METHOD
The basic design of the autoganzfeld studies was the same as that described earlier [Footnote 4]: A receiver and sender were sequestered in separate, acoustically-isolated chambers. After a 14-minute period of progressive relaxation, the receiver underwent ganzfeld stimulation while describing his or her thoughts and images aloud for 30 minutes. Meanwhile, the sender concentrated on a randomly selected target. At the end of the ganzfeld period, the receiver was shown four stimuli and, without knowing which of the four had been the target, rated each stimulus for its similarity to his or her mentation during the ganzfeld.
The targets consisted of 80 still pictures (static targets) and 80 short video segments complete with soundtracks (dynamic targets), all recorded on videocassette. The static targets included art prints, photographs, and magazine advertisements; the dynamic targets included excerpts of approximately one minute duration from motion pictures, TV shows, and cartoons. The 160 targets were arranged in judging sets of four static or four dynamic targets each, constructed to minimize similarities among targets within a set.
TARGET SELECTION AND PRESENTATION
The VCR containing the taped targets was interfaced to the controlling computer, which selected the target and controlled its repeated presentation to the sender during the ganzfeld period, thus eliminating the need for a second experimenter to accompany the sender. After the ganzfeld period, the computer randomly sequenced the four-clip judging set and presented it to the receiver on a TV monitor for judging. The receiver used a computer game paddle to make his or her ratings on a 40-point scale that appeared on the TV monitor after each clip was shown. The receiver was permitted to see each clip and to change the ratings repeatedly until he or she was satisfied. The computer then wrote these and other data from the session into a file on a floppy disk. At that point, the sender moved to the receiver's chamber and revealed the identity of the target to both the receiver and the experimenter. Note that the experimenter did not even know the identity of the four-clip judging set until it was displayed to the receiver for judging.
RANDOMIZATION
The random selection of the target and sequencing of the judging set were controlled by a noise-based random number generator interfaced to the computer. Extensive testing confirmed that the generator was providing a uniform distribution of values throughout the full target range (1-160). Tests on the actual frequencies observed during the experiments confirmed that targets were, on average, selected uniformly from among the 4 clips within each judging set and that the 4 judging sequences used were uniformly distributed across sessions.
ADDITIONAL CONTROL FEATURES
The receiver's and sender's rooms were sound-isolated, electrically shielded chambers with single- door access that could be continuously monitored by the experimenter. There was two-way intercom communication between the experimenter and the receiver but only one-way communication into the sender's room; thus, neither the experimenter nor the receiver could monitor events inside the sender's room. The archival record for each session includes an audiotape containing the receiver's mentation during the ganzfeld period and all verbal exchanges between the experimenter and the receiver throughout the experiment.
The automated ganzfeld protocol has been examined by several dozen parapsychologists and behavioral researchers from other fields, including well-known critics of parapsychology. Many have participated as subjects or observers. All have expressed satisfaction with the handling of security issues and controls.
