CHAPTER TWELVE: DEVELOPMENT OVER THE LIFE SPAN
DEVELOPMENTAL PSYCHOLOGY: ISSUES & METHODS
Nature & nurture
Critical &sensitive periods.
o Critical periodage experiences must occur for development to proceed normally
o Sensitive period optimal age range for certain experiences
Continuity versus discontinuity
Stability versus change.
Cross-sectional design:ompare people of different ages at the same point in time.
Longitudinal design:epeatedly tests same cohort as it grows older.
Sequential design: combines cross-sectional & longitudinal approaches.
Prenatal development: 3 stages of physical growth.
Germinal stage: first 2 weeks of development, 1 sperm fertilizes female egg
o Zygote: fertilized egg
Embryonic stage: end of week-8 week after conception, cell mass now is called embryo.
o Placenta: membranes allow nutrients to pass from mother's blood to umbilical cord.
Umbilical cord: blood vessels that carry nutrients & oxygen to embryo, waste products
back from embryo to mother
9 week embryo: fetus.
o Fetal stage: until birth, muscles become stronger & bodily systems continue to develop.
o At 24 weeks eyes open, 28 weeks fetus attains age of viability
GENETICS AND SEX DETERMINATION
TDF (testis determining factor) gene: triggers male sexual development.
o 6-8 weeks after conception the TDF gene initiates development of testes.
Teratogens: environmental agents that cause abnormal prenatal development.
Fetal alcohol syndrome (FAS): abnormalities that results from prenatal exposure to alcohol
o FAS children have facial abnormalities and small, malformed brains
Smoking risk miscarriage, premature birth, low birth weight. 2nd-hand linked to low birth weight
& risk of respiratory infections
Longitudinal & cross-sectional for changes heart rate & body movements with vibrator, on
mother's tummy, turned on/off. Reliable fetal body movements 27 wks after conception, with
fetal age. Heart rate acceleration fetuses 29 wks fetal age, responses remained high until birth.
Newborns of mothers who consumed certain foods & drinks also preferred those foods
Developmental psychology: process of aging. Nature & nurture, Critical &sensitive periods, continuity vs.
discontinuity, stability vs. change
Cross-sectional: people of different age groups at single point in time. Longitudinal: repeatedly tests
same age group as grows older. Sequential design: several groups at 1 point in time & again when older.
Prenatal development involves the zygote, embryonic, and fetal stages.
23rd chromosome in mother's egg cell always is X chromosome. If 23rd chromosome in father's sperm
cell is X, Child will be female; if Y, the child will male.
Behavioural responses and learning begin during the fetal stage.
THE AMAZING NEWBORN
William James suggested newborn's passive, disorganized, empty mind. View is not tenable
Newborn Sensation and Perception
Preferential looking procedure: infants' visual preferences. Infants preferred complex patterns,
such as realistic/scrambled drawings of human face, to simple patterns and solid colours
1 | P a g e Newborn Learning
Visual habituation procedure: stimulus presented repeatedly, infant looking time declines
o Newborns habituated to white lights recovered visual interest when viewed lights of
similar intensities but different dominant wavelengths
o Auditory habituation procedure to study infant memory. Head-turning toward off-
centred, recorded speech sound. After 16 presentations, infants stopped turning
o Rapidly learn to associate sounds with objects, including the mother's face and voice
Newborns can learn through classical & operant conditioning & imitation.
Visual field in each eye expands to almost adult size by 6 months age, acuity 20/800 at birth to
20/100 by 6 months of age, adult levels by about 4 years of age
o 3-4 months of age, infant pattern perception organized to certain Gestalt principles
o Turn toward sounds at birth disappears in 2nd month of life, returns 4-5 months of age
o Changes in adult speech sounds differentiate one word from another 1-2 months of age.
6-month look longer to hear pitch change in tones adults find pleasant than pitch change adults
rate as unpleasant
o 2 months of age, infants remember short melody after listening to it repeated 15 times
PHYSICAL, BRAIN, AND MOTOR DEVELOPMENT
Maturation: genetically programmed biological process, governs growth, bodies & movement
Cephalocaudal principle: tendency for development to proceed in a head-to-foot direction.
Proximodistal principle: development begins innermost parts of body, toward outermost parts
The Young Brain
Newborn's brain 25% of adult weight.
o 6 months of age = 50% adult weight.
o 5-year-olds = 90% of adult size, brain maturation continues.
Reflexes: automatic, inborn behaviours elicited by specific stimulipresent at birth.
o Stepping reflex drops out after 1-2 months, reappears around 12 months of age
Environmental and Cultural Influences
Newborn rats in enriched environment develop heavier brains, larger neurons, more synaptic
connections, and greater amounts of brain neurotransmitters that enhance learning
Physical touch affects growth in infancy.
o Depriving rats pups of normal physical contact with mothers stunts development,
Experience also can influence basic motor skill development
Biology sets limits on environmental influences.
Environmental influences can be powerful.
Biological and environmental factors interact.
Newborns have poor sensory acuity, but can distinguish between different visual patterns, speech
sounds, odours & tastes. Display perceptual preferences; learn through classical & operant conditioning
Cephalocaudal: tendency for development to proceed in head-to-foot direction. Proximodistal:
development begins along innermost parts of body, continues toward the outermost parts.
Experience is critical for normal development
Piaget's Stage Model
Believed cognitive development results from interplay of maturation & experience, viewed
children as natural-born scientists who actively explore & seek to understand their world.
Assimilation: new experiences are incorporated into existing schemas
Accommodation: new experiences cause existing schemas to change
2 | P a g eSensorimotor stage
Birth-age 2, understand world through sensory experiences & physical interactions with objects.
o Object permanence: understanding object continues to exist when no longer seen
o Plan, form simple concepts, solve problems mentally, communicate thoughts to others.
Age 2, represent world symbolically in words & mental images, dont understand basic mental
operations or rules.
Does not understand conservation: basic properties of objects stay the same
Thinking at this age displays irreversibility: difficult for them to reverse an action mentally.
Exhibit centration; focus on one aspect of the situation, such as the height of a liquid.
Egocentrism, difficulty in viewing the world from someone else's perspective
Concrete operational stage
7-12 yrs, perform basic mental operations in problems involving tangible objects & situations.
o Concept of reversibility, less centration, easily solved conservation problems
o Difficulty with hypothetical problems/problems requiring abstract reasoning
Formal operational stage
11-12 yrs, think logically about concrete & abstract problems, form hypotheses & test them.
Piaget's universality principle
General cognitive abilities in Piaget's four stages occur in same order across cultures
Culture influences cognitive development.
Early understanding of the physical world
Stared longer at impossible events, suggesting they possessed rudimentary arithmetic abilities.
o Suggests infants understand m