Describe Piaget's four stages of cognitive development. Include the major hallmarks of each stage.

Sensorimotor Infants "think" by acting on the world with their eyes, ears, hands, and mouth.

Preoperational. Development of language and make-believe play takes place.

Concrete Operational children think in a logical, organized fashion only when dealing with concrete information they can perceive directly.

Formal Operational. Adolescences can also evaluate the logic of verbal statements without referring to real-world circumstances.