Ordering the sensorimotor substages
Piaget divided the sensorimotor stage of the first 2 years into six substages, each marked by a new kind of behavior. Matching each behavior to its substage gives the order 3, 1, 4, 2: shaking a rattle to hear its sound, then pulling a cloth to get a hidden toy, then dropping toys from different heights, and finally pretending to talk on a toy phone the day after watching his father. The correct sequence is secondary circular reaction, coordination of secondary schemes, tertiary circular reaction, and mental representation.
Matching behaviors to substages
| Behavior | Substage | Usual age |
|---|
| Shakes a rattle again and again to hear the sound | Secondary circular reactions | 4 to 8 months |
| Pulls a cloth away to get a hidden toy | Coordination of secondary schemes | 8 to 12 months |
| Drops toys from different heights to see the change | Tertiary circular reactions | 12 to 18 months |
| Pretends to talk on a toy phone the day after watching his father | Mental representation (deferred imitation) | 18 to 24 months |
What each step shows about thinking
In secondary circular reactions the infant repeats an action because it produces an interesting effect in the environment. In the coordination of secondary schemes, the infant combines actions to reach a goal, such as removing an obstacle to get a toy. This search for a hidden object also shows developing object permanence. In tertiary circular reactions, the toddler deliberately varies an action to see how the result changes, like a small experimenter. Finally, with mental representation, the child can hold an image in mind and reproduce it later, which allows deferred imitation and the beginnings of pretend play.
Why the distractors are wrong
The option 3, 4, 1, 2 places experimenting with heights before searching for a hidden toy, but tertiary circular reactions come after coordination of schemes. The option 1, 3, 4, 2 puts the hidden-toy search before rattle shaking, which reverses the first two substages. The option 3, 1, 2, 4 places pretend play before experimentation, but deferred imitation needs mental representation, which develops last. Watch out! Repetition to produce an effect and variation to see a new effect are different: repeating the same action is secondary, while changing the action deliberately is tertiary.
Exam takeaway
Repeat an effect, reach a goal, experiment with variations, then imitate from memory. Key point! Deferred imitation, copying an action seen earlier, is a hallmark of the last sensorimotor substage and the bridge to preoperational thought.