Measurement in psychology

Abstract

The author asserts that experimental psychology has added not a single quantitative law since the formulation of Weber's law. He believes that a promising approach to the problem of mental measurement may lie in the possibility of correlating experiences of "more" or "less" with extensive changes of linear magnitude. The program which he suggests for carrying out the problem is as follows: "Compare two or more linear magnitudes, note the errors resulting from the different comparisons, and plot one against the other. If the resulting series of points forms a smooth curve it will be possible to express differences in terms of errors, or errors in terms of differences. The meanings will be identical. The unit distance may be defined as that distance which is reacted to correctly in 75% of the cases, or any other percentage preferred to 75." It appears to the author to make little difference whether the units be equal in the psychological sense or in the physical sense. In selecting a method we must provide at least two samples differing from each other, if possible, only in the one feature to be compared. The method of paired comparisons and the method of rank differences are two methods which satisfy these requirements. (PsycInfo Database Record (c) 2025 APA, all rights reserved)