Using Pretest-Posttest Research Designs to Enhance Jury Decision-Making


  • Jane Goodman-Delahunty Charles Sturt University
  • Natalie Martschuk Charles Sturt University
  • Anne Cossins University of New South Wales


child sexual assault, deliberation, expert evidence, jury bias, pretest-posttest research design, specialized knowledge, wrongful acquittal, wrongful conviction, Abusos a menores, deliberación, pruebas periciales, sesgo del jurado, diseño de investigación


When lay jurors are unfamiliar with key evidentiary issues, expert evidence, judicial instructions and group deliberation may enhance their understanding of this evidence. Systematic steps to assess the relationship between juror biases in cases of child sexual abuse are offered as an example to illustrate a programmatic research approach. Using pretest-posttest research designs, the effectiveness of three traditional legal procedural safeguards to reduce common jury misconceptions in the context of simulated trials were tested and compared. By measuring mock-juror knowledge before and after each intervention, knowledge gains attributable to these interventions were distinguished from practice effects. Unexpected increases in acquittals following deliberation underscored the importance of adding adequate control groups and of testing deliberation effects in jury simulation studies. Benefits of this research paradigm to assist courts, legal counsel and policy makers in devising effective methods to enhance jury decisions in complex criminal cases are discussed.

Cuando los miembros del jurado popular no están familiarizados con los temas probatorios clave, las pruebas periciales, las instrucciones judiciales y la deliberación de grupo pueden mejorar su comprensión de las evidencias. Se ofrecen pasos sistemáticos para evaluar la relación entre sesgos del jurado en casos de abusos a menores como un ejemplo para ilustrar un enfoque de investigación programática. Se probó y comparó la efectividad de tres garantías procesales jurídicas tradicionales para reducir los malentendidos comunes de los jurados en el contexto de juicios simulados, usando patrones de investigación pre y post análisis. Al medir el conocimiento de jurados en juicios simulados antes y después de cada intervención, se distinguían los conocimientos adquiridos atribuibles a estas intervenciones. Un aumento inesperado de absoluciones después de la deliberación ponía de manifiesto la importancia de añadir grupos de control adecuados y analizar los efectos de la deliberación en los estudios de jurados en juicios simulados. Se analizan los beneficios de este paradigma de investigación para ayudar a tribunales, abogados y legisladores en el desarrollo de métodos eficaces para mejorar las decisiones del jurado en casos penales complejos.


Author Biographies

Jane Goodman-Delahunty, Charles Sturt University

Trained in law and experimental psychology, Jane Goodman-Delahunty, JD, PhD, is a Research Professor at Charles Sturt University. She served as editor of Psychology, Public Policy, and Law, and president of both the American Psychology-Law Society and the Australia and New Zealand Association of Psychiatry, Psychology and Law. Her research promotes evidence-based policies to enhance justice, informed by her experience as a litigator, administrative judge, mediator, Commissioner with the New South Wales Law Reform Commission and Member of the New South Wales Civil and Administrative Tribunal. Charles Sturt University Manly Campus. P.O. Box 168. Manly NSW 1655, Australia.

Natalie Martschuk, Charles Sturt University

Natalie Martschuk, Dipl-Psych, is a Research Associate at Charles Sturt University. Her research interests are jury decision making, expert evidence, investigative interviewing strategies, witness reliability and advanced statistical methods. She is working towards her PhD at the University of Giessen on the reliability of elderly eyewitnesses. Previously, she practiced at the State Hospital for Forensic Psychiatry in Stendal, where she interviewed suspects and offenders, and provided expert evidence in court. Her postgraduate major was Legal Psychology. Charles Sturt University Manly Campus. P. O. Box 168. Manly NSW 1655, Australia.

Anne Cossins, University of New South Wales

Anne Cossins, PhD, is a Professor of Law and Criminology in the Faculty of Law, University of New South Wales. She is the Co-convenor of the Gendered Violence Research Network at UNSW and has been involved in several law reform initiatives with government bodies over the past decade. She is a member of the NSW Victims Advisory Board and the Advisory Board of the Global Foundation on Justice for Child Witnesses. She has several external grants in relation to jury studies and the sentencing of Indigenous offenders for sexual assault offences. Her research interests include: the treatment, recidivism and classification of sex offenders; sexual assault law reform, jury decision making, theoretical criminology and expert forensic evidence.




How to Cite

Goodman-Delahunty, J., Martschuk, N. and Cossins, A. (2015) “Using Pretest-Posttest Research Designs to Enhance Jury Decision-Making”, Oñati Socio-Legal Series, 6(2), pp. 283–314. Available at: (Accessed: 6 May 2021).