Two explanations of the talking board have coexisted since it was patented. For Spiritualists and for millions of informal users, the planchette moves because someone answers: the board is an instrument of communication with the dead, quicker than raps and available to anyone with a parlor table. The scientific account is older than the board itself.
In 1852 the physiologist William Benjamin Carpenter described the ideomotor effect, unconscious muscular action driven by expectation, and Michael Faraday's experiments on table-turning the next year demonstrated exactly such action in sitters who sincerely denied pushing. Applied to the board, the account holds that the sitters themselves move the planchette without knowing it, their pooled expectations spelling out answers no spirit supplied, which is why blindfolded sitters with a rotated board produce gibberish. The explanation has never dented the practice. The board's folklore grew darker over the twentieth century, fed by horror films and by religious warnings that treat it as a door better left shut; many Christian denominations counsel against its use, and popular culture supplies a steady stream of cautionary stories.
Even within Spiritualism the board is contested, with many mediums preferring disciplined circle work to an instrument they consider unpredictable. The talking board thus occupies a rare position: a mass-produced object sold in toy aisles that large numbers of people, believers and objectors alike, treat as genuinely consequential.