Lam Allan L, Wixted John T
Department of Psychology, University of California, San Diego, CA, USA.
Mem Cognit. 2025 May;53(4):1272-1286. doi: 10.3758/s13421-024-01649-x. Epub 2024 Nov 7.
A photo lineup, which consists of one suspect and several physically similar fillers, is often used by the police to test an eyewitness's memory. To optimize memory performance, how similar should the fillers be to the suspect, and how many fillers should be included in the lineup? Recent work suggests that using fillers who match the basic characteristics of the perpetrator (e.g., same age, race, and gender) but who are otherwise maximally dissimilar to the suspect optimizes discriminability. However, the optimal lineup size has been found to vary with filler similarity, with larger lineup sizes increasing or decreasing discriminability depending on whether low-similarity or high-similarity fillers were used, respectively. Because manipulating filler similarity at retrieval affects overall performance, here we investigated whether encoding manipulations that affect overall performance also affect how lineup size influences discriminability. In three experiments, we first replicated prior findings (N = 502), then reduced encoding strength by making study images blurry when low-similarity fillers were used (N = 553), and finally increased encoding strength by repeating study images when high-similarity fillers were used (N = 501). We found that whether overall performance was low or high due these encoding manipulations, discriminability still increased as a function of lineup size when low-similarity fillers were used and decreased as a function of lineup size when high-similarity fillers were used. Thus, lineup size has opposing effects on discriminability when task difficulty is manipulated at retrieval, which narrows the theoretical explanations for why that effect is observed.
照片列队辨认，由一名嫌疑人及几名外貌相似的陪衬人员组成，警方常使用它来测试目击者的记忆力。为了优化记忆表现，陪衬人员应与嫌疑人多相似，列队中应包含多少陪衬人员呢？近期研究表明，使用与犯罪者基本特征相符（如年龄、种族和性别相同）但在其他方面与嫌疑人差异最大的陪衬人员，可优化辨别能力。然而，已发现最佳列队规模会随陪衬人员相似度而变化，列队规模越大，辨别能力是增强还是减弱，分别取决于使用的是低相似度还是高相似度的陪衬人员。由于在提取时操纵陪衬人员相似度会影响整体表现，所以我们在此研究了影响整体表现的编码操纵是否也会影响列队规模对辨别能力的影响。在三项实验中，我们首先重复了先前的研究结果（N = 502），然后在使用低相似度陪衬人员时通过使研究图像模糊来降低编码强度（N = 553），最后在使用高相似度陪衬人员时通过重复研究图像来提高编码强度（N = 501）。我们发现，无论这些编码操纵导致整体表现是低还是高，当使用低相似度陪衬人员时，辨别能力仍会随列队规模增大而增强，而当使用高相似度陪衬人员时，辨别能力会随列队规模增大而减弱。因此，当在提取时操纵任务难度时，列队规模对辨别能力有相反的影响，这缩小了对为何会观察到这种影响的理论解释范围。
