Are these the five best ghost photographs?

A courtly figure dressed in a ruff and staring from a castle window would not be particularly unusual if he appeared in a period painting. But this image was captured on a digital camera some 500 years after the Elizabethan era and has for thousands of people around the world become the ultimate proof that ghosts exist.

The photograph, taken at Tantallon Castle near Edinburgh last May, was released yesterday by Professor Richard Wiseman, a psychologist, who “just for fun” embarked three weeks ago on an online research project, inviting websurfers to send him their photos of ghosts.

The response, he said, was “beyond all expectation”. Hundreds of images were sent his way, from as far afield as Mexico and Japan. Then, after 50 of the best images were placed online, some 250,000 people voted for the most convincing.

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The array of smudged photographs and crazy fakes that caught the interest of this huge audience may do little to prove the existence of ghosts, but it indisputably proves a human need to believe in them, said Professor Wiseman, of the University of Hertfordshire. “That belief is everywhere, across countries and cultures. It plays on much bigger ideas about life and death, and there's no doubt that, for many of the people who contacted me, there is comfort in the notion that people who have been harmed in life might be able to come back and wreak their revenge.”

In Britain around a third of people say that they believe in ghosts and one in ten claims to have seen one. Proof, however, remains elusive.

One explanation put forward by ghost hunters and some physicists is that in some environments low frequency sound waves - infrasound — vibrate the body, and lead to strange sensations. While Professor Wiseman does not rule that out, he believes that psychology may have a better answer, particularly in oppressive and frightening surroundings such as a ruined castle.

“In the hypervigilance model, as you become scared, you become more on edge. You begin to monitor you own environment and your own physiology,” he said. “In those circumstances, if you hear a sound like a creaking door, it only heightens your own sense of vigilance. The spiral goes on and you might easily have a panic attack.

“From an evolutionary perspective, all this is sensible, because it is comparable to a situation in the "normal world" where you might come under attack. But in these oppressive surroundings, the seemingly inexplicable becomes very worrying and you begin to look for other explanations.”

Many of the images submitted to his survey were sent in by people who had found themselves in similarly unnerving environments; dark, dusty, unfamiliar and scary. They had taken photographs, and interpreted “orbs”, the reflection of dust in a camera flash light, as evidence of ghosts. Most of these pictures, said Professor Wiseman, were “rubbish”.

He could not say the same for the photograph taken at Tantallon Castle, which, though undeniably spooky, had been photographed by a day-tripper, Christopher Aitchison, who apparently had no thought of finding a ghost. If was only back home, when he was examining his snaps of the day out, that he noticed the ghostly visage. Three experts on Photoshop, the photography software, have analysed the image and concluded that it has not been tampered with, and Professor Wiseman has been unable so far to find any convincing explanation for the ghostly apparition.

“I do find the Tantallon image curious. People are often keen to find ghostly explanations, and to kid themselves about the paranormal. But equally, science must be open to possibility - you have to hold fire when you can't explain something, or you haven't all the information,” he said.

Believers in the spirit world have suggested that the spectre in Mr Aitchison's photograph is James V, the Scottish King who was imprisoned in the castle in the 1520s when he was a teenager. None has yet been able to suggest why his spirit should have returned to haunt the place as, apparently, a full-grown man.

If that seems inexplicable, there may be another solution, said Professor Wiseman. “It could just be a trick of the light.”

Ghosts in their machine

The Brown Lady of Raynham Hall is probably the most famous image of an alleged ghost captured on film. It was taken in 1936 and is said to show Dorothy Walpole, second wife of Charles, 2nd Viscount Townshend, who died in 1729.

The image was taken by Captain Provand and Indre Shira, photographers on assignment for Country Life magazine at Raynham Hall in Norfolk. While they were shooting pictures of its interior, Shira said that he could see a figure on the staircase. Provand could not, but took the photograph anyway. It later revealed a transparent hooded figure descending the stairs. When it was published in Britain and America, the image caused a sensation.

A contemporary investigation, conducted by the Society for Psychical Research, concluded that an equipment failure had been responsible. Professor Richard Wiseman suggests that the image is the result of a double exposure — a failing that has resulted in many similar ghostly apparitions on older cameras.

Double exposure has disappeared with the advent of the digital camera but even modern photographers see spectres. “Orbs” — the reflections of dust in a camera flash — can create an eerie effect while a finger placed carelessly over the lens can convince some people that they have seen a ghost.

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