Bias in judgement: Comparing individuals and groups

The relative susceptibility of individuals and groups to systematic judgmental biases is considered. An overview of the relevant empirical literature reveals no clear or general pattern. However, a theoretical analysis employing J. H. Davis's (1973) social decision scheme (SDS) model reveals that the relative magnitude of individual and group bias depends upon several factors, including group size, initial individual judgment, the magnitude of bias among individuals, the type of bias, and most of all, the group-judgment process. It is concluded that there can be no simple answer to the question, "Which are more biased, individuals or groups?," but the SDS model offers a framework for specifying some of the conditions under which individuals are both more and less biased than groups

The effects of jury size and polling method on the process and product of jury deliberation.

612 undergraduates in 15 same-sex groups of 3, 6, or 12 Ss participated in mock jury deliberations over 9 armed robbery cases, and both individual and group verdicts were obtained, to test the predictions that larger juries would hang more often, particularly for close cases, and that secret polling would lead to fewer hung juries than open polling. It is asserted that failures to confirm these predictions in previous studies were probably due to inadequate sample sizes or to insufficiently close cases; the present study minimized these problems. Social decision scheme and social transition scheme analyses permitted comparisons of the decision-making processes of the different-sized mock juries, and jury groups used either secret written ballots or a show of hands for polling. Results show that, as group size increased, the observed probability of a hung jury significantly increased. No process differences between 6- and 12-person groups were detected, but 3-person groups exhibited several process differences in comparison to both larger groups. When cases were close, the likelihood of a hung jury for typically sized juries was found to be lower when the group was polled by secret ballot than when a show-of-hands was used

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. Exp I 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. In Exp II, Ss received either reasonable-doubt or preponderance-of-evidence instructions. After providing initial verdict preferences, some Ss deliberated in groups composed with an initial 2:2 split, whereas other Ss 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

Suspicion in the psychological laboratory. Kelman's prophecy revisited.

Describes the spontaneous occurrence, during an experimental session, of an epileptic seizure experienced by 1 S. Three of the remaining 5 Ss suspected the seizure was part of the experiment; implications are discussed in terms of H. C. Kelman's suggestion that the frequent use of deception in social psychological experimentation creates Ss who enter the laboratory expecting to be deceived and are unlikely to react to the experimental context in a natural way

Role expectations in social dilemmas. Sex roles and task motivation in groups.

Tested the impact of asymmetric role relationships (in which some group members contribute more to the group's welfare than others) on behavior in a social dilemma setting by manipulating the sex composition of cooperative performance dyads, using 47 male and 48 female undergraduates. The prescriptions of traditional sex roles suggested that Ss of both sexes would defect more (i.e., work less hard) with a male partner than with a female partner, both when the partner presented an opportunity to free ride and when the partner appeared to be free-riding on the S's efforts. Results confirm this prediction. Male Ss were less willing to free ride when the partner was female than male, while females were more willing to free ride on their male partner than on their female partner. In the sucker condition, both males and females seemed to balk more at the prospect of carrying a male free rider than a female free rider. Further analyses suggested that the effects should not be attributed to perceived sex differences in task ability. Plausible alternatives are discussed, including the possibility that interaction with women, per se, encourages greater effort, regardless of whether roles prescribe differential effort for the task

Is the leniency asymmetry really dead? Misinterpreting asymmetry effects in criminal jury deliberation

Early jury simulation research, reviewed and meta-anyalysed by MacCoun and Kerr (1988), suggested a leniency asymmetry in criminal jury deliberations such that a given faction favoring acquittal will tend to have a greater chance of prevailing than would an equivalent sized faction favoring conviction. More recently, a handful of field studies of actual juries have reported either no such leniency asymmetry or one in the opposite direction (a severity asymmetry). A potential bias in the coding of these field studies’ data is identified, one that would tend to underestimate any leniency asymmetry. The data from three field studies are re-analyzed after correcting this purported coding bias. The results of these re-analyses show a leniency asymmetry effect, although one that is less pronounced than observed in mock jury studies. It is argued that this difference in degree (not existence) of leniency asymmetry can plausibly be attributed to greater imbalance in evidence strength in the typical actual trial relative to the typical stimulus case in simulation experiments. It is also noted that failure to observe such a leniency asymmetry effect in actual juries would raise important questions about their adherence to the reasonable doubt standard of proof