To report an extremely fascinating case that sheds light on the underappreciated role of the frontal lobe in facial recognition and novelty gauging

Facial recognition requires intact visual perception pathways, temporal lobe circuits to access visual facial memories, and higher level integration of contextual data.  Lesions in right occipital-temporal-parietal circuits are known to play a role in prosopagnosia, the inability to distinguish and recognize faces.  However, rarely reported cases exist of a related problem, false recognition, in which unfamiliar faces are falsely judged as familiar.  These seldom arise in conjunction with prosopagnosia, and exceedingly rarely, in isolation.  One such case occurred with a posterior right frontal lobe lesion, illuminating the role of the frontal lobes in visual processing.  

A 57yo man with right frontal glioblastoma multiforme politely interrupted the examiner to relish with his wife how similar the medical student looked to his nephew.  She laughed at the dissimilarity, and indicated this had been taking place almost constantly since his recent tumor resection. While he had no problem recognizing familiar faces, he continuously incorrectly perceived familiarity in novel faces. 

Further testing included Benton facial recognition with normal score (43).  He could name objects and famous faces, confirming intact visual memory stores. He recognized voices well. He had two false starts on contrasting programs and impaired Luria sequence execution.

Facial recognition involves a complex chain of events- beholding a face and recognizing it as such, accessing known face memories, but also a final higher order processing which is less well understood. This involves incorporating context cues and making final judgments on whether the stimulus matches familiar memory representations.  We label this false recognition phenomenon the “Doppelganger effect,” deeming strangers as doubles for known entities.   The case informs us that right frontal lobe lesions may induce impaired facial familiarity assessment.