3.2 Human development

Brain development is the maturation and reorganisation of neural systems across childhood and adolescence. Growth in connectivity and executive control can change what a person can learn or regulate, but development is not a single timetable.

Genes, nutrition, stress, sleep and social experience interact with maturation. A developmental difference may reflect timing, opportunity or measurement rather than a fixed ability or a simple biological cause.

A teenager may improve planning as fronto-parietal networks mature, while practice and school demands also shape the skill. The same age range contains large individual variation, so averages are not a destiny.

Maturation is not the same as inevitability. Separate biological change, experience, task demands and the evidence used to infer a mechanism.

Sociocultural factors are the language, practices, relationships, institutions and norms through which people learn. They shape which skills are valued, which strategies are available and how behaviour is interpreted.

Cross-cultural differences can reflect different activities and expectations rather than different basic capacity. Compare tasks fairly, ask whose knowledge defines success, and avoid treating one schooling style as a universal baseline.

A child who learns mental arithmetic through market transactions may use strategies that a classroom test does not reward. The context changes the practice and the measurement, not necessarily the underlying potential.

Culture is not a single national label and sociocultural explanation does not deny biology. Identify the practice or institution that supplies the learning opportunity.

A developmental model is a structured account of how abilities or behaviour change over time. Models may emphasise stages, continuous growth, social interaction or technology, and each makes different predictions.

A useful model states the mechanism, age or context boundary and evidence that could distinguish it from alternatives. New tools such as AI may alter opportunities without proving that development follows one universal sequence.

If an adaptive tutor gives immediate feedback, performance may improve through practice. That result does not show that the learner has reached a new developmental stage or that the same tool works for every child.

A model is not a timetable or a label for a child. Check whether the evidence concerns performance, underlying competence, transfer or a change in context.

Theory of mind is the ability to represent another person's beliefs, intentions, knowledge or feelings, including the possibility that they are mistaken. It supports prediction and communication but is not identical to empathy.

Tasks often test whether a child distinguishes reality from another person's belief. Performance depends on language, executive control, familiarity and task demands, so a failed task does not isolate one missing mental ability.

If a child sees a toy moved while another person is absent, predicting where that person will search tests access to information rather than the child's own knowledge. The mismatch is the key evidence.

Passing a false-belief task does not prove mature social understanding in every setting, and failing it does not prove an absence of all perspective-taking.

Attachment is an enduring relationship that provides security and a base for exploration. Consistent sensitive care can support regulation, while deprivation or disrupted caregiving can increase risk for later difficulties.

Outcomes depend on timing, duration, quality of replacement care, temperament and later relationships. Correlation between early experience and later behaviour cannot by itself establish one pathway or eliminate resilience.

A child separated from a primary caregiver may show distress and later difficulty trusting adults, but stable alternative care and supportive relationships can change the trajectory. Risk is not a sentence.

Attachment is not the same as constant contact and one early event does not determine a person's future. State the mechanism, developmental window and protective factors.

Social norms are shared expectations about what people usually do or ought to do. They influence health behaviour through observation, modelling, approval, sanctions and the perceived behaviour of peers.

A norm can be descriptive (‘people like us do this’) or injunctive (‘people like us approve this’). Interventions work better when they identify which norm is inaccurate and provide a credible alternative model.

If students believe everyone skips breakfast, showing that most classmates eat before school may shift the descriptive norm. Access to food and routines still determine whether a person can act on the new information.

A stated attitude is not the same as a norm or behaviour. Measure what people perceive, what others actually do and what consequences follow.

Peer influence occurs when people of similar age or status shape behaviour, identity or norms. Social identity processes can make group membership meaningful, while comparison supplies standards for belonging and distinction.

Influence can support prosocial behaviour or increase risk, depending on the group norm, status structure, opportunity and the person's need for acceptance. Agency and multiple peer groups prevent a single-pressure explanation.

A new student may adopt a team's training routine to be recognised as a member. If the team rewards unsafe dieting, the same belonging mechanism can produce harm rather than health.

Peer influence is not automatically conformity or coercion. Identify the group, the valued identity, the reward or sanction and whether the person accepted or resisted the norm.

Childhood experiences include caregiving, conflict, trauma, opportunity and social loss. Their effects depend on exposure, interpretation, developmental timing, support and later experiences rather than on the event label alone.

War or chronic threat can affect stress regulation, learning and relationships, but studies must separate direct exposure from displacement, poverty, family disruption and selective survival. Protective relationships can moderate risk.

Two children exposed to the same move may show different outcomes because one has stable schooling and a trusted adult. Comparing only the event without the surrounding pathway hides the mechanism.

An adverse experience is not a diagnosis and resilience is not proof that no harm occurred. State the outcome, time course, alternative exposures and evidence quality.

Observation systematically records behaviour as it occurs. Naturalistic observation preserves context; controlled observation standardises the situation. Structured coding makes observations comparable but can miss unexpected meaning.

Define behaviours operationally, train observers and check inter-observer agreement. Reactivity, observer expectations, sampling time and ethical privacy limits affect validity; covert observation requires a strong justification and safeguards.

To study playground cooperation, code each helping episode, sample the same time windows and compare observers' classifications. The design can show frequency and context, but not automatically the private intention behind an action.

Seeing a behaviour does not prove its cause. Distinguish frequency, interpretation and inference, and report who was observed, when, and under what conditions.