Psych 105: Unit 11

Developmental psychology

Study of continuity and change across life span

• infancy

• childhood

• adolescence

• adulthood

Prenatal stage

End at birth, starts 9 months earlier when egg and sperm join together in fallopian tube

Conception

The moment when a sperm fertilizes an egg → forms a zygote

• typically occurs 1-2 days after intercourse but can happen as much as 5 days later

Zygote

Fertilized egg

• existence known as germinal stage

Germinal stage

Period from conception to 2 weeks after conception

• rapid cell division

• travels down to fallopian tube and attaches itself to wall of uterus (50% success rate bc of defectiveness, or improper placement)

Embryonic stage

Period that starts at about 2nd week and lasts until about 8th week after conception

• embryo: zygotic successfully implanted into uterus

• continuation of cell division

• major organs/body systems begin to form

  • beating heart

  • beginnings of female reproductive organs

  • male testosterone hormones production

• highly vulnerable to environmental factors (more than fetus)

Fetus

Has skeleton and muscle that make it capable of movement

Fetal stage

Period that starts from about 9th week after conception until birth

• insulating fat layer beneath skin

• maturing of digestive/respiratory systems

• rapid brain growth

• myelination: formation of fatty sheath around axons of neuron

• human brain is 25% of adult size here (75% of growth occurs after birth)

  • passing through birth canal

  • brain must be able to adapt to wide range of environments throughout life span → has to accommodate those challenges

Prenatal environment

• womb is environment that affects an unborn baby in many ways

• placenta: organ that links mother’s bloodstream to unborn baby, so materials/nutrients can be exchanged

• foods, substances mother takes/fails to intake affect development

  • teratogens

    • diseases mother has

    • maternal stress

    • lead, radiation

    • alcohol: fetal alcohol syndrome

    • tobacco

    • intrauterine growth restriction

Teratogens

Substances like drugs, etc. that pass from mother to infant and impair development

Prenatal sensory system

• touch: can detect touch/pressure & can respond to gentle stroking and pressure on skin

• taste: can detect diff. tastes (like sweet/sour)

• smell: can detect diff. odours

• hearing: can detect sounds outside of womb; hears mothers voice, heartbeat, other external sounds

• vision: detects light and dark

• balance/movement: develops sense of balance/movement

• can detect mothers emotional state and respond to stress/anxiety

Newborns

• poor distance vision → see things 20-30cm away

• habituate (get used to) visual stimuli; respond less to repeated exposure of same stimuli

  • see squares, triangles, diagonal lines

  • track shapes with facial features longer

• can mimic facial expressions within first hour of life

  • attend and respond to facial features and other human objects

• must spend time strengthening muscles and working on motor development

Motor development

Emergence of ability to execute physical action (reaching, crawling, walking, grasping)

• cephalocaudal rule

• proximodistal rule

Cephalocaudal rule

“Top to bottom” rule

• tendency for motor skills to emerge in sequence from head to feet (moving head first, then eventually all the way down to feet)

Proximodistal rule

“Inside to outside” rule

• tendency for motor skills to emerge in sequence from centre to periphery (learn to move trunks before elbows and knees)

Motor reflexes

• specific patterns of motor response triggered by specific patters of sensory stimulation (rooting, sucking)

• innate

• disappear as infants learn to execute more sophisticated motor behaviour

Do babies have coordinated perceptual and motor systems?

Not yet

Cognitive development

Emergence of ability to think and understand

• Jean Piaget suggest 4 stages of cognitive development

  • how physical world works

  • how their minds represent it

  • how other minds represent it

Piaget’s 4 stages of cognitive development

• Sensorimotor (birth - 2yrs) : infant experience world by sensing/moving in it

  • develops schemas

  • begins to act intentionally

  • shows evidence of understanding object permanence

• Preoperational (2yrs- 6yrs) : child acquires motor skills but doesn’t understand conservation of physical properties

  • begins stage thinking egocentrically → ends stage with basic understanding of other minds

• Concrete operational (6-11 yrs) : child can think logically about physical objects and events and understands conservation of physical properties

• Formal operational (11 yrs and up) : can think logically about abstract propositions and hypotheticals

Schemas

Theories/models of the way the world works

• develop theories

Assimilation

Process by which infants apply their schemas in novel situations

• apply theories

Accommodation

Process by which infants revise their schemas in light of new info

• adjust theories

What did Piaget suggest

Infants are lowkey clueless about some of the most basic properties of physical world → need to acquire this info through experience

• infants don’t yet have object permanence

Object permanence

Understanding that objects exist, even when they’re not visible

• (Piaget) infants during first few months of life act as though objects stop existing the moment they’re out of sight