Arnold Gesell used controlled environments to study child behavior in children at a variety of ages, videoing them through one way mirror. Gesell said that motor skills, adaptive skills, language development, and social skills were all influenced by heredity. He also wrote books on the upbringing and development of children.
"Arnold Gesell". Encyclopædia Britannica. Encyclopædia Britannica Online.
Encyclopædia Britannica Inc., 2016. 12 Sep. 2016. Web.