Question: Is there a scientific explanation for how the Ouija board works?
Skeptics say that the Ouija moves due to the "ideomotor effect" (sometimes called "automatism"). The ideomotor effect refers to the involuntary and unconscious motor behavior of a person. The term "ideomotor action" was coined by William Carpenter in 1882 in his explanation for the movements of dowsing rods and pendulums by dowsers, table turning by spirit mediums and, of course, the movement of pointers on Ouija boards.
Carpenter argued that muscular movement can be initiated by the mind independently of volition or emotions. We may not be aware of it, but suggestions can be made to the mind by others or by observations. Those suggestions can influence the mind and affect motor behavior. What is purely physiological, however, appears to some to be paranormal.
The skeptical explanation does not, however, account for predictive events and other phenomena sometimes associated with the Ouija.