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

最近，法医科学受到了批评，最明显的是受到了美国国家科学院的批评，因为在已知的DNA无罪案件中，法医科学错误的频率令人震惊。经验数据现在表明，确认偏差--即以证实一个人先前存在的信念的方式解释新证据的倾向--可能会产生这样的错误。这就是说，法医检查员的客观性和准确性可能会受到他们对嫌疑人有罪或无罪的先验信念的破坏。目前的研究将增进我们对加剧和减轻法医证据判决中确认偏差的因素的了解，希望指导改革，将代价高昂的司法不公的风险降至最低。在每项研究中，模拟法医将通过比较犯罪者和嫌疑人的笔迹样本来协助模拟刑事调查。研究一将测试被引导相信嫌疑人有罪的模拟审查员是否会因此认为无罪的笔迹证据比没有罪的笔迹证据更有说服力。此外，研究1将探索当笔迹样本高度相似和/或考官从警方调查人员那里收到模拟的负面反馈时，这种偏见是否会加剧。研究2将提供对“证据阵容”的第一次实证测试，这是一种程序改革，经常被提议作为对抗偏见的一种手段，但其有效性仍不清楚。在被引导到嫌疑人有罪、无罪或两者都没有的情况下，一些审查员会从犯罪者和嫌疑人那里分别收到一份笔迹样本--一些人声称这种方法本质上是有罪的。剩下的检验员将利用一个“证据阵容”，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，并指出其中一个(如果有)与之匹配。因此，研究2将提供第一批经验数据，为关于证据阵容潜在价值的长期辩论提供信息。

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.