Passport-issuing officers are no better at identifying if someone is holding a fake passport photo than the average person, new research suggests.
A study of Australian passport office staff by a team of psychologists showed a 15% error rate in matching the person to the passport photo they were displaying.
Tests were carried out by researchers from the universities of Aberdeen, York and New South Wales, Australia.
Passport officers had to decide whether or not a photograph of an individual presented on their computer screen matched the face of a person standing in front of their desk.
In 15% of trials the officers decided that the photograph on their screen matched the face of the person in front of them, when in fact the photograph showed an entirely different individual.
The findings, published in the scientific journal PLOS ONE, suggest a single passport photo is not sufficient for security systems to be accurate.
Professor Mike Burton, from Aberdeen University, said: "Psychologists identified around a decade ago that in general people are not very good at matching a person to an image on a security document.
"Familiar faces trigger special processes in our brain - we would recognise a member of our family, a friend or a famous face within a crowd, in a multitude of guises, venues, angles or lighting conditions. But when it comes to identifying a stranger it's another story.
"The question we asked was does this fundamental brain process that occurs have any real importance for situations such as controlling passport issuing, and we found that it does."
Dr Rob Jenkins, from York University, added: "This level of human error in Australian passport office staff really is quite striking and it would be reasonable to expect a similar level of performance at UK passport control.
"At Heathrow Airport alone, millions of people attempt to enter the UK every year.
"At this scale, an error rate of 15% would correspond to the admittance of several thousand travellers bearing fake passports."
In a second test, the passport officers were asked to match current face photos to images taken two years ago.
Error rates on this task rose to 20% - the same result as a group of untrained student volunteers who were also tested.
Prof Burton said: "This study has importantly highlighted that the ability to be good at matching a face to an image is not necessarily something that can be trained.
"It seems that it is a fundamental brain process and that some people are simply more adept at it than others.
"Our conclusion would be that focusing on training security staff may be ploughing efforts in the wrong direction.
"Instead we should be looking at the selection process and potentially employing tests such as the ones we conducted in the study to help us recruit people who are innately better at this process.
"Because of this study, the Australian Passport Office now set face-matching tests when recruiting staff and when selecting facial comparison experts."
He added: "It seems strange that we expect a single passport shot to encompass a person and allow us to consistently recognise them.
"If we are stuck on the concept that a good representation of a person is achieved through one image, then we are setting ourselves up for errors.
"Could there, in fact, be an argument for our passports to contain a multitude of images, taken at different angles, in different lighting and formats? This is certainly something our study is examining."