In simple terms
A friendly intro before the formal notes — no formulas yet.
Two builders and a blueprint
A child's mind is not fixed at birth. Development is the interaction between a biological blueprint (a maturing brain) and the social world that surrounds it. Two famous theories disagree about which builder matters more — the lone explorer or the guided apprentice — and the evidence on attachment and deprivation shows just how much the social environment can shift the outcome.
Imagine two ideas about how a child learns to build. Piaget's child is a lone scientist: given time and materials, they discover the rules of the world for themselves, one stage at a time. Vygotsky's child is an apprentice: a more skilled builder stands beside them, doing the parts they can't yet manage and handing over the tools as the child grows ready — the gap between what the apprentice can do alone and what they can do with help is the 'zone of proximal development'. Both agree the brain is the site under construction; they disagree about who holds the tools.
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Name the factor precisely — a theory (Piaget or Vygotsky) OR an environmental force (attachment; deprivation/trauma).
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State the mechanism — what does this factor actually do to thinking or to relationships?
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Support it with a named study: aim, procedure, findings — then USE the findings to answer the question.
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Evaluate — critical periods, causation, generalisability, ethics — and reach a reasoned conclusion.
Explore the concept
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Full topic notes
Formal explanation with the rigour you need for the exam.
Two theories of cognitive development
Jean Piaget saw the child as a lone scientist. Through interacting with the world the child builds schemas — mental frameworks — and updates them by assimilation (fitting new experience into an existing schema) and accommodation (changing the schema when it no longer fits). This drive to resolve the mismatch, or disequilibrium, pushes the child through four universal, invariant stages: sensorimotor (0–2), pre-operational (2–7), concrete operational (7–11) and formal operational (11+). Crucially the order never varies and each stage rests on the one before — a child cannot reason abstractly before mastering concrete logic.
Lev Vygotsky put the social world first. For him, higher mental functions appear twice — first between people, then inside the child — and language is the tool that carries thought inward. The engine of learning is the Zone of Proximal Development (ZPD): the gap between what a child can do alone and what they can achieve with help from a more knowledgeable other (MKO). Support inside that zone is called scaffolding (named by Wood, Bruner and Ross, 1976): it is tailored to the learner and gradually withdrawn as competence grows. Where Piaget says 'wait for the stage', Vygotsky says 'the right guidance can pull development forward'.
Sensorimotor (0–2): the infant learns through senses and action, and acquires object permanence — that things exist when out of sight.
Pre-operational (2–7): language blooms but thinking is egocentric and lacks conservation — the child thinks a taller glass holds more water.
Concrete operational (7–11): logical operations appear (conservation, reversibility) but only about concrete, present objects.
Formal operational (11+): abstract, hypothetical and systematic reasoning becomes possible.
Mechanism: assimilation + accommodation → equilibration. Development is individual construction, driven from inside the child.
Development is SOCIAL first, individual second — the ZPD is the space where a more knowledgeable other lifts the child beyond solo ability.
Scaffolding = temporary, responsive support that is faded out; it operationalises the ZPD.
Language is the central psychological tool; private speech becomes inner thought.
Contrast with Piaget: Vygotsky sees a guided apprentice, Piaget a lone scientist — but both see the child as ACTIVE, not a passive recipient.
Social and environmental factors (1): attachment
Cognitive milestones unfold inside relationships, and the first and most studied relationship is attachment. John Bowlby argued that attachment is adaptive — infants are biologically prepared to bond with a caregiver who provides a 'safe base' — and that early experience with a sensitive, responsive caregiver builds an internal working model, a template for what relationships feel like and whether others can be trusted. Mary Ainsworth turned this into measurable behaviour with the Strange Situation, revealing distinct attachment types that predict later social competence. The mechanism for social development is the internal working model: secure early bonds teach the child they are worthy of care and that others are reliable.
Bowlby: attachment is adaptive, monotropic (a primary bond), and shaped during an early sensitive period; it seeds an internal working model for later relationships.
Ainsworth's Strange Situation classified infants as secure, insecure-avoidant, or insecure-ambivalent (with disorganised added later).
Secure attachment predicts higher social competence, empathy and self-esteem; insecure patterns are linked to greater later difficulty in relationships.
Evaluate: the Strange Situation was developed in the US and may impose a cultural bias — what looks 'insecure' in one culture may reflect different, valued child-rearing norms.
Social and environmental factors (2): deprivation, trauma and the developing brain
If responsive care builds development, its absence can derail it. Bowlby's early 'maternal deprivation hypothesis' warned that prolonged separation harms development, but the strongest modern evidence comes from studies of children raised in severely depriving institutions — above all the Romanian orphanages of the late 1980s. Michael Rutter's English and Romanian Adoptees (ERA) study followed children adopted into UK families and found that the AGE at adoption mattered: those rescued early recovered far more fully than those who endured deprivation for longer. This points to a sensitive period and to a biological substrate — chronic neglect produces 'toxic stress' that alters the developing brain's circuits for stress, memory and impulse control, while enrichment and neuroplasticity allow striking recovery when care arrives early. Rutter argued the outcome reflected privation (an attachment never formed) plus global under-stimulation, refining Bowlby rather than simply confirming him.
Romanian orphan / ERA studies: children adopted after roughly 6 months of institutional deprivation showed more lasting cognitive deficits and disinhibited attachment than those adopted earlier.
The dose–response pattern (longer deprivation → worse outcome) supports a sensitive period for social and cognitive development.
Biological mechanism: prolonged 'toxic stress' and understimulation shape brain regions for stress regulation and executive function; neuroplasticity underpins recovery when care comes early.
Rutter reframed the effect as PRIVATION plus under-stimulation — refining, not simply confirming, Bowlby's maternal deprivation hypothesis.
Resilience: a stable relationship with at least one responsive adult buffers adversity, so outcomes are probabilistic, not fixed.
Evaluating developmental research
Causation: you cannot ethically assign children to poverty, neglect or an attachment type, so much evidence is correlational or quasi-experimental — resist strong causal claims and name possible confounds (nutrition, prenatal factors, genetics).
Generalisability & culture: Ainsworth's Strange Situation and Piaget's tasks were developed in Western settings; interpretations may not transfer to cultures with different child-rearing norms or unfamiliarity with test formats.
Longitudinal strengths and costs: studies like the ERA track real change over years — powerful for development — but suffer attrition and are expensive and slow.
Piaget critiques: later research (e.g. simpler, less confusing task wording) suggests Piaget UNDERESTIMATED young children; his stage boundaries look less rigid than claimed.
Ethics: deprivation research uses vulnerable participants; researchers rely on natural experiments precisely because manipulation would be unethical, which is both a strength (ecological validity) and a design limitation (no random allocation).
Common mistakes examiners penalise
Attaching 'ZPD' and 'scaffolding' to Piaget — these are Vygotsky's. Piaget's engine is assimilation/accommodation through stages. Swapping them signals shaky knowledge and costs Criterion B.
Muddling the attachment types — avoidant infants show LITTLE distress and avoid on reunion; ambivalent/resistant infants are highly distressed and resist comfort. Reversing them undermines your use of Ainsworth.
Confusing privation with deprivation — the Romanian outcomes reflect privation plus under-stimulation (Rutter), not simply a broken bond. Precise terms let you EVALUATE Bowlby rather than just repeat him.
Describing studies instead of USING them — a flawless aim/procedure/findings with no link to the question caps Criterion C. Always finish with 'this shows… because…'.
Over-claiming causation — writing 'poverty causes low IQ' or 'deprivation causes disinhibited attachment' from correlational or quasi-experimental data. Hedge appropriately and name confounds.
Prepared-essay drift — answering a memorised 'attachment essay' when the question specified cognitive development, or ignoring the command term. This directly lowers Criterion A (Focus).
Worked examples
See the formulas applied — reveal one step at a time, like the exam.
Explain one theory of cognitive development, with reference to one study. [Explain]
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One theory of cognitive development is Piaget's stage theory, which claims children construct knowledge by building and revising schemas, passing through four universal, invariant stages. A central claim is that pre-operational children (2–7) lack CONSERVATION — the understanding that a quantity stays the same despite a change in its appearance.
Explain the influence of deprivation on social development, with reference to one study. [Explain]
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Deprivation influences social development by disrupting the formation of the internal working model during a sensitive early period, leaving children less able to form ordinary selective attachments.
Paper 2 (Developmental psychology): Discuss the influence of one or more factors on cognitive OR social development. [22 marks]
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Model essay
How it all connects
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Glossary
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Revision flashcards
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Cognitive development
The growth of mental processes — thinking, reasoning, memory, problem-solving and language — across childhood. The two dominant explanations are Piaget's stage theory and Vygotsky's sociocultural theory.
Key takeaways
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Sensorimotor (0–2): the infant learns through senses and action, and acquires object permanence — that things exist when out of sight.
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Pre-operational (2–7): language blooms but thinking is egocentric and lacks conservation — the child thinks a taller glass holds more water.
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Concrete operational (7–11): logical operations appear (conservation, reversibility) but only about concrete, present objects.
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Formal operational (11+): abstract, hypothetical and systematic reasoning becomes possible.
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Mechanism: assimilation + accommodation → equilibration. Development is individual construction, driven from inside the child.
Practice — then mark it
The whole point: a real Cambridge question, marked mark-by-mark.
Get a Paper 2 essay marked: Discuss the influence of one or more factors on cognitive OR social development [22]
Get a Paper 2 essay marked: Discuss the influence of one or more factors on cognitive OR social development [22]
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Frequently asked
Checkpoint
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