Abstract
Researchers have suggested that perceptual impairments are a fundamental aspect of developmental prosopagnosia (DP). However, on any particular test, studies have shown that DP group-level face perception performance is within the normal range with considerable between-DP heterogeneity. This heterogeneity may be due to different types of perceptual deficits or rather different strategies that DPs employ. Comparing DP and control performance across a variety of perceptual tests could help us better understand the prevalence of perceptual deficits in DPs. Using a battery of five face matching/discrimination tasks, we sought to compare the prevalence of perceptual dysfunction (z < −.98)/perceptual deficits (z < −1.96) in a group of 20+ DPs and matched/simulated controls. Participants were asked to match/discriminate real faces (Computerized Benton Facial Recognition Test and two 2AFC face matching tasks with lighting and viewpoint changes) and face morphs (Cambridge Face Perception Test, USC Face Perception Test). We found that 50% of DPs demonstrated a perceptual deficit (z < −1.96) on at least one test and 22% on two tests, whereas 8% and 2% of the control group demonstrated deficits on one and two tests, respectively. For perceptual dysfunction (z < −.98), we found that 95% of DPs showed dysfunction on at least one test and 67% on two tests, whereas 40% and 21% of the control group exhibited dysfunction on one and two tests, respectively. Interestingly, we found that DPs demonstrated significantly more intra-individual variability across perceptual tasks than controls, even for the DPs without perceptual deficits. Further, there was a consistently lower correlation between perceptual tasks in DPs (range: .0–.4) than controls (range: .4–.6), suggesting greater inter-individual variability in DPs. In sum, these results suggest that approximately 50% of DPs have impaired face perception and perceptual intra-as well as inter-individual variability may be a defining characteristic of DP.
Acknowledgement: National Eye Institute