Object permanence, conservation, and egocentrism are key concepts in Piaget's theory of cognitive development.
Object permanence is the concept that objects continue to exist even when they are not visible. Piaget, in his theory of cognitive development, noted that children typically develop this understanding around 8 months of age.
In the preoperational stage, children may struggle with conservation, which is the understanding that changing the appearance of an object does not change its fundamental properties, such as quantity.
At this stage, children also exhibit egocentrism, where they have difficulty understanding the perspectives of others and tend to see things only from their own viewpoint.
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