It remains unclear whether object and face recognition are dissociated in prosopagnosia. For example, the many-to-many hypothesis proposes that face and visual word processing have overlapping neural substrates, and a recent review concluded that most subjects with developmental prosopagnosia have some abnormalities in object recognition.

We tested twenty-four healthy subjects and eight individuals with developmental prosopagnosia. We created three tests, in which subjects performed a same/different task with an array of faces, visual words or cars that varied between 3 and 7 in the number of stimuli shown. The set-size effect was the slope of the linear regression of response time as a function of the number of faces in the array. 

Accuracy was similar in both healthy and prosopagnosic subjects for all three object categories. Developmental prosopagnosic subjects had increased response times in search for faces but not for visual words or cars. Prosopagnosic subjects showed increased set-size effects for faces but not for cars, but did show a slightly increased set-size effect for visual words.