Rethinking the Ken Through the Lens of Psychological Science

Osgoode Hall Law Journal, Forthcoming

48 Pages Posted: 1 Jun 2018

See all articles by Jason Chin

Jason Chin

Sydney Law School

William Crozier

Duke University School of Law

Date Written: May 8, 2018


Canadian courts are loathe to admit expert evidence from psychological scientists when that evidence does not concern a disposition, typically a psychological disorder. As a result, psychological evidence concerning the unconscious processes and situational forces that underlie mistaken eyewitness identifications and wrongful confessions are regularly excluded from courtrooms. Courts justify these exclusions on the basis that the evidence is not beyond the ken of the trier of fact – the psychologist would simply be describing an experience shared by judge and jury. This reasoning stands on a fundamental misunderstanding of psychology. In fact, psychological science finds that the situation drives behaviour in a manner that regularly evades the trier of fact’s ken. This is because these situational forces rely on unconscious cognitive processes, and humans rarely have introspective access to these processes. As a result, humans cling to several deep misconceptions about memory processes and confessions.

In this Article, we first discuss the mechanics of the mischief: why humans fail to account for unconscious processes and the situation, and instead focus on disposition. Then we provide evidence for this type of reasoning in decisions to exclude expert evidence about eyewitness identifications and false confessions. We conclude with recommendations to manage prejudicial evidence in a manner that is based on a more nuanced understanding of human psychology.

Keywords: psychology and law, eyewitness, eyewitness memory, false confessions, expert evidence

JEL Classification: K14, K42

Suggested Citation

Chin, Jason and Crozier, William, Rethinking the Ken Through the Lens of Psychological Science (May 8, 2018). Osgoode Hall Law Journal, Forthcoming . Available at SSRN:

Jason Chin (Contact Author)

Sydney Law School ( email )

New Law Building, F10
The University of Sydney
Sydney, NSW 2006

William Crozier

Duke University School of Law ( email )

210 Science Drive
Box 90362
Durham, NC 27708
United States

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