
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, & 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 & whatever properties of physiological organization & function might underlie it. The central strategy advocated was to approach psi indirectly, thru intensive study of various altered states of consciousness with which it appears to have been strongly associated, historically & crossculturally. These unusual states of consciousness seem more accessible than psi itself to psychophysiological analysis with a possibility of a solution to the replicability problem.