Bloody Mary, Bloody Mary, Bloody Mary: How the classic sleepover party game really CAN summon a ghost in your mirror

Turn off the lights, burn a candle, look into the mirror and say the magic words: 'Bloody Mary, Bloody Mary, Bloody Mary'.

If you do it right, the next thing you see should be a terrifying ghost emerging from the darkness – at least according to the rules of the classic sleepover party game.

While Bloody Mary has terrified people for generations, psychologists now say there is more to this party trick than the overactive imaginations of excited teenagers.

And if you do call on Bloody Mary this Halloween, you really might see something terrifying.

Research has shown that looking at your own face in a darkened mirror produces strange hallucinations and anomalous experiences in the vast majority of people.

In one study, almost half of the participants saw 'fantastical and monstrous beings' after looking into the mirror for 10 minutes.

Scariest of all, scientists still aren't sure why these terrifying monsters and ghouls appear.

So, if you want to see how this simple game can really summon a ghost, here's how to try it out for yourself.

Although some form of the Bloody Mary game dates back as far as the early 20th century, scientists didn't start taking the idea seriously until 2010.

Dr Giovanni Caputo, assistant professor of psychology at the University of Urbino, had been conducting an experiment in which participants sat in a room entirely enclosed by mirrors.

However, while setting up the room one morning, Dr Caputo decided to sit in front of the mirrors in near–total darkness.

Before long, he began to witness strange faces leering back at him that were so alarming he initially thought he was hallucinating.

But as Dr Caputo recreated this strange ritual with others, he soon discovered that he was not alone in seeing the haunting visions.

In the first study of its kind, Dr Caputo asked 50 volunteers to sit in front of a mirror in a dimly lit, quiet room for 10 minutes and stare at their own reflection.

While the descriptions of their visions varied, 66 per cent said they saw their faces undergoing huge deformations, while many said they saw someone entirely different.

Over a quarter of people said they saw someone they had never met before, while 10 per cent said they saw a deceased parent looking back at them.

Perhaps even more surprisingly, 48 per cent said they saw 'fantastical and monstrous beings'.

Dr Caputo told Daily Mail he believes that the 'strange face in the mirror illusion' is the reason that people really do see monstrous figures during the Bloody Mary game.

What made these visions so terrifying is that people universally reported seeing their own reflection transforming into someone they didn't recognise.

Scientists think that the capacity to recognise our own reflection is a key component of our conception of the 'self', so anything that disrupts that process is extremely unsettling.

'There is the very unsettling experience of a strange connection between myself and the alter 'Bloody Mary' who stares at me from beyond the mirror,' says Dr Caputo.

However, the bigger question is why so many people experience such horrendous visions.

Dr Caputo thinks that the illusion occurs in three stages: deformation, detachment, and depersonalisation.

Deformation, in which the face in the mirror begins to warp, is likely a product of our brain's ability for selective processing.

The neurons in our brain stop responding to stimuli that don't change, which is why you aren't always aware of the feeling of your socks on your feet or the smell of your own breath.

When we stare at ourselves in the mirror, our brain starts to tune out the unchanging parts of the image, and the features begin to become distorted.

At the same time, the regions of our brain that are responsible for recognising faces scramble to piece together the warped facial features into a coherent image, creating a horrific visage. 

Next, Dr Caputo says there is a 'detachment of one's own body' from the image you are seeing in the mirror, which is similar to what people undergo in out–of–body experiences.

Finally, there is a moment of dissociation in which a 'new identity is created by the mind and is projected to "Bloody Mary" who stares at me'.

This illusion is so powerful that it even works if you look intensely at someone else's face or if you look in the mirror while wearing a mask. 

These stages also explain why so many people have the disconcerting experience of seeing their own reflection turn into a stranger, a loved one, or the terrifying ghost of Bloody Mary herself.

What this doesn't explain, however, is why so many people report seeing beasts and monsters leering out from the mirror.

Dr David Terhune, an expert on anomalous perceptions from King's College London, told Daily Mail that this is something scientists still don't fully understand. 

He believes these strange visions might be linked to the spooky setup of the Bloody Mary game and our cultural expectations about the power of mirror gazing.

He says: 'Reflective surfaces have long been used for divination. The broad cultural context surrounding these effects can produce strong expectations that an individual will also experience such faces.'

Thanks to the fame of the childhood game and the prominent role of mirrors in horror movies, such as the classic Candyman, this makes for an exceptionally strong placebo effect.

Combined with environmental factors such as the dark room, the ominous setting, and chanting the name 'Bloody Mary', our minds are prone to conjuring some truly terrifying visions.

In his own research, people were twice as likely to experience a visual hallucination if they had been told they would see faces in the mirror. 

'It's a reminder that our perception is highly malleable and can be easily modulated using relatively simple procedures,' says Dr Tehrune.

And it is this malleability that makes the Bloody Mary illusion just as scary to adults today as it always has been for children.