After completing this chapter you should be able to:

• Identify Piaget’s six substages of sensorimotor reasoning and summarize criticism of this perspective on infant and early childhood cognitive development. 
• Contrast the advances of concrete operational versus those of formal operational reasoning, and summarize common criticisms of Piaget’s perspective on these stages.
• Summarize Vygotsky’s sociocultural perspective and how it is manifested in scaffolding, the zone of proximal development, and cultural tools.
• Explain postformal reasoning and how it compares with cognitive–affective complexity.