Doctoral Dissertation Research: An Investigation of Factors that Create and Mitigate Confirmation Bias in Judgments of Forensic Evidence

法医科学最近受到了批评，尤其是美国国家科学院（National Academy of sciences）的批评，原因是在已知的DNA免责案例中，法医科学错误的频率令人震惊。现在的经验数据表明，确认偏误（confirmation bias）——即倾向于用验证自己已有信念的方式来解释新证据——会产生这样的错误。也就是说，法医审查员的客观性和准确性可能会被他们对嫌疑人有罪或无罪的先验信念所破坏。目前的研究将增强我们对加剧和减轻法医证据判断中确认偏见的因素的认识，希望指导改革，以尽量减少代价高昂的司法不公的风险。在每项研究中，模拟法医审查员将通过比较罪犯和嫌疑人的笔迹样本来协助模拟刑事调查。研究1将测试那些被引导相信嫌疑人有罪的模拟考官是否会因此认为无罪的笔迹证据比那些没有被引导相信的人更有罪。此外，研究1将探讨当笔迹样本高度相似和/或审查员收到警察调查员的模拟负面反馈时，这种偏见是否会加剧。研究2将首次对“证据阵容”进行实证检验，“证据阵容”是一种程序改革，经常被提议作为对抗偏见的一种手段，但其有效性尚不清楚。在被引导去判断嫌疑人有罪、无罪或两者都不有罪之后，一些审查员会从罪犯和嫌疑人那里各拿到一份笔迹样本——一些人声称这种方法本质上是暗示有罪的。剩下的审查员将使用“证据阵容”，这迫使他们将三个不同的嫌疑人样本与犯罪者的样本进行比较，并指出如果有的话，哪一个与之匹配。因此，研究2将提供第一个经验数据，为长期以来关于证据组合潜在价值的争论提供信息。

The forensic sciences have recently been criticized, most notably by the National Academy of Sciences, due to the alarming frequency of forensic science errors in known DNA exoneration cases. Empirical data now suggests that confirmation bias -- i.e., the tendency to interpret new evidence in ways that validate one's pre-existing beliefs -- can produce such errors. That is to say, forensic examiners' objectivity and accuracy can be undermined by their a priori beliefs regarding a suspect's guilt or innocence. The current studies will enhance our knowledge of factors that exacerbate and mitigate confirmation biases in judgments of forensic evidence, in hopes of guiding reforms to minimize the risk of costly miscarriages of justice. In each study, mock forensic examiners will assist in a simulated criminal investigation by comparing handwriting samples from the perpetrator and suspect. Study 1 will test whether mock examiners who are led to believe that the suspect is guilty will consequently perceive exculpatory handwriting evidence as more incriminating than those who are not. In addition, Study 1 will explore whether this bias is exacerbated when the handwriting samples are highly similar and/or examiners receive simulated negative feedback from police investigators. Study 2 will provide the first empirical test of "evidence lineups," a procedural reform often proposed as a means of combating bias, but whose efficacy remains unknown. Having been led to expect the suspect's guilt, innocence, or neither, some examiners will receive one handwriting sample each from the perpetrator and suspect -- a method which some claim is inherently suggestive of guilt. The remaining examiners will utilize an "evidence lineup," which forces them to compare three different suspect samples against the perpetrator's sample and indicate which, if any, matches it. Study 2 will thus provide the first empirical data to inform the longstanding debate over the potential value of evidence lineups.