Contribution of visual and semantic proximity to identification performance in a viral encephalitis patient

Identification deficits were investigated in F.S., a patient with herpes simplex viral encephalitis. F.S.'s confrontation naming abilities were assessed for multiple repetitions of 12 line drawings of artifacts. Six of the line drawings consisted of psychologically "close" objects (i.e., objects that share many visual and semantic features with other objects) and 6 were psychologically "disparate" objects (i.e., objects that share few, if any, visual and semantic features with other objects). F.S. correctly named all of the objects from the "disparate" category but only 47% of the objects from the "close" category. We also tested F.S. using novel, computer-generated shapes that were paired with artifact labels. We paired semantically close or disparate labels to shapes and F.S. attempted to learn these pairings. Overall, F.S.'s shape-label confusions were most detrimentally affected when we used labels that referred to objects that were visually close and semantically distinct. Results indicate that, at least for our patient, visual similarity contributed the most to his identification errors.