Item Selection by the Constant Process

This paper relates the constant process used in psychophysics to the problem of item selection. Each test item may be described in terms of a limen, which is an index of the point at which an item discriminates, and the standard deviation of the limen, which is an index of the “goodness” of discrimination. The method developed may be related not only to the description of items but also to the description of persons. Thus a person's ability may be described in terms of a limen and its standard deviation.