A within-person test of the form of the expectancy theory model in a choice context

The predictive efficacy of various forms of the expectancy theory model is compared with respect to a behavioral criterion of task choice. The models tested take the form of (a) a multiplicative combination of the expectancy theory model's components (instrumentality × valence), (b) an additive combination of the components (instrumentality + valence), and (c) each component (instrumentality, valence) used individually to predict the criterion. The present investigation seeks to rectify various methodological problems inherent in past comparative studies. Specifically, two studies, each employing a different experimental method, are used to compare the predictive ability of the model forms. Results suggest that the multiplicative model is the most useful predictor of the behavioral criterion.