There is an interesting new article at guardian.com on things like dowsing, ouija boards and other scams. It illustrates how there is a scientific explanation for ouija boards, and how dowsing won't stand up to scientific scrutiny.
Here's a summary:
The ideomotor effect is also behind the supposed power of Ouija boards to communicate with the dead. Sometimes referred to as 'spirit boards', Ouija boards typically consist of a round board marked with all the letters of the alphabet, the digits one to nine, and the words "yes" and "no". Sitters place their fingers lightly on a specially constructed heart-shaped piece of wood known as a planchette and proceed to address questions to the spirit world. The technique also works simply by using letters and numbers written on pieces of paper and arranged in a circle on a smooth table, along with an upturned wine glass in place of a planchette.
Amazingly, in response to questions, the planchette (or wine glass) often appears to move around, pointing to various letters and numbers to relay the responses back from the spirits. Once again, we are dealing with an example of the ideomotor effect. Although the illusion that the pointer is being moved by some outside force is extremely strong, the truth is that the sitters are actually moving it without realising it.
Whether the device is a Ouija board, a divining rod or a bomb detector, the ideomotor effect is capable of producing powerful illusions that can be exploited by the unscrupulous. Those whom they fool are usually well-intentioned, often highly intelligent individuals. But the demonstrations used to convince them of the claims are never carried out under properly controlled conditions. If anomalistic psychology shows us anything, it is that intelligence and good intentions are no protection against self-deception. The only way to avoid being taken in by such effects is through the use of properly controlled, double-blind tests.
Here's the link: http://www.guardian.co.uk/science/2013/apr/27/ouija-boards-dowsing-rods-bomb-detectors
FYI, the ouija board is manufactured by Milton Bradley and is sold at Toys-R-Us. I would expect such an evil, spritualistic tool to be crafted and sold by practicioners of the occult, not at your nearest toy store. It's just another phobia instilled by the WT to clueless JWs.