| Stage | Characteristics of the Stage | Major Change of the Stage |
|---|
| Sensorimotor (0–2 years) | Acquires understanding of object permanence. First understandings of cause-and-effect relationships. | Development proceeds from reflexes to active use of sensory and motor skills to explore the environment. |
| Preoperational (2–7 years) | Symbolic thought emerges. Language development occurs (2–4 years). Thought and language both tend to be egocentric. Cannot solve conservation problems. | Development proceeds from understanding simple cause-and-effect relationships to prelogical thought processes involving the use of imagination and symbols to represent objects, actions, and situations. |
| Concrete operations (7–11 years) | Reversibility attained. Can solve conservation problems. Logical thought develops and is applied to concrete problems. Cannot solve complex verbal problems and hypothetical problems. | Development proceeds from prelogical thought to logical solutions to concrete problems. |
| Formal operations (adolescence through adulthood) | Logically solves all types of problems. Thinks scientifically. Solves complex verbal and hypothetical problems. Is able to think in abstract terms. | Development proceeds from logical solving of concrete problems to logical solving of all classes of problems, including abstract problems. |