LIFESPAN CHAPTER 3 – PHYSICAL AND COGNITIVE DEVELOPMENT IN INFANCY
1. Physical growth and development in infancy – patterns of growth and development
cephalocaudal patterns – sequences in which early growth occurs from top to bottom; physical growth and differentiation of features works from top to bottom; sensory and motor development also follows this pattern
proximodistal pattern – growth starts at center of body and moves toward the extremities;
height and weight – at birth average north American baby 20 inches long and weighs 7 ½ lbs; first several days, lose 5-7% of body weight, before adjusting to feeding by sucking, swallowing and digesting; gain 5-6 oz per week; double birth weight by 4 mos; and 3x birth weight by age 1; grow about 1 inch/month; 1 ½ birth length by age 1. by 2 years, 26-32 lbs; 32-35 inches tall
Brain – extensive brain development during infancy and later; should protect baby’s head from falls and other injuries; shaken baby syndrome – brain swelling and bleeding;
brain development – brain does not mature uniformly during infancy; brain can be described in terms of sections or lobes – frontal, parietal, occipital and temporal; each section has a left and right counterpart; 2 halves of brain or hemispheres are not identical in anatomy or function.
lateralization – specialized function in one or the other hemisphere; specialization in hemispheres begins at birth; for example, greater electrical activity in left compared to right side when listening to speech sounds; language primarily processes on left side although complex functions require cooperation of left and right sides of the brain.
changes in brain cells or neurons – nerve cells made up of bundles of fibers for handling information; 2 types of fibers: dendrites carry information toward the cell body; axons carry information away from cell body (where nucleus and DNA are); terminal buttons at ends of axons for releasing neurotransmitters or chemicals into the synapses or small gaps between neurons;
neurons change in 2 important ways: a. myelination (covers nerve fibers with fat cells) and increased connectivity (creating new neural pathways; new dendrites develop and increasing numbers of synaptic connections – nearly 2x as many as will eventually be used)
changes in regions of the brain – dramatic growth in synaptic connections highest in visual, auditory and prefrontal cortex; peak of synaptic growth in visual cortex by 4th postnatal month; peak in hearing and language areas similar, though somewhat later; peak in prefrontal cortex area (for higher level thinking)about 1 year; mid to late adolescence achieve adult density achieved; peak myelination in visual cortex complete in about 6 months; peak myelination in hearing area not complete until age 4 or 5;
early experiences and the brain – before birth genes determine basic nerve connections; after birth, environmental experiences determines brain development.
sleep – average newborn sleeps 16-17 hours/day total; wide variability in how time spread throughout the day; by 1 month sleep longer at night; by 4 months, closer to adult sleeping patterns;
REM sleep – greater amount of time; rapid eye movement sleep; about ½ of infant sleep time; by 3 mos, REM percentage decrease to 40%; why? may provide added self-stimulation; may promote brain development in infancy;
SIDS – sudden infant death syndrome; infant stops breathing, usu at night; dies without apparent cause. American Academy of Pediatrics recommends infants sleep on back; why? sleeping on stomach impairs arousal from sleep; restricts ability to swallow; increased risk if exposed to passive cigarette smoke or sleep on soft bed
breast vs bottle feeding – 1st 4-6 mos human mild or alternative formula is main source of nutrients and energy; growing consensus that breast feeding is best; benefits- appropriate weight gain; lower risk of childhood obesity; prevention or reduction of diarrhea, respiratory infections, bacterial or urinary tract infections, otitis media (middle ear infection); denser bones in childhood and adulthood; decreased risk of childhood cancer and decreased risk of breast cancer in mothers; when should not breast feed? 1)mom infected with AIDS or other infectious disease; 2)mom has active tuberculosis; 3)mom taking drugs not safe for baby.
nutritional needs: recommend infants consume 50 cal/day per lb of body weight; early nutrition important; Family Support/Healthy Start Program in Hawaii good example of helpful services for families of newborns at risk for developmental problems;
Motor development – how do infants develop motor skills; which skills develop at what time:
dynamic systems theory – assemble motor skills for perceiving and acting; perception and action coordinated; to develop skills, infants perceive something in environment that motivates them to act; use perceptions to fine tune movements; motor skills are solutions to goals; new behavior is result of converging factors; nervous system development, body’s physical properties, possibilities for movement; goal motivated to reach, environmental support for skill; infant change movement patterns to fit new task by exploring and selecting possible movement patterns
reflexes – built in reactions to environmental signals; genetically carried survival responses; automatic and involuntary; allow adaptive response before opportunity to learn; for example, if immersed in water, automatically hold breath and constrict throat; other reflexes: rooting and sucking – if stroke cheek or touch side of mouth, turn toward side touched or stroked; to find something to suck; sucking – occurs if object placed in baby’s mouth; Moro reflex – startle response to sudden intense noise or movement; arch back, throw back head, fling out arms and legs then quickly close arms and legs; possible way of grabbing for support while falling; other reflexes persist throughout life – cough, sneeze, blink, shiver, yawn; some reflexes incorporated into more complex voluntary behaviors later (grasping reflex)occurs when something touches infant palm; by end of 3rd month, action more voluntary, smoother; manipulating and exploring.
Gross Motor Skills: involve large muscles activities; moving arms and legs; newborns cannot control posture voluntarily; after few weeks, can hold head up; and soon lift head while on stomach; 2 mos – sit while supported in lap; 6 mos; sit up independently; 8 mos – pull self to standing position while holding on to support; 10-12 mos - can stand alone; to walk upright, balance on one leg while shifting other forward; shift weight from one leg to the other; must learn which places and surfaces safe for crawling and walking; to learn where safe to crawl and walk, have to integrate perceptual information and motor skills
First year: milestones and variations (chart on page 86) timing of reaching milestones can vary by 2-4 months; some babies never crawl;
Second year – pull a toy attached to string; use hands and legs to climb steps; walk quickly; run a short distance; balance on feet while squatting; walk backward; stand and throw a ball; jump in place;
Fine motor skills – grasp a toy; use spoon, button shirt; reaching and grasping is significant achievement; at first reach by moving shoulders and swing arm around; later, move wrist, rotate hands; coordinate thumb and forefinger motions; perceptual-motor coordination necessary for grasping; 4 mos – rely more on touch to grasp; 8 mos – use vision more often as cue; experience influences grasping skills: infants who had practice with “sticky mittens” learned grasping skills sooner. exercising gross motor skills and fine motor skills important and helpful.
EXPLORING SENSORY AND PERCEPTUAL DEVELOPMENT
sensation: info interacts with sensory receptors – eyes, ears tongue, nostrils and skin
perception: interpreting what is sensed.
ecological view (Eleanor and James Gibson): we directly perceive information in the world around us. perception allows contact with environment and adapting to it.
Robert Fantz: found babies look at different things for different lengths of time. Babies in looking chamber; with 2 visual displays (p. 90) above babies head; experiments used peephole to watch babies’ eyes; babies 2 days of age preferred patterned stimuli to plainly colored discs.
Habituation and dishabituation: decreased and increased response to stimuli respectively; present stimulus a number of times; if decreased response to stimulus, indicates lower interest in it; measure of habituation: sucking, heart rate breathing rate.
High amplitude sucking: nonnutritive nipple connected to sound generator; each sucking act causes a sound; habituate to same sounds; experimenter can change sounds; babies show ability to discriminate between the sounds.
Other methods: orienting response (turn head toward sight or sound); tracking (eye movements following moving objects.
NEWBORN VISION: 20/600; 5 mos: 20/100; 1 year: approximately same as normal (20/20) adult vision. Color vision: birth - distinguish green and red; 2 mos – all color receptors active at normal levels of sensitivity.
2-3 week-old infants prefer patterns to plain stimuli; 2 mos – scans more facial details than 1 mo.
Eleanor Gibson and James Walk: develop visual cliff with drop-off covered with glass; 6-12 mos on edge of visual cliff; mothers tried to coax babies to crawl onto glass; babies just starting to crawl would cross; after a few weeks, would not cross; infants can perceive depth by about 3-4 mos
HEARING – can hear during last 2 mos before birth; babies whose moms read Cat in the Hat to them before birth gave different response to Cat in the Hat reading after birth compared to King, Mice and Cheese (different reading pace and emphasis with voice tones).
Changes in hearing during infancy – perception loudness pitch and location: 1)immediately after birth can’t hear soft sounds as well as adults; 2)newborns less sensitive to changes in pitch (frequency such as soprano or bass tones) compared to adults; at 2 years, improved pitch distinction; 3)newborns can determine general sound location; by 6 mos much better at determining specific locations
TOUCH AND PAIN - touch stimulates reflexes (rooting and sucking); pain – respond to circumcision (no anesthesia) with intense crying; recover quickly (normal eating and social responses)
TASTE – saccharin in amniotic fluid of near-term fetus resulted in increased swallowing; different facial expression to sweet, salt and bitter solutions (pictures on page 93)
Integrate information from 2 or more senses; newborns turn head at sound of rattle.
Piaget’s theory: adaptation – adjusting to new environmental demands and actively constructing mental world; schemes – actions or mental representations for organizing knowledge; infants actively use physical responses (sucking, grasping); toddlers and older children use mental schemes (cognitive activities) for organizing experiences. assimilation – use existing schemes to handle new information; accommodation – adjust existing schemes to handle new information; organization – grouping isolated behaviors and thoughts into higher order systems.
EQUILIBRATION AND STAGES OF DEVELOPMENT – process by which make shift from one stage of development to the next; 4 stages of development – first stage is sensorimotor stage (birth to 2 years);
6 SENSORIMOTOR SUBSTAGES – 1)simple reflexes: birth to 1 mo; sensation and action coordinated using reflexive behaviors; 2)first habits and primary circular reactions – 1-4 mos; coordinates sensations and 2 schemes, habits and primary circular reactions; habit is scheme based on reflex separated from triggering stimulus; primary circular reactions are repetitive actions based on trying to reproduce event first occurring by chance; stereotyped and repeated the same way each time; 3)secondary circular reactions; 4-8 mos; more object oriented; repeated because of consequences; shake rattle to reproduce sound; some imitation of behavior by others; 4) coordinated secondary circular reactions; 8-12 mos; coordinates vision and touch; eye and hand; actions more outwardly-directed; coordinates actions and intentions; 5)tertiary circular reactions – beginnings of novelty and curiosity; 12-18 mos; interested in properties of objects and things they can do to objects (fall, spin, slide, hit another object); purposely explore new possibilities of objects and experiences; 6) internalized schemes – 18-24 mos; use primitive symbols (internal sensory images or words that represent concrete objects; can think about concrete objects and events without actually seeing or touching them;
Understanding that objects continue to exist even though cannot see, touch or hear them;
EVALUATING OBJECT PERMANENCE – some modifications of Piaget’s ideas; A-not-B or AB error (playing hide toy under the blanket game); may be memory or motivation problem rather than lack of cognitive ability; some cognitive abilities can be demonstrated earlier than Piaget thought, such as object permanence
LEARNING, REMEMBERING AND CONCEPTUALIZING
CONDITIONING – Skinner’s operant conditioning; behavior’s consequences change probability that behavior will occur in the future; infants can learn using operant conditioning; especially perceptual skills; infant suck faster on nipple if sucking following by interesting visual display musical sounds, or human voice; Rovee-Collier showed 2 ½ -mo-old infant whose foot was tied to a mobile and who learned to kick to make the mobile move later kicked even when foot not tied to mobile;
ATTENTION – focus mental resources on select information; newborn can detect contours of objects; older babies scan more thoroughly; attention is influenced by novelty and habituation; if object is familiar, attention is shorter and more vulnerable to distraction; joint attention – 2 individuals (such as baby and parent or caregiver) focus on same object or event; requires 1)ability to track someone else’s attention; 2)reciprocal interaction; emerging forms at 7-8 mos; skills more developed at 10-11 mos; by 12 mos, infant can direct adult attention; increases infant’s ability to learn from other people responses, such as language.
IMITATION – Meltzoff believes infants’ imitation ability is biologically-based; observed some imitation by newborns; not 100% accepted; Meltzoff also described deferred imitation in which babies demonstrate behaviors they observed as much as 24 hours earlier;
MEMORY – retention of information over time; Rovee-Collier concluded memory skills demonstrated by infants as young as 1 ½ -2 years; disagreement whether implicit (memory without conscious recollection; performed automatically)or explicit (conscious memory of facts and experiences)memory. infantile or childhood amnesia – difficulty remembering events during first 1-3 years of life;
CONCEPT FORMATION AND CATEGORIZATION – concepts – ideas about what categories represent; categories are groups of objects and events and characteristics based on common properties; 7-9 mos use conceptual categories characterized by perceptual variability; first concepts broad and general; gradually differentiated.
LANGUAGE DEVELOPMENT – language is form of communication based on systems of symbols; consists of words used by a group and rules for combining and varying them; infinite generativity – ability to reproduce endless number of meaningful sentences using limited set of rules and words; crying – signals distress and other meanings; cooing – first observed at 1-2 mos; gurgling sounds from back of throat; usually signal pleasure; babbling – strings of consonant-vowel combinations; gestures – showing or pointing at objects or people; first observed about 8-12 mos; a wave bye-bye, nod yes. recognizing language sounds – before can make language sounds, can recognize differences in sounds; until 6 mos, recognize sound differences regardless of language source; gradually lose ability to (or interest in) recognizing differences in languages other than the one they ear most often. first words – usually observed at 8-12 mos; indicates first understanding of words; first spoken words at 10-15 mos; average 13 mos; first words usually name important people, familiar animals; vehicles, toys, food, body parts, clothes, household items, greetings; receptive vocabulary – develop faster than expressive or spoken vocabulary; expressive vocabulary increases very quickly after first spoken words; -àvocabulary spurt. 2-word utterances – 18-24 mos; convey meaning with 2 words plus gestures, tone of voice and using context; omit some parts of speech; succinct and telegraphic; omit grammatical markers such as articles, auxiliary verbs and connective words.
BIOLOGICAL AND ENVIRONMENTAL INFLUENCES – spoken language required certain vocal structures and nervous system capabilities; 2 areas of brain important (Broca and Wernicke) in left hemisphere; Noam Chomsky suggested language acquisition device (biological readiness to learn language; not referring to any specific biological or anatomical structure; environmental influence – behaviorist view explaining language as chains of reinforced verbal behaviors, not accepted ; problems – 1)does not explain novel sentences; 2) children learn syntax or grammar of own language without reinforcement; experiences, particular language learned, context of language influences language acquisition; support and involvement of caregivers and teachers influence language behavior; interactive view of language learning – learn specific languages in specific contexts; child’s vocabulary links to family socioeconomic status and speech parents direct toward their children; child-directed speech – spoken using higher-pitch with simple words and sentences; captures attention and maintains communication; includes “baby-talk”; other adult strategies: 1)recasting – rephrasing something child says; allows indicating interest and elaborating interest; 2)expanding – restating in linguistically sophisticated from what child says; 3)labeling – identifying the nature of objects and experiences; original word game; Strategies used best to guide language learning instead of overloading; encouragement is better than drill and practice;
IDEAS TO HELP PARENT GUIDE LANGUAGE LEARNING – infants – be active conversational partner; talk as if infant understands; use language style comfortable to individual parent; toddlers – continue active conversational partner; remember to listen; use comfortable language style; consider expanding child’s language abilities; adjust to child’s idiosyncrasies; interactionist view – biology and environment both important; provide rich verbal environment; provide opportunities for conversation; pay attention and listen; read to children and label things and events in environment