Abstract
Can prosopagnosia exist without object agnosia? A recent review concludes that most developmental prosopagnosics (DPs) have trouble with object recognition (Geskin & Behrmann, 2018), but a closer look at the surveyed cases highlights the need for new studies with large samples, rigorous measures, and robust statistics (various responses to Geskin & Behrmann, 2018). Here we report a systematic study of face and object recognition with 93 DPs and 100 age/sex-matched controls. DPs were selected based on impaired scores on Cambridge Face Memory Test (CFMT), a famous face test, and self-report prosopagnosia index (PI-20), plus a normal score on Leuven-Perceptual Organization Screening Test (L-POST) and a lack of history of brain damage. Controls are MTurk participants who scored in the normal range of CFMT. DPs and controls completed object recognition measures for five categories (bodies, bicycles, cars, hairs, houses), each tested using the rigorous and well-validated format of Cambridge Memory Test. DPs and controls also completed a second CFMT to avoid double-dipping CFMT scores used for participant screening. As a group, DPs are most impaired with faces and to a lesser extent with cars, but they show normal recognition of the remaining categories. However, single-case analyses reveal that individual DPs who show impaired face recognition but normal object recognition under the stringent statistics of “classical dissociation” are in the minority: 5–10% DPs are normal with all five object categories, 10–15% with four or more, and 15–20% with three or more. These estimates suggest that prosopagnosia can exist without object agnosia, but firm dissociations between face and object recognition across multiple categories are only present in some DPs.
Acknowledgement: Royal Society of New Zealand Marsden Fund 16-VUW-175