A Case of So-called Prosopagnosia : Investigation of Underlying Recognizing Mechanism

The abilities of visual recognition were studied in a 72-years old right-handed man having disturbances in recognizing familiar faces and memorizing or discriminating unfamiliar faces, without other symptoms of severe agnosia on daily life. These symptoms had been observed for 18 years since sustaining cerebral infarction. As a result, the patient showed the disability not only in recognizing familiar faces and memorizing unfamiliar faces, but also in all similar tasks demanding detailed visual recognition. He had difficulties in tasks using photographs, such as discrimination of facial expressions, identification of a person with different facial expressions, and also discrimination of different models of automobiles. He also had difficulties in identification of handwriting and recognition of complex figures like superimposed figures and mazes. The disturbance with prosopagnosia has been defined as being limited to faces. But in these patients recognition of other visually complex objects has not been fully investigated precisely. In this case the sympton of agnosia for faces may have heretofore drawn the attention, because there are not so many daily occasions which demand visual recognition as difficult as facial recognition. Therefore the underlying mechanisms of prosopagnosia and subclassificattion should be further discussed.