The background of applied kinesiology (AK) in general dates back to George Goodhart, D. C. (1964) in which the gross, striated muscle response is one of going weak to a detrimental stimulus and remaining strong to a beneficial stimulus. The same is the case for muscle responses to statements that are true and not true: Staying strong under “true” conditions and going weak under “not true” conditions, i.e., a false statement.
Likewise, it has been reported by Davis, C. 2007 (in Hawkins, D. 2008 “Reality, Spirituality, and Modern Man) that the pupil dilates to falseness and constricts to truth statements made by the individual.