A systematic review of experimental studies based on the paradigm of equivalence of stimuli including figures of human faces was performed, the variables were analyzed from the results obtained. It analyzed aspects that influence the formation of classes (general methodological aspects, procedural elements of experimental arrangement, training and equivalence tests). A search of the CAPES / MEC News Portal, an institutional repository of the Federal University of the State of Pará (UFPa), Redalyc.org and Scielo, produced sixteen studies. The results demonstrated the data consistent with the current literature in the field of stimulus equivalence. The analysis evidences the need to expand the research on the variables that affect the formation of classes including faces and contributions in the clinical, educational and social area.