The investigation is concerned with the effects on judgement of some relations between the manner in which stimuli of a series are classified and the magnitudes of the stimuli. It is shown that when the classification stands in a direct and predictable relation to a physical scale, the stimuli belonging to different classes are judged as farther apart on that scale than in an unclassified series. A classification which is not coherently related to the physical scale does not affect judgement in this manner.

There is also evidence in the results that, as a function of past experience with the classification, an increase occurs in the apparent differences between stimuli belonging to different classes, and in the apparent similarity of stimuli belonging to the same class.

The relevance of these findings to the general problem of stereotyping is discussed.