Fig. 4

Sensitivity (\(d^{\prime }\)) and response bias (c) for mask memory, 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 a given face wore a mask in the study phase, separately for familiar and unfamiliar faces. a Advantage for remembering whether a familiar face wore a mask. Higher values of \(d^{\prime }\) indicate better performance. A value of zero indicates ‘guessing.’ b Stronger liberal bias for indicating unfamiliar faces wore a mask. 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’)