Law and Human Behavior

According to the laws of negligence, jurors' liability decisions are to be influenced by the defendant's conduct, but not by the severity of the plaintiff's injuries. We conducted a jury simulation study to assess whether jurors reason in this manner. We manipulated the conduct of the defendant (reasonable, careless) and the severity of injuries to the plaintiff (mild, severe) in a simulated automobile negligence case. Jurors completed predeliberation questionnaires, deliberated to a verdict, and answered postdeliberation questionnaires. The defendant's conduct had a strong impact on liability judgments, but evidence related to injury severity also had an effect, albeit smaller. We analyze these findings in the context of various cognitive and motivational theories.

The purpose of this research synthesis was to examine treatment effects across studies of the service providers to offenders with mental illness. Meta-analytic techniques were applied to 26 empirical studies obtained from a review of 12,154 research documents. Outcomes of interest in this review included measures of both psychiatric and criminal functioning. Although meta-analytic results are based on a small sample of available studies, results suggest interventions with offenders with mental illness effectively reduced symptoms of distress, improving offender’s ability to cope with their problems, and resulted in improved behavioral markers including institutional adjustment and behavioral functioning. Furthermore, interventions specifically designed to meet the psychiatric and criminal justice needs of offenders with mental illness have shown to produce significant reductions in psychiatric and criminal recidivism. Finally, this review highlighted admission policies and treatment strategies (e.g., use of homework), which produced the most positive benefits. Results of this research synthesis are directly relevant for service providers in both criminal justice and mental health systems (e.g., psychiatric hospitals) as well as community settings by informing treatment strategies for the first time, which are based on empirical evidence. In addition, the implications of these results to policy makers tasked with the responsibility of designating services for this special needs population are highlighted.

In a simulated products liability trial, we tested the effects of bifurcating decisions regarding compensatory and punitive damage awards. Fifty-nine groups of 5–7 jurors heard evidence in a unitary or bifurcated format, deliberated about the case to a unanimous decision, and awarded damages. Trial bifurcation decreased variability in compensatory damage awards across juries hearing the same case, and also decreased the tendency for juries to award extremely high compensatory damages. In addition, deliberation led to lower compensatory awards in the low injury severity condition and higher awards in the high injury severity condition. Jurors reported that they were using evidence more appropriately when the decisions were bifurcated. Implications of evidence bifurcation in civil trials are discussed.

The effect on juror verdicts of judicial instructions to disregard inadmissible evidence was evaluated using meta-analysis. One hundred seventy-five hypothesis tests from 48 studies with a combined 8,474 participants were examined. Results revealed that inadmissible evidence (IE) has a reliable effect on verdicts consistent with the content of the IE. Judicial instruction to ignore the inadmissible evidence does not effectively eliminate IE impact. However, if judges provide a rationale for a ruling of inadmissibility, juror compliance may be increased. Contested evidence ruled admissible accentuates that information, resulting in a significant impact on verdicts. Suggestions for how the courts may mitigate the impact of inadmissible evidence more effectively are discussed.

According to the U.S. Supreme Court's decision in Jackson v. Indiana (1972), examiners must determine if a defendant has “substantial” probability of regaining competency through treatment “in the foreseeable future.” Previous research has indicated that, given the low base rate of defendants unable to be restored to competency, examiners are relatively poor at predicting which defendants will regain competency. Determining the characteristics of not restorable incompetent defendants and restorable incompetent defendants is a necessary first step toward improving examiners' ability to predict a defendant's likelihood of regaining competency. This study examined the competency evaluation reports of 468 defendants evaluated for competency to stand trial. Incompetent defendants significantly differed from competent defendants with regard to age, employment status, ethnicity, criminal charges, and psychiatric diagnosis. Few significant differences existed between defendants predicted restorable and those predicted not restorable by mental health examiners—the differences that did exist were related mainly to nonpsychiatric variables.

In this case study, 14 witnesses of an armed robbery were interviewed after 3 months. Security camera recordings were used to assess memory accuracy. Of all information that could be remembered about 84% was correct. Although accurately recalled information had a higher confidence level on average than inaccurately recalled information, the mean accuracy–confidence correlation was rather modest (0.38). These findings indicate that confidence is not a reliable predictor of accuracy. A higher level of self-reported, post-event thinking about the incident was associated with higher confidence levels, while a higher level of self-reported emotional impact was associated with greater accuracy. A potential source of (mis)information, a reconstruction of the robbery broadcasted on TV, did not alter the original memories of the witnesses.

Noisy recordings of dialogue often serve as evidence in criminal proceedings. The present article explores the ability of two types of contextual information, currently present in the legal system, to bias subjective interpretations of such evidence. The present experiments demonstrate that the general context of the legal system and the presence of transcripts of the recorded speech are both able to bias interpretations of degraded & benign recordings into interpretable & incriminating. Furthermore we demonstrate a curse of knowledge whereby people become miscalibrated to the true quality of degraded recordings when provided transcripts. Current methods of dealing with auditory evidence are insufficient to mollify the effects of biasing information within the criminal justice system.

Prisoners’ forecasts of post-release success may have implications for how they respond to imprisonment, release, and parole decisions. We examined sentenced US and UK prisoners’ forecasts of recidivism, and how well UK prisoners believed they would fare compared to the average other prisoner. In both samples, forecasts of recidivism were unrealistically optimistic when compared to official statistics on recidivism. UK prisoners also demonstrated a self-enhancement bias by forecasting that they were less likely to re-offend than other prisoners. Prisoners’ forecasts of recidivism were predicted by only a few of the pre-prison, in-prison, and post-prison factors that have been shown to be associated with actual recidivism. We discuss the implications of these findings and propose avenues for future research.