Assessing information integration processes: a comparison of findings obtained with between-subjects designs versus within-subjects designs

摘要

Within-subject designs (WSDs) remain unpopular in psychology. Social psychologists have argued that they create "demand" and "order" effects. Previous comparative studies conducted in the Information Integration Theory (IIT) framework have, however, shown that patterns of results observed using WSDs can largely be replicated using between-subject designs (BSDs). In order to add evidence to these findings, we conducted four additional studies to complement our data obtained in previous studies. Three of these studies tested three factorial plots of the appraisal of stimulus intensities resulting from a full factorial administration of stimulus components that are typically observed in IIT studies (a) parallelism only (adding), (b) parallelism plus cross-over (averaging), and (c) fan-shape open to the right (multiplying). The fourth study tested a non-linear shape factorial plot. Patterns observed in BSD and in WSD conditions were systematically compared. There was nothing in the results from the BSD studies that would contradict the conclusions drawn from the WSD studies. Advantages of WSDs over BSDs are that they are economical, they are statistically more powerful, the resulting patterns of data are less noisy (characterization of the information integration process is made straightforward), and more importantly, they facilitate analysis of individual differences in human judgment processes.