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Published in: Applied Psychology in Criminal Justice, Volume 4, Number 2, 2008.


In this study, we used a fact pattern similar to the John Mark Karr scenario to examine perceptions of DNA and confession evidence. Specifically, we hypothesized that DNA evidence, confessor level of psychopathology, and presence or absence of Miranda protections would affect participants’ perceptions of guilt and attitudes towards the interrogation process. One hundred nine undergraduates read a two-page summary based on John Mark Karr’s confession. Summaries varied based on psychopathology of confessor, the presence or absence of DNA evidence, and the provision of Miranda warnings prior to confession. The DNA manipulation explained participants’ attitudes towards specific aspects of the interrogation process. The importance of perceptions of forensic type evidence, specifically DNA, in our legal system is discussed