Final answer:
The Jean Piaget and Barbel Inhelder's three-mountain task was designed to test whether children have reached the concrete operational stage of cognitive development and overcome egocentrism. The task helps researchers understand how children develop the ability to understand different perspectives.
Step-by-step explanation:
The Jean Piaget and Barbel Inhelder's three-mountain task was designed to test whether children have reached the concrete operational stage of cognitive development. This task is used to assess children's ability to understand another person's perspective and to test for the presence of egocentrism. In this task, children are shown a model of three mountains from different angles and are asked to choose a picture that represents what someone else would see from a different viewpoint.
Piaget believed that younger children, who have not yet reached the concrete operational stage, would struggle with this task and show egocentric tendencies, while older children would be able to take another person's point of view into account. The task helps researchers understand how children develop the ability to understand different perspectives and overcome egocentrism.