Failure at object identification improves mirror image matching.

In a previous report ([5]: Davidoff J & Warrington EK. The bare bones of object recognition: implications from a case of object recognition impairment. Neuropsychologia 1999;37:279-92) the inability to differentiate between mirror images was recorded in a patient with excellent canonical view recognition. We now extend our investigation to a patient (JBA) with probable Alzheimer's disease in whom canonical view recognition was compromised. The reciprocal inhibition of two aspects of object processing are demonstrated in JBA. The patient's ability to detect mirror image rotations was dependent on her inability to identify the object. Paradoxically, her performance was more impaired for those stimuli that she was able to identify than those she was not.