When a face is positively identified from a multi-person photo lineup, it is presumably the face that generates the strongest memory signal. In addition, confidence in a positive identification is presumably determined by the strength of the memory signal associated with that face. However, when no face generates a strong enough memory signal to be identified, the entire set of faces in the lineup is collectively rejected. What latent variable underlies confidence in a lineup rejection? One possibility is that the face that generates the strongest memory signal still determines confidence (i.e., the weaker that memory signal is, the more confidently the lineup is rejected). Another possibility is that confidence in a lineup rejection is determined by the average strength of the memory signals generated by the faces in the lineup (i.e., the weaker that average memory signal is, the more confidently the lineup is rejected). The reliance on an average signal has been proposed as a possible explanation for why the confidence-accuracy for lineup rejections tends to be weak. Here, we modified two existing signal-detection-based lineup models (the Independent Observations model and the Ensemble model) and fit them to multiple lineup datasets to investigate which decision variable underlies confidence in lineup rejections. Both models agree that confidence in a lineup rejection is based on the strongest memory signal in the lineup, not on the average signal. These model fits also revealed for the first time that the memory signals in a lineup are correlated, as they theoretically should be.

当从多人照片中明确识别出一张脸时，可能就是这张脸产生了最强的记忆信号。此外，对肯定识别的置信度大概是由与该面部相关的记忆信号的强度决定的。然而，当没有人脸产生足够强的记忆信号来识别时，阵容中的整组人脸将被集体拒绝。哪些潜在变量是对阵容拒绝的信心的基础？一种可能性是，产生最强记忆信号的面孔仍然决定置信度（即，记忆信号越弱，阵容被拒绝的可能性越大）。另一种可能性是，阵容拒绝的置信度由阵容中的面孔生成的记忆信号的平均强度决定（即，平均记忆信号越弱，阵容被拒绝的信心越大）。人们提出对平均信号的依赖作为对阵容拒绝的置信准确度往往较弱的可能解释。在这里，我们修改了两个现有的基于信号检测的阵容模型（独立观察模型和集成模型），并将它们拟合到多个阵容数据集，以研究哪个决策变量是阵容拒绝信心的基础。两个模型都一致认为，对阵容拒绝的信心是基于阵容中最强的记忆信号，而不是平均信号。这些模型拟合还首次揭示了阵列中的记忆信号是相关的，理论上它们应该是相关的。