Measurement of Stress: Scaling the Magnitudes of Life Changes

Abstract

This paper evaluates models and measurements of the stress induced by life changes to determine whether a single scale can explain several different phenomena, including judgments of “ratios” and “difference” as well as “combinations.” Judgments of “ratios” and “differences” were found to be approximately monotonically related, suggesting that these judgments should not be taken at face value, but instead that the same comparison operation governs both tasks. Judgments of “combinations” of stressful events were not simply the sums of their separate events; instead, they showed two systematic departures from additivity. First, the effect of a given event was less when it was the least stressful event in a combination than when it was the most, as if the most stressful event carries extra configural weight. Second, each additional stressor had diminishing marginal effect on the overall judgment. All three sets of data could be explained with a single scale using the theory that “ratios” and “differences” are both governed by subtraction and that “combination” judgments are a configurally weighted combination of the same scale values. This unified scale of stress seems preferable to the previous scale that was based on magnitude estimation.