“…By 1940 nearly one million experimental trials had been reported under conditions which precluded sensory leakage. These included five studies in which the target cards were enclosed in opaque sealed envelopes (41,45,46,54,59), 16 studies employing opaque screens (7,8,11,19,33,34,35,38,41,42,44,45,46,59,71), ten studies involving separation of subjects and targets in different buildings (50,51,52,53,34,32,8,77,61,60), and two studies involving precognition tasks (59,75). These data are summarized in Table 1.…”