The power of directional predictions in psychology

Abstract

The vast majority of empirical hypotheses in psychology, or in the social sciences more generally, are directional whereas in other sciences, such as the physical sciences, there are more point or narrow-interval empirical hypotheses. Characteristics of theories and auxiliary assumptions play a role in the difference. Given that psychology research strongly features directional predictions, it is important to question the extent to which these provide convincing tests of theories that they are designed to test. The present work aims to provide a nuanced view that considers the complex interaction between the obviousness of directional predictions, the obviousness of the theory from which they derive, and the quality of the auxiliary assumptions that push towards directional predictions. Then, too, there is the related issue of vulnerability of directional predictions to alternative explanations and how to address them.