Developmental stage
A developmental stage is a period in which a child's thinking is organised in a distinctive way, so that development is treated as a sequence of qualitative reorganisations rather than a steady accumulation of facts. Piaget's four stages are the sensorimotor, in which the infant knows the world through action; the preoperational, in which the child uses symbols but not yet reversible logic; the concrete operational, in which logical operations apply to actual objects; and the formal operational, in which they apply to hypotheses. His central evidence was that children make consistent, systematic errors, such as saying a tall narrow glass holds more than a wide one after watching the same water poured. Later work supported the broad sequence but showed Piaget consistently underestimated infants, whose competence appears earlier when tested by looking time rather than by reaching and speaking.
Why it matters
It replaced the picture of children as small adults with less information, and made the systematic mistakes children make into evidence rather than noise.
Also written: stages of development, cognitive development, conservation
Where it comes up
Read about Developmental stage on Wikipedia
Sources
- Piaget's theory of cognitive development Wikipedia
- The Philosophy of Childhood Stanford Encyclopedia of PhilosophyIncludes a direct critical assessment of Piaget's stage model.
- Developmental psychology Wikipedia
