Final answer:
Piaget believed that the timing of a stage reflects the infant's level of physical maturation and cognitive development.
Step-by-step explanation:
Jean Piaget believed that the exact timing of a stage reflects an interaction between the infant's level of physical maturation and the level of cognitive development of the child.
For example, in Piaget's sensorimotor stage, which occurs from birth through age 2, a child learns about the world through senses and motor behavior.
This stage reflects the infant's physical maturation as well as their developing cognitive abilities to understand and interact with the environment.