusion, head turn, (Meltzoff research), and simple emotional expressions (Field research) • Paradigm also used in older infants • E.g., delayed imitation, imitation of actions on objects, imitation of intended actions - all Meltzoff studies
Perceptual Development:Hearing at Birth • NB recognize mother’s voice, and particular story mother read inutero (DeCasper) • NB categorize sounds of speech as adults do (Eimas) • NB can categorize sounds of speech from any language; adults cannot (Werker) • NB prefer parentese (Kuhn) • NB Localize roughly (L/R) sounds in space and look toward sound source at birth (MacFarlane)
Perceptual DevelopmentHearing Refinements • 6 mos lose ability for universal distinction of language sounds (Werker, Kuhl) • 6-12 mos infants prefer speech with natural vs. random pauses (Hirsh-Pasek) • 6-12 mos. Infants prefer natural rhythm structures of individual words (Jusczyk) • Highly specialized, innate structure for perceiving language of any culture, rapid fine tuning to the language of the culture infant lives in
Perceptual DevelopmentVision at Birth • Immature • Rods and cones not yet organized, but differentiated • Acuity good at 8-10 inches, poor beyond • NB visual scanning of objects focused on single element • NB depth perception uses motion cues • Color vision incomplete at birth
Perceptual DevelopmentRefinements • Visual acuity goes from 20/660 at Birth to 20/20 by 11 months, due to immature fovea • By 4 mos eyes coordinated providing stereoscopic vision, begin visually guided reaching, show categorization of color as adults • At 6 mos sensitive to pictorial cues to depth (such as shading, occlusion etc.)
Perceptual DevelopmentOrganization • The question of attaching meaning to information acquired through the senses • Scanning • Scanning internal elements and boundaries by 2 mos (Salapatek), will scan internal earlier if elements are moving (Bushnell) as in dynamic human face • Preference for human face around 2 mos
Perceptual DevelopmentOrganization, cont’d • Millewski • Are infants sensitive to a change in the overall form (configuration) when elements remain constant • Yes, at 3 mos • Bertenthal • Can infants perceive illusory forms • Yes, at 7 mos, not at 5 mos. • VanGiffen • Do infants notice when the principle of good form is violated? • Yes, at 3 mos
Perceptual DevelopmentIntermodal Perception • Precursor may be looking toward a sound source • Innate or learned association? • Most find intermodal perception at 3-4 mos, when the visual system has enough acuity • Meltzoff & Moore: sight and kinesthesia -NB • Spelke: sight and sound - at 3 mos • Meltzoff & Borton: sight and feel - by 1 mos
Intermodal Perception • Patricia Kuhl research showing that young infants can detect the relation between lip movements and speech sounds. • Older infants can also detect the relation between gender and a speaker's voice. • The auditory-visual pairings infants were presented with are on two separate monitors. • Infants responded more to the image that corresponded with what they were hearing.
Perceptual DevelopmentTheories • Gibsonian • Infant searches for invariant features in environment, stimuli offer affordances, all info is possible to pick out of the stimulus • Cognitive Constructivist • Infant imposes meaning on the information they pick up through the senses, as in perceptual organization findings • Integrated • Gibsonian account works for early perception, rapidly though organization or meaning is imposed on stimuli
