This document discusses key theorists in cognitive development, including Piaget, Vygotsky, and Bruner. It summarizes some of their main agreements and disagreements. Piaget believed that cognitive development occurs through self-discovery, while Vygotsky and Bruner emphasized the role of social and cultural influences. Specifically, Vygotsky believed that language acquisition shapes thought and problem-solving abilities. The document also compares Piaget and Vygotsky's views on topics like maturational readiness, the role of language in development, and implications for teaching practices.