Developmental Psychology Across the Lifespan

Three Domains of Human Development

Developmental psychology studies changes over the lifespan, which can be grouped into three domains: physical, socio-emotional, and cognitive.

• Physical domain: Changes in body, brain, and motor skills.

• Socio-emotional domain: Changes in relationships, emotions, and personality.

• Cognitive domain: Changes in thinking, problem-solving, and language.

Periods of Physical Growth

Three Main Periods

Physical development is divided into three periods:

• Prenatal: Conception to birth

• Infancy and childhood: Birth to adolescence

• Adolescence and adulthood: Puberty through old age

Substances Affecting Prenatal Development

Teratogens and Environmental Agents

Exposure to harmful substances during pregnancy can affect fetal development.

• Teratogens: Agents like legal and recreational drugs, alcohol, and certain medications can cause birth defects and complications.

• Examples: Fetal alcohol syndrome, premature birth, and low birth weight.

Infants and Children: Physical Development

Infancy and Childhood Milestones

Physical changes occur rapidly in infancy and childhood.

• Infancy: Birth to 18–24 months; rapid growth and development.

• Childhood: Ages 2–11; continued growth and refinement of motor skills.

Brain Development

• Synaptic pruning: Elimination of unused neural connections to improve efficiency.

• Myelination: Formation of myelin sheath around neurons to speed up transmission.

Infants and Children: Socioemotional Development

Attachment

Attachment is a strong emotional connection, usually to caregivers, that is vital for survival and development.

• Secure attachment: Child feels safe and comforted (about 60–65% of U.S. children).

• Insecure attachment: Child is avoidant or ambivalent (35–40% of U.S. children).

Infants and Children: Cognitive Development

Piaget's Theory of Cognitive Development

Jean Piaget proposed that children progress through four stages of cognitive development, each characterized by distinct ways of thinking.

• Sensorimotor stage (birth–2 years): Infants learn about the world through senses and motor actions. Object permanence develops.

• Preoperational stage (2–7 years): Children use symbols and language but think egocentrically and lack logical reasoning.

• Concrete operational stage (7–12 years): Children think logically about concrete events and understand the law of conservation.

• Formal operational stage (12+ years): Abstract, critical, and hypothetical thinking develops.

Key Concepts

• Schemas: Mental frameworks for organizing information.

• Assimilation: Incorporating new information into existing schemas.

• Accommodation: Modifying schemas to fit new information.

Language Development

Orderly Progression

Language develops in an orderly way, starting with sounds and progressing to sentences.

• Phonemes: Basic units of sound.

• Morphemes: Smallest units of meaning.

• Overregularization: Applying grammatical rules too broadly (e.g., "goed" instead of "went").

Adolescents: Physical Development

Puberty

Puberty marks the end of childhood and the start of adolescence, typically between ages 8–21.

• Primary sex characteristics: Development of reproductive organs and genitals.

• Secondary sex characteristics: Non-reproductive traits such as body hair and voice changes.

Adolescents: Socioemotional Development

Erikson's Stages

Erik Erikson described eight "crisis-oriented" stages of psychosocial development, several of which occur during adolescence.

• Trust vs. mistrust (0–2)

• Autonomy vs. shame and doubt (2–3)

• Initiative vs. guilt (4–6)

• Industry vs. inferiority (7–12)

• Identity vs. role confusion (13–19)

• Intimacy vs. isolation (20s)

• Generativity vs. stagnation (30s–50s)

• Integrity vs. despair (60s and beyond)

Culture and Ethnicity

• Culture shapes identity and values.

• Bicultural identities may form when a child strongly identifies with two cultures.

Peer Influence

• Adolescent identity development is shaped by peer relationships.

Adolescents: Cognitive Development

Kohlberg's Theory of Moral Development

Lawrence Kohlberg proposed three levels of moral reasoning:

• Preconventional: Moral behavior is determined by self-interest or pleasurable outcomes.

• Conventional: Moral behavior is determined by laws or winning approval of others.

• Postconventional: Moral behavior is based on abstract principles about the value of life.

Adulthood: Physical and Cognitive Changes

Physical Changes

• Adulthood starts at the end of adolescence and continues to old age and death.

• Adults experience a decline in muscle mass, bone density, eyesight, and hearing.

Cognitive Changes

• Learning new things and retrieving memories become more difficult with age.

• Dementia: A dramatic loss in mental ability; Alzheimer's disease is a main cause.

• Engaging in physical and brain-stimulating activities helps maintain health and happiness.

Adulthood: Socioemotional Development

Erikson's Stages in Adulthood

• Establishing intimate relationships (intimacy vs. isolation).

• Finding a sense of meaning in life (generativity vs. stagnation).

• Life review and reflection (integrity vs. despair).

Relationships and Family

• The vast majority of people marry or form some type of permanent relationship.

• Having children can strain marriages; communication is key to maintaining stability.

Summary Table: Piaget's Stages of Cognitive Development

Key Equations and Concepts

• Law of Conservation (Piaget): Understanding that quantity remains the same despite changes in shape or appearance.

• Attachment Theory: Secure attachment leads to better social and emotional outcomes.

Additional info:

• Some details about the stages and theories were expanded for clarity and completeness.

• Examples and applications were added to illustrate key concepts.