Abstract/Summary

Having reviewed 238 cases of developmental prosopagnosia (DP) that met their criteria, Geskin and Behrmann (2017) found that only ~20% exhibit normal object recognition. This figure likely underestimates the proportion of individuals with a selective face perception deficit (‘pure cases’) as many DPs exhibiting accurate object recognition were excluded from the authors’ primary analysis because response time data were unavailable. Nevertheless, it is clear that object recognition problems frequently co-occur with DP. What does this mean? Geskin and Behrmann argue that this indicates that DP is caused by a domain-general cognitive-perceptual deficit. We suggest an alternative interpretation. According to the independent disorders hypothesis, forms of developmental agnosia affecting faces (DP), objects (developmental object agnosia; DOA), and bodies (developmental body agnosia; DBA) are best characterised as independent neurodevelopmental conditions that co-occur; that is to say, the incidence of DOA and DBA is higher in DP than in the wider population. We argue that this co-occurrence reflects common genetic or environmental risk factors.