AP Psychology: Developmental Psychology Notes

Key Takeaways: Developmental Psychology

  1. There are a variety of factors that contribute to an individual’s physical, social, and cognitive development. Most psychologists agree that both nature and nurture play a role in development.
  2. Infants are born with a variety of reflexes and tend to develop motor skills in a particular order and according to certain rules.
  3. Infants are born with temperaments, characteristic ways of reacting emotionally that influence how infants become attached to their caregivers, which in turn influences how they form attachments as adults.
  4. Piaget maintained that cognitive development occurred in a series of four stages, while Vygotsky focused on sociocultural influences on cognitive development and argued that children need the assistance of others to learn new abilities.
  5. Kohlberg argued that moral reasoning occurs at three distinct stages, while his critics contend that behaviors are often not confined to a single stage and that his model ignored feminist values like empathy.
  6. People achieve significant developmental milestones as they age and pass through adolescence, adulthood, and older adulthood. Freud and Erikson use stage theories to describe these changes.

Key Terms: Developmental Psychology

Nature and Nurture

  • Nature: Innate biological factors that influence development and personality.
  • Nurture: External and environmental factors, including learning, that influence development and personality.


  • Gestation/prenatal development: The process of development from conception to birth.
  • Conception: Fusion of two gametes: one male sex cell (the sperm) and one female sex cell (the egg).
  • Germinal stage: The first stage of gestation, which lasts about 2 weeks, in which the zygote migrates from the Fallopian tube to implant itself in the uterine wall.
  • Embryonic stage: The second stage of gestation, which lasts about 6 weeks, in which cells begin to differentiate and organs begin to develop.
  • Fetal stage: The final stage of gestation, which lasts about 7 months, in which the fetus gains increased mobility and develops rapidly.
  • Teratogens: Substances that damage the process of fetal development such as tobacco and alcohol.
  • Fetal alcohol syndrome: A developmental disorder caused by a mother’s heavy alcohol use during pregnancy.

Motor Skill Development

  • Motor development: The emergence of the ability to execute physical actions such as walking, crawling, reaching, and rolling.
  • Reflexes: Innate motor responses that are triggered by specific patterns of sensory stimulation.
  • Rooting reflex: The tendency for an infant to move its mouth toward any object that touches its cheek.
  • Sucking reflex: The tendency for an infant to suck any object that enters its mouth.
  • Moro reflex: The outstretching of the arms and legs in response to a loud noise or a sudden change in the environment.
  • Grasping reflex: The vigorous grasping of an object that touches the palm.
  • Babinski reflex: The projection of the big toe and the fanning of the other toes when the sole of the foot is touched, found only in infants.
  • Plantar reflex: The curling of the toes when the sole of the foot is touched, developed after infancy.
  • Cephalocaudal rule: The tendency for motor skills to emerge in sequence from the head to the feet, also known as the “top-to-bottom” rule.
  • Proximodistal rule: The tendency for motor skills to emerge in sequence from the center to the periphery, also known as the “inside to outside” rule.

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