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.

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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