Answer:
The preoperational stage of development
Step-by-step explanation:
Under Jean Piaget's theory of cognitive development,children in the preoperational stage of development(around 2 to 7 years old) think symbollically and concretely and are also egocentric. They are egocentric as they are not able to see things from the perspective of others or how other people might view a situation. This is shown in the example where your little nephew would think his mother would want a toy train for her birthday since that is what he would want.