Cognitive theory is based on how the brain learns and processes information, as a reaction to behaviorism. It posits that people are not simply programmed by their environment. Key figures who developed aspects of cognitive theory include Piaget, Bloom, Gardner, and Paivio. Piaget's stage theory of cognitive development outlines four stages from sensorimotor to formal operations. Bloom's taxonomy categorizes cognitive skills from basic to complex. Gardner's theory of multiple intelligences recognizes eight types of intelligence. Dual coding theory, developed by Paivio, suggests language and images are both important ways of processing information.