Functions are attainment of the security needed for survival as well as social inclusion, intimacy, and the formation and maintenance of social bonds. Functions are succoring behavior that call for a response of nurturance as well as approval, attention or recognition, and physical assistance. Function is appetite satisfaction, with regard to when, how, why, how much, and under what conditions the individual eats, which is governed by social and psychological considerations as well as biologic requirements for food and fluids. Function is elimination, with regard to when, how, and under what conditions the individual eliminates waste. Functions are procreation and gratification, with regard to behaviors dependent upon the individual's biologic sex, including, but not limited to, courting and mating.
Function is protection and preservation of self and society.
The drive or goal of a subsystem refers to motivation for behavior. The specific drive of each subsystem cannot be observed directly but must be inferred from the individual's actual behavior and from the consequences of that behavior. Set, which also is inferred from observed behavior, refers to the individual's predisposition to act in certain ways, rather than in other ways, to fulfill the function of the subsystem. Choice refers to the individual's total behavior repertoire for fulfilling subsystem functions. The behavioral repertoire encompasses the scope of action alternatives from which the person can choose.