Developing Through the Life Span

Major Issues in Developmental Psychology

  • Nature and Nurture: Individual development is shaped by the interaction of biological, psychological, and social-cultural forces.
  • Continuity and Stages: Development is viewed either as a gradual, continuous process or as a sequence of genetically programmed stages.
  • Stability and Change: Personality traits demonstrate stability across the life span, providing personal identity, while developmental changes allow adaptation and growth.

Overview diagram comparing stage theories of Lawrence Kohlberg, Erik Erikson, and Jean Piaget across age.

Prenatal Development and the Newborn

  • Genetic Foundations:
    • Chromosomes: Threadlike structures made of DNA molecules containing genes.
    • DNA (Deoxyribonucleic Acid): Molecule containing genetic information.
    • Genes: Biochemical units of heredity made of DNA segments.
    • Genome: Complete genetic instructions for making an organism.
  • Gene-Environment Interaction:
    • Epigenetics: Study of environmental influences on gene expression without changes to underlying DNA, driven by epigenetic marks.
  • Prenatal Stages:
    • Zygote: Fertilized egg undergoing rapid cell division during the first 2 weeks.
    • Embryo: Developing human organism from 2 weeks through 8 weeks.
    • Fetus: Developing human organism from 9 weeks after conception to birth.
  • Prenatal Hazards:
    • Teratogens: Harmful agents (chemicals or viruses) reaching the embryo or fetus.
    • Fetal Alcohol Syndrome (FAS): Physical and cognitive deficits caused by heavy maternal drinking.
  • Twin Studies:
    • Identical (monozygotic) Twins: Develop from a single fertilized egg that splits.
    • Fraternal (dizygotic) Twins: Develop from two separate fertilized eggs.

Diagram contrasting the development of identical and fraternal twins from fertilization.

Infancy and Childhood

  • Physical & Brain Development:
    • Maturation: Biological growth processes enabling orderly changes in behavior.
    • Rapid frontal lobe growth occurs from ages 3 to 6; neural pruning discards unused connections.
  • Cognitive Development (Jean Piaget):
    • Schemas: Mental frameworks organizing information, adapted via assimilation and accommodation.
    • Sensorimotor Stage (Birth to ~2 years): Sensory exploration; key milestone is object permanence.
    • Preoperational Stage (~2 to 6 or 7 years): Symbolic thinking; characterized by pretend play and egocentrism.
    • Concrete Operational Stage (~7 to 11 years): Logical thinking on concrete events; key milestone is conservation.
    • Formal Operational Stage (~12+ years): Abstract reasoning and hypothetical logic.
    • Vygotsky's Social View: Cognitive growth relies on social interaction, language, and scaffolding.
    • Theory of Mind: Understanding one's own and others' mental states, enabling recognition of false beliefs (develops between ages 3 and 4½).

Demonstration of Piaget's conservation task using liquid in different shaped containers.

  • Social Development:
    • Attachment: Emotional bond with caregivers, providing a secure base for exploration.
    • Attachment Styles (Mary Ainsworth):
    • Secure Attachment (~60%): Play comfortably in mother's presence; distressed upon departure; seek contact upon return.
    • Insecure Attachment: Anxious (clingy/distressed) or avoidant (indifferent to departure/return).
    • Parenting Styles:
    • Authoritarian: Coercive and demanding.
    • Permissive: Unrestraining and lenient.
    • Neglectful: Uninvolved.
    • Authoritative: Confrontive and responsive; yields highest self-esteem and social competence.

Harlow's monkey attachment experiment with wire and cloth mothers.

Adolescence

  • Physical Development:
    • Puberty introduces sexual maturation.
    • Frontal lobe maturation lags behind limbic system development, driving impulsiveness and risk-seeking behavior.

Line graph showing sensation seeking peaking in mid-teens while impulse control steadily rises into the twenties.

  • Cognitive & Moral Development:
    • Lawrence Kohlberg’s Stages of Moral Reasoning:
    • Preconventional Morality (before age 9): Rule obedience driven by punishment avoidance or reward gain.
    • Conventional Morality (early adolescence): Upholding rules/laws for social approval or order.
    • Postconventional Morality (adolescence and beyond): Moral choices based on self-defined ethical principles and basic rights.
  • Psychosocial Development (Erik Erikson):
    • Adolescent primary task is Identity vs. Role Confusion (synthesizing past, present, and future into a unified sense of self).

Adulthood and Aging

  • Physical Development:
    • Physical vigor, sensory keenness, and muscle strength peak in the mid-twenties.
    • Middle adulthood brings gradual decline in physical vigor and fertility (menopause in women).
    • Late adulthood features reduced sensory perception, stamina, and immune response, along with gradual net brain cell loss.
  • Cognitive Development:
    • Word recall declines with age, while word recognition memory remains stable.
    • Terminal cognitive decline occurs during the final 4 years of life.

Chart showing recall declining with age while recognition memory remains stable.

  • Social Development:
    • Key Eriksonian tasks are Intimacy vs. Isolation (young adulthood) and Generativity vs. Stagnation (middle adulthood).
    • Positive emotions increase after midlife, and older adults experience reduced stress and anger.
    • Happiness across all age groups correlates strongly with time spent with others.