Are within-subjects designs transparent?

Abstract

Researchers frequently argue that within-subjects designs should be avoided because they result in research hypotheses that are transparent to the subjects in the study. This conjecture was empirically tested by replicating several classic between-subjects experiments as within-subjects designs. In two additional experiments, psychology students were given the within-subjects versions of these studies and asked to guess what the researcher was hoping to find (i.e. the research hypothesis), and members of the Society for Judgment and Decision Making (SJDM) were asked to predict how well students would perform this task. On the whole, students were unable to identify the research hypothesis when provided with the within-subjects version of the experiments. Furthermore, SJDM members were largely inaccurate in their predictions of the transparency of a within-subjects design.