Final answer:
Blair is in the preoperational stage of development, where she focuses more on perceptual changes rather than logical reasoning, which is typical for children aged 2 to 7.
Step-by-step explanation:
Blair is likely in the preoperational stage of development according to Jean Piaget's theory of cognitive development. This stage typically occurs between the ages of 2 and 7 and is characterized by egocentrism and the inability to perform conservation tasks. In Blair's case, she is showing a focus on the perceptual aspect of the ice cream changing color in the dark, rather than understanding that its taste and edibility remain unchanged. The preoperational stage is significant in a child's development as they begin to engage in symbolic play and struggle to take the perspective of others.