[Studies of the system analysis of social motivation, IV: The varieties of smiling and the problem of motivational adjustment].

A formal theory is proposed that accounts for the motivational architecture underlying the spontaneous smiling response in its most salient varieties (i.e., smiling due to security, relief, embarrassment, fear, amazement, submission, and triumph). The theory is based on a single assumption according to which the smiling response, in all instances named, is due to a reduction of "autonomy claim" as defined within the framework of the Zurich Model of Social Motivation. The theory's consistency is evinced by way of computer simulation, its phenomenological plausibility can be demonstrated by animation based on Ekman's Facial Action Coding System.