Gesell recorded and analyzed children's daily behavior reaction with movies in his early days, and found the law of children's development process. He believes that children's growth and development is orderly, from simple differentiation to fine differentiation and gradually mature. Children's behavior will show a special leap forward at a certain stage. Children's new behavior is representative in the process of maturity, which reflects that they have reached a new stage of growth and development. Gesell called these age stages the central age, and determined the central age as the key examination items and diagnostic criteria of the scale. According to gesell scale, every four weeks in 1 year-old is a stage, four weeks, 16 weeks, 28 weeks, 40 weeks and 52 weeks are the key ages, and 1 ~ 3 years old is the stage from March to June, and1August, 24 months and 36 months are the key ones. The content of the exam is divided into: ① coping ability: test the child's ability to respond to the people around him and take care of his own life; (2) adaptability: test children's ability to see, pick and draw; 3 speech ability: test children's listening, understanding and speech ability; ④ Movement ability: Test children's ability to sit, walk and jump. Results Developmental quotient was used to evaluate children's developmental level. Gesell believes that the observed development phenomenon reflects the maturation process of the central nervous system. This theory has been affirmed by all sides.
Gesell scale has clinical diagnostic value. It is not only suitable for measuring children's development level, but also more suitable for disabled children than other scales. It is considered as a classic method of infant intelligence test. In the early 1960s, China began to use gesell Scale in clinic.