Impaired face identity discrimination in individuals with cerebral visual impairment: a pilot study

Cerebral visual impairment (CVI) is the leading cause of pediatric visual impairment and results from brain-related injury or maldevelopment. Higher-order visual processing deficits are commonly reported and can include difficulties recognizing faces, which can adversely affect the development of communication and socialization skills. In this study, we aimed to measure face discrimination ability in CVI compared to controls using a rapid, self-administered, remote paradigm.

We quantified face discrimination ability with a Foraging Interactive D-prime (FInD) paradigm that measured the threshold distance between Basel Model Faces required for participants to report whether faces were of the same or different people. We measured face discrimination thresholds in 8 control and 8 CVI participants viewing forward-facing and tilted faces.

Face discrimination thresholds were significantly higher for CVI than control participants [t(13)=-3.439, P=0.004]. Contrary to controls, CVI participants showed no significant difference between forward-facing and tilted faces [t₍₇₎=-1.355, P=0.22]. Importantly, visual acuity did not correlate with face discrimination performance in the CVI group for forward-facing (r=0.040, R²=0.002, P=0.93) or tilted faces (r=-0.100, R²=0.010, P=0.813). A follow-up experiment with control participants (N=23) manipulating digital blur confirmed that face discrimination ability is resilient to visual acuity differences [t₍₂₂₎=-11.291; P<0.001, d=4.152].

These findings quantify a face processing deficit in individuals with CVI and show that this impairment is independent of visual acuity. We hypothesize that while control participants can exploit point-wise comparisons between identical images, individuals with CVI possibly do not utilize this additional source of information.