One line of psychological research that can be traced back to early investigations of spiritualist phenomena concerns the concept of the ‘ideomotor’ effect. Table tilting was one of the original spiritualist proofs of direct spiritual intervention in the physical world. In its most basic form, a table-tilting test could simply involve a group of participants sitting around a table. Each would place their fingertips on the table, and apparently without any effort on the part of the sitters the table would mysteriously begin to sway, sometimes even float into the air. For believers, table-tilting effects served to reinforce their belief that external invisible forces could indeed act on the physical world.

While anyone who had felt or seen the table tilt could agree that a force was at work, the precise nature of that force has been the subject of intense and distinctly odd debates. Some observers feared that the movement of the table resulted from the actions of demonic forces drawn by the unholy urges of the deviant spiritualists.

Mesmerists, such as the self-proclaimed ‘Electrical Psychologist’ John Bovee Dodds (1795–1872), speculated that such movements might result from “electro-magnetically charging the table from a living battery of many human hands”, that “the million pores in the table are filled with the electro-magnetism from human brains” and that the electromagnetism was “lighter than gas”, causing the table to rise, like a balloon.

Most spiritualists were of the opinion that the forces were actually physical manifestations of the souls of the dead. In 1916, Oliver Lodge wrote that his spiritualist convictions were reinforced when a medium spelled out the name of his late son, Raymond, by counting the movements of a table and assigning them letters.

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