ry, notably using sets of photographs of the facial affect of emotions as material support for experiments (McClain 2004). If the use of photographs as a tool to represent the emotions in the laboratory was not new when Ekman and Friesen published their Pictures of Facial Affect, the specificity of their photographic set resides in the fact that its images participate not only in a scientific rhetoric of proof or experimental methodology, but they also and above all constitute a black box (Latour 1995) that stabilizes and preserves the principle of the universality of the emotions. Ekman and Friesen’s photos of the facial expression of emotions have incorporated all the theoretical productions connoting them (Barthes 1961), that is to say, they include all the meanings resulting from the work on emotions conducted by these researchers. Through a process of translation and transcription (Latour and Woolgar  1988), the creative and interpretive elements of these images seem to have left room only for the reproduction of the “real”, thus allowing the use of a photograph of a facial expression of emotion to signify the emotion itself.
Now I turn to the dynamic process among researchers, discourses, images, actors and observers that participated in the production of these photographs which offer a relationship of identity with what they signify that goes beyond mere analogy.
The brochure that accompanies the set of Pictures of Facial Affect explains that,
With the aid of the best current technology in lighting and photography, more than a dozen persons were photographed repeatedly while attempting to express one of six emotions. Hundreds of photographs were studied over a period of several years to obtain a series which yielded consistent agreement among viewers about the emotion being expressed. […] Posers were trained to contract or relax different facial muscles associated with various facial expressions. Generally, posers were instructed to activate certain muscles rather than to pose a particular emotion. (Ekman and Friesen 1976, p. 1)
This quote shows that the photographs are the result of the coordination of numerous elements whose direct relationship with the emotions is not stated upfront. It also underlines the fact that the univocal recognition of the emotions represented by these photographs depends upon preliminary theoretical and technical achievements that are embodied both in models with the ability to control their facial muscles and in observers who are expected to associate those muscular configurations with emotions. In other words, the validity of these images lies in the established proof (in the authors’ opinion) of the universality of six so-called basic emotions and of the equivalence between the facial actions and the emotions themselves ; the subsequent development of a standardized technique for describing facial affect, i.e. the Facial Affect Scoring Technique (FAST) (Ekman, Friesen and Tomkins 1971) ; the quality of the photographs ; the ability of the actors to activate their face in precise ways ; and the statistical consensus obtained from the observers. The POFA set is the answer to Ekman and Friesen’s intention to reproduce in the laboratory typical expressions of emotion whose scientific reliability can be validated, since they judge expressions of emotion captured in reality to be experimentally problematic due to their contextual contingence (Ekman, Friesen and Ellsworth 1972).
Nevertheless, it seems paradoxical that the primary tool that allowed these researchers to prove the universality of the emotions and develop the FAST consists precisely of photographs of the facial expression of emotion which they judge to be insufficiently reliable. In fact, between 1966 and 1970, Ekman and his colleagues show groups of people in more than twenty countries a series of photos provided by their mentor, Tomkins, according to the following protocol : the subjects are shown photographs of facial affect, one by one, for about ten seconds. These photos represent portraits of Caucasian-type men and women