Product Description: First published in the 1970s, this edition has an updated preface that renders the material current. The authors feel that the distribution of voluntary psi abilities within the general population is far from the bell-shaped or "normal" curve, and that many of the field's strongest experimental outcomes are obtained in a repeatable fashion because high between-subject variation seemed certain in terms of psi capacity and whatever properties of physiological organization and function might underlie it...read more