Juror Need for Cognition and Sensitivity to Methodological Flaws in Expert Evidence¹

Abstract

This study examined whether need for cognition (NC) moderated jurors' sensitivity to methodological flaws in expert evidence. Jurors read a sexual harassment trial summary in which the plaintiff's expert presented a study that varied in ecological validity, general acceptance, and internal validity. High NC jurors found the defendant liable more often and evaluated expert evidence quality more favorably when the expert's study was internally valid vs. missing a control group; low NC jurors did not. Ecological validity and general acceptance did not affect jurors' judgments. Ratings of expert and plaintiff credibility, plaintiff trustworthiness, and expert evidence quality were positively correlated with verdict. Theoretical implications for the scientific reasoning literature and practical implications for trials containing psychological science are discussed. Mitchel) for granting us access to the jury pool. We also thank dissertation committee members Brian Cutler and Ronald Fisher for their helpful suggestions.

Can jurors recognize missing control groups, confounds, and experimenter bias in psychological science?

“…At least two studies have investigated the effects of ecological validity on juror decisionmaking (Kovera, McAuliff, & Hebert, 1999;McAuliff & Kovera, 2008). Mock jurors used ecological validity as a heuristic cue to evaluate the trustworthiness and credibility of certain witnesses in the Kovera et al study, but their verdicts and evaluations of expert evidence quality did not differ as a function of ecological validity in either study.…”

“…Based on previous work by McAuliff and Kovera (2008) and Levett and Kovera (2007), we predicted that mock jurors would be sensitive to missing control group information but not the more sophisticated internal validity threats of a confound or experimenter bias. Support for this hypothesis would consist of a statistically significant main effect for the study's internal validity in which mock jurors' ratings of expert evidence quality are higher for the valid versus missing control group version of the expert's study but no different from the confound and experimenter bias versions.…”

“…Two different trial simulations in which jurors were sensitive to the absence of control group information are particularly relevant to the present study. Citizens reporting for jury duty in an experiment by McAuliff and Kovera (2008) read a hostile work environment case in which the plaintiff's expert testified about a study she had conducted on men's reactions to sexualized television commercials. Only jurors who were high in the need for cognition (NC) (i.e., individuals who naturally engage in and enjoy effortful cognitive endeavors; Cacioppo & Petty, 1982) were more likely to find for the plaintiff and to rate the quality of the expert's study more favorably when it included a control group than when it did not.…”

“…Jurors may judge a study more favorably when it contains participants who are similar to members of the population to which the expert wishes to generalize his or her research findings than when it does not. This heuristic inference may occur irrespective of the study's internal validity.At least two studies have investigated the effects of ecological validity on juror decisionmaking (Kovera, McAuliff, & Hebert, 1999;McAuliff & Kovera, 2008). Mock jurors used ecological validity as a heuristic cue to evaluate the trustworthiness and credibility of certain witnesses in the Kovera et al study, but their verdicts and evaluations of expert evidence quality did not differ as a function of ecological validity in either study.…”

From Meaning to Money: Translating Injury into Dollars

“…For example, cognitive style variables such as need for cognition (NC) and cognitive reflection, which figure promienntly in contemporary theories of judgment and decision making (Frederick, 2005;Stanovich & West, 2008) and have been found in prior research to influence juror decisions (Bornstein, 2004;McAuliff & Kovera, 2008), may also affect damage award decisions. Earlier research has explored the role of NC in judgments of expert testimony.…”