Which stage of Piaget's development is NOT included in his theory?

In Piaget's theory of cognitive development, he identified four distinct stages: sensorimotor, preoperational, concrete operational, and formal operational. The preoperational stage occurs approximately between ages 2 to 7 years, where children begin to engage in symbolic play and learn to manipulate symbols, but they do not yet understand concrete logic. The concrete operational stage follows, typically from ages 7 to 11, where children start thinking logically about concrete events. Finally, the formal operational stage emerges from age 12 and onwards, characterized by the ability to think abstractly, reason logically, and use hypothetical thinking.

The correct answer points out that "empirical" is not one of the stages defined in Piaget's developmental theory. Piaget's framework focuses specifically on the stages of cognitive development rather than empirical approaches or methodologies, which pertain to observational research rather than structured stages of cognitive growth. Thus, identifying "empirical" as not being included aligns with understanding the foundational structure of Piaget's cognitive development stages.