If you've ever watched a paranormal investigation show on TV or been on a ghost hunt yourself then you're probably familiar with concept of communicating with spirits by encouraging them to tap once for "yes" and twice for "no" but why is it such a common practice?
Usually a medium or whoever is leading a seance will encourage the participants to join hands in a circle, this is said to focus their energy allowing spirits to draw on it and energise them. Knowing everyone is holding hands also means you know that no one at the seance is creating the tapping noises themselves.
The spirit is then asked a series of closed (yes or no) questioned and told that they can respond by tapping on a surface one time to answer "yes", or two taps to answer "no". It's said that spirits need to draw on psychic energy in order to make a sound, communicate or manifest, the focussed energy of those holding hands should be enough to give the spirit the strength to manipulate or knock on a surface.
In the 2016 Netflix series 'Stranger Things' Joyce Byers, played by Winona Ryder communicates with her missing son using a similar technique, but instead of tapping, she used the flashing of a string of lights. She asks Will to "blink once for yes, twice for no."
Will Ferrell also uses the technique to communicate with his dog in 'Anchorman: The Legend of Ron Burgundy', while speaking on the phone to a silent caller he suspects his dog might be at the other end and says "Baxter, is that you? BAXTER! Bark twice if you're in Milwaukee."
It's the easiest way to communicate with a spirit as it doesn't require the use of a ouija board, spirit box or any other equipment. Although if you're not careful you could interoperate two knocks as an excitable "yes, yes!" rather than the intended "no".
It's important to only ask questions which can be answered with "yes" or "no" such as:
Did you die here?
Are you male?
Are you stuck in this place?
As the standup comedian Jasper Carrott once pointed out, it's probably not worth asking "is there anybody there? Knock once for yes, twice for no."
Don't assume that the spirits understand the principles of tapping, it's important to frequently remind any spirits present that they should knock in order to communicate as often spirits drift in and out of seances.
The first recorded case of rapping as a way of communicating with ghosts dates back to New York in the 1848. Two sisters, Kate, Margaret Fox were just 12 and 15-years-old when they moved with their family to a new house in an area that was known as Hydesville.
The girls soon came to the conclusion that their house was haunted after experiencing frequent unexplained sounds that they described as being like knocking.
One night, Kate asked the spirit to copy her when she snapped her fingers and it's reported that the spirit obliged, she then asked the ghost to tap out the ages of the girls, which again it got right. From here the girls developed the technique of responding to question or indicating a letter of the alphabet with taps.
Over the next few weeks the girls determined that the spirit they were talking to, "Mr. Splitfoot" was the ghost of a market trader named Charles B. Rosna, they believed he'd been murdered five years earlier and buried in the cellar.
The events gave birth to modern spiritualism, when Kate and Margaret's older sister, Leah started to promote them as mediums, they became famous as well-known mediums and some of the first spiritualists to publicly display their skills.
However, in 1888, Margaret and Kate confessed that their rappings had been a hoax and publicly demonstrated their methods but by this time it was already common practice in seances and spiritualism around the world.