Robert J. MacCoun

Asymmetric influence in mock jury deliberation: Jurors' bias for leniency.

Investigators have frequently noted a leniency bias in mock jury research, in which deliberation appears to induce greater leniency in criminal mock jurors. One manifestation of this bias, the asymmetry effect, suggests that proacquittal factions are more influential than proconviction factions of comparable size. A meta-analysis indicated that these asymmetry effects are reliable across a variety of experimental contexts. Experiment 1 examined the possibility that the leniency bias is restricted to the typical college-student subject population. The decisions of college-student and community mock jurors in groups beginning deliberation with equal faction sizes (viz., 2:2) were compared. The magnitude of the asymmetry effect did not differ between the two populations. We hypothesized that the asymmetry effect was caused by an asymmetric prodefendant standard of proof--the reasonable-doubt standard. In Experiment 2, subjects received either reasonable-doubt or preponderance-of-evidence instructions. After providing initial verdict preferences, some subjects deliberated in groups composed with an initial 2:2 split, whereas other subjects privately generated arguments for each verdict option. A significant asymmetry was found for groups in the reasonable-doubt condition, but group verdicts were symmetrical under the preponderance-of-evidence instructions. Shifts toward leniency in individual verdict preferences occurred for group members, but not for subjects who performed the argument-generation task. The theoretical and applied significance of these findings is discussed.

Drugs and the Law: A Psychological Analysis of Drug Prohibition

There is an ongoing American policy debate about the appropriate legal status for psychoactive drugs. Prohibition, decriminalization, and legalization positions are all premised on assumptions about the behavioral effects of drug laws. What is actually known and not known about these effects is reviewed. Rational-choice models of legal compliance suggest that criminalization reduces use through restricted drug availability, increased drug prices, and the deterrent effect of the risk of punishment. Research on these effects illustrates the need for a more realistic perspective that acknowledges the limitations of human rationality and the importance of moral reasoning and informal social control factors. There are at least 7 different mechanisms by which the law influences drug use, some of which are unintended and counterproductive. This framework is used to explore the potential behavioral effects of decriminalization and legalization.

Assessing alternative drug control regimes

The debate over alternative regimes for currently illicit psychoactive substances focuses on polar alternatives: harsh prohibition and sweeping legalization. This study presents an array of alternatives that lies between these extremes. The current debate lacks an explicit and inclusive framework for making comparative judgments. In this study, we sketch out such a framework, as a reminder of possible policy levers and their costs and benefits that might otherwise be neglected or go unrecognized. The framework identifies a range of pharmacological and economic characteristics of substances, potential harms and their bearers, and the sources of those harms, including drug use, trafficking, law enforcement, and illegal status per se. The framework highlights the difficulty of making objective, rigorous comparisons among regimes, but we believe that it can serve a useful heuristic role in promoting more constructive debate and identifying fruitful questions for research.

Experimental Research on Jury Decision-Making

Because trial juries deliberate in secrecy, legal debates about jury functioning have relied heavily on anecdote and speculation. In recent years, investigators have begun to challenge many common assumptions about jury behavior. An important tool in this effort has been the mock jury experiment, in which research participants are randomly assigned to alternative trial conditions and asked to reach a verdict in a simulated case. Researchers have used mock jury experiments to test hypotheses about causal influences on jury behavior and to develop theoretical models of the jury deliberation process.

Calibration Trumps Confidence as a Basis for Witness Credibility

Confident witnesses are deemed more credible than unconfident ones, and accurate witnesses are deemed more credible than inaccurate ones. But are those effects independent? Two experiments show that errors in testimony damage the overall credibility of witnesses who were confident about the erroneous testimony more than that of witnesses who were not confident about it. Furthermore, after making an error, less confident witnesses may appear more credible than more confident ones. Our interpretation of these results is that people make inferences about source calibration when evaluating testimony and other social communication.

Does Social Cohesion Determine Motivation in Combat? An Old Question with an Old Answer

Based on a new Army War College study of unit cohesion in the Iraq War, Wong et al. argue that successful unit performance is determined by social cohesion (the strength of interpersonal bonds among members) rather than task cohesion (a sense of shared commitment to the unit’s mission). If correct, these conclusions have important implications for scholarship as well as for numerous U.S. military policies such as the Unit Manning System. However, this article disputes their contentions. Wong et al. ignore a large body of empirical research on military and nonmilitary groups showing that social cohesion has no independent impact on performance. They provide no evidence for the representativeness of the interview quotes they cite as evidence for the reliability or validity of their measures. Their methodology fails to meet social science standards for causal inference (e.g., ruling out causal rival factors)

Are the Wages of Sin

One hundred and eighty-six probationers in Washington, D.C., who acknowledged a recent history of drug dealing were interviewed regarding their legitimate and illegitimate activities. They reported median net earnings of

30 an Hour? Economic Aspects of Street-Level Drug Dealing

721 per month from drug sales -

Free press and fair trial: The role of behavioral research

2,000 per month among the 37% who reported selling drugs selling drugs on a daily basis. These figures compare with median monthly earnings of

Design considerations for legalizing cannabis: lessons inspired by analysis of California's Proposition 19.

800 from legitimate employment for the 75% who reported such earnings. Street-level drug dealing appears to be a complement to, rather than a substitute for, legitimate employment, and it appears to be less profitable than media reports would suggest.