In a series of studies, the authors examined (a) public perceptions concerning forensic scientific evidence, (b) the relative influence attributed to DNA evidence compared to other forms of forensic identification evidence, and (c) the impact of cross-examination addressing the limitations of DNA testimony. In Studies 1 and 2, both undergraduate students and representative jurors rated DNA as the most accurate and persuasive type of evidence compared to other types of forensic evidence. This finding was consistent across samples of individuals with varied exposure to media coverage of scientific evidence. Experimental results further revealed the strong influence of DNA evidence in verdict decisions regardless of the type of crime or whether the evidence was incriminating or exculpatory. In Studies 2 and 3, DNA-based expert testimony demonstrated strong effects on juror decisionmaking even after cross-examination. These effects were mitigated to some extent in Study 3, however, by the interaction of the reliability of DNA evidence and the focus of cross-examination. The implications regarding the use of DNA and other scientific evidence for public policy and practice in legal decisions are discussed.

Future dangerousness of a criminal defendant is an important consideration in eight states' capital sentencing provisions, and in Oregon and Texas a finding of dangerousness is an essential requirement for the imposition of the death penalty (Worrell, 1987).

This paper reviews the four types of validity that make up Cook and Campbell's traditional approach for social science research in general and psychological research in particular: internal validity, statistical conclusion validity, external validity, and construct validity. The most important generalizability threat to the validity of jury research is not likely a selection main effect (i.e., the effect of relying solely on undergraduate mock jurors) but is more likely the interaction of sample with construct validity factors. Researchers who try to capture the trial process with experimental paradigms may find that undergraduate mock jurors react differently to those efforts than do more representative community samples. We illustrate these issues with the seven papers that make up this volume, and conclude by endorsing Diamond's call for a two-stage research process in which findings with samples of convenience gradually add more realistic trial processes and representative samples to confirm the initial findings and increase the research program's credibility.

Despite concerns about generalizability, past mock trial research has concluded that effects of sample (i.e., students versus representative mock jurors) are negligible. The current study was conducted to explore this conclusion within the conceptual framework of cognitive-experiential self-theory (CEST). Through a mock civil commitment hearing of a sexually violent predator, responses of student (n = 138) and representative (n = 240) mock jurors were compared. Results revealed several important differences between samples: (a) the student sample scored higher on the rational processing measure (i.e., need for cognition); (b) students' verdicts were also significantly correlated to a measure of their cognitive processing style, an enduring personal characteristic related to the extent to which an individual engages in either effortful/effortless cognition; and (c) the representative sample was more punitive, was more persuaded by clinical expert testimony, and evidenced a greater gender effect in its decisions. Implications for jury decision-making research are discussed.