The development and legacy of Jean Piaget's cognitive development research Jean Piaget conducted many experiments involving children, eventually introducing the idea of ​​four stages in children's cognitive development. His research has met with criticism over the years, but his work paved the way for psychologists who came after him. Psychologist Jean Piaget made amazing contributions to the field of developmental psychology. At a young age Jean Piaget showed interest and potential for scientific research, but he had no institutional training in psychology. His interest in knowledge that encompassed much of his work came from his godfather, Samuel Cornut. One of his first jobs in psychology was recording children. Piaget's research helped him discover that children structure their knowledge differently than adults. He believed that there were four stages of a child's intellectual development (Cohen, 2011, p. 27). The sensorimotor stage was the first stage and described how infants learn about their environment through senses and motor action. This phase also includes the concept of object permanence which usually lasts until the child's eighth month of life. Children who have not overcome object permeation do not search for an object once it is out of sight and will focus their attention on something new. The preoperative phase is the second and occurs in children between the ages of two and seven. At this stage they do not have to rely on physical contact to gain knowledge and can think about an event after it has happened (Cohen, 2011, p. 161). However, they cannot decentralize, which means they only give their attention to one object at a time. Cohen (2011), gives the example of children believing that taller people should be older than shorter ones (p. 161). The third phase is the concrete operational phase, which lasts seven to eleven years. At this stage they have the concept of decantation. Unlike the preoperational phase, children can acquire more than one detail of an object at the same time. The last stage is the formal operational stage, which begins around age twelve. At this stage children begin to think about possible, abstract and hypothetical ideas (Cohen, 2011, p..