ABSTRACT
Having reviewed 238 cases of developmental prosopagnosia (DP) that met their criteria, Geskin and Behrmann found that only ~20% exhibit normal object recognition. According to the independent disorders hypothesis, forms of developmental agnosia affecting faces, objects, and bodies are best characterized as independent neurodevelopmental conditions that co-occur; that is to say, the incidence of developmental object agnosia and DBA is higher in DP than in the wider population. Co-occurrence is a common feature of many neurodevelopmental conditions. Many DPs, for example, exhibit reduced integrity of the inferior longitudinal fasciculus: a white matter tract connecting occipital and temporal cortices. The domain-general account offered by J. Geskin and M. Behrmann predicts that the extent of an observer’s deficit in one category ought to relate closely to their relative performance in other categories. The independent disorders hypothesis predicts that individuals predisposed to DP should be more likely to develop other neurodevelopmental conditions, such as autism spectrum disorder, and vice versa.
