Law and Human Behavior, Voi. i3, No. 3, t989 Using Psychology to Control Law From Deceptive Advertising to Criminal Sentencing* Shari Seidman Diamond? Legal decision makers often fail to make use of relevant psychological research. In two areas, decep- tive advertising and criminal sentencing, legal decision makers have welcomed social science research. In each, the research provided has been substantially flawed. Using a commercial that several courts evaluated for deception, I illustrate how the typical study that purports to measure deception produces results that are unnecessarily ambiguous. Then, based on research that looks closely at public re- sponses to criminal cases, I show that the frequently cited stlrvey measures of public preference reflect sentencing preferences for unrepresentative stereotypic criminal offenders. The weaknesses demon- strated in these examples suggest that psychologists can present legal decision makers with a more accurate picture of human perceptions and preferences, ff researchers present legal decision makers with informative research when the relevance of researEh is acknowledged, legal decision makers are likely to become more receptive and more knowledgeable when a new question warrants the appli- cation of social science evidence. Psychologists increasingly appear on the witness stand, in legal briefs, and in legislative hearings to offer their research to the legal system (Melton, 1987). These efforts to use psychological research to influence legal decisions do not always meet with wild enthusiasm or even thoughtful consideration (see, e.g., Lockhart v. McCree, 1986). ~ Although researchers on law often conduct research that has no obvious and indeed no expected legal or policy implications, they are * An earlier version of this paper was delivered as the presidential address for Division 41, the American Psychology--Law Society, at the 1988 American Psychological Association meetings in Atlanta, Georgia. All requests for reprints should be sent to the author at the Department of Psy- chology, University of Illinois at Chicago, Box 4348, Chicago, IL 60680. "~University of Illinois at Chicago/American Bar Foundation. : 476 U.S. 162 (1986). 239 0147-7307/89/0900-0239506.00/0 9 1989 Plenum Publishing Corporation