Lifespan Human Development: Theories, Stages, and Research Methods

Lifespan human development

The ways in which people grow, change, and stay the same throughout their lives, from conception to death.

Stages of human development

Prenatal, Infancy & Toddlerhood, Early Childhood, Middle Childhood, Adolescence, Early Adulthood, Middle Adulthood, Late Adulthood, Death.

Principles of lifespan development

Multidimensional, Multidirectional, Plastic, Influenced by multiple contexts, Multidisciplinary.

Physical development

Body maturation and growth.

Cognitive development

Maturation of thought processes and tools for knowledge, awareness, and problem-solving.

Socioemotional development

Changes in personality, emotions, self-view, social skills, and relationships.

Plasticity

Development is malleable; individuals can adapt to challenges.

Cohort

A generation of people born at the same time who share similar historical and cultural experiences.

Continuous change

Development that unfolds slowly and gradually over time.

Discontinuous change

Development that occurs in abrupt stages, where individuals of various ages are dramatically different.

Theory

A way of organizing a set of observations or facts into a comprehensive explanation of how something works.

Hypothesis

Proposed explanations for a given phenomenon that can be tested by research.

A good theory

Is falsifiable and testable.

Freud's Psychosexual Theory

Development occurs through stages focused on different body parts, driven by unconscious drives; emphasizes importance of early family experience.

Erikson's Psychosocial Theory

Development progresses through psychosocial stages influenced by the social world, driven by maturation; relevant for all stages of life.

Radical Behaviorism

Behavior is determined by biological variables, past experiences, and environmental consequences.

Classical conditioning

Learning where a neutral stimulus elicits a response after association with another stimulus; developed by Ivan Pavlov.

Operant conditioning

Learning where behavior is strengthened or weakened by its consequences; developed by B. F. Skinner.

Reinforcement

A consequence that increases the likelihood of a behavior recurring.

Punishment

A consequence that decreases the likelihood of a behavior recurring.

Social learning theory

People learn through observing and imitating others; developed by Albert Bandura.

Observational learning

Learning by watching others' behaviors and their outcomes.

Piaget's Cognitive-Developmental Theory

Children are active explorers, constructing knowledge through interaction with their environment, organized into cognitive schemas.

Information Processing Theory

The mind works like a computer, processing input, storing information, and producing output.

Vygotsky's Sociocultural Theory

Cognitive development is a social process shaped by cultural context and interaction.

Bronfenbrenner's Bioecological Systems Theory

Development is shaped by interactions across multiple systems: microsystem, mesosystem, exosystem, macrosystem, and chronosystem.

Dynamic Systems Theory

Development emerges from continuous interaction among biological, cognitive, and contextual factors; developed by Esther Thelen.

Ethology

The scientific study of the evolutionary basis of behavior.

Evolutionary Developmental Theory

Applies evolutionary principles to understand how genetic and environmental mechanisms influence development across the lifespan.

Naturalistic observation

Observing and recording behavior in real-world settings.

Structured observation

Observing behavior in a controlled, experimental setting.

Longitudinal Research Design

Follows the same group of participants across multiple points in time.

Cross-sectional Research Design

Compares people of different ages at one point in time.

Sequential Research Design

Combines longitudinal and cross-sectional approaches by studying multiple cohorts over time.

Applied developmental science

Field that applies research to prevent and intervene on problems and promote positive, healthy development.

Neonate

A newborn.

Zygote

Cell formed at conception containing 46 chromosomes (23 from sperm, 23 from egg).

Germinal period

First 0-2 weeks; zygote divides and travels toward uterus, implantation occurs.

Blastocyst

A fluid-filled sphere of cells that forms a protective circle around an inner cluster of cells, which becomes the embryo.

Implantation

When the blastocyst burrows into the uterine wall (day 6-11).

Embryo

The developing organism from implantation until the 8th week.

Ectoderm

Outer layer that becomes skin, sense organs, brain, and spinal cord.

Mesoderm

Middle layer that becomes muscles, blood, bones, and circulatory system.

Endoderm

Inner layer that becomes the respiratory system, digestive system, liver, and pancreas.

Amnion

Membrane that encloses the amniotic fluid.

Placenta

Organ of exchange between mother and embryo/fetus.

Neural tube

Structure that develops into the central nervous system.

Fetal period

9 weeks to birth; organs grow and begin to function, rapid growth occurs.

Fetus

Name for the organism during the fetal period.

Lanugo

Fine, down-like hair covering fetus.

Vernix caseosa

Greasy material protecting fetal skin.

Age of viability

About 22 weeks; earliest age at which a fetus can survive outside womb with medical help.

Teratogen

Any agent (disease, drug, environmental factor) that can harm prenatal development.

Critical period

Specific window when a teratogen can cause greatest damage (embryonic period is most sensitive).

Sleeper effect

Impact of teratogen exposure that appears later in development.

Fetal alcohol spectrum disorders (FASD)

Range of outcomes caused by prenatal alcohol exposure.

Fetal alcohol syndrome (FAS)

Cluster of defects including facial abnormalities, growth deficiencies, and central nervous system problems due to heavy alcohol exposure.

Cigarette smoking during pregnancy

Increases risk of low birthweight, fetal death, and complications.

Opioid exposure during pregnancy

Leads to withdrawal symptoms, low birth weight, and long-term developmental issues.

Spina bifida

Neural tube defect where lower tube fails to close; spinal nerves grow outside vertebrae.

Anencephaly

Neural tube defect where top of tube fails to close; brain fails to develop (fatal).

Maternal age over 35

Increases risks of complications, though most women still deliver healthy babies.

Paternal smoking

Associated with DNA damage and mutations in sperm.

Prenatal care

Set of services to improve pregnancy outcomes and engage family in health care decisions.

Barriers to prenatal care

Lack of insurance, poverty, lack of education, systemic disparities.

First stage of labor

Dilation; longest stage, cervix opens.

Second stage of labor

Delivery; begins when cervix is fully dilated and baby is born.

Third stage of labor

Placenta is expelled.

Cesarean section (C-section)

Surgical delivery of baby through mother's abdomen; ~32% of U.S. births.

Natural childbirth

Uses breathing and relaxation techniques to reduce pain.

Doula

Caregiver who provides support during labor and delivery.

Low birthweight (LBW)

Infants born weighing less than 5.5 pounds.

Preterm

Infants born before due date.

Small-for-date

Infants full term but smaller than expected for gestational age.

Kangaroo care

Skin-to-skin contact that promotes LBW infant survival and development.

Apgar scale

Quick test of newborn's health (Appearance, Pulse, Grimace, Activity, Respiration).

Brazelton Neonatal Behavioral Assessment

Assessment of newborn behavior and neurological responses.

Auditory stimuli

Newborns can respond to sounds as early as 23 weeks in the womb.

REM sleep in newborns

Critical for brain development; resembles active wakefulness.

Growth norms

Standards for typical height and weight gains based on age and ethnic background.

Cephalocaudal development

Pattern of growth that proceeds from the head downward.

Proximodistal development

Pattern of growth that proceeds from the center of the body outward.

Breastfeeding benefits

Provides immunizing agents, reduces maternal risk of disease, and supports infant health.

Infant mortality

Death within the first year; leading causes include birth defects, low birthweight, SIDS, respiratory distress, and unintentional injuries.

Stunting

Reduced growth due to chronic malnutrition; affects about 1 in 4 children worldwide.

Marasmus

Wasting disease from calorie deficiency; body fat and muscle severely depleted.

Kwashiorkor

Disease from protein deficiency; causes bloating, swelling, and organ damage.

Growth faltering (failure to thrive)

Condition where infants show substantially below-average growth; linked to medical and socioemotional factors.

Vaccination

Injection of inactive virus to stimulate immunity; prevents disease.

Sudden Infant Death Syndrome (SIDS)

Unexpected death of infant under 1 year during sleep; associated with prone sleeping position and biological vulnerabilities.

Neuron

Specialized brain cell that communicates information.

Synapse

Gap between neurons where communication occurs.

Myelin

Fatty coating that insulates axons, speeding neural transmission.

Myelination

Process where glial cells coat axons with myelin, improving communication.

Synaptogenesis

Process where dendrites grow and branch, creating new synapses.

Synaptic pruning

Process of eliminating unused neural connections to increase efficiency.

Sensitive period

Time during which experience has a particularly strong impact on brain development.

Experience-expectant brain development

Brain depends on typical experiences (e.g., vision, language exposure) to develop normally.

Experience-dependent brain development

Brain growth shaped by unique individual experiences.

Neonate sleep

Newborns sleep about 16-18 hours a day, mostly in short cycles.