Lagnado David A, Harvey Nigel
University College London, London, England.
Psychon Bull Rev. 2008 Dec;15(6):1166-73. doi: 10.3758/PBR.15.6.1166.
How do people revise their beliefs when evidence is discredited? In three studies, mock jurors read simplified criminal cases and then judged the probability that a suspect was guilty on the basis of sequentially presented evidence. Study 1 showed an extension effect: When two items of incriminating evidence were presented, a subsequent discrediting of the second item also lessened belief in the first item, irrespective of whether it was directly related to the discredited item. Study 2 showed that this effect depended on the order of evidence presentation: When the discrediting evidence was presented early, rather than late, in the sequence, there was no extension to unrelated items. Study 3 showed that the extension effect held only when items of evidence were both incriminating or both exonerating, but not when they were mixed. To explain these findings, we draw on coherence-based models of juror reasoning and propose that people group evidence according to its direction with respect to the guilt hypothesis.
当证据被质疑时，人们如何修正自己的信念？在三项研究中，模拟陪审员阅读简化的刑事案件，然后根据相继呈现的证据判断嫌疑人有罪的概率。研究1显示了一种延伸效应：当呈现两项有罪证据时，随后对第二项证据的质疑也会减少对第一项证据的信任，无论第一项证据是否与被质疑的证据直接相关。研究2表明，这种效应取决于证据呈现的顺序：当质疑证据在序列中较早而非较晚呈现时，不会延伸至不相关的证据项。研究3表明，延伸效应仅在证据项均为有罪或均为无罪时成立，而在证据混合时不成立。为了解释这些发现，我们借鉴了基于连贯性的陪审员推理模型，并提出人们根据证据与有罪假设的方向对证据进行分组。
