According to Jean Piaget, a Swiss clinical psychologist known for his pioneering work in child development, children go through four key stages of cognitive development. The sensorimotor stage, from birth to age 2. The preparation of stage, from age 2 to about age 7. The concrete operational stage, from age 7 to age 11. Then the formal operational stage, which begins in adolescence and spans to adulthood. Now, seeing that this was in a sense my re-rebirth, everything moved as if it was on speed. What happened in years seemed to happen in months to me, disorienting, to say the least. I Googled stages of child development thinking I would get something far different, but I was wrong.