More than just a problem with faces: Altered body perception in a group of congenital prosopagnosics

It has been estimated that one out of forty people in the general population suffer from congenital
prosopagnosia (CP), a neurodevelopmental disorder characterized by difficulty identifying people by
their faces. CP involves impairment in recognising faces, although the perception of non-face stimuli
may also be impaired. Given that social interaction does not only depend on face processing, but also
the processing of bodies, it is of theoretical importance to ascertain whether CP is also characterised
by body perception impairments. Here, we tested eleven CPs and eleven matched control participants
on the Body Identity Recognition Task (BIRT), a forced-choice match-to-sample task, using stimuli
that require processing of body, not clothing, specific features. Results indicated that the group of CPs
was as accurate as controls on the BIRT, which is in line with the lack of body perception complaints
by CPs. However the CPs were slower than controls, and when accuracy and response times were
combined into inverse efficiency scores (IES), the group of CPs were impaired, suggesting that the
CPs could be using more effortful cognitive mechanisms to be as accurate as controls. In conclusion,
our findings demonstrate CP may not generally be limited to face processing difficulties, but may also
extend to body perception