AP Psychology – Unit 3: Developmental Psychology

Continuous vs. discontinuous development

gradual vs. stage-like changes

Continuous

Gradual, ongoing process.

Example: Vygotsky – learning happens bit by bit through social interactions.

Discontinuous

Happens in stages.

• ⭐ Example: Piaget’s cognitive stages:

  • Sensorimotor → Preoperational → Concrete operational → Formal operational

Cross-sectional

Studies different ages at once.

• ✅ Quick, easy comparison.

• ❌ Doesn’t track individual growth; cohort effects possible.

Longitudinal

Follows same group over time.

• ✅ Tracks real development, shows causal effects.

• ❌ Takes a long time, expensive, people may drop out.

Teratogens

Harmful substances.

• ⭐ Example: Alcohol → Fetal Alcohol Syndrome → cognitive & physical issues.

Genetic mutations

• Can cause disorders.

Order

Milestones follow patterns but timing varies

Fine motor

Small muscles → hold spoon, write.

Gross motor

Large muscles → crawl, walk, jump

Reflexes

Signs of healthy development.

• ⭐ Rooting reflex: Turn head toward nip when cheek stroked.

• ⭐ Moro reflex: Startle → arms spread then pull in.

Critical periods

 Certain experiences are essential.

Sensitive periods

Brain is very receptive but not absolutely required.

Imprinting (animals)

Attach to first moving object (ducklings).

Reproductive ability

Declines → menopause in women (~50s).

Physical abilities

Slower reaction, less flexible, weaker senses.

• ⭐ Why important: Helps plan health care and lifestyle.

Intersex

~1 in 2000 → intersex

Lifespan Development

The study of physical, cognitive, and social development from conception to death.

• Development happens across the entire life, not just childhood

Socialization

The process by which individuals learn cultural norms, values, behaviors, and expectations through family, peers, school, and media.

• Socialization = nurture

Developmental Disorders

Disorders that begin in childhood and involve impairments in learning, behavior, or social functioning.

• Autism Spectrum Disorder (ASD) → social communication difficulties

• ADHD → attention and impulse control issues

Crystallized Intelligence

Accumulated knowledge, skills, and experience gained over time.

• Increases or stays the same with age

•  Examples:

  • Vocabulary

  • General knowledge

Fluid Intelligence

Ability to reason quickly, solve new problems, and think abstractly.

Prenatal Development

• Teratogens are most harmful during the embryonic stage