Physical and Cognitive Development in Childhood

Do Now: Brain Dump

• Write all the ideas/words you associate with infancy, birth, and childhood

infancy birth childhood

Genetics

•Chromosomes, DNA, Genes•Genotype/Phenotype•Dominant/Recessive Genes•Sex-Linked Recessive Characteristics

•Color blindness, night blindness, hemophilia

Prenatal Development

• Germinal period— 0-2 weeks

• Embryonic period— 2-8 weeks

• Fetal period— 8 weeks to birth

8 week embryo 12 week fetus

18 week fetus 24 week fetus

32 week fetus

Prenatal Influences on Development

• Teratogen - any environmental agent that causes a birth defect (e.g., drugs, radiation, viruses)

Teratogen EffectAlcohol Fetal Alcohol Syndrome - set of birth defects

(underdeveloped brain, heart, eyes, nervous system), moderate retardation

Cigarettes Low birth weight, premature birth

Cocaine and other Street drugs

Miscarraige, birth defects (in limbs), in utero strokes, SIDS, addicted babies

Lithium, anti-convulsants

Facial and limb deformities, mental retardation in some cases

Rubella Eye, hearing, heart defects, retardation,

Toxiplasmosis Low birth weight, prematurity, enlarged internal organs, retardation

ReflexesReflex Description

babinski When the bottom of the baby’s foot is stroked, the toes fan out and then curl

crawling When baby is on stomach and pressure is applied to the soles of the feet, body makes a crawling motion.

eyeblink Rapid closing of eyes in response to bright lights or foreign objects

grasping When object placed in baby’s palm, fingers close around it.

moro If baby is dropped or frightened by loud noise, he will throw his arms out to the sides and arch back

rooting When cheek is touched, baby turns head and opens mouth.

stepping When held upright on flat surface, baby makes stepping movements.

sucking Baby sucks something that is placed in mouth

Infant Reflexes

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Grasping Reflex Rooting Reflex Sucking Reflex

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Stepping Reflex Babinski Reflex Moro Reflex

Development of Senses• Vision

– Visual acuity (fuzzy)– can see color, but prefer bold B/W contrast– minimal tracking of moving objects– will mimic facial expressions in first month– 3 months = 20/100, 6 months 20/20

• Hearing – can orient toward sounds• Smell – will turn head away from unpleasant odors

(preference for mother’s odor after 2 days)• Taste - prefer sweet to sour tastes (differentiate taste

immediately, lambs = prenatally)• Touch – will react to virtually any touch, especially painful

stimuli (greatest onset at 2 months)• Vestibular sensitivity

– baby in room, wall moves forward, gives baby impression that s/he is leaning forward, baby compensates and falls backwards - even newborns adjust heads in response to visual stimuli!

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Body Development

• Brain and neuron development– At birth, brain is 25% of adult weight

• By 5, brain is 95% adult size

– Body weight is only 5% of adult weight

Motor Skills and Cognitive Development

• Motor skills related to a number of cognitive developments– Moving makes children active learners (Piaget)

• Fear learning corresponds to motor skills– If a baby is placed on a visual cliff before developing the ability to crawl, the child will not show fear when

crossing the “cliff”– Once the baby has started crawling, s/he will not cross the gap without showing a fear response, which is

measured by its heart rate

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Cognitive Development

in Infancy

• Memory increases over time– Recognition

• LTM (24 hours or longer) for newborns– When remembering that kicking foot moves

a mobile, memory gradually increases» 2m: 3 days, 3m, 8 days, 6m, 21 days

– Recall• Primary circular reactions show some recall and

it is clearly evident by the time language appears

– Infant amnesia prevents people from remembering events prior to two years old

• The brain’s memory system rewires around 18 months

• The baby lacks language so is unable to store episodic memories in a way that can be recalled

• Emotions become more refined over time– Newborns: can show distress, interest/surprise– 6-12 weeks: smiles more obvious, response to

external stimuli– 3-4 months: distress becomes anger/sadness

• Fear = 7 months (corresponds to crawling)– 1 year: all 6 basic emotions present

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Information-Processing Perspective on Development

• Piaget: mind = whole

• IPP: mind = built into individual components (modules)

– Attention, working memory, LTM

• Specific functions and interactions

• Development = changes in capacity for each system

– ∆t = increased capacity for working memory

• Accounting for Piaget stages in terms of gradual increases in working memory

– ∆t = increased speed for information processing

• Reaction times decrease with age

– ∆t = increased acquisition of rules and approaches to problem-solving

• EX: balance-beam problems explained by acquiring rules over stage-based differences in mental abilities

– Ability to apply feedback about aspects of task

– Domain-specific development (domain-specificity)

– ∆t: increased access and manipulation of memory

• Explicitation: implicit memories become explicit (consciously available)

Temperament (Nature) as Foundation for Development

• Temperament: Early-appearing individual differences in reaction and regulation; the “nucleus” of personality

• Critical in interplay of nature/nurture• Starting point for “reciprocal determinism”

• Criteria– Early-appearing - temperament typically (but not always) refers to traits that can

be identified early in childhood– Stable - The dispositions should be relatively stable, but some change is

possible– Constitutionally based - typically referring to a genetic predisposition, but can

also be related to other biological influences, such as prenatal hormone exposure

– Reactivity - can be both positive and negative, can be of different systems (physiological, behavioral, affective)

– Regulation - can be to increase or decrease arousal (approach/withdrawal), can refer to regulating either internal state (attention shifting) or regulating external activity (impulse control)

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Rothbart’s Temperament Dimensions

Temperament: Early-appearing individual differences in reaction and regulation; the “nucleus” of personality

- Surgency (positive affect, activity level) - similar to Extraversion

- Negative Affect (frustration, sadness) - similar to Neuroticism

- Effortful Control/Orienting (attention focusing, resistance to temptation) - similar to

Conscientiousness

Biology of Temperament• Kagan was intrigued by these differences

and looked for biological roots– Hypothesized that behavioral inhibition

was due to low threshold for sympathetic nervous system activity

– Studied kids from infancy through late adolescence. In addition to stability, found biological roots for negative affect children:

• higher baseline HR• less variable HR • bigger HR response to novelty• more salivary cortisol• more muscle tension• greater pupil dialation

• Temperament, then, can be seen as a result of internal wiring

Stability• many studies have documented short-term stability of a

number of dimensions– Anger/frustration

• Frustration predicted 7-yr anger• Irritable 3-4 year olds became aggressive and alienated

18-year-olds– Positive affect/surgency

• Infants to 7-yr old stability– Approach/withdrawal/shyness

• The most stable dimensions– 21 months to 18 years– 3 to 30 in males, 6 to 30 in females

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