The stimulus equivalence paradigm defined symbolic behaviors providing operational criteria that allowed experimental simulations of the acquisition and manipulation of symbols. This paper describes a validation of equivalence as a model of meaning and deals whit quantitative properties of symbolic relations. Results obtained in experimental studies that used a semantic differential to evaluate equivalent stimuli. The semantic differential also allowed an evaluation of quantitative properties of equivalence relations through the measurement of the degree of meaning transfer seemed to vary according to the experimental parameters involved. Variations in the transfer of functions indicate variations in the relatedness of equivalent stimuli.