Developmental psychology (WACE Year 12 Psychology Unit 4)
“Explain theories of development including Piaget's cognitive stages, attachment, and Erikson's psychosocial stages, with reference to nature and nurture.”
Development is explained by stage theories: Piaget's four stages of cognitive development (sensorimotor to formal operational), Bowlby and Ainsworth's attachment theory, and Erikson's eight psychosocial stages. All interact with the nature versus nurture debate, which today is resolved as an interaction of genes and environment.
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Developmental psychology is not part of the SCSA Psychology ATAR Year 12 syllabus (Units 3 and 4, taught since 2024), so this page is not examined in the WACE Psychology ATAR exam. Lifespan development, Piaget and attachment are now in the Year 11 syllabus (Unit 1: Biological and lifespan psychology). For the Year 12 theories of how behaviour is acquired, see learning and cognition.
What this dot point is asking
This Unit 4 dot point asks you to describe how thinking, relationships and identity develop across the lifespan and to apply the nature-nurture framework.
Piaget's cognitive development
Jean Piaget proposed that children construct understanding through schemas (mental frameworks), modified by assimilation (fitting new information into existing schemas) and accommodation (changing schemas to fit new information). He described four stages:
- Sensorimotor (0 to 2 years): learning through senses and movement; the key achievement is object permanence (knowing objects exist when out of sight).
- Preoperational (2 to 7 years): symbolic thought and language, but egocentrism (difficulty taking another's view) and a lack of conservation (not understanding that quantity stays the same despite changes in appearance).
- Concrete operational (7 to 11 years): logical thinking about concrete objects; conservation is achieved.
- Formal operational (11+ years): abstract and hypothetical reasoning.
In Piaget's conservation task, a preoperational child says a tall thin glass holds more water than a short wide glass even after seeing the same amount poured across. Achieving conservation marks the shift into concrete operational thinking.
Attachment (Bowlby and Ainsworth)
John Bowlby proposed that infants form an attachment to a primary caregiver that is biologically adaptive and provides a secure base. He argued for a critical (sensitive) period for forming attachments and that disruption could have lasting effects (his maternal deprivation hypothesis).
Mary Ainsworth's Strange Situation procedure classified infant attachment styles:
- Secure: distressed at separation, comforted on reunion, uses the caregiver as a base.
- Insecure-avoidant: little distress at separation, avoids the caregiver on reunion.
- Insecure-resistant (ambivalent): very distressed, but hard to soothe and resists contact on reunion.
Harry Harlow's monkey studies showed infant monkeys preferred a soft cloth "mother" over a wire one that provided food, indicating attachment is driven by contact comfort, not just feeding.
Erikson's psychosocial stages
Erik Erikson described eight stages across the lifespan, each centred on a psychosocial crisis to be resolved.
The fifth stage, identity versus role confusion (adolescence), is the central task of forming a coherent sense of self. Successful resolution produces a stable identity; failure produces confusion about one's roles and values.
Other stages include trust versus mistrust (infancy), autonomy versus shame and doubt, initiative versus guilt, industry versus inferiority, intimacy versus isolation (young adulthood), generativity versus stagnation, and integrity versus despair (late adulthood).
Nature versus nurture
The nature position emphasises heredity, genes and maturation; the nurture position emphasises environment, learning and experience. The modern consensus is interaction: development arises from genes and environment together. Twin and adoption studies, especially comparing identical (monozygotic) and fraternal (dizygotic) twins, are the main method for estimating the relative contribution of each, because identical twins share all their genes.
A child's capacity for language reflects nature (a maturational readiness and brain structures for speech) and nurture (exposure to a specific language and reinforcement of speech). Neither alone is sufficient: without exposure during sensitive periods, the innate capacity does not develop fully. A strong answer names a method (twin studies) and concludes that the two interact rather than compete.
Piaget's and Erikson's stages occur in a fixed order and are not skipped, but the ages are approximate, not exact cut-offs. Also avoid framing nature versus nurture as an either-or contest; WACE markers reward the interactionist conclusion. Finally, do not confuse Ainsworth's attachment styles: avoidant infants show little distress, resistant infants show high distress but resist comfort.
In the exam, name the theorist, the stage or style, and link it to observable behaviour, then close development questions with the interactionist view of nature and nurture.
Exam-style questions
Questions in the style of SCSA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Original6 marksDescribe Piaget's four stages of cognitive development, naming the age range and one defining achievement or limitation of each stage.Show worked answer →
A 6 mark response needs all four stages with an age range and a defining feature.
- Sensorimotor (0 to 2 years)
- Learning through senses and movement; the key achievement is object permanence, knowing objects exist when out of sight.
- Preoperational (2 to 7 years)
- Symbolic thought and language, but egocentrism and a lack of conservation.
- Concrete operational (7 to 11 years)
- Logical thinking about concrete objects; conservation is achieved.
- Formal operational (11+ years)
- Abstract and hypothetical reasoning.
Markers reward each stage paired with the correct age range and a defining ability or limitation, without mismatching abilities to stages.
Original8 marksExplain how the nature-nurture interaction shapes development, and discuss how twin and adoption studies help estimate the contributions of heredity and environment.Show worked answer →
An 8 mark extended response needs the interactionist view plus the research method.
- Nature and nurture
- Nature refers to genetic and biological influences; nurture refers to environment, learning and experience. The modern consensus is interaction: genes set a range of possibilities and the environment determines where within that range a person develops, and people partly shape their own environments.
- Twin studies
- Identical (monozygotic) twins share all their genes; fraternal (dizygotic) twins share about half. If identical twins are more alike on a trait than fraternal twins, that points to a genetic contribution; twins reared apart who still resemble each other strengthen this, while their differences highlight the environment.
- Adoption studies
- Comparing adopted children with both biological and adoptive parents separates shared genes from shared environment.
- Conclusion
- Markers reward the interactionist framing, the logic of comparing twin types, and the conclusion that most traits reflect both genes and environment rather than either alone.