Expert cautious over 'Madeleine' photo

It will be very difficult to prove whether Madeleine McCann is the young girl in a photograph taken in Morocco, a facial recognition expert warned today.

Dr Rob Jenkins, a psychologist at Glasgow University, agreed the picture looked “similar” to images of the missing British child.

But he cautioned that there were “thousands” of young girls fitting Madeleine’s description who might resemble her in the right conditions.

There is likely to be “a good deal of wishful thinking” among people believing the missing girl is in the new photograph, taken just over three weeks ago by a Spanish tourist in Zinat in northern Morocco, he said.

But Madeleine’s family would be “extremely good” at judging if it is her.

Dr Jenkins said: “It is very difficult to look at two photographs and say ’that’s the same person’ when it’s someone we’re not familiar with.

“There is a sense in which we’re familiar with Madeleine’s face now because it has been all over the papers and on the TV, but it tends to have been the same few photos repeated.

“We have not had that much exposure to all the ways her face can move.

“Although we are familiar with particular images of her face, we are not really very familiar with her face itself – that is a critical difference.

“When we are unfamiliar with faces, we are very bad at accurately saying these two faces are the same person. That is a reason to be cautious.

“The reason is that changes in the camera used, changes in lighting, small changes in pose and expression can have a big effect on the appearance of the image, but they don’t tell you anything about who the person is.

“You can end up with photos of different faces being more similar than photos of the same face.”

These problems are compounded with a poor quality image, as in the case of the picture taken in Morocco.

“It looks as if this is a Caucasian girl, about the right age, build and complexion. But there are thousands of girls who match that description,” the psychologist said.

He went on: “If you test this unfamiliar face matching, you find that people have a bias to say, ’yes, they do match’.

“Presumably there is a good deal of wishful thinking here – everybody would like this to come to a happy resolution.”

But it is a very different situation when you are looking at a photograph of a close friend or relative.

Dr Jenkins said: “We are really, really good with familiar faces. It would be interesting to see what the reaction of the McCann family is.”

Computers can be a “helpful tool” in comparing the faces in two photographs, but they are not foolproof, he said.

“Computer analysis is far from perfect, although there are conditions where a computer can outperform a human with unfamiliar face matching,” he said.

“If the computer has confirmed that it’s a match, and people unfamiliar with the face and people familiar with the face do likewise – if there was a match across the board, that would be encouraging.”