Human development: core definition

· Developmental psychology = the study of how and why behaviour and cognition change over time.
· Exam focus: explain development using biological, cognitive, and sociocultural influences rather than relying on one perspective only.
· Development may be understood as continuous change or as stage-like change with qualitatively different phases.
· High-scoring answers should link claims to research methods, ethics, and concepts such as change, causality, measurement, bias, perspective, and responsibility.

Models of development: what students must know

· Students should understand one or more models of cognitive, social, moral, or language development.
· Use models to explain patterns of development, not just describe age-related changes.
· Compare explanations: stage theories suggest clear developmental phases; continuous models suggest gradual growth over time.
· Strong evaluation points: cultural bias, determinism, reductionism, generalizability, and whether evidence is cross-sectional or longitudinal.

Brain development

· Brain maturation = biological growth and organization of the brain that supports developmental changes in behaviour and cognition.
· Critical periods = limited windows when certain abilities or behaviours may develop most effectively; exam answers should discuss the extent to which they explain human development.
· Neuroplasticity = the brain’s ability to change in response to experience; useful for explaining both developmental flexibility and recovery/adaptation.
· Avoid biological determinism: brain development interacts with experience, culture, learning, and environmental input.

This diagram shows how repeated practice can be linked to structural or functional brain change. It is useful for illustrating neuroplasticity as a biological mechanism in human development. It also supports evaluation of the interaction between maturation and experience. Source

Stage theories and continuous models

· Stage theories = development occurs through distinct phases, often with age-linked changes in thinking or behaviour.
· Continuous models = development occurs gradually through accumulated learning, maturation, and environmental influence.
· Use the comparison to evaluate whether development is best explained by qualitative shifts or incremental change.
· Key exam phrase: “The effectiveness of a model depends on whether it can explain variation between individuals and cultures.”

Sociocultural factors in development

· Sociocultural factors = social and cultural influences that shape development, such as family, schooling, peers, language, norms, values, and cultural expectations.
· Development is not only individual: behaviour changes within social systems and cultural contexts.
· Strong answers should explain how sociocultural factors influence development through enculturation, social learning, peer influence, and identity formation.
· Evaluate with emic vs etic approaches, cultural bias, and whether Western models can be applied across cultures.

This diagram shows how development is shaped by multiple layers of social context. It is useful for explaining sociocultural factors such as family, school, community, and wider culture. It supports holistic answers that go beyond one biological or cognitive cause. Source

Theory of mind

· Theory of mind = the ability to understand that other people have beliefs, intentions, knowledge, and perspectives that may differ from one’s own.
· It is important for explaining social cognition, perspective-taking, empathy, and children’s understanding of false beliefs.
· Useful example: false-belief tasks test whether a child understands that another person can hold an incorrect belief about reality.
· Evaluation: performance may be affected by language ability, task demands, culture, and measurement validity.

This resource illustrates the classic Sally–Anne false-belief task used to study theory of mind. It shows whether a child can predict behaviour based on another person’s mistaken belief. Use it to connect theory of mind with social and cognitive development. Source

Development of self

· Development of self = how individuals develop a sense of identity, self-understanding, social belonging, and personal continuity.
· IB focus areas: attachment, enculturation of social norms, peer influence, and childhood experiences.
· Best exam answers show how these factors interact, rather than treating them as isolated causes.
· Link to concepts: change over time, causality in explaining influences, and responsibility when researching children.

Attachment

· Attachment = an emotional bond between a child and caregiver that can influence the development of self.
· Attachment can affect later self-concept, emotion regulation, trust, and expectations in relationships.
· Use attachment carefully: avoid claiming early attachment determines all later outcomes; discuss probabilistic influence and later protective factors.
· Evaluation points: child participants, informed consent, naturalistic observation, cultural variation in caregiving, and ethics.

This visual summarises major attachment styles and their links to beliefs about self and others. It is useful for revising how attachment may contribute to the development of self. Use it as a prompt for evaluating whether early relationships influence later identity and relationships. Source

Enculturation of social norms

· Enculturation = the process by which individuals learn and internalise the norms, values, and expected behaviours of their culture.
· In development of self, enculturation shapes identity, gender roles, moral expectations, communication styles, and ideas of independence/interdependence.
· Exam answers should connect enculturation to social learning, family practices, schooling, and media.
· Evaluation: beware of imposed etic bias when applying one culture’s developmental model to another.

Peer influence

· Peer influence = the effect of same-age or similar-status individuals on attitudes, identity, behaviour, and self-concept.
· Peers may support social development, belonging, and identity exploration, but may also increase pressure to conform.
· Good examples include changes in risk-taking, academic behaviour, social norms, and self-esteem during childhood/adolescence.
· Evaluation: peer influence is often bidirectional because individuals also choose peers who match their existing traits.

Role of childhood experiences

· Childhood experiences can influence later development through learning, relationships, trauma, schooling, culture, and family environment.
· Avoid deterministic claims: childhood experiences may increase the likelihood of certain outcomes but do not guarantee them.
· Use diathesis-stress, resilience, protective factors, and gene–environment interaction as evaluation language where relevant.
· Strong answers distinguish between correlation and causation when discussing childhood experiences and later self-development.

Research methods for human development

· Recommended class practical: observation.
· Observation types may be naturalistic or controlled, overt or covert, and participant or non-participant.
· Suitable examples: language-learning classes, playground observations, or group dynamics in a public setting.
· Developmental research often uses longitudinal designs to track change over time or cross-sectional designs to compare age groups.
· Key evaluation terms: observer bias, inter-rater reliability, ecological validity, sampling bias, and operationalisation.

Ethics in human development research

· Research with children requires strong attention to protection from harm, informed consent, right to withdraw, anonymity, and debriefing.
· For participants under 16, parental/guardian consent is required; school-based research may also require teacher consent.
· Naturalistic observation may not always allow direct consent, so the setting must be genuinely public and low risk.
· No practical should cause anxiety, stress, pain, or discomfort.
· High-scoring evaluation links ethics to methodology: ethical controls may affect validity, participant behaviour, and sample representativeness.

Exam application: how to build a high-scoring answer

· Start with a clear claim using the command term: explain, discuss, evaluate, or to what extent.
· Define the key term precisely, e.g. neuroplasticity, attachment, enculturation, or theory of mind.
· Apply one relevant study or example to show how the factor influences human development.
· Evaluate using at least two of: methodological limitations, cultural bias, ethical issues, alternative explanations, correlation vs causation, or individual differences.
· End by linking back to the question and the concept of developmental change over time.