Answer: He lacks an understanding of the concept of conversation.
Explanation:
Piaget's theory of cognitive development is a theory about the human intelligence, it's nature and its development. The theory deals with how human beings acquire and use knowledge.
Piaget's theory of cognitive development explains how children develop their ability when reasoning. Paiget believed that there are four developmental stages which shapes the thinking capability of every children.
Regarding the question, Colin's reply to the question been asked shows that Colin's doesn't really understand the question being asked and hence, lacks an understanding of the concept of conversation.