developmental-psychology

Developmental Psychology

Developmental psychology studies how people grow, change, and maintain stability across the lifespan -- from conception to death. The field addresses cognitive, social, emotional, moral, and physical development, asking not just what changes but why and how. The central tension is between nature (genetic endowment, maturation) and nurture (environment, experience, culture), with modern developmental science treating the interaction between them as the fundamental unit of analysis.

Agent affinity: piaget (cognitive development, stages), vygotsky (social/cultural development, scaffolding)

Concept IDs: psych-developmental-stages, psych-attachment-theory, psych-language-development, psych-adolescent-development

Developmental Domains at a Glance

| # | Domain | Key Question | Major Theorists | |---|---|---|---| | 1 | Cognitive development | How does thinking change with age? | Piaget, Vygotsky, information processing theorists | | 2 | Attachment | How do early bonds shape later relationships? | Bowlby, Ainsworth, Main | | 3 | Moral development | How does moral reasoning mature? | Kohlberg, Gilligan, Turiel | | 4 | Language development | How do children acquire language? | Chomsky, Bruner, Tomasello | | 5 | Identity and adolescence | How does the self emerge? | Erikson, Marcia | | 6 | Adult development and aging | What changes (and what doesn't) in adulthood? | Baltes, Schaie, Carstensen |

Domain 1 -- Piaget's Stages of Cognitive Development

Jean Piaget (1896-1980) proposed that children actively construct knowledge through interaction with the world. Development proceeds through four invariant stages, each characterized by qualitatively different forms of thought. Children do not simply know less than adults -- they think differently.

Core mechanisms

• Schema -- an organized pattern of thought or action. Schemas are the building blocks of knowledge.
• Assimilation -- fitting new experience into existing schemas ("that four-legged animal is a dog").
• Accommodation -- modifying schemas when new experience does not fit ("that four-legged animal has stripes -- I need a 'zebra' schema").
• Equilibration -- the drive to balance assimilation and accommodation. Cognitive conflict (disequilibrium) motivates schema change.

The four stages

Stage 1: Sensorimotor (birth to ~2 years). The infant knows the world through action -- sucking, grasping, looking. The major achievement is object permanence: the understanding that objects continue to exist when out of sight (demonstrated by Piaget's A-not-B task). Before roughly 8 months, "out of sight" is literally "out of mind."

Stage 2: Preoperational (~2 to ~7 years). Symbolic thought emerges: language, pretend play, drawing. But thinking is egocentric (the child assumes others see the world as they do -- the three-mountains task), centrated (focusing on one dimension at a time), and lacks conservation (pouring water into a taller glass makes "more water"). Reversibility of mental operations is not yet achieved.

Stage 3: Concrete operational (~7 to ~11 years). Conservation is achieved. The child can perform mental operations (reversibility, classification, seriation) on concrete objects. Logical thinking emerges but is tied to the physical world -- hypothetical and abstract reasoning remain difficult.

Stage 4: Formal operational (~11+ years). Abstract, hypothetical, and systematic thinking becomes possible. Adolescents can reason about possibilities (not just realities), test hypotheses systematically, and think about thinking (metacognition). Not all individuals reach formal operations in all domains; cultural and educational factors play a significant role.

Critiques of Piaget

• Underestimated infant abilities. Baillargeon (1987) showed object permanence understanding as early as 3.5 months using looking-time paradigms.
• Stage transitions are gradual, not abrupt. Children often demonstrate abilities in one domain before another (horizontal decalage).
• Cultural variation. Formal operational thinking depends heavily on schooling; it is not a universal endpoint.
• Social dimension neglected. Piaget focused on the individual child constructing knowledge; Vygotsky provided the social corrective.

Domain 2 -- Attachment

Attachment theory (Bowlby, 1969) proposes that infants are biologically predisposed to form emotional bonds with caregivers, and that the quality of these early bonds shapes internal working models of relationships that persist into adulthood.

Bowlby's ethological framework

Bowlby drew on ethology (Lorenz's imprinting studies) and psychoanalysis to propose that attachment is an evolved behavioral system. The attachment system is activated by threat (separation, danger, illness) and deactivated by proximity to a responsive caregiver (the "safe haven" and "secure base" functions).

Ainsworth's Strange Situation

Mary Ainsworth (1978) developed the Strange Situation procedure to classify attachment patterns in 12-18 month olds:

| Pattern | Behavior | Caregiver style | Prevalence (~US) | |---|---|---|---| | Secure (B) | Distressed at separation, comforted at reunion, uses caregiver as base | Sensitive, responsive | ~60% | | Avoidant (A) | Little distress at separation, ignores caregiver at reunion | Rejecting, emotionally unavailable | ~20% | | Anxious-resistant (C) | Very distressed at separation, ambivalent at reunion (seeks contact but resists) | Inconsistent responsiveness | ~15% | | Disorganized (D) | No coherent strategy, freezing, contradictory behaviors | Frightening or frightened caregiver | ~5% |

Adult attachment

Main and colleagues (1985) extended attachment classification to adults via the Adult Attachment Interview (AAI). Adults who can discuss childhood attachment experiences coherently (even if those experiences were negative) are classified as "autonomous" and tend to have securely attached children. The intergenerational transmission of attachment is one of the most robust findings in developmental psychology.

Criticisms

• Cross-cultural variation in attachment distributions (van IJzendoorn & Kroonenberg, 1988) raises questions about universality of the "secure = optimal" assumption.
• The temperament hypothesis (Kagan, 1984) suggests infant temperament contributes to attachment classification, not just caregiver sensitivity.
• Earned security (Roisman et al., 2002) shows that adults can revise insecure working models through later relationships.

Domain 3 -- Moral Development

Kohlberg's stages

Lawrence Kohlberg (1969) proposed six stages of moral reasoning across three levels, based on responses to moral dilemmas (the Heinz dilemma):

Level 1: Preconventional (childhood). Stage 1: Obedience and punishment orientation ("it's wrong because you get punished"). Stage 2: Instrumental purpose ("I'll do it if there's something in it for me").

Level 2: Conventional (adolescence/adulthood). Stage 3: Good boy/good girl ("it's right because people will approve"). Stage 4: Law and order ("it's right because it's the law").

Level 3: Postconventional (rare in adults). Stage 5: Social contract ("laws are agreements that can be changed through democratic process"). Stage 6: Universal ethical principles ("some principles transcend law -- justice, human dignity").

Gilligan's critique

Carol Gilligan (1982) argued that Kohlberg's stages were biased toward a justice orientation (typically male) and neglected an equally valid care orientation (typically female). The care perspective emphasizes relationships, responsibility, and contextual sensitivity over abstract principles. Modern moral development research acknowledges both orientations without privileging either.

Domain theory

Turiel (1983) distinguished moral rules (harm, fairness -- universal, not authority-dependent) from social-conventional rules (dress codes