Question

The difference between primary and secondary circular reactions is that secondary circular reactions involve the infant responding to people and _____.

Answer 1

The answer is "secondary circular reactions involve the infant responding to people and objects in outer world."

An example is that when a mother hands the infant a duck or something he squeezes it, sometime creating a sound which the infant feels like responding to and that is why he/she will repeat the action again and again.
The idea was presented by a Swiss scientist Jean Piaget and is known as Piaget's stages of sensorimotor intelligence.