New research from The University of Western Ontario suggests the sometimes eerie feeling experience when recognizing someone, yet failing to remember how or why, reveals important insight into how memory is wired in the human brain.

In research published recently in one of the world's most-cited multidisciplinary scientific publications, "Proceedings of the National Academy of Sciences USA," Western psychology graduate student Ben Bowles and psychology professor Stefan Köhler have found that this feeling of familiarity during recognition relies on a distinct brain mechanism and does not simply reflect a weak form of memory.

"Recognition based on familiarity can be contrasted with recognition when we spontaneously conjure up details about the episode in which we encountered the person before, such as where we met the person or when it happened," explains Köhler.

The authors report that a rare form of brain surgery that can be highly effective for treatment of epilepsy can selectively impair the ability to assess familiarity.

"It is counterintuitive but makes a lot of sense from a theoretical perspective that familiarity can be affected, while the ability to recollect episodic detail is completely spared," adds Köhler.

The research is based on Bowles' Master's thesis and was supported by a grant from the Canadian Institutes of Health Research (CIHR) to Dr. Köhler. It has important implications for understanding memory deficits in neurology, including in Alzheimer's disease.

The study was conducted in collaboration with researchers at the London Health Sciences Centre, McGill University, and at the University of California.