AbstractA comparison of ratingsof five intensional and of five extensional concepts by both separate and combined batteries of fifteen intensional and fifteen extensional semantic differential scales showed significant patterns of differences. The results indicate that the troublesome scale/concept interaction which in past studies has lowered the internal validity of many investigations can be reduced by the simple expedient of controlling for homogeneity of domain of scales and concepts employed. Some evidence also was found indicating the existence of a group of scales which apply equally well to both types of concepts.