Abstract
The analysis of facial – emotional behavior through the FACS represents an objective, powerful and rigorous method for the fine and sophisticated investigation of some behavioral aspects, such as emotions, cognitive activity, temperamental traits, personality traits and clues of lies that as such escape self-report measures.
Empirical evidence also exists in favor of the ability of FACS to discriminate between different psychopathological disorders and to identify the indications of dysfunctional processes, such as defenses, resistances, variations of the mental states that may emerge during the analyst-patient relationship.
FACS was developed to determine how the contraction of each facial muscle, singly or in combination with other muscles, changes the appearance of a face. Ekman and Friesen videotaped more than 5,000 different combinations of muscle actions, which were carefully examined to determine the most significant changes each of They contributed to the structure of the face, also studying how it was possible to differentiate one movement from another. 44 AUs (Action Units) were calculated to account for changes in facial expressions. and 14 AU which more roughly describe movements in the direction of gaze and orientation of the head. AUs are features of change of the face with respect to the neutral face (starting point for face analysis), which may involve stretching, bulge, the contraction of muscles. Such AUs create 10,000 visible facial configurations of which 3,000 are significant.
The measurement of facial expressions in the FACS system is done through AU, instead of muscle units, as there are good reasons for economy in the decoding activity. A first reason could be the fact that in the case of some configurations, multiple muscles are combined to compose a single AU, since their role in the changes produced In the facial configuration can not be distinguished. In fact, a particular facial configuration can involve several AUs and the change associated with a particular AU can be altered (increased or decreased) by the action of other units. The interaction of several units of action results in facial expressions that are notandvoltaively different from those that might be expected from the simple sum of the individual units. A second reason is that by means of the FACS system the changes produced in the facial configuration by a single muscle are sometimes separated into two or more AUs since they represent relatively independent actions of different parts of the muscle.
Our study, which includes over 6,000 participants in over 10 years of work, allowed us to divide AUs into “substantial”, “modifiing” and “accidental” thus allowing us to identify new coding patterns and combinations for better and more functional coding and decoding.
