Abstract

The current study was conducted to i) introduce the method of successive intervals, a stimulus-centered scaling that has not received much attention in psychology, ii) show that it can be applied to measure the blameworthiness of behavior, and iii) demonstrate the scaled behaviors could be applied to measure an individual’s psychological property. The authors classified psychometric methods and introduced several stimulus-centered scaling methods. The usefulness of the method of successive intervals was discussed by comparing those stimulus-centered scaling methods. In order to find the scale value of the stimulus and the boundary of the response category, the method of successive intervals determines the relative positions of all stimuli and response categories based on the proportion of raters who responded to each response category to individual stimuli. In Study 1, a list of 33 morally justifiable behaviors was constructed from existing studies. Then, scale values of the blameworthiness of the behaviors were calculated (N=500). As a result, the scale values of behaviors prohibited by law were higher than others. On the other hand, the scale values of behaviors that could not be punished but could be perceived as bad were relatively low. In Study 2, the representation of innocence (representation of ‘innocent’), meaning people’s psychological representation of ‘not blameworthy’ was measured (N=108) based on the scale values obtained in Study 1. The relationship between the representation of ‘innocent’ measured by the list of behaviors and related variables had a theoretically predictive direction. These results show that the scale values of stimulus based on the method of successive intervals can be applied to measure individual’s psychological attribute related to the stimulus. This study is expected to allow researchers to consider various scaling methods by showing the applicability of the method of successive intervals that have not been used frequently by researchers in psychology.