Developmental Psychology: This is the scientific study of how and why human beings change over the course of their life. It involves growth and changes in physical abilities, cognitive skills, emotional patterns, social roles etc.
Child Psychology: This branch of psychology deals with the mental processes and behavior of children from prenatal development through adolescence.
Theory of Mind: This is the ability to attribute mental states—beliefs, intents, desires, emotions—to oneself and others and to understand that others have beliefs, desires, intentions, and perspectives that are different from one's own.