Biological Psychology, 3, 197.5, 31-47. @ North-Holland Publi.shing Cornpatty

HYPNOSIS

AND EYE MOVEMENTS

A. K. TEBEClS* Departments Australia

Accepted

and K. A. PROVINS

of Psychology

for publication

and Physiology,

31 December

Australian

National

Unicsersity, Canberra,

1974

Eye movements (with closed lids) were studied in a group of highly hypnotizable experimental subjects experienced in self-hypnosis, and compared with a random sample of control subjects that had never been hypnotized and were low in waking suggestibility. Approximately half the experimental subjects rolled their eyes upwards to a greater extent when hypnosis was induced than during eye closure while awake. In some subjects eye flutter occurred during hypnosis, but not in the awake condition. During passive hypnosis the mean rates of rapid eye movements were lower, but those of slow eye movements were higher than during the resting awake condition of the same subjects or the random control subjects. The mean rates of horizontal eye movements during suggestions about being in a train and watching passing telephone poles were higher for the experimental subjects in the hypnosis and ‘imagination’ sessions than that of the random control group in the imagination session. A proportion of the experimental subjects made more lateral eye movements during hypnosis than during the imagination session, but an equal proportion did not differ between the two conclitions. The mean rates and durations of horizontal eye movements during dreaming about a tennis match were greater during hypnosis (‘hypnotic’ dream), than during the awake condition a few minutes later (‘natural’ dream), or the awake condition in the imagination session (‘imagination’ dream) of the same subjects or random controls. The performance and subjective involvement of the experimental subjects during the Barber suggestibility scale, ‘nystagmus’ suggestions and ‘dreaming’ did not differ significantly between the two hypnosis sessions, but in most cases were significantly greater during hypnosis than during the imagination session of the same group or the random control group.

1. Introduction The movements of the eyes during hypnosis and other altered states of awareness have been the subject of study for a number of years (see the review by Sarbin and Slagle, 1973). During a recent investigation of the electroencephalogram (EEG) and hypnosis (Tebkis, Provins, Farnbach and Pentony, 1975) characteristic changes in eye movements were observed during hypnosis in some subjects. If true generally, such observations may have an important bearing on the ‘trance versus non-trance’ theories of hypnosis (Hilgard, 1973). We therefore systematically studied the eye movements of a group of subjects *Now at the Department of Psychosomatic University, Fukuoka City, Japan.

Medicine,

31

Faculty

of Medicine,

Kyushu

during hypnosis and the awake condition, and further compared these with the eye movements of another group (random sample) of subjects in the awake condition. Theexperimental subjects were highly hypnotizableandexperienced in self-hypnosis, whereas the random controls were low in suggestibility and had never been hypnotized. In addition, studies of eye movements were made during suggestions about being in a train and watching passing telephone poles, and during ‘dreaming’ about a tennis match. A brief report has been made of some of these observations (Tebecis and Provins, 1974a). We~t~enhoffer (t971a) has previously described interesting changes in eye movements during hypnosis with the eyes open, the main finding being decreased motility. However, this report is concerned with eye movements with closed lids. 2. Methods The selection of subjects, the experimental procedures and the equipment used have recently been described in detail (Tebecis et al., 1975). Since the results presented in this paper were obtained during the earlier investigation of hypnosis and the EEG, the methods will be outlined only briefly here. In each experimental session (which lasted between 2 and 3 hrf, one investigator remained in the experimental room with the subject while the other operated the recording equipment in an adjacent room. For each subject continuous recordings were made of the EEG from bipolar electrode placements on the right and left sides of the parietal scalp(thesewerealsod~splayed via an analog frequency analyser), electromyogram of the right masse&r muscle, electrocardiogram, skin temperature of the forehead, skin conductance of the palms, and movements of the eyes (as described by Tebecis et al., 1975). The d.c, potential changes produced by vertical (left eye) and horizontal (both eyes) movements were displayed on two different channels of a Grass Polygraph chart recorder, using preamplifiers routinely calibrated at 0.5 mV/cm. Since most eye movements are conjugate, it was assumed that theverticat el~ctro-oculogram (EOG) recorded from the left eye would represent the activity of both eyes, even though binocularly asynchronous eye movements (especially slow movements) are known to occur (Aserinsky and Kleitman, 19SS)* Thirty-three adult subjects of either sex and diverse occupations vohtnteered for this study. Nineteen subjects who were thoroughly experienced in the practice of self-hypnosis comprised the ‘experimental’group and were totdthat their ‘brain waves and other body responses’ would be recorded during hypnosis which would be induced ‘instantly’ by a prearranged cue. The other (‘control’) group (random sample) of I4 subjects was told that recordings would be made of ‘brain waves and other body responses during periods of imagination’. These subjects had never been hypnotized and did not practise meditati~~n.

Hyptzosis ad

eye rnoi~erne~[.~

33

2.1. Experimental procedure Virtually all the instructions to subjects during the experiment proper were pre-recorded and administered by tape recorder. For the hypnosis experiments, the first few minutes following induction in each subject consisted of taped suggestions for increasing the depth of hypnosis, an explanation of a O-5 self-rating scale of hypnotic depth and the administration of the Barber suggestibility scale (BSS, Barber, 1965). A number of different pre-recorded tests (most of which are described elsewhere; Tebecis and Provins 1974b, 1975) were then administered during hypnosis. Those specifically concerned with eye movements were as follows. 2.1.1. ‘~ystagmu~’ (subject seated). ‘What is your depth of hypnosis? (4 see pause). ‘Good. Now listen carefully once more. On the count of three, not before, you are actually sitting in a train, looking out of the window at the countryside flying past. The train is travelling quickly. It is travelling parallel to an endless line of telephone poles, and you are looking at these poles, trying to see each one in detail. One, two, three’ (29 set pause). ‘Now the train is travelling much faster’ (12 set pause). ‘Now the train is slowing down again’ (14 set pause). ‘Now the train has stopped’ (10 set pause). ‘Your train journey is now over. On the count of three you are not in a train any more, but back in the laboratory. Everything is normal again, but you remain in hypnosis. One, two, three.’ 2.1.2. ‘Dreaming’ (subject lying on a bed). ‘What is your depth of hypnosis?’ (4 set pause). ‘Fine. Just pay attention to my voice. On the count of three, not before, you begin to dream. You dream that you are actually at a tennis match, watching the game from your seat, which is about ten yards away from the court, near the net. It is a very exciting and vigorous game to watch. You have this dream for exactly two minutes after I count to three, and then stop dreaming, but remain in hypnosis. One, two, three’ (4 min pause). ‘This time on the count of three, not before, you fall into a natural sleep. You come out of hypnosis on the count of three and sleep as you do normally at night. When you have slept for a little while, I shall say “start dreaming”‘. At this instant you dream that you are actually at the same tennis match as before, watching the exciting game. The dream is normal as occurs when you sleep at night. You dream for exactly two minutes after I say “start dreaming” and then continue to sleep without dreaming as before. One, two, three’ (2 min pause). ‘Start dreaming’ (3 min pause). ‘Wake up now . . . what is your depth of hypnosis ?’ After all the tests involving complex suggestions had been administered, the subject was asked not to move unnecessarily during the final recording periods. Two-minute artifact-free records were obtained of the awake (eyes closed and then open) and hypnotized conditions (eyes closed and open), followed

immediately by 20 min periods of the ‘awake, eyes closed’ and ‘hypnosis, eyes closed - blank mind’ conditions. This was termed session I. All the tests were administered in an identical manner to each subject l-18 weeks later, except that the awake/hypnosis periods were reversed (session 2). The same subjects returned for a third session l-12 weeks later to test their imagination while awake. The preliminary instructions and the recording periods during the resting condition have been described previously (Tebecis et al., 1975). The instructions relevant to eye movements for the n~stagmus records were exactly the same as in the hypnosis conditions except that subjects were told to close their eyes and to imagine that they are actually sitting in a train instead of being hypnotized and told they are actually sitting in a train, etc. Similarly the instructions about dreaming of being at a tennis match were also rephrased appropriately, but otherwise the procedure was the same as for the hypnosis runs. The scores for eye movements of the experimental subjects in the hypnotized and awake (imagination) conditions were labelled the hypnosis group and control group I, respectively. The imagination tests administered (only once) to the random sample of control subjects in the awake condition gave scores which were called control group 2. 3. Results As described recently (Tebecis et al., 1975) on the basis of mean scores for self-reported hypnotic depth and the BSS, the experimental subjects: (a) were highly hypnotizable, (b) responded fairly consistently in the two hypnosis sessions, (c) performed more intensely during hypnosis than while awake and imagining, and (d) were more suggestible while awake than the group of random control subjects. 3. I. Amplitude of eye closure and eyejutter An examination of the EOG revealed that the eyes of some subjects rolled upwards to a greater extent on the induction of hypnosis than during eye closure in the awake condition. Sample records to illustrate this are shown in fig. I A-C. In A an approximately 0.6 mV potential change resulted when the subject was asked to close her eyes while awake, whereas an approximately 0.9 mV change resulted when hypnosis was induced a few seconds later. The records in B (from a male subject) show an even greater difference (approximately 0.9 and I .3 mV change for the awake and hypnotized conditions, respectively). Similar findings are illustrated in C, for yet another subject. Moreover, after this subject had closed her eyes while awake, the induction of hypnosis resulted in a further upward roll of the eyes (C,). For statistical comparison, up to IO estimates (mean, 6.2 estimates per subject) of the amplitude of eye movement on closure for both the awake and hypnotized conditions were made for each experimental subject, and the values

AWAKE, A

E/C

L/O

HYPNOSIS,

EYES

CLOSED

HYPNOSIS,

EYES

CLOSED

+--&j--i--

AWAKE,

EYES

CLOSED

AWAKE,

E/C

AWAKE,

EYES

E/O

CLOSED

v

HYPNOSIS,

AWAKE,

EYES

EYES

HYPNOSIS,

E/C

HYPNOSIS I

CLOSED

CLOSED

t

UP

‘00 p” tL-------

SECS

Fig. 1. Comparisons of the EOG (vertical components only) in the awake and hypnotized conditions of four different subjects. Abbreviations: E/C (eyes closed), E/O (eyes open). A: From a 27-year-old woman. B: From a 31-year-old man. The gap in the two tracings represents a period of less than 2 min. C,, C2: From a 25year-old woman. Both records were obtained in the same session. The rapid spike-like fluctuations during periods with the eyes open in A-C2 reflect blinks. D,, D,: From a 31-year-old male. The EOG and simultaneous EEG records in D, were obtained 15 set after the beginning of a 2 min ‘hypnosis, eyes closed’ period: those in Dz were obtained 17 set after the beginning of a 2 min ‘awake, eyes closed’ period following the hypnosis period. The 100 pV caiibration refers to both EEG tracings. The I .O mV calibration refers to all the EOG records in the figure. The uppermost time scale fsec) refers to A, the middle one to B, C, and C,, and the lowest one to D, and DZ.

were compared using the t-test for dependent samples. The amplitude of eye movement was measured only if an obvious baseline and final plateau were apparent on the record shortly before and after eye closure and if an equal number of measurements could be made of the awake and hypnotized conditions within 2 min of each other. There was considerable variability between individuals. Of the 19 subjects studied, there was a significantly larger upward excursion of the eyes following hypnotic induction in nine (p < 0.05), no significant difference in eight, and a significantly smaller eye-roll during hypnosis in two subjects (p < 0.05). Considering the 19 subjects as a group, the means (0.4 and 0.5 mV for the awake and hypnotized conditions, respectively) did not differ significantly. Another common observation was the occurrence of much small-amplitude, high-frequency vertical eye movements (‘flutter’) during hypnosis, but little during the awake condition with the eyes closed (fig. I A and C, for example). Eye flutter was not analysed statistically because it occurred sporadically during hypnosis: in some subjects it occurred frequently although intermittently during hypnosis, but not at all during the awake condition (e.g. fig. ID). The EEG recorded simultaneously indicated that the eye flutter during hypnosis was not obviously associated with the alpha or any other EEG rhythm (cf. Lippold, 1973). 3.2. Rupid and slow eJ,e mor’ernents (eyes closed) Some experimental subjects displayed obvious differences in the pattern of eye movements between the passive awake and hypnotized conditions. In the awake condition (eyes closed) eye movements were generally rapid, frequent and of small amplitude (jerky), sometimes interspersed with blinks. During hypnosis such movements were generally less frequent or absent, but largeramplitude, slower, rolling eye movements were more prevalent, especially during the 20 min resting periods. Blinks were rarely observed during hypnosis. Sample tracings of the 20 min records obtained from three subjects are presented in fig. 2. The large-amplitude, rolling eye movements during hypnosis were usually more pronounced in the EOG for the vertical components (as in fig. 2B and D), but for a small proportion of subjects left-right movements were more marked (fig. 2F, for example). Small-amplitude blinks during the awake, but not the hypnotized condition can be seen in fig. 2C and E. Two types of eye movements were scored during the 2 and 20 min resting records, the tracings analysed being the final 60 set of each period, both vertical and horizontal movements, eyes closed only. A rapid eye movement (REM) was defined as a pen deflection of at least 0. I5 mV occurring within 0.5 set, whereas a slow eye movement (SEM) was defined as a pen deflection of at least 0.30 mV occurring in 2 set or more. These definitions are similar to the descriptions of REMs and SEMs originally given by Aserinsky and Kleitman ( 1955).

AWAKE

AWAKE

---

D

AWAKE -.--

E

HYPNOSIS

Fig. 2. Comparisons of the EOG during the awake condition and hypnosis (with closed eyes). The top tracing of each pair is the vertical EOG; the bottom tracing is the horizontal EUG recorded simultaneously. Each set of four records is from a different subject. For a particular subject, the EUG records shown were taken at comparable times within the final 5 min of the 20 min ‘eyes closed, awake’ and ‘eyes closed, hypnosis - blank mind’ periods. The marked backward slant in some tracings resulted from drift of the pen on the Polygraph recorder chart near the limits of its range. The calibrations and time scale in F refer to all the records in the figure.

Table

1.

Summary of the mean rates of REMS and SEMs during hypnosis and the awake condition of the different groups. Figures refer to the mean number of eye movements t+ standard error of the mean in parentheses) occurring in the final 60 set of the 2 and 20 min recording periods (eyes closed). REMs Period tmin) 2 Vertical

r 20

I Horizontal

Hypnosis 2.4 (jZO.9) 1.7 tkO.6)

2

1.7

., 2.

tkO.6) 1.4

I

c+o.9

Control 6.8 (k1.9) 3.6 (_+0.8) 7.7 (+I .9) 3.1 (kO.9)

SEMs

1

Control 5.0 (rt1.3) 4.4 (51.4)

2

Hypnosis 2.0 (f0.6) 2.3 f-f-0.5)

Control 0.8 (+0.3)

I .o (kO.3)

1

Control

2

I .6 (kO.4) 1.4 (kO.4)

3.2 (-cl .4) 3.6

I.8

0.7

0.9

(tO.6) 3.6

(k-0.4)

I.2

W.5) 1.3

(&IS)

(kO.9)

(AYO.5)

(kO.7)

The mean REM and SEM rates were calculated for each of the awake and hypnotized conditions and the results are summarized in table I. The data for hypnosis sessions I and 2 have been combined to cancel out any possible order effects. Data from two subjects who displayed unusually large-amplitude eye flutter (cf. fig. 1D) were omitted from the analysis. Similarly, the EOG was not analysed if the subject fell asleep to any observable extent (as indicated by the EEG, subjective reports or behavioural criteria). For both the 2 and 20 min resting records the mean REM rates (both vertical and horizontal) were significantly lower during hypnosis than during the awake condition of the same group or the awake condition of control group 2 (p < 0.05; with the exception of the comparison of the 2 min periods, horizontal REMs), using two-tailed t-tests. Control groups 1 and 2, however, did not differ significantly in mean REM rates (both 2 and 20 min periods, vertical and horizontal components). The mean SEM rates (2 and 20 min periods, vertical and horizontal components) during hypnosis were significantly greater than during the awake condition of the same subjects, but were not significantly different from those of control group 2, except in the comparison of 20 min periods, horizontal components only (p < 0.05). The mean REM rates did not differ significantly between the 2 and 20 min recording periods for the hypnosis group of control group 2, but were significantly lower during the 20 min periods for control group I (p < 0.05). 3.3. ‘Nystagmus’ Most subjects of the experimental group displayed pronounced left-right eye movements, and some showed left-right head movements during suggestions that the train was travelling past a line of telephone poles. Two subjects opened their eyes for the exact duration of these suggestions; the remainder

Hypnosis ad eye movements

39

responded with their eyes closed. In virtually all cases there were no such movements shortly before the suggestions and when ‘the train had stopped’. The patterns of eye and head movements were generally similar in the two hypnosis sessions. In contrast, only three of the 14 control subjects displayed lateral eye movements (eyes closed) during the ‘nystagmus’ suggestions, and two others made lateral head movements. Table 2 summarizes the mean rates of horizontal eye movements during the nystagmus suggestions for the different groups. Only movements exceeding 0.35 mV in amplitude occurring within I set were scored for analysis. For all groups the means for the faster phase were higher than those for the slower phase. There were no significant differences between corresponding phases of the two hypnosis sessions. The corresponding means for the imagination session of this group (control group 1) were all lower than those of the hypnosis sessions, but the differences were not statistically significant. However, the means for the hypnosis sessions and control group I were all significantly greater than the corresponding means for control group 2 (p < 0.05 by r-test for independent samples). Records of the types of eye movements seen in two subjects are presented in fig. 3. For both subjects in hypnosis (fig. 3A and C) the frequency of horizontal eye movements increased when ‘the train was travellingfaster’, decreased when ‘it slowed down’ and stopped when ‘the train stopped’. In contrast, lateral eye movements occurred much less often in the imagination session a few weeks later (fig. 3B and D). The second subject also moved her head from side to side during the suggestion period in both hypnosis sessions, but made no discernible head movements in the imagination session (not illustrated). 3.4. ‘Dreaming’ Suggestions to dream about a tennis match were given under four different conditions. The hypnotic dream followed appropriate suggestions given during hypnosis without any reference to sleep. A few minutes later the same subjects were given hypnotic suggestions that shortly after awakening from hypnosis they would fall asleep naturally and would later dream naturally when the posthypnotic cue words ‘start dreaming’ were given. This was desigTable

2.

Mean rates of left-right eye movements (numher per 10 set) during the different phases of the ‘train ride’ for the various groups. The figures in parentheses denote the standard errors. Group Hypnosis 1 Hypnosis 2 Control 1 Control 2

Train _ 4.5 4.9 3.6 0.8

Fastel ~~~ 5.3 5.2 4.3 1.1

Slower 3.9 3.9 3.0 0.4

Stopped 0 0.7 0.3 0

Totals 13.7 (k3.5) 14.7 (k3.8) 11.2(*3.1) 2.3 (k1.1)

HYP

IMAG

Train

T .

---_--

Foster

F .

Stenoed

Slower

S ‘I

S .

D

Fig. 3. A comparison of eye movements occurring in the nystagmus tests administered during hypnosis (HYP) and imagination in the awake condition (lM.4G). The top tracing of each pair is the vertical EOG; the lower one is the horizontal EOG. The first arrow (train or T) for each pair of records indicates the beginning of the moving phase of the suggested train ride (that is, the *three’ of the cue words ‘one, two, three’). Similarly, the other arrows indicate the time the words ‘faster’ (F), ‘slower’ (S) and ‘stopped’ (second S) were administered. For one subject the imagination session (B) followed the hypnosis session (A) by six weeks. For the other, the difference was five weeks. Both subjects were females, 27 years of age. Calibrations refer to all records. The change in chart speed during the suggestion period in A is the reason why the corresponding arrows of the hypnosis periods are not all in line on the figure. The lower time scale (see) refers to B, C, D.

nated as a natural dream. As additional controls, similar suggestions to sleep and then dream were administered to the same subjects in the awake condition during the imagination session, as well as to the random sample of control subjects. These dreams will be referred to as imagination dreams of control groups 1 and 2, respectively. Lateral eye movements were scored as for the nystagmus tests. No or negligible EEG rhythms characteristic of sleep occurred shortly before, during or after any of the dreams of any subject (all groups); the EEG remained similar to that of the waking condition and included alpha activity.

41

Hypnosis and eye mor~ements

F c-c

> E 0 -

f

r ,

i

‘I

a

\ m

Fig. 4. A comparison of eye movements during a hypnotic (A) and a natural (R) dream recorded a few minutes later in a 36-year-old man. In C, the subject (a 25-year-old woman) received hypnotic suggestions to dream for exactly 1 min. Her eyes opened and horizontal head movements were also pronounced during the I min period following the cue words to begin (indicated by the arrow). The top record ofeach pair is the vertical EOG, whereas the lower one is the horizontal EOG. The calibrations and tinle scale in C refer to all records.

Questioning after the sessions revealed that dreaming during hypnosis was subjectively experienced as being much more real (including more emotion, detail and overall involvement) than the natural or imagination dreams. Analyses of the EOG further suggested that the hypnotic dream was the

Tahlc

3.

Mean rutcr of hori/ot1tal qc n~ovcnwnt~ ;~nd nx~n cluri~tiom 01 dreaming for the diKerent groups. The \tan&rtl error\ of the means arc given in parentheses. The imagin:ition dream is abbreviated to Imag. Lateral

eye movcnients Total

I\!o. per min

Dream Hypnotic 1 Hypnotic 2 Natural 1 Natural 2 Imag. control Imag. control

X.6

(33.4) 23.0 (k5.4)

5.6 (_t2.I) I 2

5.6 C-tZ.4) 4.0 Ci I ,9) 4 9 (1-3.5)

duration (secj

89. I c+14.5) 74.9 (i 133) 3X.6(t17.2) “9.4 (+15.i) 20.7 (1-14.7) 29.8 (kl5.5)

most vivid. The mean rates and durations of horizontal eye movements during the different dreams are summarized in table 3. Neither the mean rates nor mean durations for the hypnotic dreams difrered significantly between sessions I and 2. Similarly, the means for the natural dreams did not differ significantly between sessions I and 2, but in both cases these means were significantly lower than those of the hypnotic dreams (rate, p < 0.001 ; duration, p < 0.05). There were no significant differences in the means between the natural dreams of either session and those of the imagination dreams for control groups 1 and 2. 4. Discussion As remarked earlier (Tebecis et al., 1975), generalizations from this study must be made cautiously since the sample size was small and the subjects may not be representative of the whole population. It is also true that since the magnitude of the eye movements recorded in this investigation is dependent on both the amplitude of the eye movements and the size of the cornea-retinal potential, the effects described here may be due to electro-ocular differences between the conditions examined rather than changes in actual excursion of the eyes. Each interpretation has its own implications of course, and these may be just as important for one possibility as the other. 4.1. Atnplitude qf’ e)-e clos~we mu’ e>.e,flutter Approximately half the experimental subjects rolled their eyes upwards to a significantly greater extent on hypnotic induction than when closing them in the awake condition. Spontaneous fluctuations in the electro-ocular potential probably had a negligible effect on the results obtained, as absolute values were not determined; relative changes from a particular baseline were compared over relatively short periods of time, and in no case were compared movements separated by more than 2 min.

That the amplitude of upward eye movement is somehow related to hypnosis has been recently demonstrated by Spiegel (1972), who found that the degree of upward eye roll predicts hypnotizability in most individuals - the greater the roll, the higher the hypnotizability. The possible mechanisms involved are open to speculation. Of some interest in this regard is the study by Bakan (1969), who found that the direction of Iaterul eye movements during reflection or inwardly directed attention is related to hypnotic susceptibitity, a predominance of left eye movements being associated with greater hypnotizability. Bakan interpreted this in terms of functional asymmetry of the brain. The occurrence of vertical eye flutter during hypnosis is well known and is used clinically, but no systematic study has been reported about the duration of eye flutter in hypnosis and the awake condition of a large number of subjects varying in hypnotic susceptibility. The observation that at least some individuals display pronounced eye flutter during hypnosis but not while awake warrants further investigation (see also Lippold, 1973). Bogoslovsky, Kovalchuk and Makarenko (1973) reported that the electroretinogram was not obviously affected by hypnosis, but that spontaneous nystagmus disappeared during hypnosis even though no specific suggestions were given. However, few details were given in this short comnlunication. 4.2. Rapid eye morements (eyes closed) The results reported here confirm and extend the observations by Schiff, Bunney and Freedman ( 196 I ), Amadeo and Shagass ( 1963), Brady and Rosner (1966) and Weitzenhoffer (1969) who also found that REMs decrease during hypnosis compared with the awake condition. Amadeo and Shagass (1963) concluded that the REM rate increases as a non-specific concomitant of attention, and that the decrease during hypnosis indicates a state of diminished attention. These conclusions were based on the observations that in the awake condition, REM frequency increased during tasks involving visual imagery and increased attention, and that the decrease in REM rate during passive hypnosis was to some extent counteracted by asking subjects to do mental arithmetic while hypnotized. Although Antrobus, Antrobus and Singer (1964) subsequently confirmed that the REM rate decreases during lessened attention in the awake state, Weitzenhoffer and Brockmeier( 1970) have recently challenged this view. In their experiments, REM rate decreased during attentive activity when the eyes were open, and there were no consistent changes when the eyes were closed (awake). The reasons for the discrepancies are not clear, but may be due to methodological differences. 4.3. S/OM~ere moremenls (eyes closet/) Weitzenhoffer (1969, 197ia) has described SEMs (of the type reported here) occurring during hypnosis only in highly hypnotizable subjects, generally when

hypnosis was prolonged. In particular, the subjects who exhibited SEMs during hypnosis were unable to reproduce them voluntarily without extensive coaching and practice. In the deeply hypnotized subjects instructions to open the eyes abolished the SEMs, but they returned when the eyes were closed again. SEMs have not been studied as extensively as REMs, but it is likely that the SEMs described here and by Weitzenhoffer (1969, 197la) are similar to the slow eye movements originally described by Aserinsky and Kleitman (1955) as occurring at the onset of sleep (descending stage 1 or transitional sleep), but not during later stages of sleep unless the individual makes body movements. Although the EEG patterns, behavioural observations and subjective reports suggested that our subjects had not fallen asleep to any notable extent during the 20 min periods analysed, it was impossible to be certain if or how much contamination there was from sleep (see Tebecis et al., 1975). However, the mean SEM rates were also higher during the 2 min hypnosis periods, when the subjects certainly did not sleep. Aserinsky and Kleitman (1955) suggested that the SEMs which appear during stage 1 sleep (extreme relaxation) result from the loss in tone of the extraocular muscles, the loss of supra-nuclear fixational control producing uncoordinated movements of antagonist muscles. This is a reasonable possibility, but does not explain why SEMs do not occur during other phases of sleep which are associated with deep relaxation.

The eye movements observed in these tests are clearly different from those that occur during normal optokinetic nystagmus conditions (Dichgans and Jung, 1969). The mean rate of horizontal eye movements during each hypnosis session was higher than that for the imagination session of the experimental subjects, but the differences were not statistically significant, although approximately one-third of these subjects made significantly more lateral eye movements during hypnosis than in the imagination condition. However, the mean rates of eye movements for both the hypnosis groups and control group I were significantly greater than that for control group 2, confirming the conclusion from the BSS scores that theexperimental subjects were more suggestible while awake than the random controls. Thus, either these subjects performed better during hypnosis because they thought this was expected of them or hypnosis can be considered a state in which responses to suggestions are facilitated. 4.5. ’ Dreamitlg’ The word dream in this paper is merely used descriptively and is not to be likened to nocturnal dreams that occur in natural sleep. A critical review of most studies of hypnotic dreams suggests that they are not equivalent to sleep dreams, although a number of similarities are apparent (Tart, 1965; Levitt

and Chapman, 1973). In the present study all dreams occurred during waking EEG patterns (including alpha activity), an observation made earlier of hypnotic dreams (Schiff et al., 1961 ; Tart, 1964). The main aim of our ‘dreaming’ study was to determine whether subjects perform differently between the hypnotized and awake conditions if they receive practically identical instructions on both occasions. An inescapable criticism of most studies of this type is that subjects perform better during hypnosis because of the experimenters’ expectations (demand characteristics). In the dreaming study, however, it is unlikely that subjects expected to dream more vividly during hypnosis in which sleep was not mentioned than during the awake period in which suggestions were given to sleep and to dream naturally. Our results are consistent with those of Brady and Rosner (1966) (see also Schiff et al., 1961; Weitzenhoffer, 1971 b) who found that the range of eye movements during hypnotic dreams is significantly increased above that induced by attention in either the waking or hypnotized condition. Eye movements did not increase during imagined dreaming by their control subjects, and in our study less than a third of the random control subjects made eye movements during the imagined dream, although the mean number of movements was significantly lower than those of the hypnotic dreams of the experimental subjects. 4.6. Trmtce z~ersus non-trance theories ofhypltosis A number of theories to explain hypnosis have been proposed, but all of these can be broadly placed into either those supporting or those opposing a special state or trance for hypnosis. Meares (1957) and Gill and Brenman (1959) consider hypnosis to be a regression (in the service of the ego or primitive mental functioning). Orne (1959, 1962) and Shor (1959, 1962) also consider hypnosis as a particular state which adds something to the suggestions given. Opposed to the trance concept are Sarbin and Coe ( 1972) who explain hypnotic behaviour in terms of role theory, and Barber (I969), who has adopted the behaviouristic ‘input-output’ approach. These and other views have been adequately discussed in recent reviews (Hilgard, 1973; Barber, 1973) and will not be repeated here. In this study of eye movements characteristic differences appear to be associated with the awake and hypnotized conditions. During passive hypnosis the eyes rolled upwards to a greater extent, fluttered, REMs decreased and SEMs increased (and body movements decreased) compared with the awake state of a number of subjects. Similarly, the subjective involvement and performance of subjects generally improved during hypnosis when the BSS, nystagmus and dreaming tests were done. It is not implied that these physiological changes are specific to the hypnotic state, but it is noteworthy that certain changes do occur during hypnosis and that these can often be qualitatively and quantitatjvely distinguished from the awake conditjon.

Acknowledgements We are grateful to Professor P. Pentony and Dr. R. W. Farnbach, who participated in some of these experiments. We sincerely appreciate the support of Professor P. 0. Bishop, the skilled assistance of Mr. G. Klock and Mr. N. Harvey, the typing done by Ms. Lyn Speight, Ms. Marguerite Woodward and Ms. Susan Macdonald and the voluntary co-operation of all the subjects.

Amadeo. M. and

Shagass,

Nervous and Mmfaf

C. (1963).

movements, attention and t 45.

Eye

Di.semr. 136, l39-

hypnosis.

Jowttaf of

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47 SchitT, S. K., Hunney, W. E. and Freedman, D. X. (1961).A study of ocular movements in hypnotically induced dreams. Journal qf’Nerrous and h4ental Disease, 133, 59-68. Shor, R. E. (1959). Hypnosis and the concept of general reality orientation. .4merican Journal of’Psychotherapy, 13,582-602. Shor, R. E. (1963). Three dimensions of hypnotic depth. international Journal of’ Clinical and Experimental Hypnosis, 10,23-28. Spiegel. H. (1972). An eye-roll test for hypnotizability. AmericanJourna/ofC/inica/ Hypnosis, l&25-28. Tart, C. T. (1964). A comparison of suggested dreams occurring in hypnosis and sleep. International Journal q,f Clinical and E.vper-imental Hypnosis, 12,263-289. Tart, C. T. (1965). The hypnotic dream: methodological problems and a review of the literature. Psychological Bulletin, 63, 87-99. Tebccis, A. K. and Provins, K. A. (1974a). An investigation of some physiological concomitants of hypnosis. Proceedings of’rhe First Conference in E.\-perimental Ps_vchology, Monash University, Australia, 28-30 June, 1974. Tebecis, A. K. and Provins, K. A. (1974b). Accuracy of time estimation during hypnosis. Perceptual und Motor Ski!l.v, 39,1123-l 126. Tebecis, A. K. and Provins, K. A. (1975). Further studies of physiological concomitants of hypnosis: Skin temperature, heart rate and skin resistance (submitted for publication). Tebecis, A. K., Provins, K. A., Farnbach, R. W. and Pentony, P. (1975). Hypnosis and the EEG: A quantitative investigation. Journal oJ’Nerwus and Mental Disease (in press). Weitzenhoffer, A. M. (1969). Hypnosis and eye movements. I. Preliminary report on a possible slow eye movement correlate of hypnosis. American Journal qf’C/inica/ Hypnosis, 11, 221-227. Weitzenhoffer, A. M. (197la). Ocular changes associated with passive hypnotic behavior. American Journal of Clinical Hypnosir, 14, 102-I 21. Weitzenhoffer, A. M. (1971b). A case of pursuit-like eye movements directly reflecting dream content during hypnotic dreaming. Perceptualand Motor Ski//s, 32,701-702. Weitzenhoffer, A. M. and Brockmeier, J. D. (1970). Attention and eye movements. Some results and general considerations. Journal o/‘Nerrous und Mental Disease, 151, 130-142.