CRYPTOM:\ESIA AND PARAPSYCHOLOGY* by IAN STEVENSONt 'Originality is the suppression of sources' -George Watson (19 78) INTRODUCTION The canons of research in parapsychology require us not to favor a paranormal explanation fora case unless we have eliminated-either completely or as nearly so as makes no difference-all possibilities for the subject to have obtained through normal means the knowledge shown in the experience. This rule applies whether we are concerned with a telepathic dream, a death­ coinciding apparition, a mediumistic communication, a claim to remember a previous life or any other experience in which the paranormal communication of information appears to have occurred. Communicated information must be verified as correct, which means that it must (usually) exist somewhere, either in a printed form or in the mind of a living person. (Other sources, important as they sometimes are, need not detain us here.) Each of these two types of deposit has advantages. On the one hand, information existing only in someone's mind is less accessible to other persons than is printed material; but it is also subject to the weaknesses of memory-both of forgetfulness and embellishment. On the other hand, written documents remain stable, but some types, such as newspapers and books, often have wide distribution so that it may become formidably difficult to exclude the possibility of the subject's having seen a particular source of information. Thus the same source that verifies an apparent paranormal experience may also suggest a normal explanation for it. Subjects of an experience in which information has apparently been communicated paranormally always deny that they had any prior knowledge of this information. It is a strength of experimental work in parapsychology that properly designed experiments can always exclude previous knowledge on the part of the percipient of the information acquired. We can similarly eliminate such knowledge in the majority of spontaneous cases in which the events communicated occurred at a physical distance fromthe subjects and close to the time of their experiences, so that information about the events could not have reached them normally; and if the events were not contemporaneous with the per:eptions, but occurred in the past, there should have been no publicly available record or route of other normal transmission available to the subjects. When we appraise the likelihood that the subject of a case that seems to mclude a paranormal communication might have had normal access to relevant sources of information, we cannot rely exclusively on the subject's own ;��ts paper is an enlarged version of the Myers Memorial Lecture delivered in London on I 9 March t Th anks are due to the McDonnell Foundation, Inc. and the Bernstein Brothers Parapsvchologv :�� �e�lth Foi:ndation for support of my research in parapsychology. I am grateful to La�ra Dal� Ennly Williams Cook for numerous suggestions that helped to 1mproYe the paper. 0037-H-75183/51/792!0265 $] 00/l © 1983 Socw!\. for Ps)rh;cal Re-search i Journalof the Society,farP sychical Research [Vol. 52, No. 793 February 1983] Cryptomnesia and Parapsychology a ar a a o a enth n testimony as been os e o at some pp ently p r n rm l fi:t� -ce tury Fr�n e a are . It h p sibl t show th c ; nd they equally apt o e oo a e o s r r c e t ov rl k other sources communic tions derived, or almost certainly deriv d, fr m the subject' p io \-1,?1 h th subject might ha e ea e firom . v l rn d pertinent details. e t a no a e a or o e e s a o e On th o her h d:1 ' som rm l exposur to such sources. In the m j ity f these cases th subj ct h d cntKs f thes cases a ssume a a o . e th t if b ok th t ta e a l o r o e he a er e e o e a o h re o a e ms m det s c mpletely fo g tt n t ir e rli xposur t th inform ti n. In suc p vi us life' h s b en l e o e e � /�t ;;: i ?f the ' pub ish d s m wher t e ices e ca s en a a e s a a e o i on su to xpla e se -wh we c n ssume the honesty of th subject -we s y th t they 'pr vi us life'. They then m a o ' m th ke no effi rt to t s u dY t he corres e e e e a e n s o a e e o a e o s pond nc m· d eta1·1 xhibited cryptomn si . This term was d fi ed by the p ychol gist J m s b tw�en b ok nd 'pr vi u life', a n e r e . to le r wh the th subje a a re re e a o ho a n a e o or t ass ct h. d i f: ct ad the D v r ( 1952, p. 55) s 'mem ry wit ut identific tion or recognitio s book m qu sti n, o ess a the likelihood th t he or � a e e e r ence o a e er e e e r o n or e re se a a c . she. mig h t v done s pr vious xpe i , [the] rigin l xp i nc s b ing fo g tte r p s d, nd N ive incredulity an e s as c o. imped u J ust m u h as a c e . e a e n a e r n a a n e r e e e o s e s a r e can n ive r dulity· their r inst t me t pp a i g s ew xpe i nc .' Som psychol gist pr fer I h 11 p opos three e s a n rul s for e t blishi g cryptomnes a a · er . ase source amnesia o r cryptomnesia. 1 r a e r i an mt pre a the phr t the te m fo a c s . In o_ de t o a t t10_n r bo h t show how I c me o e es s e e to ff r th e rute nd es o a er e e r o n a es o s a s fuln s s e a e s to t t then f prop se in this p p to revi w th bette -kn wn i st nc f cryptomne i u ss agam t p cific c s s, I a t h ll review many of he b ; ases a se n a e e a s e a e e an e e cryptomne a n e o � of with view to ei g wh t g n r l le sons w c n deriv from th m d wh th r si i th� fi ld f parapsyc n e a /:�:,7own hology. Alo g th w y r e a e e s e e r n o a e a the sake of compa o o e s s ment10n, fo w c n dev lop from th ir tudy guid lin s fo judgi g crypt mnesi to b ns n, s m ca e of unackno e o . e wl dg de b rrowmg er e a a ca a e e at e r who wer accused a 2 n s by writ s, likely xpl n tion for ses th t w inv stig e in th futu e. of plagi rism ·A. d final! a s ica · Y, I hs ll d1scus. a a as r o some p r psych I og· l c es 10r w h.Ich crypt mne a as e s e · r si h be n uggest d , ibut ror · n 0 · · n a a s a w h'IC h It Is· � -ot 1n PROPOSED RULES FOR INTERPRETING A CASE AS ONE OF CRYPTOMNESIA my pm10 , s t1 1 ctory m· terpretation. It woul� e ar as a a a a n o a a a r a e e a a b emb r singly unfitting a r o I h ve lre dy said th t the propo ent f p r no m l int rpr tation of c se c t n for the utho f a a e r p om es a o e e rces p r on a e o a n o e e no a o e o n a a a � 1 t forg t th sou of his n n r at ; 1 h s th blig tio t xclud rm l pr c sses of c mmu ic tion. If we re d am ow i fo m ion I h t h r a p s to expose all a er o e t ken o a a a e y e e en e s s o of mine; nd this is all the e �;:a report f such c se nd r main unconvinced b th vid c for uch exclu i n, a e mor necess�ry use ; r a on of sp c I must s a a a � re s s e a r t e a o a a n s g o e umm rize m nv c ses briefly e .