What does the developmental Theory explain?

Answer 1

The Cognitive Theory of Development was created by Piaget.

There are four stages:

Stage one: The Sensorimotor Stage (Age Birth-2 years)

This is where the individual plans in their mind how the world works, so they develop schema's. This is also the stage where they need to pass Object Permanence (even if you don't see the object, you know it still exists)

Then they move into the

Stage two: The Preoperational Stage (Age 2-7 years)

This is when the individual believes the "world revolves around them". In this stage is where Ego-centrism takes place, they also begin understanding others.

They then move into

stage three: The Concrete Operational Stage (Age 7-11 years)

In this stage individuals have mental representations, meaning the picturing of objects in their minds, decentration, which is understanding others, reversibility, which is doing things according to them and conservation which is the knowing the difference of same size same amount, different size different amount.

Then they move into

stage four: Formal Operations Stage (Age 11 - adulthood)

this stage includes Abstract reasoning meaning reciting things from memory and deductive reasoning, meaning making conclusions.

Answer 2

The answer simply stated is to converge multiple ideas.