Final answer:
Shelley's ability to locate her hidden stuffed bear demonstrates the development of object permanence, a significant cognitive milestone typically achieved in the sensorimotor stage of development according to Jean Piaget's theory.
Step-by-step explanation:
Shelley's ability to find her favourite stuffed bear in the other cabinet after her brother moved it from her toy chest is a clear demonstration of her having developed object permanence. According to Jean Piaget's theory of cognitive development, object permanence is an understanding that children typically develop in the sensorimotor stage, which occurs from birth to about 2 years old.
It is the concept that objects continue to exist even when they cannot be seen, heard, or otherwise sensed. Shelley's realization that her bear still exists even though it was not in its usual place indicates that she understands this concept, which is a significant milestone in a child's cognitive development.
Object permanence is fundamental to children's understanding of the world around them. It is a precursor to engaging in more complex cognitive tasks, such as strategic thinking and problem-solving. As children develop object permanence, they may start enjoying games like hide and seek, and realize that people continue to exist when out of sight and will return.