Fig. 2

Sensitivity (\(d^{\prime }\)) and response bias (c) for identity recognition, depending on the familiarity of faces. Note. Black horizontal lines indicate median values. Same colors indicate data points from the same participant. Each data point shows the sensitivity (\(d^{\prime }\); panel a) or response bias (c; panel b) of a single participant indicating whether they saw a given face in the study phase, separately for familiar and unfamiliar faces. a Advantage for remembering familiar faces. Higher values of \(d^{\prime }\) indicate better performance. A value of zero indicates ‘guessing.’ b Stronger conservative bias for unfamiliar faces. Values greater than zero indicate a conservative bias (tendency to answer ‘no’), and values lower than zero indicate a liberal bias (tendency to answer ‘yes’)