Photos said unreliable for identification

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GLASGOW, Scotland, July 9 (UPI) -- Photographs of faces are not always proof of a person's identity, with serious implications for the accuracy of passport photographs, British researchers say.

An image of a person may look strikingly different from one photograph to the next, the Economic and Social Research Council said Monday in announcing the results of a study.

In the study at the University of Glasgow, viewers unfamiliar with the subject of a sample of photos taken from the Internet believed the photos they were viewing were of different people, when in fact they were simply different presentations of the same person.

Participants who were familiar with the subject of the photograph found it much easier to identify the person across the different images, showing familiarity was the key, researchers said.

Faces and facial photographs cannot be considered to be representative of each other, researchers said, since different facial expressions -- a smile versus a scowl, for instance -- can distort normal facial features.

"The sheer variation in photos of an individual's face did bring us up short," Glasgow researcher Rob Jenkins said. "Previous research on identification has focused on differences between faces. Now it turns out that differences within faces are just as large.

"This research makes us consider much more deeply what it means to have a 'good likeness,'" he said.