Diagnosis of developmental or congenital prosopagnosia (CP) involves self-report of everyday face recognition difficulties, which are corroborated with poor performance on behavioural tests. This approach requires accurate self-evaluation. We examine the extent to which typical adults have insight into their face recognition abilities across four experiments involving nearly 300 participants. The experiments used five tests of face recognition ability: two that tap into the ability to learn and recognize previously unfamiliar faces [the Cambridge Face Memory Test, CFMT; Duchaine, B., & Nakayama, K. (2006). The Cambridge Face Memory Test: Results for neurologically intact individuals and an investigation of its validity using inverted face stimuli and prosopagnosic participants. Neuropsychologia, 44(4), 576–585. doi:10.1016/j.neuropsychologia.2005.07.001; and a newly devised test based on the CFMT but where the study phases involve watching short movies rather than viewing static faces—the CFMT-Films] and three that tap face matching [Benton Facial Recognition Test, BFRT; Benton, A., Sivan, A., Hamsher, K., Varney, N., & Spreen, O. (1983). Contribution to neuropsychological assessment. New York: Oxford University Press; and two recently devised sequential face matching tests]. Self-reported ability was measured with the 15-item Kennerknecht et al. questionnaire [Kennerknecht, I., Ho, N. Y., & Wong, V. C. (2008). Prevalence of hereditary prosopagnosia (HPA) in Hong Kong Chinese population. American Journal of Medical Genetics Part A, 146A(22), 2863–2870. doi:10.1002/ajmg.a.32552]; two single-item questions assessing face recognition ability; and a new 77-item meta-cognition questionnaire. Overall, we find that adults with typical face recognition abilities have only modest insight into their ability to recognize faces on behavioural tests. In a fifth experiment, we assess self-reported face recognition ability in people with CP and find that some people who expect to perform poorly on behavioural tests of face recognition do indeed perform poorly. However, it is not yet clear whether individuals within this group of poor performers have greater levels of insight (i.e., into their degree of impairment) than those with more typical levels of performance.

Adding visual noise to facial images has been used to increase reliance on configural processing. Whether this enhances the ability of tests to diagnose prosopagnosia is not known. We examined 15 subjects with developmental prosopagnosia, 13 subjects with acquired prosopagnosia, and 38 control subjects with the Cambridge Face Memory Test. We compared their performance on the second phase, without visual noise, and on the third phase, which adds visual noise. We analyzed the results with signal detection theory methods. The performance of controls worsened more than did that of prosopagnosic subjects when noise was added. The second phase showed better ability to discriminate between prosopagnosic and control subjects than did the third phase. For developmental prosopagnosia, a test using only the 48 trials of the first and second phases yielded sensitivity of 88% and specificity of 91% with a criterion of 33/48 correct, performance characteristics that are similar for a criterion of 43/72 for the whole test. We conclude that a shortened Cambridge Face Memory Test without the noisy images may be a quicker yet equally effective instrument for diagnosing prosopagnosia. The theoretical advantage of noisy images is outweighed by the poorer performance of control subjects with visual noise.