Behavioral Sciences & the Law

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Volume 36 Issue 3 (May/June 2018), Pages 271-389

Mental state at time of offense in the hot tub: An empirical examination of concurrent expert testimony in an insanity case (pages 358-372)


The role of experts and their presentation of testimony in insanity cases remain controversial. In order to decrease possible expert bias associated with this testimony, a number of different alternatives to adversarial presentation have been suggested. Two such alternatives are the use of court‐appointed experts and the use of concurrent testimony (or “hot‐tubbing”), in which opposing experts provide testimony concurrently and converse with each other directly. An experiment using a sample of venire jurors (n = 150) tested the effect of these alternatives.

Results indicate that participants' pre‐existing attitudes towards the insanity defense had significant effects on their comprehension of expert testimony, their evaluations of the two opposing experts, and their eventual verdicts, over and above the presentation format (i.e., concurrent vs. traditional testimony) or the use of court‐appointed experts (vs. traditional adversarial experts). When concurrent testimony was presented, defense‐favoring experts were perceived by jurors as more credible than their traditional counterparts, though comprehension of the testimony did not increase; nor did the presentation format or the affiliation of the experts affect verdicts. The legal and policy implications of the incorporation of the hot‐tubbing procedure to US courts are discussed.

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