The discrimination of facial sex in developmental prosopagnosia

Abstract

Developmental prosopagnosia (DP) is a neurodevelopmental condition characterised by difficulties recognising and discriminating faces. It is currently unclear whether the perceptual impairments seen in DP are restricted to identity information, or also affect the perception of other facial characteristics. To address this question, we compared the performance of 17 DPs and matched controls on two sensitive sex categorisation tasks. First, in a morph categorisation task, participants made binary decisions about faces drawn from a morph continuum that blended incrementally an average male face and an average female face. We found that judgement precision was significantly lower in the DPs than in the typical controls. Second, we used a sex discrimination task, where female or male facial identities were blended with an androgynous average face. We manipulated the relative weighting of each facial identity and the androgynous average to create four levels of signal strength. We found that DPs were significantly less sensitive than controls at each level of difficulty. Together, these results suggest that the visual processing difficulties in DP extend beyond the extraction of facial identity and affects the extraction of other facial characteristics. Deficits of facial sex categorisation accord with an apperceptive characterisation of DP.

Normal recognition of famous voices in developmental prosopagnosia

“…The fact that DPs show typical voice recognition therefore argues against this account. Instead, these findings are more consistent with the view that DP is associated with an impairment early in the face processing stream that hinders the visual encoding of face structure 6,9,11,69 .…”

“…The groups did not differ significantly in terms of age [t(28.854) = 0.998, p = 0.326, d = 0.280, CI 95% = − 0.258, 0.775] or the proportion of male participants [X 2 (1) = 0.127, p = 0.723]. Sample size was determined a-priori based on similar group studies of DP 8,9,11,12,27,69 . DP participants were recruited through https ://www.troub lewit hface s.org and reported face recognition difficulties in the absence of brain damage or neurological illness.…”

“…Comparison data (N = 54) for the PI20, and CFMT were taken from Biotti et al 6 . Comparison data (N = 75) for the CFMT-A were taken from McKone et al 11 . Comparison data (N = 61) for the CCMT were taken from Gray et al 14 .…”

Holistic processing of facial identity in developmental prosopagnosia

“…DP impairs the perception of same and other-ethnicity faces alike (Cenac, . Many DPs experience subtle problems recognising facial expressions (Biotti & Cook, 2016) and facial sex (Esins, Schultz, Stemper, Kennerknecht, & Bulthoff, 2016;Marsh, Biotti, Cook, & Gray, 2019), and some show signs of co-occurring body (Biotti, Gray, & Cook, 2017) and object recognition difficulties (Geskin & Behrmann, 2017;. Cases of DP were once thought to be rare (McConachie, 1976), however current estimates suggest that ~2% of the general population may experience lifelong face recognition difficulties severe enough to disrupt their daily lives (Kennerknecht et al, 2006;Kennerknecht, Ho, & Wong, 2008).…”

Normal colour perception in developmental prosopagnosia

“…DP individuals generally have little to no trouble categorising a face as a face 7 , but they are frequently unable to recognise the identity of the person it belongs to 8 – 11 . Some individuals also have difficulties when asked to compare the faces of unfamiliar people 11 – 13 , or to discriminate facial expression 14 , 15 , sex 16 , 17 , and race 18 . To compensate, DP individuals typically rely on other non-facial cues for recognition such as voice, gait, context, and general mannerisms.…”