Stage

Description

Examples

Sensorimotor

(Birth to age 2)

Differentiates self from others.

Recognizes self as a person and begin to act intentionally.

Achieves object permanence—realizes that people and things exist even when no longer physically present.

• Points to self in the mirror when asked “Where is Alex?”
• Pushes a button to start a toy.
• Shakes a rattle to make a noise.
• No longer cries when caregiver walks out of the room.
• Moves blanket to find pacifier hidden underneath.

Preoperational

(age 2 to age 7)

Learns to represent events and objects in various ways.

Thinking is still egocentric: difficulty taking the viewpoint of others.

Classifies objects by a single feature.

• Holds block up to ear and says “Hello?”
• Engages in pretend play with baby dolls and bottles.
• Upon seeing that a peer is upset, brings peer a blanket.
• Groups all red blocks together, regardless of size.

Concrete Operational

(age 7 to age 11)

Can think logically about objects and events.

Achieves conservation of numbers (age 6), mass (age 7), and weight (age 9).

Classifies objects according to several features and can order them in a series.

• Understands that a feather cannot break a window because it is too soft.
• Recognizes that five pennies stacked and five pennies spread across a table are the same amount of pennies.
• Organizes all farm animals on one paper and all safari animals on another paper, then pairs the big and small like animals together.

Formal Operational

(age 11 through adulthood)

Can think logically about abstract propositions and test hypotheses systematically.

Is concerned with the hypothetical, the future, ideological problems.

• Able to solve abstract algebraic equations.
• Compares self to pictures in a magazine.