Most eyewitness identification research simulates single perpetrator crimes, but real-world crimes often transpire at the hands of multiple perpetrators. It is unclear how multiple perpetrators might impact the ability of eyewitnesses to discriminate between the guilty and innocent. To address this issue, we conducted two experiments in which large nationwide samples of participants read a vignette about a crime being committed, and then viewed one to two target faces. If there were two targets, they were either similar or dissimilar, and presented either simultaneously or sequentially. Participants later viewed a target-present or -absent lineup for each target. As predicted, presenting one target enhanced discriminability compared to two targets presented simultaneously (Experiments 1 and 2), and two targets presented sequentially (Experiment 2). Results were mixed regarding the effect of similarity, with discriminability better for dissimilar compared to similar target pairs in just one experiment. Lastly, high confidence indicated high accuracy across all conditions.

中文翻译：

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一名肇事者，两名肇事者：多名肇事者对目击者身份识别的影响

大多数目击者鉴定研究模拟单一肇事者犯罪，但现实世界的犯罪往往发生在多个肇事者手中。目前尚不清楚多名肇事者可能会如何影响目击者区分有罪与无罪的能力。为了解决这个问题，我们进行了两个实验，在这些实验中，全国范围内的大量参与者样本阅读了关于正在犯罪的小插曲，然后查看了一到两个目标面孔。如果有两个目标，它们要么相似，要么不同，并同时或顺序呈现。参与者随后查看了每个目标的目标存在或不存在的阵容。正如预测的那样，与同时呈现的两个目标（实验 1 和 2）和顺序呈现的两个目标（实验 2）相比，呈现一个目标增强了可辨别性。关于相似性的影响，结果喜忧参半，仅在一项实验中，与相似的目标对相比，不同的可区分性更好。最后，高置信度表明所有条件下的准确性都很高。