The idiographic approach in social judgment theory : A review of components of the lens model equation components

The Lens Model Equation (Tucker, 1964) quantifies the judge-environment interactions expressed as judgment achievement and reveals the underlying sources of judgment achievement. Since Tucker’s publication (1964), there has been no comprehensive review of the literature applying the Lens Model Equation to individuals, i.e. idiographic approach. By describing and analysing variations of individual data this review shows, by means of a meta- analysis, restricted to idiographic studies, the importance of focusing on the idiographic approach, which is mostly neglected by research on judgment and decision-making. Consequently, only 14 of 34 studies, using an idiographic approach, were included in our review. The findings of 263 judgment achievements, analysed by our meta-analysis, led to the conclusion that, generally speaking, our individuals judge a given criterion moderately well. Furthermore, the high error-free judgment achievements of most of our judges imply that there often is room for improvement of judgment achievement. Most important, however, is the result from our idiographic analysis, showing that there are great individual differences among the judges with regard to achievement level, knowledge and consistency. There are also indications in the analysis of our idiographic data that both task-variables like the number of cues and person-variables like the judge’s expertise or knowledge level, might influence the judgment and decision process. Further research, based on the Lens Model Equation supplemented by a qualitative approach, describing and analysing single judges’ performance is needed to prevent premature conclusions about eventual commonalities across persons