The Ouija board, in its current version, dates back to 1891 when three men decided to standardize the “talking board” and market it as a toy. But devices for communing with the spirits had been around for decades. The Fox sisters created their own contraptions for rapping and moaning. Spiritualists made tables float and made ectoplasm appear out of thin air.
The game board allowed people to become their own mediums, in their own homes. Anyone could channel the spirits if they were patient enough for the ghost to spell things out. And to get the patent, the designers had to “prove” it worked. To demonstrate its legitimacy, the toy makers spelled out the name of the patent officer, which they supposedly didn’t know. The officer approved the patent and the businessmen were sure to include that it had been “proven at the US Patent Office” in their marketing.
Since then, writers have claimed to be channeling famous dead authors. One said she was talking to Mark Twain and that her new book he had actually dictated to her.
So how do they work? It’s likely something called the Ideomotor effect, which says that muscle movement can happen involuntarily, without conscious direction. Therefore, it is possible for everyone around the Ouija board to sincerely believe they are not moving the planchette, and they just don’t realize they are.
Read more about the origins from the Smithsonian Magazine.