It is more likely that the child, when playing dress up as a doctor and pretending to take exams of his peers in preschool, is in the pre-operational stage of Piaget's development.
It occurs during early childhood, from 2 to 7 years. The fundamental developmental characteristics at this stage are symbolic thinking and learning to use words and images to represent objects and situations.
Therefore, with the development of language, at this stage children are more able to play and develop imagination and creativity.
Find out more information about Piaget's four stages here:
https://brainly.com/question/984110