Every person is predominantly one of four different human types. One's type is determined by one's natural predisposition to function more in one center of response than in the others. We can distinguish the various human types by their different speeds of response to both external and internal' stimuli, and by where their energy is directed. The four basic human types also each have characteristic behavior patterns. The four types are vegetative, motor, emotional, and intellectual. It is possible in addition to distinguish sub‑types based on a person's predisposition to function more in a specific part of a given center. Through education and practice one can develop different centers, parts, and subparts and change the basic human type.