Irrelevant quantity effects: a meta-analysis

This paper explores irrelevant quantity effects in judgment by carefully defining the term, thoroughly discussing different kinds of irrelevant quantity effects and where they can be found in the literature, and subsequently submitting irrelevant quantity effect studies to a quantitative meta-analysis. It is suggested that an irrelevant quantity effect occurs when a quantitative stimulus dimension affects a conceptually and procedurally unrelated quantitative judgment. Such effects can be found in different areas of research (e.g., judgment and decision-making, marketing, perception) but, to the knowledge of the author, have never before been investigated across areas. The purpose of the present study was to find out if an overall irrelevant quantity effect exists and how strong that effect might be. Another reason for conducting the study was to identify conditions in which the effect appears stronger or weaker. The meta-analysis revealed a significant overall irrelevant quantity effect but no interpretable differences across studies. Further analyses suggested the possibility of publication bias. A discussion of study limitations, future empirical work, and possible future meta-analyses follows.