The Ouija Board is a point of contention among paranormal investigators. Some say it's a portal for demons, others say it's a great way to communicate. I say it's bunk, and I'll explain why.
First, grab yourself a shoestring or any string about a foot long. Tie something to the end- a button, a small clip, something with a bit of weight to it, but nothing fancy is needed. Now, hold your arm out straight and keep your arm and hand still, holding the end of the string, letting the weight hang. You'll notice that no matter how still you try to remain, the "pendulum" will invariably move in a circular pattern or back and forth, its own kinetic energy allowing it to build and swing more and more. You can even begin to ask questions and see the pattern shift from one direction to another. This is known as Chevreul's Pendulum, named for the 19th century researcher who discovered this ideomotor effect.
This effect is seen as well with the ever-famous Ouija Board. It's seen with pendulum and dowsing rod use, and even amongst those facilitators who help those who need guidance to type out a message on a computer communication board. It's just how we work. Small little muscles move without realizing it, because our brains send out constant non-conscious thoughts. We want to see something happen, so we set up our bodies to make something happen, and we don't even realize we're doing it. In fact, people will swear that they aren't moving at all, yet there are movements in our bodies we're completely unaware of, and our brains will answer our questions if we ask them, bringing forth the non-conscious thoughts.
Reading
Daniel Wegner's book The Illusion of Conscious Will can explain further the processes by which we create these movements without realizing them or meaning to, and why our brain connects these things to an outside force.
The first "talking board" was sold in a Pittsburgh toy shop in 1891 for $1.50. It was sold as an incredible way for people to get answers to questions, and indeed, some therapists actually use the Ouija Board with patients to understand more of what's going on in the inner mind. Kennard Novelty Company was founded and began production of the boards in 1890 on the tail of Spiritualism, and with a huge public interest in speaking to the dead, Charles Kennard joined some other businessmen to create a huge money-maker. None of them knew a thing about Spiritualism, but they knew how to make money and cash in on a fad.
The name "Ouija" is said to have come from the board itself, but more than likely was from a picture of a woman named Ouida whose name above her image was misread by the woman using the board when it mysteriously chose its own name. The board even received a patent, somehow, without even declaring how it worked, just saying that it did. Some say that some money may have been snuck around to make things happen. The woman using the board when it supposedly named itself was the sister of one investor, and she was sitting across from the image of Ouida at the time.
It was a movie that changed the Ouija Board from innocent talking board into a portal for demons. The Exorcist, a movie so loosely based on a factual story that it's considered fiction, was widely believed. Suddenly the Church and Christians around the world were declaring the board to be a portal for Satan and burning them on bonfires. Since the 1850s, scientists have studied and proven the ideomotor effect time and time again, even your crying at a sad movie is an ideomotor effect. It happens. It's undeniable scientifically. With a group of people, you have the ideomotor effects and non-conscious thoughts of a group of people, all expecting an outcome. Even if it makes no sense, 'replies' from the board are seen as messages. They are nothing more than messages from within the minds of those present with hands on the planchette.
Researchers have even discovered that our non-conscious brain is much smarter than we realized. When people answered questions in one study verbally, they were only right half the time, but they were right 65% of the time when they used a Ouija board. They thought they were using it with another person they could not see, but it was just a robot that mimicked their own movements, making them more impressionable. People thought the answers were from the Otherside, but they were just proving they were more intelligent than previously thought!
The Ouija Board has become a wonderful tool for psychologists and other medical professionals trying to discover the non-conscious brain, and it's proven to show promise in working with those with Alzheimer's disease. It is not, however, a good tool for paranormal investigators. Unless you believe your non-conscious brain is paranormal, you're really just exploring the depths of your own mind. All these ideomotor effects on various tools in the paranormal field (dowsing rods, pendulums, Ouija Boards, etc) are useless in trying to provide real scientific evidence of the Otherside. Our goal is to find solid evidence, not delve into our own minds on every investigation.
There will be those who call what I've said here bunk. That's ok. People have to believe in something. But if you are looking for a team to investigate your location, and they show up with a bunch of ideomotor tools, you might want to question their science and their approach. They're not stirring up demons from Hell, just those within their own minds. Often those are much more frightening than anything paranormal.