thirteen days: joseph delboeuf versus pierre janet on the nature of hypnotic suggestion

THIRTEEN DAYS: JOSEPH DELBOEUF VERSUS PIERRE JANET ON THE NATUREOF HYPNOTIC SUGGESTION

ANDRÉ LEBLANC

The problem of post-hypnotic suggestion was introduced in 1884. Give a hypnotic subjectthe post-hypnotic command to return in 13 days. Awake, the subject remembers nothingyet nonetheless fulfills the command to return. How then does the subject count 13 dayswithout knowing it? In 1886, Pierre Janet proposed the concept of dissociation as a solu-tion, arguing that a second consciousness kept track of time outside of the subject’s mainconsciousness. Joseph Delboeuf, in 1885, and Hippolyte Bernheim, in 1886, proposed analternative solution, arguing that subjects occasionally drifted into a hypnotic state inwhich they were reminded of the suggestion. This article traces the development of thesecompeting solutions and describes some of Delboeuf’s final reflections on the problem ofsimulation and the nature of hypnosis. © 2004 Wiley Periodicals, Inc.

On September 15,1883, Dr. Hippolyte Bernheim (1840–1919), professor on the facultyof medicine at Nancy, France, reported the following experiment in post-hypnotic suggestion:

I instructed S that he would come back and see me after thirteen days at ten in themorning. Awake, he remembered nothing. On the thirteenth day, at ten in the morn-ing, he was present . . . He told me that he had not had this idea during the precedingdays. He did not know that he was supposed to come. The idea presented itself to hismind only at the moment at which he was required to execute it. (Bernheim,1883–1884, pp. 555–556)

In the following year, the eminent French philosopher Paul Janet (1823–1899)1 noted aproblem with this experiment: If the subject never remembered Bernheim’s suggestion, howwas he able to perform it at the appropriate moment (1884, p. 201)? If Bernheim had askedhis subject to return on his birthday or on New Year’s Day, we could posit that the memory ofthe suggestion had lain dormant until it could be awakened by an associated idea. But in thiscase, as in many others like it, no such trigger seemed available. How then did Bernheim’ssubject manage to count 13 days without knowing it?

Among the several proposed solutions, the most important were from the Frenchphilosopher and physician Pierre Janet (1859–1947; Paul Janet’s nephew), on the one hand,and the Belgian philosopher and psychologist Joseph Delboeuf (1831–1896; see Figure 1)and Bernheim, on the other (see LeBlanc, 2001, p. 60). Pierre Janet (1886) proposed the ex-istence of a dissociated consciousness that remembered the suggestion and kept track of timewithout the main consciousness being aware of it. This was the origin of his concept of dis-sociation, which has become so prominent in recent years with the epidemic of multiple per-sonality disorder, renamed dissociative identity disorder in 1994 (LeBlanc, 2001).2

Journal of the History of the Behavioral Sciences, Vol. 40(2), 123–147 Spring 2004Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002 /jhbs.20000© 2004 Wiley Periodicals, Inc.

ANDRÉ LEBLANC is currently a researcher at the Centre Interuniversitaire de Recherche sur laScience et la Technologie (CIRST) at the Université du Québec à Montréal. His recent research interestsinclude Joseph Delboeuf’s work on the placebo effect and free will.

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1. On Paul Janet, see Brooks (1993) and LeBlanc (2001).

2. Others had proposed the possibility of coexisting consciousnesses, but Janet coined the term and brought the con-cept to serious scientific attention.

Delboeuf, in 1885, and Bernheim, in 1886, independently advanced similar solutions to theproblem of post-hypnotic suggestion. They each proposed that, from time to time, subjectsdrifted into a hypnotic or dream state in which they were reminded of the suggestion and ofthe time remaining until its execution. Like Pierre Janet, they subscribed to a kind of doubleconsciousness theory. But unlike Janet, the consciousnesses of their theory alternatewhereas in Janet’s they are concurrent. These solutions are very different and, as we shallsee, deeply incompatible.

This article traces the development of these competing solutions to the problem of post-hypnotic suggestion and describes some of Delboeuf’s advanced views on the problem ofsimulation and the nature of hypnosis. During the past several years, the concept of dissocia-tion has commanded considerable scholarly attention (e.g., Borch-Jacobsen, 2002; Burnham,1986; Carroy & Plas, 2000a, 2000b; Crabtree, 2003; Ellenberger, 1970; Gauld, 1992;Hacking, 1995; Kenny, 1986; LeBlanc, 2001; Leys, 1994, 2000; Rieber, 2002; Young, 1995).It will therefore be of some historical significance to show that Pierre Janet substantially re-fined his theory in the face of Bernheim’s and, especially, Delboeuf’s experimental findings.Most of the historical writings on Delboeuf are in French (Borch-Jacobsen, 1997/2002;Carroy, 1991, 1997; Duyckaerts, 1989, 1990, 1992, 1993, 1997; Nicolas, 1995, 1997, 2000).However, there is also a small but growing body of English work on Delboeuf (Fancher, 1985;Gauld, 1992; Laurence & Perry, 1992; Macmillan, 1979; Nicolas, Murray, & Farahmand,1997; Wolf, 1973), to which my article contributes by providing the first extended treatmentof his work on hypnosis. Let us first consider Pierre Janet’s solution to the problem of post-hypnotic suggestion before turning to Bernheim’s and Delboeuf’s.

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FIGURE 1.Joseph Delboeuf (1831–1896). Source: Gilkinet, 1905.

JANET ON THE PROBLEM OF POST-HYPNOTIC SUGGESTION I

Janet (1886) first demonstrated the concept of dissociation and his solution to theproblem of post-hypnotic suggestion through a series of hypnotic experiments with Lucie,a nineteen-year-old woman diagnosed with hysteria (for details, see LeBlanc, 2001). Afteran initial set of experiments, he gave her the post-hypnotic suggestion to answer in auto-matic writing the questions he would ask her in her waking state (for more on automaticwriting, see Koutstall, 1992 and Shamdasani, 1993). This consisted of being engaged inconversation with a group of people while writing out answers to the questions Janet whis-pered in her ear. Since Lucie had apparently no idea that her hand was conversing withJanet, he naturally posited the existence of a dissociated consciousness. In further experi-ments, this dissociated consciousness was given a name, Blanche, which was later changedto Adrienne. Janet also undertook several experiments in post-hypnotic suggestion that re-quired Lucie to count events without knowing it. These experiments demonstrated thatAdrienne had been performing the suggestions of which Lucie was apparently unaware.This solution to the problem of post-hypnotic suggestion, Janet argued, could be extendedto hypnosis in general by assuming that all hypnotic suggestions were performed by a dis-sociated consciousness. The same processes, he continued, could well be at work in spiri-tualistic phenomena. Through his automatic writing experiments, Janet moreover discov-ered that Adrienne re-experienced a childhood fright during Lucie’s hysterical attacks. Thisdiscovery broadened the psychological dimension of Charcot’s famous theory of traumaticparalysis put forth in 1885. In Charcot’s formulation, it is an idea or a group of ideas, orig-inating in a traumatic event, that generates the symptoms of hysteria, whereas in Janet’s itis an actual consciousness. Thus, in the span of a 25-page article, Janet proposed a solutionto the problem of post-hypnotic suggestion; a general theory of hypnosis, spiritualism, andhysteria; and the first fully psychological conceptualization of trauma. He borrowed ele-ments from various sources, to be sure, but no one before him had succeeded in linkingthem together into such a comprehensive theory. He further developed this work in his clas-sic doctoral thesis L’Automatisme Psychologique (1889), and continued to build on theseideas throughout his long career.

Let us now consider Bernheim’s and Delboeuf’s solution to the problem of post-hypnoticsuggestion, followed by the influence it had on Janet’s work.

BERNHEIM ON THE PROBLEM OF POST-HYPNOTIC SUGGESTION

In a paper entitled “Latent Memories and Long-term Suggestions,” Bernheim (1886a)put forward what he believed was the first solution to the problem of post-hypnotic sug-gestion.3 He argued that subjects periodically fall into a hypnotic state in which they re-member, and ultimately perform, the suggestion. They cannot remember the suggestion intheir waking state simply because the memory of the suggestion is only available in a hyp-notic state. The memory is not unconscious, Bernheim emphasized; it is latent. It lies dor-mant and is revived each time the subject’s brain returns to a state of hypnotic conscious-ness. To bring this memory back, Bernheim simply told his subjects that they wouldremember, and they reverted spontaneously to a state of hypnotic consciousness. His sub-

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3. The paper is reproduced in his book De la suggestion et Ses Applications à la Thérapeutique (Bernheim, 1888a).My translation of the cited texts draws upon the English translation Hypnosis and Suggestion in Psychotherapy(Bernheim, 1888c/1973). All page numbers in this section refer to the original article.

jects switched states very easily; for some, it was simply a matter of opening and closingthe eyes. All somnambules, he believed, could be made to remember the details of theirhypnotic or somnambulic state. He argued, furthermore, that we do precisely the same thingwhenever we concentrate on recalling something or on creating a deep impression. The sen-sation disappears when we scatter our attention onto several objects at a time but immedi-ately reappears when we refocus our concentration. “The hypnotic state is not an abnormalstate,” Bernheim added. “It does not create new functions or extraordinary phenomena . . .it exaggerates in favor of a new psychic modality the normal suggestibility that we all pos-sess to a certain degree. . .” (1886a, p. 103).

Bernheim conducted experiments with two subjects to show that they actually remem-bered the post-hypnotic suggestion during the period between receiving and executing it. Hereis the text of a conversation with the first subject:

To one, I tell her during her sleep:—“Next Thursday (in five days) you will take the glassthat is on the night table and put it in the suitcase that is at the foot of your bed.” Threedays later, having put her back to sleep, I say to her: “Do you remember what I orderedyou to do?” She answers: “Yes, I must put the glass in my suitcase Thursday morning, ateight o’clock.”—“Have you thought about it since I told you?”—“No”—“Thinkhard.”—“I thought about it the following morning at eleven o’clock.”—“Were youawake or asleep?”—“I was in a drowsy state.” (Bernheim, 1886a, pp. 109–110)

Bernheim ordered his second subject to ask him a medical question the next day. Afterthe suggestion was executed, he hypnotized his subject and asked him if he had thought aboutthe suggestion since the hypnotic session of the day before. His subject answered that he haddreamt about it (1886, p. 110). In sum, these experiments demonstrated that 1) subjects spon-taneously remember the events of their hypnotic sleep when awake and 2) post-hypnotic sug-gestions are remembered in a sleep-like state that resembles the hypnotic state in which theyreceived the suggestion.

Delboeuf (1885) had already put forward the same hypothesis a year previously. In hispage-long note “On Fixed Date Suggestions,” he wrote: “[t]he subject must be remindinghimself of the suggested date each time he enters into his hypnotic state––and how manytimes could this happen without our knowing anything about it!” (Delboeuf, 1885, p. 514).His solution to the problem of post-hypnotic suggestion was further developed in a series ofstudies published in 1886 and 1887, to which we now turn.

DELBOEUF ON THE PROBLEM OF POST-HYPNOTIC SUGGESTION

Here are Delboeuf’s arguments for his solution to the problem of post-hypnotic suggestion.1. The first time one of his subjects performed a post-hypnotic suggestion, he was

“struck by her strange air,” which led him to suspect that she was not awake (Delboeuf, 1886a,pp. 450, 467; 1886b, p. 153; 1886d, p. 168).

2. On two occasions in which a subject was prevented from successfully executing apost-hypnotic suggestion, she returned to tell him that she was “now awake.” This indicatedthat falling asleep was perhaps a precondition for the successful execution of a suggestion(Delboeuf, 1886b, p. 156; 1886d, p. 168; 1887a, pp. 119–120).

3. His subjects considered their hypnotic state to be “completely analogous” to “physio-logical sleep” (Delboeuf, 1886d, p. 169). He noted, furthermore, that Bernheim had made thesame observation in a paper published in the Revue de l’Hypnotisme a month previously.There Bernheim had written: “I would like to show them that so-called hypnotic sleep does

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not differ from normal sleep, that all the phenomena provoked in one can be provoked in theother” (Bernheim, 1886c, p. 133, cited in Delboeuf, 1886d, p. 169).4

4. His subjects reported experiencing the hypnotic state exactly as they would adream (Delboeuf, 1886d, p. 169). Delboeuf noted that this was invariably the case eversince his memorable visit to the Salpêtrière in December 1885, when he set out to contra-dict the accepted doctrine that waking subjects could not remember the events of theirhypnotic sleep. He believed that the amnesia upon waking from hypnotic sleep was anal-ogous to the amnesia upon waking from normal sleep (Delboeuf, 1887a, p. 113). The rea-son we do not normally remember our dreams, he stated, is because of the difficulty of es-tablishing a link between our waking and dream states. We remember our dreams mostoften, for instance, when we wake up in the middle of one, because our first waking ex-perience is also our last dreaming experience—the common experience bridges togetherthe two dissimilar worlds. If the same conditions of recall applied to hypnotic sleep,Delboeuf theorized, it should be possible for subjects to remember their hypnotic sleep ifthey are awakened in the middle of performing an action. Delboeuf first demonstrated histheory with Blanche Wittman, the star subject of the Salpêtrière. He and Charles Féré(1852–1907), one of Charcot’s pupils, abruptly woke Wittman in the middle of a hypnotichallucination in which she was frantically attempting to extinguish her scarf that hadcaught fire. “On seeing her scarf intact,” Delboeuf wrote, “she wore the physiognomy ofa person emerging from a distant dream and cried (the moment was solemn for me, andher words engraved themselves indelibly in my mind): “My God! It was a dream that Ihad! It’s strange. That is the first time that I remember what I did while a somnambule. It’sstrange. I remember absolutely everything” (Delboeuf, 1886a, p. 447; 1886d, p. 169).Delboeuf repeated the experiment with other subjects and consistently obtained the sameresult: “[E]verything that they think, say or do in somnambulism, they think it, say it or doit as in a dream” (1886d, p. 169).

These experiments convinced Delboeuf of the total analogy between hypnotic illusionsand ordinary dreams. They also enabled him, as we have seen, to account for the amnesia ofhypnotic subjects. The reason amnesia was so long considered a distinctive trait of hypnosis,he reasoned, was because attention had not been directed to the conditions necessary for therecall of memories of hypnosis (1886a, p. 471).

5. His subjects all claimed to fall into a somnambulic/dream state when executing a post-hypnotic suggestion (Delboeuf, 1886d, p. 169). Their surroundings would change and theycould think of nothing else but the action or dream that they were told to realize. All post-hyp-notic suggestions, Delboeuf therefore argued, were accompanied by an unspoken commandto go into hypnotic sleep (1887a, pp. 134–135). “As for the explanation of the phenomenon,”he wrote, “it is most simple. All suggestion or injunction of which execution is fixed at a fu-ture time is presumably formulated in the following terms: ‘At such-and-such time, you willfall asleep and you will see or do such-and-such thing.’ It is this latent order that is the causeof the later hypnosis” (Delboeuf, 1887a, pp. 135–136).

The same situation is obtained, Delboeuf remarked, for suggestions that are given to sub-jects in their waking state: “Most suggestions are, at bottom, counter-realities. To see or feelwhat is not there, is to be outside of the real world and to inhabit the world of dreams. The sug-gestion therefore implicitly includes the sign which plunges the subject into hypnosis”


4. Bernheim had expressed the same view in a previous paper that same year—“in my opinion, nothing, absolutelynothing, distinguishes natural sleep from induced sleep” (Bernheim, 1886a, p. 106).

(Delboeuf, 1887a, p. 266). Delboeuf explained, “If I say to one of them: ‘You see full well thatI have a silver nose,’ this simple affirmation plunges the person into the hypnotic state, and it isin this manner that the hallucination can be produced and is produced. It is as though I hadbegun by telling him: Sleep! and then: You will see me with a silver nose” (1886d, p. 170; 1887a,pp. 135, 269).

6. By chance, Delboeuf stumbled upon a strong proof of the analogy between dreamingand so-called hypnotic sleep. On two occasions his subjects failed to execute a suggestion be-cause they had instead dreamt of doing so (1886d, p. 169; 1887a, p. 128). Regarding one ofthese occasions, Delboeuf noted, “When, after a more or less prolonged wait, believing that thesuggestion had not taken, I woke him and reproached him for his lack of condescension, hemaintained that he had obeyed me, told me his dream and was deeply surprised to learn thathe had not moved” (1886d, p. 169).

Delboeuf’s solution to the problem of post-hypnotic suggestion was still unsatisfactory inone important respect, however. Neither he nor Bernheim could explain how the subject knowswhen he or she must enter a state of sleep, be it normal or hypnotic, in order to execute the com-mand. The French physiologist Henri-Etienne Beaunis (1830–1921), a colleague of Bernheim’son the faculty of medicine at Nancy, pointed out this flaw in the second edition of his book LeSomnambulisme Provoqué (1887). He wrote, “If the suggestion is spontaneously recalled in theinterval, instead of remaining latent up to the time fixed upon, there is the same difficulty; theexplanation reduces it, but does not solve it” (Beaunis, 1887, p. 243). Bernheim’s response wasfeeble: “To reduce a difficulty is to solve it partly; to reduce it sufficiently is to solve it totally”(Bernheim, 1888a, p. 221). He argued that the subjects not only switched states easily and fre-quently but also spent the greater part of their day in their hypnotic state. Delboeuf mentionedthis limitation of his theory. He admitted that “the subject, in whom we have inspired a sugges-tion, is, after all, under the dominion of the suggestion so long as it remains to be accomplished;he is in the expectation of a moment or signal” (Delboeuf, 1887a, p. 127). He noted, moreover,that his subjects often felt uneasy, as though a weight were oppressing them, during the intervalbetween the moment of the suggestion’s acceptance and the moment of its execution. Perhapsthey felt the anxiety we all feel when we do not wish to miss an important appointment. AsDelboeuf (1885) said in his very first publication on the problem of post-hypnotic suggestion,“who among us, in his ordinary state, would dare to agree to execute at a date fixed long in ad-vance an act that has no natural relationship to this date?” (p. 514). Let us now consider howJanet dealt with the difficulties raised by Bernheim and Delboeuf.

JANET ON THE PROBLEM OF POST-HYPNOTIC SUGGESTION II

Delboeuf’s and Bernheim’s solutions to the problem of post-hypnotic suggestion pre-sented a serious challenge to Janet’s concept of dissociation. At stake were the issues of mem-ory and awareness.

Memory. Delboeuf and Bernheim demonstrated that subjects remember the events oftheir hypnotic state by either falling into that state or, as Delboeuf showed, by using an arti-fice to bridge the waking world and the hypnotic/dream world. But according to Janet’s dis-sociation model of hypnosis, it is never actually the “subject” who remembers the suggestionbut rather a dissociated consciousness. The concept of dissociation is meaningless if the hyp-notic subject remembers what only a dissociated consciousness is supposed to know.

Awareness. When executing their post-hypnotic suggestions, Delboeuf’s and Bernheim’ssubjects were usually aware of the suggestion although they could not help themselves fromperforming it. Janet’s subjects, on the other hand, were usually not aware of the post-hypnotic

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suggestion, even at the moment of its execution. For Janet, it was a dissociated consciousnessand not the official consciousness that was responsible for executing the suggestion.

This section describes Janet’s response to these difficulties. The next section examineshis use of the concept of dissociation in attempting to explain another psychological problemin hysteria and hypnosis, the problem of negative hallucination—the disappearance of an ob-ject through hypnotic suggestion.

From the beginning, Janet tried to weaken and contradict the inferences Delboeuf drewfrom his hypnotic memory experiments. In the opening pages of his first dissociation paper, henoted an exception to the general rule, put forward by Delboeuf, that a subject will rememberher hypnotic state as she would a dream if she is abruptly wakened in the middle of perform-ing a hypnotic act: “When the subject has already been abruptly put to sleep in the middle ofa waking act, the idea that appears in the consciousness after an equally abrupt awakening isnot the memory of the somnambulism, it is the continuation of the act begun and interruptedduring the waking state” (Janet, 1886, p. 579). Thus, if the subject is awakened suddenly, hav-ing been put to sleep with equal suddenness, she will remember not her last somnambulic act,as Delboeuf claimed, but rather the last act she performed before being put to sleep.

Janet further restricted the range of Delboeuf’s rule by arguing that it is only true in casesof light somnambulism because subjects in deep somnambulism cannot be wakened with suf-ficient suddenness. According to Janet, it takes time to wake subjects who have undergone theprofound changes in personality, sensibility, and intelligence that characterize deep somnam-bulism, and this delay interrupts the somnambulic act in such a way that the memory of theact cannot be preserved (Janet, 1889, p. 82). Janet arrived at this observation by repeating theexperiment Delboeuf had performed with Blanche Wittman at the Salpêtrière. He suggestedto Lucie that her dress (rather than her scarf) had caught fire and he woke her in the middleof her attempts to extinguish it. He obtained Delboeuf’s result at first, but in time Lucie’ssomnambulism deepened to the point that it took at least a full minute to wake her (1889, p.82). Janet did not state the period of time over which the quality of somnambulism changed.He merely remarked that subjects normally only enter a light sleep when they are first hyp-notized but fall into deeper sleep if the process is repeated. (It seems possible, of course, thatJanet simply repeated the experiment until Lucie behaved in accordance with his theory.)

Even when subjects do remember their somnambulism after waking from light som-nambulism, Janet continued, this memory is of short duration. The same is true, he claimed,of subjects who remember the post-hypnotic suggestion while performing it: “M. Beaunis hascompletely demonstrated what I have always observed. If a subject executes a suggestion withconsciousness and memory at the moment of its execution, it is only a few moments beforehe completely loses not only the memory of the command, but the memory of its executionas well” (Janet, 1889, p. 80; see also Beaunis, 1887, p. 122).5 He reasoned that if the mem-ory persists at all, it is because the subject has not fully wakened from somnambulism. “In re-ality,” he wrote, “the psychological states are continuous and the subject does not jump fromone to the other. There is a post-hypnotic period that sometimes extends itself a fair amountof time after waking, and it is perfectly natural that the memory of the somnambulism per-sists for some time during this period” (Janet, 1889, p. 83). In other words, for the somnam-bulic act to continue after waking, it is necessary that the somnambulism continue as well.Hence, according to Janet, when Delboeuf or Bernheim succeed in lifting the subject’s am-


5. He repeated the same point on p. 251. This does not so far contradict Delboeuf’s explanation of post-hypnoticsuggestion since hypnotic subjects need only momentarily fall into somnambulism at the moment they execute thesuggestion.

nesia during the waking state, it was only because 1) the somnambulism was too light or 2)the subject was still in somnambulism and only apparently awake.

For Janet, it was a priori impossible to remember one’s somnambulic state while awake.As far as he was concerned, amnesia upon waking is a characteristic trait of somnambulismand if this trait is lacking, it is because the somnambulism never occurred: “Hence we con-serve forgetting upon waking as the most important trait of the state of somnambulism andwe persist in believing that, if it is completely absent, there has been suggestion during thewaking state and no somnambulism” (Janet, 1889, p. 84).6

The hypnotic phenomena described above belonged to the study of what Janet called totalautomatism, the subject of the first half of his thesis. (The second half dealt with partial automa-tism.) By automatism, Janet meant the automatic psychological activity that is thought to char-acterize hypnosis or somnambulism—hence the title of his thesis, L’Automatisme Psychologique(for details, see Crabtree, 2003). The hypnotic subject is considered an automaton in the hands ofthe hypnotist. Total automatism refers to the psychological condition of complete somnambu-lism—the opposite of being completely awake. Partial automatism referred to the condition inwhich both the waking and somnambulic states were present. The automatism was partial be-cause only a portion of consciousness was subject to an automatism of which the remaining con-sciousness was unaware (Janet, 1889, pp. 223–224). Automatic writing and post-hypnotic sug-gestion are examples of partial automatism. They were unconscious acts, that is, “actions havingall the features of a psychological phenomenon except one, that it is always ignored by the per-son executing it at the very moment it is being executed” (Janet, 1888, p. 239; 1889, p. 225).

But according to Delboeuf, at the moment of executing a post-hypnotic suggestion, hyp-notic subjects fell into the same somnambulic state in which they first received the sugges-tion. They were conscious of executing the suggestion but they experienced and rememberedit exactly as one would experience and remember a dream. To use Janet’s terminology,Delboeuf’s post-hypnotic subjects experienced the alternating states of total automatism andnot the simultaneous consciousnesses of so-called partial automatism.

Janet attempted to undermine Delboeuf’s (and Bernheim’s) position in two importantways. The first was to affirm again and again what Delboeuf would always deny: that somehypnotic subjects perform conscious actions of which they are not aware (Janet, 1887, pp.451–452, 462; 1888, pp. 240–241; 1889, pp. 223–225, 258, 299, 330). Janet claimed thatpost-hypnotic suggestions, for instance, could be executed in three different ways: 1) thesubject executed the suggestion with full awareness; 2) the subject fell into a somnambulicstate and executed the suggestion; or 3) the subject executed the suggestion without mem-ory or awareness (Janet, 1888, pp. 240–241). Janet repeatedly criticized Delboeuf for failingto note these different ways in which post-hypnotic suggestions could be carried out, and forconsequently making tenuous generalizations based on a limited number of cases (Janet,1888, p. 240; 1889, p. 253).

The second way in which Janet defended the concept of dissociation was by pointing outDelboeuf’s and Bernheim’s inability to adequately explain the problem of post-hypnotic sug-gestion (Janet, 1889, pp. 254, 258). Janet maintained, contrary to Delboeuf and Bernheim,that some subjects executed post-hypnotic suggestions without memory of the suggestion,without consciousness of executing it, and without falling, therefore, into the same hypnotic

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6. Like Janet, both Bernheim and Jules Liégeois (1833–1908) claimed that the only subjects that remember are thosethat have not been truly or sufficiently hypnotized. “But this is pure question-begging,” Delboeuf would later chargeboth Bernheim (Delboeuf, 1889b, pp. 67–68) and Liégeois (Delboeuf, 1889b, pp. 81–82). “It is exactly as thoughwe argued that the only dreams that exist are those that cannot be remembered” (pp. 81–82).

state in which they received the suggestion. But where subjects did fall into somnambulismwhen executing a post-hypnotic suggestion, Janet argued that the phenomenon remained un-explained. If the suggestion were performed immediately on waking, he believed that it couldreasonably be assumed (as discussed above) that the subject was not yet fully awake. But ifthe suggestion is long-term, he asked, why does the subject fall asleep at precisely the rightmoment? “It serves no useful purpose to say,” Janet wrote, “and it is at any rate inexact, thatall post-hypnotic suggestions amount to saying: ‘You will fall asleep at such-and-such mo-ment and you will do such-and-such thing,’ because the post-hypnotic suggestion to sleep isjust as difficult to explain as any other. Why does this forgotten memory appear at that mo-ment?” (Janet, 1889, p. 254).7

To understand what is really going on, one must examine, Janet (1889) proposed, “othersubjects who present in a clear and somewhat typical manner, another way of executing thesuggestion” (p. 255). One such subject was Lucie: “A hysterical woman, whom I had thechance to study, displayed in the highest degree and in an extremely clear manner an impor-tant phenomenon that exists in all subjects in a more or less concealed manner. It is one ofthose prerogative instances of which Bacon spoke that must be well understood before mov-ing on to others” (1889, p. 255).

The phenomenon was, of course, an apparently dissociated consciousness that per-formed post-hypnotic suggestions that her main consciousness knew nothing about. In a sec-tion entitled “The Subconscious Execution of Post-Hypnotic Suggestions,” Janet reiterated,near the middle of his thesis, his solution to the problem of post-hypnotic suggestion (1889,pp. 255–269). The argument and much of the text was the same as in his 1886 paper, but henow placed greater emphasis on the fact that his hypnotic subjects had no memory of the sug-gestion and were completely unaware of performing subconscious actions. He pointed out, forexample, that in order to return after 13 days:

from the moment he wakes and during the entire interval, [the subject] must constantlybe thinking: ‘Today is the first day, or the second. . .’ and once he thinks to himself: ‘Itis the thirteenth,’ the association will occur. Now of course it is obvious to everyone thatwaking somnambules do not at any time have such memories, and that they have no con-sciousness of counting or of making these remarks. (Janet, 1889, pp. 259–260)

The exact same passage can be found in his first publication on dissociation except forthe addition of the words “at any time,” which I have italicized (1886, p. 583). In discussingBernheim’s solution, moreover, Janet (1889) held that it did not reflect the facts: “If we seri-ously examine the mind of a subject during every moment that precedes the execution of thesuggestion, we will not find one moment in which he truly remembers. There is not forget-ting, but a true unconscious, as M. Beaunis remarked in discussing M. Bernheim’s hypothe-sis” (p. 258; see also Beaunis, 1887, p. 243).

Janet’s direct attack on Bernheim’s findings was a crucial move in his defense of sub-conscious phenomena. This state, call it unconscious, subconscious, dissociated, or partial au-tomatism, was presented less as theory by Janet than as fact. It was therefore important forhim to ensure that nothing contradicted the apparent reality of a consciousness that could existbeyond the awareness of the subject’s main consciousness. And besides, the problem of post-hypnotic suggestion seemed to be insoluble in the absence of this purported fact. Even forthose who fell into somnambulism at the moment of executing a post-hypnotic suggestion, the


7. This passage was directed at Delboeuf. Four pages later he criticized Bernheim on the same point (p. 258).

somnambulism was only secondary to the execution of the act, argued Janet, because theremust be a subconscious process that accounts for why the subject falls asleep at the right time:

Post-hypnotic suggestions . . . only apparently present different features. In reality, thesephenomena always include a common element. The idea that was suggested during som-nambulism does not disappear after waking, though the subject seems to have forgottenand to retain no consciousness of it; the idea subsists and develops outside and beneathnormal consciousness. Sometimes it reaches full completion and brings on the executionof the suggested act without ever having penetrated into this consciousness; sometimes,when it reaches completion, during its execution, it enters the mind for a moment, mod-ifies it, and brings about the more or less complete and initial somnambulic state. Themain thing, however, is the existence of the subconscious thought that is revealed bypost-hypnotic suggestions, more than by any other phenomenon, because they cannot beunderstood without it. (Janet, 1889, p. 269, italics added)

Thus, even in the case of a subject who fell into somnambulism when executing a post-hyp-notic suggestion, it was not an alternate consciousness but rather an area of an ever-present stateof dual consciousness that dominated at the preassigned moment. Bernheim’s and Delboeuf’s po-sitions were thus subsumed within Janet’s more comprehensive solution of dissociation.

Given the apparent success of his solution to the problem of post-hypnotic suggestion, Janetnaturally sought to extend the concept of dissociation to other hypnotic phenomena. The next sec-tion describes his attempts to apply dissociation to the problem of “negative hallucination.”

BERNHEIM AND JANET ON NEGATIVE HALLUCINATION

The term negative hallucination was coined by Bernheim to refer to the disappearanceof a sensation by hypnotic suggestion (1883, p. 559; see also 1888a, pp. 62–67; 1888b;1888c/1973, pp. 43–50, 137–138). What we would ordinarily call a hallucination he named a“positive hallucination.” His examples of negative hallucination consisted typically of sug-gestions to subjects that they would no longer be able to see him once awake. Here followsthe text of one of Bernheim’s experiments with a subject called Elise B.:

She was, from the first session, very easy to put into somnambulism, with hypnotic andpost-hypnotic hallucinability and amnesia upon waking. I easily induce in her a negativehallucination. I say to her, during her sleep: “When you wake, you will no longer seeme—I will be gone.” When she wakes, she looks for me and does not seem to see me. Imay speak to her, shout in her ear, insert a needle in her skin, in her nostrils, beneath hernails, apply the needle point to the mucus membrane of her eye . . . try as I may, she doesnot show the least reaction. I no longer exist for her and all the acoustic, visual, tactile,etc., impressions that emanate from me, leave her impassive; she is unaware of every-thing. As soon as someone else touches her with a needle without warning, she keenlyperceives it and retracts the pricked limb. (Bernheim, 1888b, p. 162)

Bernheim argued that she perceived the sensations associated with him but formed noconception of him; there was perception but not conception. “That is what constitutes a neg-ative hallucination” he wrote. “The imagination neutralizes, or the consciousness ignores thetruly perceived sensation; the subject does not know of it and denies that he has perceivedit” (Bernheim, 1888b, p. 161). How did Bernheim know that Elise B. perceived him at all?Because, as with all his hypnotic subjects, he was able to make her remember everything thatshe apparently did not see. Bernheim (1888b) wrote: “She saw me with her body’s eyes, shedid not see me with her mind’s eyes. She was struck by psychic blindness, deafness, andanesthesia for me: all the sensorial impressions emanating from me were perceived, but they

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remained unconscious for her. It is truly a negative hallucination, an illusion of the mind tosensory phenomena” (p. 164). He maintained, furthermore, that exactly the same processwas going on in cases of the hysterically and hypnotically suggested blindness of a singleeye. Using optical devices, he was able to show that such blindness was only psychical sinceboth his hysterical and hypnotic subjects saw patterns that could be seen only if both eyeswere used (Bernheim, 1886b, pp. 585–588).

Alfred Binet (1857–1911) and Féré arrived at similar conclusions in an article publishedin the Revue Philosophique in 1885, only they preferred the term systematic anesthesia tonegative hallucination (Binet & Féré, 1885, pp. 21–24). They argued that the systematic anes-thesia of vision was analogous to the systematic paralysis of a limb in hysterical subjects. Ifa hypnotic subject is told that he can no longer write, for example, he will lose the ability towrite but conserve the ability to perform other types of movements. It is a systematic paraly-sis because it only affects a specific type of movement. It is the same with vision. In cases inwhich a person is rendered invisible through hypnotic suggestion, the subject continues to seeeverything else. “Calling these anesthesias negative hallucinations,” they wrote, “is not onlyto misjudge their nature and significance, it is also to impose upon them a name that misleadsthe mind into false comparisons: it is almost as if the systematic paralyses of movements wereinstead to be called negative motor impulsions” (Binet & Féré, 1885, pp. 23–24).

“It seems to me,” Bernheim retorted, “that my esteemed opponents deserve the reproachwhich they have cast upon me, of having imperfectly grasped the nature of the phenomenon”(1888a, p. 65; 1888c/1973, p. 151). He argued that when he caused his subjects to be blindedto something, he produced the disappearance of an image in the mind and not a paralysis inthe eye. He charged Binet and Féré with mistaking an imaginary paralysis for a real one. Theeye sees, he asserted, but the image is not conscious because it is neutralized by the imagina-tion (Bernheim, 1888a, pp. 65–66).

Outside of terminology, it is not clear that Binet and Féré actually disagreed withBernheim’s general view of the phenomenon. They too seemed to believe that the blindness,whether total or systematic, occurred at the level of perception and not the eye. By 1887, theywere conducting experiments like Bernheim’s that demonstrated the paradoxical fact that hyp-notic subjects somehow saw the objects that they apparently could not see. In one experiment,for instance, they designated one of ten identical cards as invisible to the subject during hypnoticsleep. Upon waking, the subject was unable to see the designated card—but not always, as whenthe cards were too minutely similar or only a small portion of each card was shown. Binet andFéré reasoned that the subject must have unconsciously been relying on visual reference pointsin order to be blind to the designated card. “[T]he subject must recognize the object in order notto see it,” they wrote. “The recognition of the card, which requires a very delicate and complexoperation, amounts however to a phenomenon of anesthesia; it is therefore probable that the actoccurs entirely in the unconscious . . . There is always an unconscious reasoning that precedes,prepares and guides the phenomenon of anesthesia” (Binet & Féré, 1887, p. 236).

This unconscious was not only probable, Janet admonished Binet and Féré, but also nec-essary (Janet, 1889, p. 276). When awakened, the subject had neither memory of the sugges-tion nor awareness of what was expected of her. Yet, she somehow recognized the card with-out being aware of doing so. “It seems to me,” Janet continued:

that there is something of an analogy between this problem and the problem I previouslystudied. How does a somnambule whom we have ordered to return in eight [sic] days,count these eight days when she has no memory of the suggestion? How does she rec-ognize a sign that she does not remember and that she does not even seem to see? Thesetwo problems are identical, and if [my] observations . . . of Lucie have allowed me to cast


some light on the first one, perhaps they will allow me to illuminate the second. (1887,p. 457; 1889, p. 276)8

Janet began by repeating Binet and Féré’s experiment (Janet, 1887, pp. 457–458; 1889,pp. 276–277). While Lucie was in complete somnambulism, Janet placed on her lap fivewhite cards of which two were marked with a cross. She was told that once awake she wouldnot see the cards marked with a cross. He later woke her and noted that she remembered nei-ther the suggestion nor the somnambulism. When asked to pick the cards up from her lap, shetook three and left the two cards marked with a cross. He asked for more. She answered thatthere were no more. Next, he placed all five cards on her lap, this time flipped over so thatthe crosses were hidden. Now she picked up all five cards. Janet concluded, in line with Binetand Féré, that the crosses were somehow recognized without being seen. He then askedAdrienne to tell him what was on her lap by way of automatic writing. “There are two piecesof paper marked with a small cross.—Why did Lucie not hand them over a moment ago?—She cannot, she does not see them.—Did she recognize a cross on the pieces of paper? (Shedoes not answer right away and writes:)—I do not know, I am the one who sees them with across” (Janet, 1887, p. 458).

And so, just as a second consciousness was responsible for performing post-hypnoticsuggestions, so it was with negative hallucinations or systematic anesthesia. “In a word,” Janetwrote, “this anesthesia is but a simple dissociation of [psychological] phenomena, such thatany sensation or idea removed from the normal consciousness continues to exist and cansometimes be found to form part of another consciousness” (Janet, 1887, p. 462).

In another experiment, Janet rendered Lucie completely blind through a post-hypnoticsuggestion, but was able to confirm through automatic writing that Adrienne in fact saweverything (1887, p. 459; 1889, pp. 279–280). He pointed out that the same results could beobtained with all the other senses (1889, p. 280). He further argued not only that systematicanesthesia and post-hypnotic suggestion operated by the same mechanism of dissociation butalso that they were one and the same phenomenon, and demonstrated his claim in a series ofvariations on Bernheim’s negative hallucination experiment (1889, pp. 276–277). A few pageslater he wrote “we have already seen phenomena of this kind while studying post-hypnoticsuggestions. The subconscious acts thus obtained have a general, obvious and even necessaryfeature: they are accompanied, if not constituted, by a systematic anesthesia of the same typethat we are currently studying” (p. 282).

To bring his point home, Janet placed his work at the end of a long line of earlier at-tempts to explain negative hallucination (1887, pp. 453–455; 1889, pp. 271–274). Some mag-netists, like Teste (1845), believed that “[i]t is the magnetic fluid, an inert, opaque and whitishvapor, lingering like a fog where it is left by the hand, that conceals objects from the som-nambule” (p. 415, cited in Janet, 1887, p. 454; 1889, p. 272). Charpignon (1848) likewise at-tributed negative hallucinations to a thick layer of magnetic fluid (p. 81, cited in Janet, 1889,p. 272). Janet remarked that other more scientifically respectable writers like Bertrand, Braid,and Liébeault explained negative hallucinations as mental operations that either completelyeliminated the sensation or replaced it with another. “Finally we suspected,” he continued,“that the sensation was not really destroyed but merely ‘neutralized by the imagination’(Bernheim), or it became an ‘unconscious perception’ (Binet and Féré)” (Janet, 1887, p. 471).But these more recent studies were still incomplete in Janet’s judgment. He preferred, for ex-ample, Binet and Féré’s term systematic anesthesia to Bernheim’s negative hallucination.

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8. For the purposes of clarity, this quotation is a blend of two very nearly identical passages.

Since everything seemed to indicate that the same mechanism was at work in the disappear-ance, by hypnotic suggestion, of visual, auditory, olfactory, gustatory, and tactile sensations,it was preferable to adopt the more general term anesthesia instead of hallucination. It wassimply too awkward, Janet believed, to call a suggested or hysterical anesthesia a negative hal-lucination (1887, p. 455; 1889, p. 274). In short, Janet (1887) agreed with his colleagues buthe felt that they should have pushed their arguments “still further in the same direction” byconcluding that:

The apparently suppressed sensation remains as perfectly real and conscious as before,it is simply separated from the totality of psychic phenomena whose synthesis forms theidea of the ego [moi]. Facts in science are only explained by subsuming a specific factinto a more general one; systematic anesthesia is a case of the dissociation of psychicphenomena like the long term suggestions that we have studied and perhaps many otherfacts as well. (p. 471)

Pierre Janet called for the need, in other words, to take the next step and accept dissoci-ation as the only psychological theory capable of adequately explaining the problem of post-hypnotic suggestion, negative hallucination or systematic anesthesia, and possibly all hyster-ical and hypnotic phenomena. Let us now examine Delboeuf’s consideration of the problemof negative hallucination.

DELBOEUF ON NEGATIVE HALLUCINATION

In January 1889, Delboeuf (1889a) published a short article called “On M. Bernheim’sExplanation of Suggested Negative Hallucinations.” Near the beginning, he mentioned aremark he had made in 1886 to the effect that negative hallucinations were difficult to ex-plain because the subject was required to see the invisible object in order not to see it(Delboeuf, 1886c, p. 137; reprinted in Nicolas, 2000). “If this is the case,” he added, “it isclear that the subject is only pretending not to see the object, that he is putting on an act ex-actly as would any waking person behaving with total goodwill. There is not one of EliseB.’s [Bernheim’s subject] actions that she could not have performed while awake.Everything that she does or allows to be done can be explained without difficulty if weadmit an absolute willingness, on her part, to please and accommodate [complaisance]”(Delboeuf, 1889a, pp. 202–203).9

Delboeuf supported this strong and unexpected statement with the following evidence:1. The subject who is told that she or he will not be able to hear, feel, or see you will

nonetheless wake the moment you tell her to—unless, Delboeuf added, you suggest that theywill not wake, even when ordered to (1889a, p. 203).

2. Proof that they see the object is revealed in the care they take to avoid it—“unless,again,” he repeated, “you expressly command them to bump into the object without feelingit” (p. 203).

3. The somnambule will not be surprised—unless told to be surprised, he reiterated—bythe fact that the unseen object obscures the view of the objects hidden behind it (p. 203).

4. Further proof of their complaisance, he continued, is that they will see these hiddenobjects more or less accurately when told to do so. “They then go to incredible pains to guess,


9. The phrase willingness to please and accommodate is my translation, in this context, of the French word “com-plaisance.” It is a key word in Delboeuf’s vocabulary. To ensure clarity, I will include the original word in bracketsalongside each translation.

by certain clues, what these objects are and how they behave. Needless to say they are fre-quently mistaken” (p. 203).

5. Delboeuf here related the case of a young woman undergoing the magic mirror exper-iment. The woman was given a small screen and told it was a mirror in which she would seebehind herself. “The young girl applied all her senses to succeed, and, in particular, projectedher eyes out of their sockets to literally enlarge the visual field. It would be difficult to imag-ine to what point she could guess, from subtle clues, our actions and movements” (p. 203).

On this point, Delboeuf cited “an extremely interesting article” by the young Henri Bergson(1859–1941), later to become one of the twentieth century’s most eminent philosophers, winningthe 1927 Nobel Prize in literature. In his article, “On Unconscious Simulation in the HypnoticState,” Bergson (1886) described experiments with a group of boys who displayed the apparentability to supply page numbers, words, and sentences from a book that a hypnotist read whilestanding opposite them. Their telepathic powers had telling limitations, however. Bergson no-ticed, for example, that all attempts at reading the book failed when the experimenter’s eyes werekept hidden. He also found that one of the subjects sometimes read the numbers backwards, forinstance, 312 as 213 and 57 as 75, as though he were reading from a mirror. These clues ledBergson and a colleague to suspect that the subjects were reading the pages of the book from thereflection in the hypnotist’s eyes. Further testing revealed that one of the subjects was even ableto discern on a microscopic slide details that were small enough to show that he could easily readthe letters of the size they were estimated to be in the reflection of the cornea. They put forth var-ious questions and traps with the aim of detecting any conscious deception on the part of theirsubjects. They were never able to extract a confession and, in the end, felt sure that their subjectswere not conscious of reading the reflection in the experimenter’s corneas. “The hypnotized sub-ject is thus not exactly a simulator,” Bergson wrote, “and yet everything happens as though wewere dealing with the most able of simulators. Could we not say that we have here a kind of ‘un-conscious simulation?’” (1886, p. 529, italics original). In other words, the subjects really be-lieved they were somehow able to read the minds of their experimenters or through the cover ofa book. They consciously saw the image in the experimenter’s eye, but they mistook the sourceof that image as originating from a special faculty within their minds.10

Returning now to the magic mirror experiment described above, it can be suggested thatDelboeuf’s subject might also have believed she was able to see what was going on behindher. She may not have realized she was actually constructing the reflection by widening herperipheral vision and concentrating all her senses on the task. She was only, technically speak-ing, pretending to see into the “mirror.”

For all intents and purposes, subjects behave like waking people, Delboeuf continued.When a subject sees into a mirror or through a supposedly invisible object, her imaginationfills the void just as “we ourselves, in our waking state, can see through the partition that

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10. Pierre Janet also cited Bergson’s paper, but as evidence for, rather than against, the existence of a dissociatedconsciousness:

When the suggestion is connected to a reference point, it is the unconscious person who keeps the memory ofthe signal: “You told me to do such-and-such thing when the clock struck”, Lucie writes automatically afterwaking from somnambulism. It is she also who recognizes the signal with which the normal person does notconcern herself. “There is a spot on the top left portion of the paper”, writes Adrienne in the picture experi-ment. It is she who combines the processes in those most curious unconscious tricks reported by M. Bergson.(Janet, 1889, p. 311; see also Janet, 1887, pp. 452–453)

But this was wishful thinking on Janet’s part, for it was by no means given that, had they been questioned by Janetunder hypnosis or through automatic writing, Bergson’s subjects could have told him any more than they toldBergson. Everything indicates that they simply did not realize what they were doing.

separates us from a neighboring apartment, the people that we hear walking or talking”(Delboeuf, 1889a, p. 205). “There is therefore perception,” he concluded, “and no actualneutralization of the sensation, but only a simulated neutralization. It is enough to say that Iam at [Bernheim’s] side in rejecting the real and systematic paralysis by which Messrs. Féréand Binet, and others, have tried to explain negative hallucination. These types of hallucina-tions are the apparent result of the subject’s directed will” (p. 205).

Bernheim was, to say the least, surprised by Delboeuf’s paper. In his reply, he upheld hisinterpretation against Delboeuf’s (Bernheim, 1889). He agreed, using Delboeuf’s words, thatthe subject obeys “with passivity, but with intelligence” (Delboeuf, 1889a, p. 205, cited inBernheim, 1889, p. 226). “Did I not say, in my book,” he added one sentence later, “that thesomnambule always acts with spontaneity, that he plays an active role in invoking the sug-gested phenomenon, that each of them produces it in his own way, according to how he con-ceives and interprets it?” (Bernheim, 1889, p. 226). He preferred to believe, however, thatDelboeuf had overstated his case in saying that the subjects were only pretending the negativehallucinations. Some subjects, he wrote, do not succeed in fully realizing the hallucination.They then “believe that to fulfill the suggestion they must in good faith adopt an accommo-dating attitude [complaisance] and affirm that they do not see me when in fact they do. . . .There are some, I admit, who believe that the suggestion commands them to simulate”(Bernheim, 1889, p. 227). He ended his article by adding: “The reader could have concludedfrom [Delboeuf’s] article that the phenomenon of negative hallucinations and, by extension,all the phenomena of hypnotism are but the result of pure simulation, of an unconscious andaccommodating [complaisante] game of play-acting. This is surely not what M. Delboeufwished to say” (1889, p. 229).

But this was precisely what Delboeuf had said and meant to say. His article on negativehallucination marked a turning point in his understanding of hypnosis. In subsequent publi-cations, he developed the view that hypnosis is indeed a game of play-acting in which boththe hypnotist and subject are sometimes duped into believing it is real. And in this respect,he later admitted that he must have unwittingly trained his first two subjects to be amnesicupon waking from hypnosis.

But I was myself then persuaded that amnesia was normal, and my experiments had noother goal––we need only reread them [Delboeuf, 1886a, 1886d, 1887a]––but to showthe possibility and uncover the process of artificial recall. Thus, I am today convincedthat, neglecting to watch myself, I had, without realizing it, announced to them that theywould forget what they were going to say or do. (1889b, p. 82)

Delboeuf was afterwards careful not to train new subjects to be amnesic––and henceforthnone of them were (Delboeuf, 1889b, p. 82). By 1889, he believed that hypnotic amnesia con-sisted of either “a voluntary amnesia or an amnesia by inertia” (1889b, p. 68). In other words,the subject either chooses not to remember or simply does not try to remember. It is by nomeans inconceivable, then, that a subject could “honestly” claim never to have remembered apost-hypnotic suggestion while having in fact previously remembered it.

As noted before, dissociation is meaningless if the hypnotic subject can be made to re-member what only a dissociated consciousness is supposed to know. But if hypnosis is a matterof play-acting, then not only dissociation but hypnosis is meaningless as well. Janet was wellaware of this problem and of the need for an objective trait that could distinguish real hypnoticsubjects from simulators. Like other scientists associated with Charcot and the Salpêtrièreschool, Janet believed that this trait was an underlying pathology allied to hysteria. Some histo-rians seem to view this belief as a quaint error that was corrected by subsequent investigators


(e.g., Crabtree, 2003, p. 68; Gauld, 1992, pp. 375–381), but if Janet never abandoned it, it is be-cause he could see no other way of ruling out the possibility of simulation. Binet and Féré ex-pressed this doctrine rather explicitly in the summer of 1884. They affirmed that if the facts ofhypnosis have remained so long outside the purview of science, “it must be attributed to theirlack of objective traits, to the impossibility of assuring oneself of the subject’s sincerity. Theprincipal merit of contemporary research has been to attach itself to physical traits, as Charcothas done, from which hypnotism can be described like any other illness according to regularnosological rules” (Binet & Féré, 1884, p. 45; italics added). In identifying hypnosis with an es-tablished medical entity, Charcot appeared to offer a means for getting around the delicate prob-lem of simulation.

When Paul Janet first raised the problem of post-hypnotic suggestion in August 1884,he severely criticized Bernheim, the country physician Ambroise A. Liébeault (1823–1904)and the law professor Jules Liégeois (1833–1908)—all from Nancy—for failing to show thattheir hypnotic subjects were either hysterics or afflicted with some other nervous condition.This was the first round in the famous war between Nancy and the Salpêtrière. Paul Janet’spaper was based on an earlier critique of a paper by Liégeois in the Séances et Travaux del’Académie des Sciences Morales et Politiques in the spring of 1884.11 Liégeois’ paper pre-sented hypnotic experiments in which subjects had obeyed criminal suggestions and urgedthat existing laws be revised to protect hypnotic subjects from being blamed for crimes en-gineered by unscrupulous hypnotists. This paper launched another well-known debate overwhether or not subjects could be made to obey criminal suggestions (Gauld, 1992, pp.494–503; Laurence & Perry, 1992; Plas, 1989). It so happens that Liégeois’ most formida-ble opponent was none other than Delboeuf. The problem of post-hypnotic suggestion istherefore intimately related to the problem of criminal suggestion, and as we shall see,Delboeuf went on to develop an extremely subtle analysis of the problem of simulation thatplagued them both.

DELBOEUF ON CRIMINAL SUGGESTION

Delboeuf’s detailed critique of Liégeois’ conclusions appeared in the final chapter of hisbook Le Magnétisme Animal (1889b) and in similar form in an article six years later. I willthus present two of Liégeois’ more notable examples and follow with Delboeuf’s analysis.

Example 1:I produced, in Mlle E. an automatism so absolute, a disappearance so complete of allsense of morality, of all freedom, that I made her fire, without batting an eyelid, a pistolat her mother at point blank range. The young criminal seemed as completely awake asthe witnesses of this scene, but she was much less moved than they were. And, almostwithout transition, when her mother reproached her for what she had done and accusedher of wanting to kill her, Mlle E. answered, smiling and with much good sense: “I didnot kill you, since you are speaking to me!”

Who would then believe that this was only play-acting or simulation, and that a girl isplaying at deceiving the audience by shooting her mother with a pistol that she does notknow is not loaded? (Liégeois, 1889, p. 178)

Example 2:I equipped myself with a revolver and a few shells. To remove the idea of a mere gamefrom the mind of the hypnotic subject––whom I picked at random among the five or six

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11. Janet’s critique appeared in the discussion that was published alongside of Liégeois’ paper.

somnambules that could be found that day at M. Liébeault’s––I loaded one of the shellsand fired it into the garden. A few moments later, I entered and showed to the assistantsa piece of cardboard that the bullet had perforated.

In less than fifteen seconds, I suggested to Mme G. the idea of killing M. P. with thepistol. With absolute unconsciousness and perfect docility, Mme G. went to M. P. andfired the revolver.

Interrogated immediately after by M. P., the chief superintendent [of Nancy], she ad-mits her crime with total indifference. She killed M. P. because he did not please her.They may arrest her; she knows what to expect. If they take her life, she will go into theother world, like her victim, that she sees on the ground bathing in his blood. She is askedif it was not me who suggested to her the murder that she had just accomplished. Shesays no; she acted spontaneously; she alone is guilty; she is resigned to her fate; she willaccept, without complaining, the consequences of the act she committed. (Liégeois,1889, pp. 179–180)12

Delboeuf maintained from the beginning that hypnotic suggestions were only dangerousin cases of indecent assault and fraud, and that money, promises, drunkenness, persuasion,circumvention, and confession had always been, and always would be, more effective meth-ods of corruption than hypnosis (Delboeuf, 1889b, p. 90; 1895, pp. 229–230, 266).

He held that the somnambule is not as easily fooled by his or her dreams as is commonlybelieved––and neither are we in our own dreams, he added. We are rarely moved, he noted, bya shocking scene in our dreams: “There is like something inside of us that tells us it is notreal” (Delboeuf, 1889b, p. 90). When Liégeois’ subject enacts the murder of her mother, sheis obviously not unconscious of playing out a scene. This is why she is not distressed. She iseven less distressed, he continued, than if she had actually been dreaming (Delboeuf, 1889b,p. 91; 1895, p. 234).

The dreamer who would have dreamt of killing his mother would see her terrified and be-seeching, imploring the pity of her son or the aid of indignant witnesses. He himself wouldfeel moved by some motive, absurd or plausible, but imperious. In a word, the dream wouldbe a kind of incoherent drama, composed, as always, of real elements and of memories, inwhich horror would not be banished. Or else, if he saw his victim smiling and speaking tohim in the middle of a merely attentive audience, he would himself doubt, in his own sleep,that what he sees and does is pure illusion. (Delboeuf, 1895, p. 235)

Yet Liégeois insisted that Mlle E. did not know that the gun was not loaded. Nonsense!Delboeuf exclaimed. Why should we assume, he argued, that this woman who speaks withsuch good sense to her mother would not have the sense to know that the whole scene wasarranged and that Liégeois would not, after all, give her a loaded gun to fire at her own mother(1889b, p. 91; 1895, p. 236).

The same applies to the second example, Delboeuf continued:

The more I now reflect on these experiments, the less they seem to establish what theyare supposed to prove. The perfect tranquility of Mme G., her generosity at not accusingM. Liégeois, the humorous motive with which she justified her act, her resignation to thefate that awaits her, patently show, I dare say, that she is not duped and that she could notfor an instant have thought of killing M. P. She consciously plays a role that she impro-vises in part, that in part she makes up from bits learned by heart, and in which she in-termingles features in her own way, juvenile features, such as the statement that her vic-tim displeased her. (1895, p. 239)


12. Liégeois does not seem to see anything suspicious in the fact that Mme G. could somehow converse with thechief superintendent and also claim that she saw him lying on the ground in a pool of blood.

Delboeuf put little stock, moreover, in the claim that she saw her victim bathing in blood.Her own serenity is proof that she is not fooled by her illusion, he remarked. And there aremany more facts that prove hypnotic subjects are not so easily duped (1895, p. 239). “When,in our dreams,” he wrote in 1889, “we see a man-gun, or a dog-boat, we are not the dupes, butthe complicit [complaisants] instruments of our own dupery” (1889b, p. 91).

Delboeuf asked J., his prized subject and maid, how she saw him when he suggestedto her that he had a full head of hair and a black beard. She said that she saw him as such,but that in a strange way, “behind the young head, I see a bald head and white beard, butsort of erased” (1889b, p. 92). Delboeuf qualified her answer as typical. These examplesseemed to confirm his theory “on the hypnagogic character of somnambulic dreams. Thesomnambule’s illusions,” he concluded, “would be analogous to those which are producedat the beginning and at the end of sleep or, better still, in the sleep in which many peopleindulge themselves in the middle of the day. They hear almost everything, are in a certainsense aware of everything, but the dreams float in front of reality, in part masking and de-naturing it” (1889b, pp. 93–94).

They also seemed to confirm his view that hypnotic hallucinations rarely have the sameforce as dreams do. He wrote that he had never seen a somnambule bump into an object shewas not supposed to see, but that if the somnambule were told to, he felt sure that he or shewould then do so. “Would this be due to illusion or to a desire to please and cooperate [com-plaisance]? I lean in favor of complaisance” (1889b, p. 93).

“And when I say complaisance, or play-acting,” he wrote eight pages later,

M. Liégeois and his readers will do me the honor of understanding that this consists ina complaisance of a special nature. When a subject’s arm is put into catalepsy and he istold to lower it, he does not make the appropriate movements. He instead pretends to bein catalepsy by exercising the antagonistic muscles. It is a simulated catalepsy, and heis the dupe of his own simulation. It is in this sense that I say he lends himself by com-plaisance to playing his catalepsy. This complaisance is unconscious; it is he who, with-out knowing it, wants what we command of him. (1889b, p. 101)

Now here we may ask if it would not be possible for a subject to be sufficiently dupedby the hypnotic situation to commit a crime? Delboeuf did not want to deny this possibil-ity. It would violate the principles of scientific reasoning to make such an a priori affir-mation or denial (1889b, p. 108). He conceded that a somnambulic father could kill his sonby mistaking him for a wild beast that is attacking him or that a mother could dream thatthere is a fire and throw her baby from the window. But these are rare pathological cases,he affirmed, and cases of hypnotic subjects who could be deluded to the point of commit-ting similar acts must be equally rare (1889b, p. 97).

Having made this qualified concession, Delboeuf then pushed his argumentation to afurther level of sophistication. He related an experiment conducted with his subject J., whowas very gifted at accommodating hypnotic hallucinations. Since Delboeuf could makeher accept that her head was rolling before her on the floor, or that she was a sofa or what-not, he believed that he could make her accept any illusion whatsoever. But he was mis-taken (1889b, pp. 98–99). He once asked her to tell him, during a kind of telepathy ex-periment, what her sister was doing in her house in the countryside. She saw nothing. Hethen told her that her sister was presently mending her husband’s trousers. J. answered thatshe never mended trousers. Delboeuf tried “every imaginable persuasive means” to get herto see her sister mending her husband’s trousers but did not succeed. She rememberednothing once awake. He asked her about her sister’s habits and discovered that she “always

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refused to sew because she could not do it very well” (1889b, p. 99). “Now here is a fact,insignificant in appearance,” he wrote:

but one that by its singularity will certainly strike all those who wish to know what goeson in the minds of hypnotized subjects, or, what amounts to the same thing, in the mindsof sleeping people. Here is a person who saw nothing unnatural in running after herhead that is rolling away from her, who was made to believe that she was a boy, that shehad a beard, that we had played her the trick of dressing her as a girl while she wassleeping and that she would do well to fetch her men’s clothes––which she immediatelyset out to do––and who deems it impossible that her sister should be mending a pair oftrousers! (1889b, pp. 99–100)

Delboeuf made the same observation regarding two young women who refused, under hyp-nosis, to believe that they were married. “And yet,” Delboeuf remarked, “one of them believesthat a doll is her sick child, and the other sees no difference between her small room, almost en-tirely filled by her small bed, and a large room of more than thirty square meters, filled withbooks, engravings, statuettes, and a large bed half covered with things” (1889b, pp. 110–111).

How can one account for these apparently contradictory inclinations to believe some hal-lucinations and not others? Delboeuf explained that an illusion must have something to whichit can attach itself in the subject’s mind if it is to be accepted. It was easy for the subject toimagine herself in her room because she saw it every day. It was likewise easy for the othersubject to accept the illusion of tending to her baby because she had no doubt played“mommy” countless times. But unless someone has already thought about marriage and “rep-resented herself as married,” the illusion of marriage will not take (1889b, p. 111).

As we have seen, Delboeuf presented an analogous explanation for why hypnotic sub-jects could not normally remember their hypnotic condition once awake—it was because ofthe apparent difficulty of establishing a link between the dissimilar hypnotic and wakingworlds. This explanation accounts for one of the great myths of hypnosis: hypnotic amnesia.Another great myth is the notion that hypnotic subjects cannot resist their hypnotist’s com-mands. Again, Delboeuf turned to dreams to account for why subjects obey some commandsand not others, and simultaneously dispelled the myth that hypnotic subjects will carry outsuggestions that offend their deepest sensibilities. As Delboeuf (1895) noted, “The problemat hand is a very serious one. It is a problem of psychology” (p. 263).

If I now wished to summarize my thought in a word and to conclude, I would say that,for each hypnotic subject, the key to the suggestions that he is capable of accepting is tobe found in his dreams, that is to say we could have him perform the acts that, issuingfrom his character, his education and his habits, are likely to present themselves sponta-neously during his sleep. (1889b, p. 112)

Delboeuf wished to show that the somnambule is not as passive and does not lack asmuch freedom as we might at first think. He did not want to affirm, he cautioned, that it isimpossible for a subject to divorce herself from reality and to lose her reason and freedom.He wished only to point out that we would need powerful proof to admit such subservienceof someone’s will to another’s (1889b, p. 100).

Delboeuf was extremely wary of Liégeois’ experiments. “They have the irremediablefault,” he wrote, “of being necessarily artificial” (1889b, p. 100). Liégeois had many timesproposed that they conduct hypnotic experiments together, but Delboeuf had always refused.“Why? Because from the experiment,” Delboeuf explained, “whether it succeeds or does notsucceed, nothing can be concluded. If the subject does not stab, M. Liégeois will reject him


as a bad somnambule; if he does stab, I will maintain that he is doing out of playful complicity[complaisance] an action he knows is not wrong” (1889b, p. 101).

On the other hand, if the subject actually went through with a real crime, Delboeufcould argue that they were dealing with “a born criminal, a latent thief, or someone unself-consciously licentious” (1895, p. 232). “The problem is therefore unresolvable,” Delboeufconcluded, because it cannot be settled on the terrain of experimentation (1895, pp.264–265).13 “But the question can be breached in a non-experimental way,” he advanced.“It can be approached by observation and by the attentive and scrupulous examination ofthe magnetized subjects’ actions” (1895, p. 266). We have seen how Delboeuf’s subjectsseemed only to accept suggestions that conformed to their moral character, experience, andhabits. Here now is a similar example that suggests a way of circumventing the inconclu-siveness of laboratory crimes.

J. and her husband had their first baby in Delboeuf’s home. The next day, just beforeDelboeuf’s son-in-law went upstairs to congratulate her, Delboeuf hypnotized J. and in-structed her to slap his son-in-law when he would try to embrace her. She refused, at first, butfinally agreed after some insistence from Delboeuf. He then warned his son-in-law and, froma concealed position, watched while he waited for the action to begin. But when the youngman leaned over J. to embrace her, instead of slapping him, she merely nudged him with herelbow. After he left the room, Delboeuf rehypnotized J. and asked her why she had failed toobey his command. “I did not want to,” she said. “I do not want you to give me such com-mands, and I won’t obey them if you do” (1895, p. 263).

Delboeuf continued three pages later:

If ever reasoning by analogy has been legitimate, it is when it assures that [a hypnotizedsubject] who will not slap a person will not stab a person, that [a subject] who refuses akiss will rebuff more serious advances, and that a wolf will never make a good pastor.

From the facts furnished by observation we may therefore infer that a hypnotized per-son conserves a sufficient amount of intelligence, reason, and freedom—I emphasize theword—to defend himself from realizing acts that are irreconcilable with his characterand beliefs. (1895, p. 266)

CONCLUSION

The opposition I presented between Janet and Delboeuf has its modern counterpart inthe debate between neo-dissociationists like Ernest R. Hilgard (1904–2001), J. F. Kihlstrom,and K. S. Bowers and role-playing theorists like Nicholas Spanos (1942–1994), W. C. Coe,and T. R. Sarbin.14 Despite over 30 years of experiments and counterexperiments, neither sidehas emerged a clear winner. Like Janet, the neo-dissociationists attempt to explain most hyp-notic phenomena in terms of dissociated units of consciousness. Hilgard, for example, be-lieved that there is always a “hidden observer,” a dissociated consciousness, who watches overeverything that happens during hypnosis (Hilgard, 1977, pp. 204–215). He coined the termneo-dissociation because, unlike Janet, he did not believe that hypnosis was indicative of an

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13. Ruth Leys, a historian of medicine at Johns Hopkins University, recently arrived at the same conclusion. “Indeed,after decades of theoretical work and laboratory experiments,” she writes in Trauma: A Genealogy, “the question ofthe nature of hypnosis is still not settled, which suggests that it is unlikely to be resolved on empirical or experi-mental grounds” (Leys, 2000, p. 171).

14. On the debate between the neo-dissociationists and the role-playing theorists, see Gauld (1992, pp. 586–608) andLeys (2000, pp. 165–172), upon which my brief description of the debate is indebted.

underlying disorder, nor that dissociated units of consciousness did not overlap or interferewith the subject’s main consciousness (the reader may recall that these are the very conditionson which Janet relied to defend the concept of dissociation). Like Delboeuf, the advocates ofthe role-playing approach (also known as the social psychological or sociocognitive perspec-tive) believe that hypnotic subjects are merely enacting the culturally defined role of a hyp-notic subject. They also argue that good subjects will use whatever “cognitive strategy” theycan to comply with the demands of the hypnotic situation. To meet the requirement of hyp-notic amnesia, for example, subjects might focus their attention on a different mental taskwhen asked to recall their hypnotic experiences—not unlike Delboeuf’s hypothesis that sub-jects might suppress their hypnotic memories through “a voluntary amnesia or an amnesia byinertia” (Delboeuf, 1889b, p. 68). Yet, for all their similarities to Delboeuf, most role-playingtheorists do not trace their ancestry as far back as the nineteenth century. In recent years, how-ever, the historically sensitive philosopher Mikkel Borch-Jacobsen has championed Delboeufas a sophisticated precursor of their ideas.

In his paper, “The Bernheim Effect,” Borch-Jacobsen (1997/2002) maintains that we can-not establish a “psychic reality” to hypnosis that might exist outside the experimental context.Citing the work of the psychologists Robert Rosenthal and Martin Orne, he reminds us thatmuch experimental psychology is always unavoidably contaminated by experimenter ex-pectancy effects (Rosenthal, 1966) or demand characteristics (Orne, 1962) that unintentionallyelicit from its subjects the behavior that is anticipated of them. “We do not therefore experimenton the subject,” he points out, “we play with them the game of experimentation: tell me whatyou wish to establish, and I will help you to prove it. What Bernheim and Delboeuf observed inthe widening mirror of hypnosis and hysteria, was a feedback effect found in any experimentalsituation, however ‘controlled’ it may be” (Borch-Jacobsen, 1997, p. 166; 2002, p. 200).

Borch-Jacobsen’s critique is also directed against the Freudian unconscious. We haveseen how the concept of dissociation—the concept that only the existence of an unconsciousconsciousness can explain how someone could count 13 days without knowing it—is ground-less if hypnosis is merely a game of play-acting. But if the concept of dissociation is false,there are good reasons to suspect that the concept of the unconscious might be false as well.Borch-Jacobsen writes:

Without seeming to realize it, Bernheim and Delboeuf here demolish a great myth, thatof the psychic unconscious. We know that the idea of a psychic activity independent ofconsciousness owes everything, historically, to the somnambules and hypnotic subjectsof the nineteenth century (on this see Henri Ellenberger’s fundamental work). That I ig-nore what is happening in me, that I am the toy of thoughts and memories that I ignore,is an observation that Freud, like so many others at the time, had first made on subjectsunder hypnosis. (Borch-Jacobsen, 1997, p. 156; 2002, p. 190)

This historical claim is, in fact, strongly confirmed by Freud himself. For example, in“Justification for the Concept of the Unconscious,” the opening section of his article “TheUnconscious,” Freud (1915/1953–1974) wrote: “Even before the time of psychoanalysis, hyp-notic experiments, and especially post-hypnotic suggestion, had tangibly demonstrated theexistence and mode of operation of the mental unconscious” (pp. 168–169).

The role-playing approach faces an important challenge of its own, however, in the prob-lem of self-deception. Borch-Jacobsen (1997/2002) insists that, deep down, hypnotic subjectsare aware of the game they are playing. Yet many subjects will later swear that they really werehypnotized and that they were materially incapable of resisting the hypnotist’s suggestions. Iftheir actions are indeed involuntary, this would seem to imply the existence of a dissociated


consciousness, functioning outside their immediate awareness and control, or, if their actionsare only apparently involuntary, then, as the historian of medicine Ruth Leys argues, some-thing like the Freudian unconscious is necessary to explain “how they can deceive themselvesin this way” (Leys, 2000, p. 169). Either way, it would seem, the existence of an unconsciousconsciousness is required to account for why hypnosis is so often experienced as real.

In a related argument, Leys (2000) points out, “Borch-Jacobsen himself cannot do with-out the very concept of the unconscious that he otherwise wishes to discard. For example, the‘experimenter expectancy effect’ to which he appeals in his discussion of hypnosis . . . de-pends on a notion of unconscious communication between subject and experimenter” (p.183). Indeed, even Delboeuf seemed to invoke a notion of the unconscious when, in the caseof the young man who simulated his catalepsy through complaisance, he wrote: “This com-plaisance is unconscious; it is he who, without knowing it, wants what we command of him”(Delboeuf, 1889b, p. 101).

“Without knowing it?” Borch-Jacobsen objects, “Upon what basis are Delboeuf andBernheim so certain that the subject ignores he is simulating? . . .” (Borch-Jacobsen, 1997, p.159; 2002, p. 193). To my knowledge, this is the only point on which Borch-Jacobsen has everdisagreed with Delboeuf, and the reason why is fairly obvious: how are we to explain the factthat a subject could both want something and not know that he wants it without appealing tosome notion of the unconscious?

When Delboeuf described the subject’s complaisance as unconscious, however, the psy-chological process he had in mind was very different from Janet’s or Freud’s. Consider, forexample, the following reflections on the nature of that complaisance:

[I]n his extreme desire to obey his hypnotizer, whom he identifies in a certain sense withhimself, the subject ends up by doing just about whatever he wants to his body and hismind. . . . And if I were asked to specify the origin of this complaisance, I would answer,as I have just done, that the magnetizer who whispers in his ear, appears to him like acreation of his own mind who is speaking to him in a dream, such that, in the end, heobeys his own will. (Delboeuf, 1887b, pp. 804–805)

Here again Delboeuf draws upon the activity of dreaming to account for the subject’s ex-treme willingness to accommodate the hypnotist’s commands. I shall briefly return, at the endof this article, to the significance of dreams in understanding the nature of hypnosis. Let usfirst consider Delboeuf’s more advanced reflections, published five years later, on the identi-fication between subject and hypnotist.

When I am in the presence of a patient, I feel his illness quite deeply; if he suffers, I sharehis suffering; if he cries, I cry with him. There is thus between him and me a kind ofcommunion. From this sympathy, which produces the effect that when I speak to him Ispeak as it were to myself, does it not result that, when he hears me, he thinks he is hear-ing his own words? . . . If this way of seeing things contains some truth, it would followthat the patient in a way also hypnotizes the agent. (Delboeuf, 1892, p. 210)

Returning now to the problem of self-deception, when Delboeuf wrote that the subject“without knowing it, wants what we command of him,” he meant that, by imagining himselfin Delboeuf’s shoes, the subject momentarily adopted Delboeuf’s desires and expectations.And by the word unconscious, Delboeuf did not mean anything nearly as mysterious as an un-conscious consciousness; he simply meant that the subject was “not aware of ” or “not aliveto” the fact that she was modeling her thoughts after Delboeuf’s. Here is a personal exampleof this kind of unwitting simulation.

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When I meet someone who leaves a strong impression on me, someone I admire andwould like to resemble, I frequently begin to mimic his or her mannerisms and style. I actas though I were this other person but I usually do not realize I am doing so unless I catchmyself in the act; I simulate without realizing it, as it were. The effect is quite strong afterI have become engrossed in a movie. By imagining myself as one of the characters in themovie, from the moment I exit the theatre I often see the world as the movie character mighthave seen it. But even when I catch myself behaving this way, the effect is no less real, andit persists for some time afterwards. It is in this sense that I suggested, in a recent review ofBorch-Jacobsen’s Folies à Plusieurs (“The Madness of Several”), that hypnotic subjectsmight be “deluded into believing—sometimes along with the hypnotist in a folie à deux—they are hypnotized and that this experience is in itself real and unique” (LeBlanc, 2003).

These delusions—be they of an unwitting impersonator, a spellbound moviegoer, or amesmerized subject—are analogous to the delusions we all experience in our dreams. In otherwords, if, as Delboeuf maintained, hypnotic sleep is really just ordinary sleep by anothername, then it should come as no surprise that hypnotic subjects, like all dreamers, frequentlyfail to realize that their trancelike experience is in fact a dream.

ACKNOWLEDGMENTS

This article was prepared while I was a postdoctoral fellow in the Department of the History of Science at HarvardUniversity. Funding was provided in the form of a Hannah Institute for the History of Medicine Post-DoctoralFellowship from Associated Medical Services, Inc., for which I am very grateful. The article is drawn from the mid-dle chapters of my doctoral dissertation, “On Hypnosis, Simulation and Faith: The Problem of Post-hypnoticSuggestion in France, 1884-1896,” University of Toronto, 2000. I wish to thank Ian Hacking for supervising the workand Oliver Stunt for proofreading it. I also wish to thank the referees for their comments and suggestions. Thanks fi-nally to Ori Friedman for suggesting the article’s title.

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thirteen days: joseph delboeuf versus pierre janet on the nature of hypnotic suggestion

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