Randi also spoke about the ideomotor effect, which is the basis of how these things "work". The short version is that if someone believes a force is present, there is a tendency to subconsciously generate a corresponding body movement. To the extent that any actual information is involved, the user is feeding information to the device, not the other way around. See also: Ouija boards, facilitated communication, no-touch martial arts, etc..

I guess they tried it without the ants, and it didn't work?