Themes and Methods in Developmental Psychology
Developmental psychology studies how people grow and change throughout the lifespan—from conception to death. This field examines physical, cognitive, and social-emotional development.
| Debate | Question | Modern View |
|---|---|---|
| Nature vs. Nurture | Genes or environment? | Both interact; neither alone determines development |
| Continuity vs. Stages | Gradual change or distinct stages? | Some aspects are continuous, others occur in stages |
| Stability vs. Change | Do traits persist or change over time? | Some traits stable, but change is possible throughout life |
📊 Cross-Sectional
Compare different age groups at one point in time.
Fast but can't separate age from generational effects (cohort effects)
📈 Longitudinal
Follow the same people over a long period.
Shows true development but expensive, time-consuming, subject attrition
🔄 Cross-Sequential
Combines both: multiple age groups studied over time.
Best of both worlds but complex and costly
- Cross-sectional limitation: Cohort effects can be mistaken for developmental changes.
- Longitudinal limitation: Participant dropout (attrition) and practice effects from repeated testing.
- Teratogens: Harmful agents (alcohol, drugs, viruses) that can cause birth defects during prenatal development.
1) A researcher compares problem-solving abilities in 20-year-olds, 40-year-olds, and 60-year-olds at the same time. What method is this?
2) What's the main limitation of this design?
Show Answers
1) Cross-sectional design—comparing different age groups at one point in time.
2) Cohort effects—differences might be due to the era each group grew up in (different education, technology, culture) rather than actual developmental changes.
Physical Development Across the Lifespan
Physical development encompasses changes in the body and brain from conception through old age, including motor skills, sensory abilities, and biological maturation.
🔬 Germinal Stage
Weeks 1-2
Zygote divides and implants in uterine wall
🫀 Embryonic Stage
Weeks 3-8
Major organs and body systems form; most vulnerable to teratogens
👶 Fetal Stage
Week 9-Birth
Organs mature; rapid growth; movement and responsiveness
| Reflex | Stimulus | Response |
|---|---|---|
| Rooting | Touch cheek | Turn head toward touch, open mouth |
| Sucking | Object in mouth | Rhythmic sucking |
| Grasping (Palmar) | Object in palm | Fingers close around object |
| Moro (Startle) | Loud noise or sudden movement | Arms extend, then pull in; crying |
| Babinski | Stroke sole of foot | Toes fan out and curl |
These reflexes are present at birth and disappear within months as the brain matures.
Key principles:
- Synaptic pruning: Unused neural connections are eliminated ("use it or lose it")
- Myelination: Continues into the 20s; frontal lobes myelinate last
- Plasticity: Young brains are more adaptable; decreases with age but never fully disappears
Motor skills develop in a predictable sequence (though timing varies):
2-3 mo
Roll over
6 mo
Sit with support
8-9 mo
Crawl
11-12 mo
Stand alone
12-15 mo
Walk
Puberty:
- Triggered by hormones (estrogen, testosterone)
- Primary sex characteristics (reproductive organs)
- Secondary sex characteristics (body hair, voice changes)
- Growth spurt; brain continues developing
Aging:
- Gradual decline in sensory acuity
- Slower reaction times
- Menopause (women) around age 50
- Brain shrinkage but new neurons can still form (neurogenesis)
- Embryonic stage is most vulnerable to teratogens (major structures forming).
- Frontal lobe (judgment, impulse control) isn't fully developed until mid-20s—explains adolescent risk-taking.
- Reflexes are commonly tested—know the triggers and responses!
1) A pregnant woman drinks alcohol heavily. During which prenatal stage would this cause the most severe structural damage?
2) Why do teenagers often engage in risky behavior despite knowing the dangers?
Show Answers
1) The embryonic stage (weeks 3-8), when major organs and body structures are forming. This is when teratogens cause the most severe damage.
2) The prefrontal cortex (responsible for judgment, impulse control, and long-term planning) isn't fully myelinated until the mid-20s. Meanwhile, the limbic system (emotions, rewards) is very active during adolescence.
Gender and Sexual Orientation
Gender development involves the interplay of biology, cognition, and social learning. Understanding the difference between sex, gender, and sexual orientation is essential.
| Theory | Key Idea | Theorist |
|---|---|---|
| Social Learning Theory | Gender roles learned through observation, imitation, and reinforcement | Bandura |
| Gender Schema Theory | Children develop mental frameworks for gender and organize information accordingly | Bem |
| Biological Theory | Hormones and brain differences influence gender-typed behavior | Various |
| Psychoanalytic Theory | Gender identity develops through identification with same-sex parent | Freud |
- Not a choice: Sexual orientation appears to be influenced by a complex interaction of genetic, hormonal, and environmental factors
- Twin studies: Identical twins have higher concordance rates than fraternal twins, suggesting genetic influence
- Prenatal hormones: Exposure to certain hormones during critical periods may influence sexual orientation
- Brain differences: Some structural differences observed between heterosexual and homosexual individuals
- No single "cause": Like most human traits, sexual orientation is multifactorial
- Sex vs. Gender: Sex = biological; Gender = psychological/social.
- Gender schema: Children actively construct understanding of gender, then filter experiences through this lens.
- Androgyny: Combining both masculine and feminine traits; associated with flexibility and well-being.
1) A child notices that girls in her class play with dolls and decides she should too. Which theory best explains this?
2) What does research suggest about the origins of sexual orientation?
Show Answers
1) Social learning theory—the child is observing and imitating same-gender peers. Gender schema theory could also apply if she's using her mental framework of "what girls do" to guide her behavior.
2) Research suggests sexual orientation results from a complex interaction of genetic, hormonal, and environmental factors. It is not a choice, and no single factor determines it.
Cognitive Development Across the Lifespan
How does thinking change as we age? Jean Piaget's stage theory remains the most influential framework, but other theorists have offered important additions and critiques.
1. Sensorimotor Stage (Birth - 2 years)
Key feature: Learning through senses and motor actions
Major milestone: Object Permanence — understanding that objects exist even when not visible (develops around 8 months)
Example: Peek-a-boo is exciting because babies are surprised the face still exists!
2. Preoperational Stage (2 - 7 years)
Key feature: Symbolic thinking develops, but logic is limited
Limitations:
- Egocentrism: Can't see others' perspectives (Three Mountain Task)
- Centration: Focus on one aspect, ignoring others
- Lack of Conservation: Don't understand quantity stays same despite appearance changes
- Animism: Believing inanimate objects have feelings
3. Concrete Operational Stage (7 - 11 years)
Key feature: Logical thinking about concrete (physical) objects
New abilities:
- Conservation: Understand quantity remains despite appearance changes
- Reversibility: Can mentally reverse actions
- Classification: Can group objects by multiple characteristics
Limitation: Still struggles with abstract/hypothetical thinking
4. Formal Operational Stage (12+ years)
Key feature: Abstract and hypothetical reasoning
New abilities:
- Abstract thought: Can think about concepts like justice, freedom
- Hypothetical-deductive reasoning: Can form and test hypotheses systematically
- Metacognition: Thinking about thinking
Note: Not everyone reaches this stage, and it's not universal across all domains.
Lev Vygotsky emphasized the role of social interaction and culture in cognitive development.
Key difference from Piaget: Vygotsky saw development as driven by social interaction, not just individual exploration.
- Object permanence = Sensorimotor; Conservation = Concrete operational
- Egocentrism in Piaget ≠ selfishness; it means inability to take another's perspective
- Piaget vs. Vygotsky: Piaget = stages, individual discovery; Vygotsky = social interaction, cultural tools
1) A 4-year-old insists there are "more" crackers when you spread them out on a plate. What Piagetian concept does this demonstrate?
2) How would Vygotsky explain how a child learns to solve math problems?
Show Answers
1) Lack of conservation (and centration)—the child focuses on one dimension (spread/appearance) and doesn't understand that quantity remains the same.
2) Vygotsky would emphasize social interaction: a teacher or parent works with the child in the Zone of Proximal Development, providing scaffolding (support that is gradually reduced) until the child can solve problems independently.
Communication and Language Development
Language is one of humanity's most remarkable abilities. How do children go from babbling to speaking in complete sentences in just a few years?
| Age | Stage | Examples |
|---|---|---|
| 0-4 months | Cooing | Vowel sounds: "ooo," "aaa" |
| 4-6 months | Babbling | Consonant-vowel combos: "ba-ba," "da-da" |
| ~12 months | One-word (Holophrastic) | "Mama," "ball," "up" (one word = whole idea) |
| 18-24 months | Two-word (Telegraphic) | "Want cookie," "Daddy go" (like a telegram) |
| 2+ years | Sentences | Rapid vocabulary growth; grammar develops |
🧒 Nativist (Chomsky)
Language Acquisition Device (LAD): Innate brain mechanism for learning language
Universal Grammar: All languages share basic structural features
Language is biologically programmed
🎓 Learning Theory (Skinner)
Language learned through reinforcement and imitation
Parents reward correct speech, children model adults
Language is learned behavior
These errors actually show children are learning rules, not just memorizing words!
Strong version: Language determines thought (largely rejected)
Weak version: Language influences thought and perception (supported by research)
Example: Languages with more color terms may help speakers distinguish colors more easily. Russian speakers, who have separate words for light and dark blue, are faster at distinguishing these shades.
- Chomsky vs. Skinner: Chomsky = innate (LAD); Skinner = learned (reinforcement)
- Telegraphic speech: Contains meaning but lacks function words ("Want milk" not "I want some milk")
- Overgeneralization (like "goed") shows children learn rules, not just words
1) A child says "I runned fast!" What does this error demonstrate about language acquisition?
2) What evidence supports Chomsky's nativist theory?
Show Answers
1) Overgeneralization—the child has learned the rule for past tense (-ed) and is applying it to an irregular verb. This shows language learning involves extracting and applying rules, not just imitation.
2) Evidence includes: (1) all children learn language at similar ages regardless of culture, (2) all languages share basic structural features (universal grammar), (3) children produce sentences they've never heard, (4) there's a critical period for language acquisition, (5) specific brain areas (Broca's, Wernicke's) are dedicated to language.
Social-Emotional Development Across the Lifespan
How do we form bonds with others, develop a sense of self, and navigate social relationships throughout life? This section covers attachment, temperament, and psychosocial development.
Attachment: The emotional bond between infant and caregiver that provides security and comfort.
| Attachment Style | Behavior When Parent Leaves | Behavior When Parent Returns | Caregiver Style |
|---|---|---|---|
| Secure (60-70%) | Distressed but can be comforted | Happy, seeks contact, easily soothed | Responsive, consistent |
| Anxious-Ambivalent (10-15%) | Very distressed | Angry and clingy; hard to comfort | Inconsistent |
| Avoidant (15-20%) | Little distress | Ignores or avoids parent | Unresponsive, rejecting |
| Disorganized | Confused, contradictory | Confused behaviors (approach then freeze) | Frightening, abusive |
Thomas and Chess identified three temperament types present from birth:
😊 Easy
Regular routines, positive mood, adaptable
~40% of infants
😤 Difficult
Irregular routines, negative mood, slow to adapt
~10% of infants
🐢 Slow-to-Warm-Up
Low activity, mild reactions, gradual adjustment
~15% of infants
Note: ~35% don't fit neatly into any category.
Erik Erikson proposed 8 stages of development, each with a central conflict to resolve:
| Stage | Age | Crisis | Key Question |
|---|---|---|---|
| 1. Trust vs. Mistrust | Infancy (0-1) | Trust vs. Mistrust | "Is the world safe?" |
| 2. Autonomy vs. Shame/Doubt | Toddler (1-3) | Autonomy vs. Shame | "Can I do things myself?" |
| 3. Initiative vs. Guilt | Preschool (3-6) | Initiative vs. Guilt | "Can I make things happen?" |
| 4. Industry vs. Inferiority | School Age (6-12) | Industry vs. Inferiority | "Am I competent?" |
| 5. Identity vs. Role Confusion | Adolescence | Identity vs. Confusion | "Who am I?" |
| 6. Intimacy vs. Isolation | Young Adult | Intimacy vs. Isolation | "Can I love?" |
| 7. Generativity vs. Stagnation | Middle Adult | Generativity vs. Stagnation | "Can I make my life count?" |
| 8. Integrity vs. Despair | Late Adult | Integrity vs. Despair | "Was my life meaningful?" |
| Style | Demandingness | Responsiveness | Child Outcomes |
|---|---|---|---|
| Authoritative | High | High | Best outcomes: confident, self-reliant, socially skilled |
| Authoritarian | High | Low | Obedient but less happy, lower self-esteem |
| Permissive | Low | High | Immature, poor impulse control |
| Uninvolved | Low | Low | Poorest outcomes: attachment issues, behavior problems |
- Secure attachment is linked to better outcomes in relationships, self-esteem, and emotional regulation.
- Erikson's adolescent crisis (Identity vs. Role Confusion) is especially common on AP exams.
- Authoritative ≠ Authoritarian: AuthoritaTIVE = best; AuthoritarIAN = strict and cold.
1) In the Strange Situation, a child cries when mother leaves but is easily comforted when she returns. What attachment style is this?
2) A 45-year-old feels unfulfilled because they haven't contributed meaningfully to the next generation. According to Erikson, what stage crisis are they experiencing?
Show Answers
1) Secure attachment—the child shows appropriate distress at separation and is easily soothed upon reunion, using the parent as a "secure base."
2) Generativity vs. Stagnation (Stage 7, Middle Adulthood). Generativity involves contributing to society and helping the next generation; failure leads to feelings of stagnation and emptiness.
Classical Conditioning
Classical conditioning, discovered by Ivan Pavlov, is learning through association. A neutral stimulus becomes associated with an automatic response.
| Term | Definition | Pavlov's Dogs Example |
|---|---|---|
| Unconditioned Stimulus (US) | Naturally triggers a response | Food |
| Unconditioned Response (UR) | Natural, unlearned reaction to US | Salivation (to food) |
| Neutral Stimulus (NS) | Initially produces no relevant response | Bell (before conditioning) |
| Conditioned Stimulus (CS) | Previously neutral stimulus that now triggers response | Bell (after conditioning) |
| Conditioned Response (CR) | Learned response to the CS | Salivation (to bell) |
| Term | Definition | Example |
|---|---|---|
| Acquisition | Initial learning of the CS-US association | Dog learns bell predicts food |
| Extinction | CR weakens when CS presented without US | Bell rings but no food → salivation stops |
| Spontaneous Recovery | CR reappears after a rest period following extinction | Next day, bell causes salivation again (briefly) |
| Generalization | Responding to stimuli similar to the CS | Dog salivates to similar bells |
| Discrimination | Learning to respond only to the specific CS | Dog learns only one specific bell means food |
9-month-old Albert was conditioned to fear a white rat:
- US: Loud noise (naturally frightening)
- UR: Fear/crying (to loud noise)
- NS → CS: White rat (paired with noise)
- CR: Fear/crying (to white rat)
Albert also showed generalization—he feared other white, furry objects (rabbit, dog, fur coat). This demonstrated that emotional responses can be classically conditioned.
- ID the US, UR, CS, CR in any scenario—this is a classic AP question!
- UR and CR are often the same response (salivation), just triggered by different stimuli.
- Taste aversion is a biological exception—can be learned in one trial, even with long delays between NS and US.
1) After getting food poisoning from sushi, you feel nauseous whenever you smell sushi. Identify the US, UR, CS, and CR.
2) You now also feel sick when you smell any raw fish. What phenomenon is this?
Show Answers
1) US: Bacteria/toxin causing illness. UR: Nausea (from bacteria). CS: Sushi (smell). CR: Nausea (from sushi smell).
2) Generalization—responding to stimuli similar to the original CS (raw fish smells similar to sushi).
Operant Conditioning
Operant conditioning, developed by B.F. Skinner, is learning through consequences. Behaviors followed by favorable consequences are strengthened; those followed by unfavorable consequences are weakened.
| Schedule | Description | Example | Response Pattern |
|---|---|---|---|
| Continuous | Reinforce every response | Treat every time dog sits | Fast learning, fast extinction |
| Fixed-Ratio (FR) | Reinforce after set # of responses | Pay per 10 items produced | High rate, brief pause after reward |
| Variable-Ratio (VR) | Reinforce after unpredictable # of responses | Slot machines, sales calls | Highest, steadiest rate; most resistant to extinction |
| Fixed-Interval (FI) | Reinforce first response after set time | Weekly paycheck | Scalloped pattern; increase near reward time |
| Variable-Interval (VI) | Reinforce first response after unpredictable time | Checking email, fishing | Slow, steady rate |
- Negative reinforcement ≠ punishment! Negative reinforcement INCREASES behavior by removing something unpleasant.
- Variable-ratio is most resistant to extinction (gambling addiction).
- Know the difference: Classical = involuntary responses; Operant = voluntary behaviors.
1) A child throws a tantrum in the store and the parent buys them candy to stop it. What type of consequence is this for the child? For the parent?
2) Why are slot machines so addictive according to reinforcement schedules?
Show Answers
1) For the child: Positive reinforcement (candy added → tantrums increase). For the parent: Negative reinforcement (tantrum removed → buying candy increases).
2) Slot machines use a variable-ratio schedule—payouts come after an unpredictable number of plays. This produces the highest, steadiest response rate and is most resistant to extinction because you never know if the next pull will win.
Social, Cognitive, and Neurological Factors in Learning
Learning isn't just about associations and consequences. We also learn by watching others, thinking about situations, and through biological predispositions.
We learn by watching and imitating others—no direct reinforcement required!
Four Requirements for Observational Learning:
1. Attention
Must notice the behavior
2. Retention
Must remember it
3. Reproduction
Must be able to do it
4. Motivation
Must want to do it
Children watched an adult model either play calmly or act aggressively toward a Bobo doll (hitting, kicking, yelling). Results:
- Children who saw aggressive model imitated the aggression
- They even invented new aggressive behaviors
- Boys showed more physical aggression than girls
- Children more likely to imitate same-sex models
This demonstrated that aggression can be learned through observation without reinforcement—major implications for media violence.
Not all associations are equally easy to learn—biology matters!
🤢 Taste Aversion
One-trial learning of food-illness associations, even with long delays
Evolutionary advantage: don't eat poison twice!
🦊 Instinctive Drift
Tendency for learned behaviors to revert to innate patterns
Breland & Breland: "The pig kept rooting the coins"
- Bandura's 4 steps: Attention, Retention, Reproduction, Motivation (ARRM)
- Latent learning challenges pure behaviorism—learning can happen without observable behavior change
- Learned helplessness = linked to depression; important for clinical applications
1) A teenager watches YouTube tutorials for months before ever picking up a guitar. When they finally try, they play surprisingly well. What concepts explain this?
2) Why is taste aversion considered evidence that biological factors constrain learning?
Show Answers
1) Observational learning (learning from watching models) and latent learning (learning occurred but wasn't demonstrated until they had the motivation/opportunity to play).
2) Taste aversion violates normal classical conditioning rules: it occurs in one trial and with long delays between CS (taste) and US (illness). This suggests we're biologically prepared to quickly learn food-illness associations—an evolutionary adaptation that doesn't apply to other types of learning.