Answer:
Infants are not aware that hidden objects exist.
A child cannot be in multiple stages of cognitive development at once.
Explanation:Jean Piaget is a Swiss born psychologist, who has advanced the knowledge of Cognitive learning for children in 1936. He classified children Cognitive learning into the following stages
sensorimotor, preoperational, concrete, and formal. But modern Cognitive theorists have challenged Jean Piaget's position with the following findings.
(1) Infants are not aware that hidden objects exist.
(2) A child cannot be in multiple stages of cognitive development at once.