Evidence for extrasensory perception in dream content: a review of experimental studies

Surveys and collections of spontaneous cases suggest that a large number of people have had experiences during their dreaming life that they interpret as instances of extrasensory perception. Interpretation of these accounts is made difficult by the lack of control over the circumstances in which they occur, which leave open the possibility that such experiences can be explained in terms of normal modes of communication or inference and errors of perception and memory. Experimentation allows these normal explanations to be controlled for so that we can determine if any anomalous exchange of information remains unaccounted for. In this chapter we review the experimental studies of dream ESP that have been conducted to date, beginning with a substantial and influential series of experiments conducted at the Maimonides Medical Centre and including those conceptual replications that have followed, termed ‘post-Maimonides studies’. Combined effect size estimates for both sets of studies (Maimonides r = 0.33, 95% C.I. 0.24 to 0.43; post-Maimonides r = 0.14, 95% C.I. 0.06 to 0.22) suggest that judges could correctly identify target materials, more often than would be expected by chance, using dream mentation. Maimonides studies were significantly more successful (p < 0.05) than post-Maimonides studies, which may be due to procedural differences, including that post-Maimonides receivers tended to sleep at home and were generally not deliberately awakened from REM sleep. Methodological shortcomings of some studies are discussed. Nevertheless, we conclude that home dream ESP research has been successful and offers a more cost effective and less labour-intensive alternative to sleep-laboratory-based research.