Binaural-Beat Induced Theta EEG ActivityBinaural-Beat Induced Theta EEG Activity
        and Hypnotic Susceptibility
        D. Brian Brady 
        Northern Arizona University
              May 1997
 
ABSTRACT
 
Six participants varying in degree of hypnotizability (two lows, two mediums, 
and two highs) were exposed to three sessions of a binaural-beat sound 
stimulation protocol designed to enhance theta brainwave activity. The Stanford 
Hypnotic Susceptibility Scale, Form C (SHSS:C) was used for pre and 
post-stimulus measures of hypnotic susceptibility. Time-series analysis was used 
to evaluate anterior theta activity in response to binaural-beat sound 
stimulation over baseline and stimulus sessions. A protocol designed to increase 
anterior theta activity resulted in a significant increase in theta measures (% 
activity) between pre-stimulus baseline and stimulus observations for five of 
six participants. Hypnotic susceptibility levels remained stable in the 
high-susceptible group, and increased moderately in the low and medium 
susceptible groups.
 
INTRODUCTION
Differential individual response to hypnosis, has, captured the attention of 
hypnosis practitioners and researchers since the time of Mesmer, in the late 
18th century. Despite the long recognized importance of individual variation in 
hypnotizability, efforts to modify or increase individual hypnotic 
susceptibility have proven to be problematic and controversial.
Part of the difficulty in addressing the nature of hypnotizability has been the 
lack of consensus regarding the basic phenomena of hypnosis. The central issue 
has been whether observed hypnotic responses are due to an altered stated of 
consciousness or merely the product of psychosocial factors.
Considering hypnosis as either an altered state or as a purely psychosocial 
phenomenon served to provide two opposing factions into which most theories of 
hypnosis could be grouped. Contemporary hypnosis researchers tend to hold less 
extreme positions, realizing the benefit of a perspective which is comprised of 
the strengths of both the special-process (i.e., altered state of consciousness) 
and the social-psychological theoretical domains.
Theoretical Perspectives of Hypnosis
The 1960's witnessed the advent of standardized hypnotic susceptibility 
measurements. Reliable standardized instruments have been developed for use with 
groups and individuals. Early work with the electroencephalogram (EEG) designed 
to identify hypnotic susceptibility also began around this time. More recent EEG 
/ hypnosis research has focused on electrocortical correlates of both the state 
of, and differential individual response to, hypnosis. The concept of a reliable 
electrocortical correlate of hypnotic susceptibility draws attention to the 
recent applications of neurofeedback therapy, which has employed a number of 
protocols designed for individual brainwave modification. Recent advances in the 
application of binaural-beat technology and the associated EEG frequency 
following response, which can be either relaxing or stimulating, have 
demonstrated efficacy of brainwave modification in areas such as enriched 
learning, improved sleep, and relaxation (Atwater, 1997). In consideration of 
recent EEG / hypnosis research along with the recently demonstrated efficacy of 
EEG neurofeedback training research and the binaural-beat technology 
applications, it would seem that the lingering question of hypnotizability 
modification can now be addressed by utilizing brainwave modification within a 
systematic protocol.
As mentioned earlier, it has often been the case in the past to view the field 
of hypnosis as being dominated, theoretically, by two opposing camps; the 
special-process and the social-psychological. In general, the special-process 
view holds that hypnosis induces a unique state of consciousness; whereas, the 
social-psychological view maintains that hypnosis is not a distinct 
physiological state.
Popular authors of the post-Mesmeric period (i.e., mid 19th century), such as 
James Braid, proposed psychophysiological and sometimes neurophysiological 
explanations for the hypnotic phenomenon (Sabourin, 1982). In fact, Braid 
adopted the term "neuro-hypnology" to describe the phenomenon and is credited as 
the originator of the term "hypnosis" (Bates, 1994, p. 27). The work of other 
English physicians, such as John Elliotson and James Esdaile, on surgical 
anesthesia and clinical pain relief in the mid-19th century (Soskis, 1986), are 
indicative of the psychophysiological zeitgeist of hypnosis in that time. This 
physiologically-oriented perspective is reflected in Hilgard's neodissociation 
model (Hilgard, 1986), which suggests that hypnosis involves the activation of 
hierarchically arranged subsystems of cognitive control. This dissociation of 
consciousness is clearly manifested in the realm of hypnotically induced 
analgesia. Hilgard's conception of a "hidden observer" (Hilgard, 1973) as a 
dissociated part of consciousness, a part that is always aware of nonexperienced 
pain and can be communicative with the therapist, is exemplified in his 
description of a hypnotically analgesic individual whose hand and arm were 
immersed in circulating ice water as follows:
 
All the while that she was insisting verbally that she felt no pain in hypnotic 
analgesia, the dissociated part of herself was reporting through automatic 
writing that she felt the pain just as in the normal nonhypnotic state. (p. 398)
 
In Hilgard's model, the hidden observer is the communication of the above 
described subsystem not available to consciousness during hypnosis. It is 
reasonable to assume, considering hypnosis research with pain control, that such 
a dissociative effect of cognitive functioning (i.e., cortical inhibition) would 
have, as a substrate, some neuropsychophysiological correlate.
Often the social-psychological or social-learning position sees hypnotic 
behaviors as other complex social behaviors, the result of such factors as 
ability, attitude, belief, expectancy, attribution, and interpretation of the 
situation (Krisch & Lynn, 1995). The influence of such variables as learning 
history and environmental influences are described by Barber (1969). In this 
influential discourse, Barber presents a framework in which hypnotic responding 
is related to antecedent stimuli, such as expectations, motivation, definition 
of the situation, and the experimenter-subject relationship. Diamond (1989) 
proposed a variation of the social-psychological view which emphasized the 
cognitive functions associated with the experience of hypnosis, as described in 
the following:
 
It may be most fruitful to think of hypnotizability as a set of cognitive skills 
rather than a stable trait. Thus, it is conceivable that the so called 
"insusceptibe" or refractory S [subject] is 'simply less adept at creating, 
implementing, or utilizing the requisite cognitive skills in hypnotic test 
situations. Similarly, what makes for a highly responsive or "virtuoso" S may 
well be precisely the ability or skill to generate those cognitive processes 
within the context of a unique relationship with a hypnotist. (p. 382)
 
According to the social-psychological paradigm, an individual's response to 
hypnosis is related to a disposition toward hypnosis, expectations, and the use 
of more effective cognitive strategies, not because the individual possesses a 
certain level of hypnotic ability. An important implication of the social 
psychological or social-learning theory is that an individual's level of 
hypnotizability can be modified and thus enhanced with systematic strategies to 
accommodate for individual deficiencies. These two positions can no longer be 
perceived as a dichotomy, but more accurately as overlapping areas in a Venn 
diagram. It is not difficult for one to recognize the role of both individual 
characteristics (i.e., differential neurological activity) and contextual 
variables (i.e., psychosocial constructs) in measuring and determining the 
hypnotic response. In other words, the hypnotic response can be viewed as a 
product of a trance-like state of altered consciousness, which is itself 
moderated by psychosocial factors such as social influence, personal abilities, 
and possibly the effects of modification strategies. Such a perspective allows 
for a more complete investigation of the nature of hypnotic susceptibility by 
taking into account the relevant issues within each position.
Importance of Individual Differences
In the middle 1960's the focus on hypnotic research was dominated by a trait, or 
individual difference, approach. The use of standardized hypnotic susceptibility 
measurements became common. Most practitioners today tend to view hypnotic 
susceptibility as a relatively stable characteristic that varies across 
individuals. This view, and the realization of individual variability in the 
ability to experience hypnosis, are not new ideas, as Mesmer long ago emphasized 
the individual's receptivity to hypnotic process (Laurence & Perry, 1988). 
Braid, an English physician during the 19th century, described the remarkable 
differences of different individuals in the degree of susceptibility to the 
hypnotic experience (Waite, 1960). The importance of within-individual 
variability in hypnotic susceptibility is also found in Braid's comments that 
individuals are affected differently, and that even the same individual could 
react differently at different times to hypnosis (Waite, 1960). Differential 
responses to hypnosis were recognized by Freud in his attempts to determine 
which patients would be the most responsive to hypnotic training. Freud, like 
others at this time, was unable to identify reliable correlates of 
hypnotizability. Freud's frustration is reflected in his observation that "We 
can never tell in advance whether it VAII be possible to hypnotize a patient or 
not, and the only way m have of discovering is by the attempt itself' (Freud, 
1966, p. 106). This view is reflected in the methodology of current standardized 
scales of hypnotizability which use direct measures of hypnotic responses to 
determine level of hypnotizability.
Differential treatment outcome, associated with individual differences in the 
way individuals respond to hypnosis, has been observed by practitioners for 
centuries. Hypnotic susceptibility may also be a relevant factor in the practice 
of health psychology / behavioral medicine. Bowers (1979) suggested that 
hypnotic ability is important in the healing or improvement of various somatic 
disorders. He has also provided evidence that therapeutic outcomes with 
psychosomatic disorders "re correlated with hypnotic susceptibility, even Men 
hypnotic procedures were not employed (Bowers, 1982). Significant relationships 
have been found between hypnotizability and the reduction of chronic pain, 
chronic facial pain, headaches, and skin disorders (e.g., warts, chronic 
urticaria, and atopic eczema) with hypnotic techniques (Brown, 1992). Support 
for the interaction of negative emotions and hypnotic ability as a mediator of 
symptoms and disease has also been provided by recent research (Wickramasekera, 
1979,1994; Wickramasekera, Pope, & Kolm, 1996). A recent article by 
Ruzyla-Smith, Barabasz, Barabasz & Warner (1995), measuring the effects of 
hypnosis on the immune response, found significant increases in B-cells and 
helper T-cells only for the highly hypnotizable participants in the study. This 
report not only suggests that hypnosis can modify the activity of components of 
the immune system, but also highlights the importance of individual variability 
in response to hypnosis.
In terms of modification of hypnotizability, initial hypnotic susceptibility 
level may be a factor in the resulting degree of modification. In a paper 
discussing the issue of hypnotizability modification, Perry (1977) presented a 
number of studies employing a range of less susceptible individuals for 
modification training. Overall, the attempts to modify hypnotizability were 
unsuccessful in these studies. Perry suggested that successful modification 
tends to be more common in medium susceptible individuals. It may be that the 
medium susceptible individual, having already demonstrated a certain degree of 
hypnotic ability, possesses the underlying cognitive framework essential to the 
hypnotic experience. This line of reasoning could explain the differential 
responses of low susceptible and medium susceptible individuals to 
hypnotizability modification training. The high susceptible individual could 
also prove to be less responsive to modification strategies compared to the 
medium susceptible individual, as a potential exists for a ceiling effect with 
the high susceptible individual.
Standardized Measures of Hypnotic Susceptibility
The long observed differences in individual response to hypnosis eventually led 
to the development of the first viable measures of hypnotizability, the Stanford 
Hypnotic Susceptibility Scale, Forms A and B (SHSS:A and SHSS:B) by 
Weitzenhoffer and Hilgard (1959). The introduction of the Stanford Hypnotic 
Susceptibility Scale, Form C (SHSS:C) by Weitzenhoffer and Hilgard (1962) 
represented an improved version of the two earlier forms; it was comprised of a 
greater proportion of more difficult cognitive items. The SHSS:C is still the 
prevalent measure of hypnotic susceptibility in current use and is often the 
criterion by which other measures of hypnotizability are evaluated (Perry, 
Nadon, & Button, 1992). This instrument is essentially an ascending scale which 
begins with relatively easy hypnotic induction procedures and progressively 
moves to more difficult trance challenges.
A recent study by Kurtz & Strube (1996), comparing a number of hypnotic 
measures, described the SHSS:C as the gold standard of susceptibility tests. 
This study also addressed the idea of using multiple measures of hypnotic 
susceptibility in order to improve predictive power over using a single 
administered test. Kurtz & Strube (1996) concluded that the use of multiple 
measures of susceptibility was not warranted, and that the "rational" choice for 
a single measure of hypnotic susceptibility would be the SHSS:C.
Research with the EEG and Hypnotic Susceptibility
Brainwaves are the far-field electrical wave patterns set up by neurochemical 
activity in the living brain. The electroencephalograph (EEG) is an instrument 
which can measure this activity and determine its strength (higher or lower 
amplitude) and speed (high or low frequency). Scientists have characterized 
brainwaves into four broad categories: (a) beta, brainwaves above 13 cycles per 
second (or hertz), indicative of active consciousness; (b) alpha, a slower 
brainwave ranging from 8 to l2 hertz, characteristic of a relaxed conscious 
state of awareness; (c) theta, the next slower waves ranging from 4 to 8 hertz, 
often associated with dreamlike imagery and deep relaxation; (d) delta, the 
slowest waves from 0 to 4 hertz which can predominate during dreamless sleep.
 
The majority of early research with hypnosis shared a common goal: the 
development of a methodology to determine if, and when, an individual is 
hypnotized. The majority of early EEG research with hypnosis focused on the 
state of hypnosis, often attempting to distinguish the state of hypnosis from 
the state of sleep (Sabourin, 1982). Weitzenhoffer's 1953 review of studies 
utilizing the EEG with hypnosis concluded that hypnosis is perhaps more akin to 
light sleep than either deep sleep or the waking state.
A shift occurred in the late 1960's as researchers began investigating possible 
electrocortical correlates of hypnotic susceptibility using the EEG. The 
predominant focus in hypnosis research from this time forward was on individual 
differences rather that the hypnotic state per se. Much of the early research 
focused on alpha wave indices of hypnotic susceptibility. A review by Dumas 
(1977) found that no alpha-hypnotizability correlation existed in the general 
population. Additionally, a recent critical review by Perlini & Spanos (1991) 
offered little support for an alpha-hypnotizability relationship. Other early 
studies found greater resting theta wave activity with highly susceptible 
individuals (Galbraith, London, Leibovitz, Cooper & Hart, 1970; Tebecis, 
Provins, Farnbach & Pentony, 1975; Akpinar, Ulett, and ltil, 1971). Overall, the 
comparison of early EEG research proves difficult given the aggregate of 
technologies and methodologies employed over a span of time characterized by 
extreme variance in technological development.
Recent studies have reexamined the relationship between EEG measures and 
hypnotic susceptibility based on rigorous subject screening and control, along 
with enhanced recording and analytic techniques. Sabourin, Cutcomb, Crawford, 
and Pribram (1990) found highly hypnotizable subjects to generate substantially 
more mean theta power than did low hypnotizable subjects in frontal, central, 
and occipital derivations during resting nonhypnotic baseline, with largest 
differences observed in the frontal (F3, F4) locations. According to a review by 
Crawford and Gruzeiler (1992), theta activity, which is strongly and positively 
related to hypnotic susceptibility, is the most consistent EEG correlate of 
hypnotic susceptibility. The results of a recent study by Graffin, Ray & Lundy 
(1995) indicate that highly hypnotizable subjects demonstrate significantly more 
theta activity in frontal (F3, F4) and temporal (T3, T4) areas in comparison to 
low hypnotizable subjects at baseline measures. The studies by Sabourin et al. 
(1990) and Graffin et al. (1995) are alike in that each employed fast Fourier 
transformation (FFT) and power spectral analysis of monopolar EEG derivations, 
which allows for the examination of activity within each component frequency of 
each EEG epoch.
The position which is most supported in the contemporary literature is a 
consistent pattern of EEG activity which can differentiate individuals according 
to standardized hypnotic susceptibility scores. It is suggested that 
high-susceptible individuals produce more anterior theta activity as compared to 
low-susceptible individuals. This baseline individual difference is an important 
neuropsychophysiological indicator of hypnotizability and could prove to be a 
more stable individual difference measure than standard psychometric measures 
(Graffin et al., 1995).
Theta Waves and Perceptual Variations
The relationship between theta activity and selective attentional processes 
lends further support to a coexistent relationship with hypnotizability. The 
concepts of Class I and Class 11 inhibition have been presented by Vogel, 
Broverman, & Klaiber (1968). Class I inhibition is described as being correlated 
with a general inactivity or drowsiness, whereas Class 11 inhibition is related 
to more efficient and selective attentional processes. The Class 11 concept of 
slow wave activity is described by Vogel et al. (1968) as "a selective 
inactivation of particular responses so that a continuing excitatory state 
becomes directed or patterned (p. 172)". Sabourin et al. (1990) suggested that 
the theta activity observed in highly hypnotizable subjects reflects involvement 
in greater absorptive attentional skills. As in the Sabourin et al. (1990) 
study, Graffin et al. (1995) provide suggestions regarding the selective 
attentional component of theta: " high hypnotiizables either possess, or can 
manifest, a heightened state of attentional readiness and concentration of 
attention" (p. 128). The relationship between greater attentional readiness and 
frontal theta has also been suggested in psychophysiological studies (Bruneau et 
al., 1993; Ishihara & Yoshii, 1972; Mizuki et al., 1980). Another possible 
supportive line of research involves the examination of psychological absorption 
and hypnotizability relationships. Studies have found absorption to be 
consistently correlated with hypnotizability (Glisky, Tataryn, Tobias, 
Kihlstrom, & McConkey, 1991; Nadon, Hoyt, Register, & Kihlstrom, 1991; Tellegen 
& Atkinson, 1974). In a review of psychological correlates of theta, Schacter 
(1977) described the relationship between the hypnagogic state and the presence 
of low voltage theta activity. Green & Green (1977) described the theta state as 
that of reverie and hypnogogic imagery. They employed theta neurofeedback 
training to induce quietness of body, emotions, and mind, and to build a bridge 
between the conscious and unconscious. In describing theta EEG brainwave 
biofeedback, the Life Sciences Institute of Mind-Body Health (1995) associated 
increased theta activity with "states of reverie that have been known to 
creative people of all time" (p. 4).
Considering these findings related to theta activity, a relationship between 
individual levels of hypnotizability, selective inhibition, hypnogogic reverie, 
and theta activity is more easily understood. Relatively high theta activity may 
be indicative of a characteristic brainwave pattern which reflects an underlying 
cognitive mechanism that relates to a type of selective inhibition and 
hypnogogic imagery.
Research with Neurofeedback Training
Neurofeedback training works on the brain's ability to produce certain 
brainwaves the way exercise works to strengthen muscles. EEG biofeedback 
instruments show the kinds of brainwaves an individual is producing, making it 
possible for that individual to learn to manipulate the observed brainwaves.
Demonstrated individual success acquiring the ability to self-regulate 
characteristic brainwave patterns is evident in the neurofeedback literature. 
Various protocols have been employed by many practitioners to enhance both 
relaxation (an increase in production of slow waves, such as theta, and a 
decreased production of fast beta waves) and mental activity (a decrease 
production of excessive slow wave, such as delta and lower frequency theta; with 
an increase in the production of 'fast" beta waves). An impressive number of 
recent studies have demonstrated the efficacy of brainwave neurofeedback 
training. The work by Peniston and others with individuals with alcohol abuse 
issues (Peniston & Kulkosky, 1989, 1990, 1991; Saxby and Peniston, 1995) has 
provided remarkable results. Peniston has shown 13 month follow-up relapse rates 
of 20% (compared to 80% using conventional medical training), significant 
reductions in Beck Depression Inventory scores, and decreased levels of 
beta-endorphin in subjects treated with Alpha-Theta brainwave training. The area 
of attention deficit hyperactivity disorder (ADHD) has received strong attention 
from neurofeedback researchers (Barabasz & Barabasz, 1995; Lubar, 1991; Rossiter 
& Vaque, 1995). Lubar's work has provided strong support for the effectiveness 
of a protocol designed for Beta-training (16-20 Hz) and Theta inhibition (4-8Hz 
), with 80% of 250 treated children showing grade point average improvements of 
1.5 levels (range 0-3.5) (Lubar, 1991). Objective assessments of the efficacy of 
neurofeedback training for ADHD have shown significant improvements on the Test 
of Variables of Attention (T.O.V.A.) scales and Wechsler Intelligence Scale for 
Children-Revised (WISC-R) IQ scores with subjects who demonstrated significant 
decreases in theta activity across sessions (Lubar, Swaamod, Swartwood, & 
O'Donnell, 1995). Additional studies with post-traumatic stress disorder (PTSD) 
with Vietnam veterans (Peniston, 1990; Peniston & Kulkosky, 1991; Peniston, 
Marrinan & Deming, 1993) have provided unprecedented results with a condition 
often very resistant to training with other interventions.
The work by Ochs (1994) with the use of light and sound feedback of EEG 
frequencies, EEG disentrainment feedback (EDF), is also promising in terms of 
modification of EEG patterns. However, unlike traditional EEG biofeedback, with 
Dr. Ochs' device there is no need for the individual to be consciously involved 
in the process. The visual and auditory stimuli respond to and match the 
individual's brainwaves and these stimuli are in turn generated by the overall 
frequency of the individual's brainwaves. The aptitude of this system is the 
capacity for the clinician to alter the feedback frequencies upward or downward, 
in effect, providing flexibility into a "set" or "characteristic" brainwave 
pattern.
The flexibility of individual neurofeedback training is evident in the various 
approaches designed to intensify certain types of EEG activity either by itself, 
or to intensify certain types of EEG activity and decrease other types of EEG 
activity occurring at the same time. Overall, the relatively high number of 
recent neurofeedback training studies with consistent positive results strongly 
demonstrate the changes in cognitive and behavioral variables resulting from the 
alteration of individual brainwave patterns.
Research with Binaural-Beat Sound Stimulation
Binaural-beat stimulation is an important element of a patented auditory 
guidance system developed by Robert A. Monroe. In fact, Robert Monroe has been 
granted several patents for applications of psychophysical entrainment via sound 
patterns in (Atwater, 1997). In the patented process referred to as Hemi-Sync 
individuals are exposed to factors including breathing exercises, guided 
relaxation, visualizations, and binaural beats. Extensive research within the 
Monroe Institute of Applied Sciences, which has documented physiological changes 
associated with Hemi-Sync use, along with consistent reports of thousands of 
Hemi-Sync users, appears to support the theory that the Hemi-Sync process 
encourages directed neuropsychophysiological variations (Atwater, 1997).
The underlying premise of the Hemi-Sync process is not unlike that adopted by 
many EEG neurofeedback therapists, that an individuals' predominant state of 
consciousness can be reflected as a homeostatic pattern of brain activity (i.e., 
an individual differential bandwidth activity within the EEG spectrum) and can 
often be resistant to variation. Atwater (1997) reported that practitioners of 
the Hemi-Sync process have observed a state of hypnagogia or experiences of a 
kind of mind-awake/body asleep state associated with entrainment of the brain to 
lower frequencies (delta and theta) and with slightly higher-frequency 
entrainment associated with hyper suggestive states of consciousness (high theta 
and low alpha). In line with current EEG research relating to ADHD (see 
Lubar,1991), Hemi-Sync researchers have noted deep relaxation with entrainment 
of the brain to lower frequencies and increased mental activity and alertness 
with higher frequency entrainment. The Monroe Institute has been refining 
binaural-beat technology for over thirty years and has developed a variety of 
applications including enriched learning, improved sleep, relaxation, wellness, 
and expanded mind-consciousness states (Atwater, 1997).
Binaural beat stimulation can be further understood by considering how we detect 
sound sources in daily life. Incoming frequencies or sounds can be detected by 
each ear as the wave curves around the skull by detraction. The brain perceives 
this differential input as being "out of phase", and this waveform phase 
difference allows for accurate location of sounds. Stated simply, less noise is 
heard by one ear, and more by the other. The capacity of the brain to detect a 
waveform phase difference also enables it to perceive binaural beats (Atwater, 
1997). The presentation of waveform phase differences (different frequencies), 
which normally is associated with directional information, can produce a 
different phenomenon when heard with stereo headphones or speakers. The result 
of presenting phase differences in this manner is a perceptual integration of 
the signals; the sensation of a third "beat" frequency (Atwater, 1997). This 
perception of the binaural-beat is at a frequency that is the difference between 
the two auditory inputs. 
Binaural beats can easily be heard at the low frequencies (<30 Hz) that are 
characteristic of the EEG spectrum (Austere, 1973). This perception of the 
binaural-beat is associated with an EEG frequency following response (FFR). This 
phenomenon is described by Atwater (1997) as EEG activity which corresponds to 
the fundamental frequency of the stimulus, such as binaural-beat stimulation.
The sensation of auditory binaural beating occurs when two coherent sounds of 
nearly similar frequencies are presented one to each ear with stereo headphones 
or speakers. Originating in the brainstem's superior olivary nucleus, the site 
of contralateral integration of auditory input (Oster, 1973), the audio 
sensation of binaural beating is neurologically conveyed to the reticular 
formation (Swann, Bosanko, Cohen, Midgley & Seed, 1982) and the cortex where it 
can be observed as a frequency-following response with EEG equipment. The word 
reticular means 'net-like' and the neural reticular formation itself is a large, 
net-like diffuse area of the brainstem (Anch, et al. 1988). The RAS regulates 
cortical EEG (Swann et al. 1988) and controls arousal, attention, and awareness 
- the elements of consciousness itself (Tice & Steinberg, 1989; Empson, 1986). 
How we interpret, respond, and react to information (internal stimuli, feelings, 
attitudes, and beliefs as well as external sensory stimuli) is managed by the 
brain's reticular formation stimulating the thalamus and cortex, and controlling 
attentiveness and level of arousal (Empson, 1986). Binaural beats can influence 
ongoing brainwave states by providing information to the brain's reticular 
activating system (RAS). If internal stimuli, feelings, attitudes, beliefs, and 
external sensory stimuli are not in conflict with this information, the RAS will 
alter brainwave states to match the binaural-beat provocation.
A recent study by Foster (1991) was conducted in an effort to determine the 
effects of alpha-frequency binaural-beat stimulation combined with alpha 
neurofeedback on alpha-frequency brainwave production. Foster found that the 
combination of binaural-beat stimulation and alpha neurofeedback produced 
significantly higher alpha production than that of neurofeedback alone, but that 
the group which received only binaural-beat stimulation, produced significantly 
higher alpha production than either group. In a review of three studies directed 
towards the effects of Hemi-Sync tapes on electrocortical activity, Sadigh 
(1994) reported increased brainwave activity in the desired direction after 
virtually minutes of exposure to the Hemi-Sync signals. 
Research to date, therefore, has suggested that the use of the binaural-beat 
sound applications can contribute to the establishment of prescribed variation 
in individual psychophysiological homeostatic patterns (brainwave patterns), 
which can precipitate alterations in cognitive processes. The relationship 
between individual patterns of cognitive variables and characteristic brainwave 
patterns affords not only a methodology for change, but also an objective unit 
for measure of change.
Purpose of the Present Study
The present study was an effort to develop, and to test the efficacy of, 
techniques designed to increase anterior theta activity and susceptibility to 
hypnosis as measured by currently employed standardized instruments. 
Contemporary hypnosis / EEG research studies have found individual 
electrocortical differences (anterior theta activity) to be reliable predictors 
of hypnotic susceptibility. Clinicians and researchers within the field of 
neurofeedback training have also demonstrated the efficacy of prescribed changes 
in individual EEG patterns and behavioral variables, with a number of medical 
and psychological disorders. Practitioners and researchers utilizing the 
binaural-beat technology developed by the Monroe Institute have produced 
impressive changes in individual EEG patterns. Given the strong support of 
brainwave modification, and the efficacy of the binaural-beat sound patterns to 
modify brainwave patterns, it is logical and advantageous to make use of a 
binaural-beat sound based protocol. Since theta activity is positively related 
to individual level of hypnotic susceptibility, it follows that the employment 
of a protocol designed to increase frontal theta activity could also mediate an 
increase in hypnotic susceptibility. It was proposed that a binaural beat 
protocol designed to increase anterior theta activity will result in a 
significant increase in theta measure (% activity), and a related increase in 
hypnotic susceptibility, as measured by standardized instruments. In 
consideration of the previous association between hypnotic susceptibility and 
anterior theta activity, the potential exists for differential increases in 
theta activity relative to hypnotizability group. The examination of potential 
differential changes in theta activity relative to initial level of 
hypnotizability could provide further data supporting the association of theta 
activity and hypnotic susceptibility. 
Research Hypotheses
Hypothesis l. Increases in hypnotic susceptibility, after exposure to 
binaural-beat sound stimulation protocol, will be observed for all participants 
from pre to post-measures. The Significant Change Index (SCI) was used to 
evaluate change between pre and post SHSS:C scores. Graphing was used to provide 
visual interpretation of individual level of hypnotizability.
Hypothesis 2. Theta activity will increase in all individuals as a result of the 
binaural beat sound stimulation protocol. The C Statistic was performed on the 
time series of theta measures across baseline and stimulus sessions for each 
individual.
Hypothesis 3. Increases in theta activity after exposure to binaural-beat sound 
stimulation protocol YAII be of greatest significance in individuals in the 
medium-hypnotizable group. The C Statistic was performed on the time series of 
theta measures across baseline and stimulus sessions for each individual.
Hypothesis 4. Increases in theta activity after exposure to binaural-beat sound 
stimulation protocol will be of least significance in individuals in the low 
hypnotizable groups. The C Statistic was performed on the time series of theta 
measures across baseline and stimulus sessions for each individual.
METHOD
Participants
Six participants were selected from a pool of Northern Arizona University (NAU) 
undergraduates who were administered the Stanford Hypnotic Susceptibility Scale, 
Form C (SHSS:C, Weitzenhoffer & Hilgard, 1962). The six participants were 
grouped according to varying degrees of hypnotizability (two lows, two mediums, 
and two highs) for participation in the stimulus sessions. The variations in 
hypnotic susceptibility within each group were minimal, assuring the 
participants were relatively homogeneous in terms of initial hypnotic 
susceptibility measures. To reduce the risk of attrition during this study, 
participants were paid $40.00 each for participation in the study.
Instrument
Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C). Each participant's 
score on the SHSS:C served as a baseline measure of hypnotic susceptibility. 
Also, after completion of the three stimulus sessions, raw scores were obtained 
on the SHSS:C for each participant a second time. The raw scores obtained in 
this post4reatment evaluation provided an index of each participants' hypnotic 
susceptibility level after exposure to the binaural-beat stimulus protocol. The 
following general hypnotizability level designation and raw-score ranges are 
used with the SHSS:C: (a) low hypnotizable (0-4), (b) medium hypnotizable (5-7), 
(c) high hypnotizable (8-10), and (d) very-high hypnotizable (1 1-12).
The Kuder-Richardson total scale reliability index, which provides a measure of 
the degree of consistency of participants' responses, was reported by E. R. 
Hilgard (1965) as .85, with retest reliability coefficients ranging from .60 to 
.77 over the range of twelve items on the SHSS: C.
Apparatus
EEG-Recording. The NRS-2D (Lexicor Medical Technology, Inc.) is a miniaturized 
two channel Electroencephalograph (EEG) system. The device is approximately one 
inch tall, three inches wide, and six inches long and is connected directly to a 
486 computer via the parallel port. It has a built in impedance meter and 
operates with both BIOLEX (BLX) neurotherapy software and NeuroLex (NLX) EEG 
acquisition software. The BLX and NLX systems comprise an array of tools 
including an audio/visual display system, graphing and reporting features, fast 
Fourier transformation and spectral analysis of complex wave forms, as well as 
conventional EEG recordings. An artifact inhibit feature stops all recording 
v,/hen the artifact (e.g., eye movement or other muscle signals) exceeds the 
selected artifact inhibit amplitude threshold. The computerized system was used 
to measure participants' theta activity for each 2-second epoch. In the EEG data 
analysis, fast Fourier transformation was performed, and a power spectrum 
calculated, for each epoch.
Binaural-Beat Sound Tapes. The audio cassette tapes used in this study were 
produced by the Monroe Institute specifically for this study. Both a control 
tape and experimental tape were used in this study. The binaural beats provided 
in the experimental tape are unique in that they were designed to be complex 
brain-wave-like patterns rather than simple sine waves. The right-left 
differences in stereo audio signals on these tapes were assembled in a sequence 
to produce a dynamic wave pattern (brain-wave-like) as compared to a static, 
uniform sine wave pattern. Specifically, the experimental tape used in this 
experiment was produced with a binaural-beat pattern that represents a theta 
brainwave pattern of high hypnotic susceptibility. The Monroe Institute provided 
objective data verifying the binaural-beat components imbedded in the 
experimental tape, both in wave form and frequency spectra formats.
The experimental tape was produced with pink sound and theta binaural beats 
imbedded in carrier tones. The control tape was produced with pink sound and 
tones without binaural beats.
Procedures
General. For all participants, informed consent forms were provided. All 
participants mere debriefed at the completion of the study. All participants, at 
each stage of the study, were treated according to the ethical guidelines of the 
American Psychological Association.
Participant EEG Setup. During all sessions earlobes and the forehead electrode 
sites were cleaned with Ten-20 Abrasive EEG Prep Gel to decrease skin resistance 
prior to attaching EEG electrodes. Ten-20 EEG conductive paste was used as a 
conduction medium to fill the cups of silver-chloride electrodes. One monopolar 
EEG derivation was used, located according to the 10-20 system (Jasper, 1958) at 
FZ; the references were linked ears (R1, R2).
Participant Binaural-Beat Audio Setup. During all sessions participants wore 
headphones, providing audio input of pink sound and tones (baseline) or pink 
sound and theta binaural beats imbedded in carrier tones (stimulus).
Multiple Baseline EEG Recordings. The length of pre-stimulus session baseline 
for participants within each category of hypnotizability varied as follows: the 
duration of baseline recordings for Participant #1 was 5 minutes, Participant #2 
was 10 minutes. For each category of hypnotizability, the two participants were 
exposed to a baseline session of either 5 or 10 minutes, and three 20 minute 
stimulus sessions. This procedure allowed participants to be exposed to the same 
stimulus sessions under "time-lagged" conditions. This approach is the 
foundation of the Multiple Baseline single-subject experimental design, which 
allows for examination of changes in stimulus sessions relative to the varied 
baseline periods.
Theta Measures. EEG measures of percent theta activity at frontal (FZ) placement 
were recorded during all sessions. Data were recorded at each 2second epoch 
during EEG recording. These data support trend analysis over time of baseline 
and stimulus sessions.
Hypnotizability Measures. Pre-stimulus data for level of hypnotizability (SHSS:C 
scores) were collected for each participant during the selection process. 
Post-stimulus sessions data for level of hypnotizability (SHSS:C scores) were 
collected following each participant's last stimulus session.
Baseline Session. During this session participants were given information 
regarding-. (a) general understanding of theta binaural-beat sound stimulation 
and (b) the purpose/protocol of stimulus sessions. Prior to recording of EEG 
data, the experimenter instructed participants to close their eyes and to take 
two to three minutes to allow themselves to become relaxed. The experimenter 
instructed the participant to visualize herself as relaxed and comfortable and 
still, to experience a feeling of inner quietness. This procedure was used to 
allow the participant's brainwave activity to stabilize prior to baseline 
recordings.
Binaural-Beat Stimulus sessions. The duration of each session was 20 minutes. 
Prior to recording of EEG data, the participants were allowed 2-3 minutes for 
stabilization of brainwave activity as previously described in the baseline 
session procedures. Prior to exiting the room, the experimenter started the 
cassette tape, the EEG recording function, and turned off the overhead light, 
leaving a single table lamp as a source of illumination in the room. The 
stimulus session was preset to terminate at 20 minutes. Each participant 
completed three sessions over a period of one week.
Interviews. Following each stimulation session, each participant was asked about 
her experience. This free-flow interview was used to assess the participants' 
subjective experience of listening to the binaural-beat sound stimulation, and 
to test for adverse effects or reactions on the part of each participant. 
Schedule of Sessions. The four sessions (1 baseline and 3 stimulus) were 
completed for each participant in two meetings within a five day period. During 
the initial meeting, the participants completed the first two stimulus sessions 
in addition to the baseline session. The sessions were scheduled in this manner 
to reduce participant response cost and to decrease participant attrition. 
Participants were allowed to take breaks of approximately 1 0 minutes between 
each session. The second meeting took place on the second day following the 
initial meeting. During this second meeting the participants completed the third 
stimulus session.
Data Analysis
Data were analyzed in order to evaluate changes in theta activity across 
sessions and changes in hypnotizability levels from pre-stimulus to 
post-stimulus scale administrations (SHSS:C).
The EEG data of each 2-second epoch during the baseline sessions were averaged 
to yield 10 data points for the 5-minute baseline recording and 20 data points 
for the 1 0-minute baseline recording. The EEG data for each stimulus session 
was averaged to yield 25 data points for each 20-minute recording.
In an effort to determine if the pretest to posttest change hypnotizability 
scores on the SHSS:C exceeded that which would be expected on the basis of 
measurement error, the Significant Change Index (SCI) as suggested by 
Christensen & Mendoza (1 986) was used. Descriptive techniques (graphical 
representations) were used to indicate the change in hypnotizability from pre to 
post-measures.
The C statistic was used to analyze the series of theta activity data across 
baseline and stimulus sessions. This approach was used to determine if a 
statistically significant difference existed between baseline and stimulus 
session observations of theta activity.
When comparing baseline and stimulus sessions observations, the C statistic 
provides information about changes in the level and direction between the two 
time series. In the determination of statistical significance of an obtained C 
value, a Z value is obtained from the ratio of the C value to its standard error 
of the mean. Graphical representations of the time series of theta activity 
measures were used to allow confirmation of the statistical findings by visual 
inspection of the data. 
RESULTS
Participant Characteristics
The six participants in this study were female, ranging in age from 19 to 32. In 
order to facilitate association of each participant with relevant data, the 
following labels will be used in reference to the participants by 
hypnotizability group ( LOW, MED, HIGH) and by duration of baseline (1 = 
5-minute baseline, 2 = 1 0-minute baseline). The three participants (one from 
each hypnotizability group) with 5-minute baselines are referred to as LOW1, 
MED1 and HIGH1, the three participants (one from each hypnotizability group) 
V,/ith 10 minute baselines are referred to as LOW2, MED2, and HIGH2. The 
majority of participants reported having no previous experience with 
relaxation-oriented experiences such as hypnosis, meditation, or formal 
relaxation training. 
Test of Hypotheses
Hypothesis 1. Increases in hypnotic susceptibility, after exposure to 
binaural-beat sound stimulation protocol, will be observed for all participants 
from pre to post-measures. Both participants in the low-susceptibility group 
(LOW1, LOW2) increased by a raw score of 1 from pre to post-measures. Both of 
the participants in the medium-susceptibility group (MED1, MED2) increased to 
the raw score of 8. MED1 increased from a raw score of 6 to a raw score of 8, 
MED2 increased from a raw score of 7 to a raw score of 8. No changes in raw 
score values were observed with the participants in the high-susceptibility 
group (HIGH1, HIGH2) between pre and post- measures. A calculation of the 
Significant Change Index (SCI) [used to assess pretest to posttest SHSS:C scores 
considering the standard error of the difference (SD) between the two test 
scores: SCI value > 1.65 denotes significance at p<.05 ] for each participant in 
the low and medium susceptibility groups revealed the following values: LOW1 - 
SCI = 1.96, SD =.51, p< .05; LOW2 - SCI = 1.96, SD = .51, p< .05, MED1 - SCI = 
3.92, SD = .51, p< .05, MED2 - SCI = 1.96, SD =.51, p<.05. According to these 
calculations, a change of .84 or greater in raw-score value was required to 
establish a significantly different change in hypnotic susceptibility. 
Therefore, these data suggest that this hypothesis was supported in participants 
LOW1, LOW2, MED1, and MED2.
Hypothesis 2. Theta activity will increase in all individuals as a result of the 
binaural-beat sound protocol. Evaluation of intersession theta activity relative 
to baseline theta activity first required an analysis of baseline data to assure 
stability for subsequent comparison. In the examination of baseline trends of 
theta activity, the C statistic was calculated for each participant. LOW1 
demonstrated no significant trend during the 5-minute baseline session (C = .18, 
n=10, p>.05). LOW2 demonstrated a significant downward trend during the 
10-minute baseline session (C =.75, n=20, p<.05). MED1 demonstrated no 
significant trend during the 5-minute baseline session (C -.20, n=10, p>.05). 
MED2 demonstrated no significant trend during the 10-minute baseline session (C 
=.32, n=20, p>.05). HIGH1 demonstrated no significant trend during the 5-minute 
baseline session (C = -.28, n=10, p>.05). HIGH2 demonstrated no significant 
trend during the 10-minute baseline session (C = -.07, n=20, p>.05).
In five of six participants, the baseline time series of theta activity data did 
not show a constant direction or trend, and indicated no departure from random 
variation. One participant (LOW1) demonstrated a significant downward trend. 
Therefore, the baseline data for all six participants provided adequate support 
for subsequent comparisons.
In the examination of trends in theta activity across baseline and the three 
binaural-beat stimulation sessions, the C statistic was calculated for each 
participant. LOW1 demonstrated a significant upward trend (C = .36, n=85, 
p<.01). LOW2 demonstrated a significant upward trend (C =.35, n=95, p<.01). MED1 
demonstrated a significant downward trend (C =.74, n=85, p<.01). MED2 
demonstrated a significant upward trend (C = .88, n=95, p<.01). HIGH1 
demonstrated a significant upward trend (C =.70, n=85, p<.01). HIGH2 
demonstrated a significant upward trend (C =.77, n=95, p<.01).
Thus, in five of six participants significant upward intersession trends in 
theta activity were observed. This significant intersession activity in relation 
to nonsignificant baseline activity provides support for this hypothesis in five 
of six participants.
Hypothesis 3. Increases in theta activity will be of greatest significance in 
the participants in the medium-hypnotizable group. An examination of the derived 
C statistic values for each hypnotic susceptibility group provided data 
regarding the relative significance of theta activity increases between groups. 
Mean C values for each susceptibility group (LOW, MED, HIGH) were calculated. 
The mean value for the medium-hypnotizable group does not include MED1, as this 
participant demonstrated a decrease in theta activity across stimulus sessions. 
Therefore, comparing the mean C value for the low and the high susceptible 
groups with the single C value for the medium susceptibility group which 
increased, the following values were obtained: LOW (M =.36), MED (M =.88), HIGH 
(M =.74). This analysis indicates a supportive trend in the data, but without 
inclusion of participant MED1, it does not provide support for this hypothesis.
Hypothesis 4. Increases in theta activity will be of least significance in the 
participants in the low-hypnotizable group. An examination of the derived C 
statistic values for each hypnotic susceptibility group provided data regarding 
the relative significance of theta activity increases between groups. Mean C 
values for each group of susceptibility (LOW, MED, HIGH) were calculated. The 
mean value for the medium-hypnotizable group does not include MED1, as this 
participant demonstrated a decrease in theta activity across stimulus sessions. 
The mean C values for each group of susceptibility are as follows: LOW (M =.36), 
MED (M = .88), HIGH (M = .74). Therefore, these data suggest support for this 
hypothesis.
DISCUSSION
Hypothesis l.
Increases in hypnotic susceptibility, after exposure to binaural-beat sound 
stimulation protocol, will be observed for all participants from pre to 
postmeasures. As mentioned earlier, the participants who demonstrated a 
significant increase in hypnotic susceptibility were Participants LOW1, LOW2, 
MEDI, and MED2. The participants in the high-hypnotizable group did not change 
in the measure of hypnotic susceptibility. Graphical analysis allowed for a 
simplified examination of the changes in hypnotizability levels from the pre to 
post binaural-beat stimulation administrations.
Inasmuch as no decreases in demonstrated raw-score values were observed across 
the six participants, these data suggest support of previous data indicating the 
relatively stable nature of hypnotic ability over time (Perry, Nadon & Button, 
1992).
As previously mentioned, a potential ceiling effect may be present in the 
SHSS:C. The items on the SHSS:C are presented in a progressively greater 
difficulty. Data reported by Perry, Nadon & Button (1992) showed that 68% of the 
normative sample passed the first four items, and only 16% passed the last four 
items. The items begin relatively easy and become progressively more difficult 
and therefore are rank-ordered and do not meet interval level requirements. 
Thus, to accurately interpret of the findings of this study, the progressive 
organization of the SHSS:C items must be taken into consideration. The obtained 
changes in the medium-susceptible group may be more meaningful than observed 
changes in the low-susceptible group, as a change of 1 raw-score point would be 
a more difficult task in the medium-susceptible group than would a change of 1 
raw-score point in the low-susceptible group. This indicates that the 
application of the Significant Change Index may not reveal the true significance 
of changes in hypnotic susceptibility with the SHSS:C. The organization of the 
SHSS:C is also an important factor in the ceiling-effect phenomena observed in 
the two participants in the high-susceptible group.
Low-Hypnotizable Group. The two participants in the low-hypnotizable group 
demonstrated modest increases in SHSS:C raw score values. Both participants LOW1 
and LOW2 increased 1 raw-score value from 2 to 3. As previously suggested, the 
lack of initial hypnotic ability in less hypnotizable individuals often leads to 
unsuccessful attempts at modification of hypnotizability with this population. 
Although both participants in this group demonstrated only a single point 
increase in raw-score values on the SHSS:C, a positive increase suggests that 
modification of hypnotizability % with less susceptible individuals using 
binaural-beat stimulation can lead to positive results.
Medium-Hypnotizable Group. Considering the previously mentioned hierarchy of 
difficulty with the SHSS:C, it may be said that the two participants in the 
medium-hypnotizable group demonstrated the greatest increase in SHSS:C raw score 
values. Both participants MED1 and MED2 changed in general hypnotizability level 
from medium to high, with raw-scores of 6 to 8 and 7 to 8, respectively. These 
data also suggest support for Perry's (1977) findings, in which successful 
modification of hypnotizability was most common in medium hypnotizable subjects.
These individuals appear to possess a certain essential cognitive framework or a 
predisposition which provides for a variety of hypnotic experiences, as 
demonstrated on the SHSS:C.
In relation to the effects of binaural-beat sound stimulation on hypnotic 
susceptibility, these data reveal mixed conclusions. An interesting point is 
that Participant MED1 demonstrated the largest increase in hypnotic 
susceptibility and also a significant decrease in theta activity in response to 
the binaural-beat sound stimulation. In contrast, Participant MED2 demonstrated 
the most significant increase in theta activity in response to the binaural-beat 
sound stimulation. Therefore, these data indicate that theta activity is not the 
only contributing factor in hypnotic susceptibility, suggest that modification 
of hypnotizability with medium susceptible individuals using binaural-beat 
stimulation can be effective, and highlight the importance of individual 
variation. These data can provide a meaningful direction for researchers and 
practitioners of hypnosis interested in increasing hypnotic susceptibility.
High-Hypnotizable Group. The two participants in the high-hypnotizable group 
demonstrated no change in SHSS:C raw-score values. The possibility exists for a 
ceiling-effect with individuals scoring at the upper end of the SHSS:C scale. 
Both participants HIGH1 and HIGH2 had the same pre and post raw-scores, 9 and 
10, respectively. The items or skills an individual must demonstrate to increase 
in raw score above 9 are cognitive items of greater difficulty including, 
negative and positive hallucination tasks. This potential ceiling-effect is also 
evident in Hilgard's (1965) report on relative item difficulty within the 
SHSS:C, in which only nine percent of participants in the normative base passed 
the positive and negative hallucination tasks. These data suggest that those who 
are high in hypnotizability, in terms of the SHSS:C, may be less responsive to 
binaural-beat stimulation relative to individuals who demonstrate less hypnotic 
ability. Perhaps there is a ceiling effect on an individual's ability to produce 
theta as well.
Hypothesis 2.
Theta activity will increase in all individuals as a result of the binaural-beat 
sound protocol This hypothesis was supported in data from five of six 
participants, each showing an upward intersession trend in theta activity across 
stimulus periods. The subject in the medium hypnotizable group with the 5-minute 
baseline (MED1) demonstrated a downward intersession trend in theta activity 
across stimulus periods. The theta activity of Participant MED1 changed 
significantly in session-3. No significant change or trend in theta activity was 
observed for this participant prior to session-3. These data indicate that some 
confounding factor(s) may have been in effect during the session-3 
stimulation/recording period of participant MED1.
In a post-hoc analysis of intersession theta activity, the C statistic was 
calculated for the five participants who demonstrated a significant increase in 
theta activity over the three binaural-beat stimulation periods. This analysis 
was employed to determine which of the three binaural-beat stimulation sessions 
produced the most significant increase in theta activity relative to the 
baseline measures. For all five participants, the data from the third 
stimulation session (session-3) produced C values of the highest significance 
relative to baseline. These third session C values follow. LOW1 (C =.49, n=35, 
p<.01), LOW2 (C = .67, n=45, p<.01), MED2 (C = .89, n=45, p<.01), HIGH1 (C = 
.62, n=35, p<.01, HIGH2 (C =.83, n=45, p<.01. These data suggest that continued 
exposure to binaural-beat stimulation could have an incremental positive effect 
on theta activity, and that in this study the most significant incremental 
effect was observed in the third stimulus session.
In a post-hoc analysis of intersession theta activity, the C statistic was 
calculated for all six participants using the combination of data from session-1 
and session-2 relative to data from the baseline session. This comparison was 
done to further evaluate the initial effects of the binaural-beat sound 
stimulation. The following C values were revealed: LOW1 (C =.36, n=60, p<.01), 
LOW2 (C .30, n=70, p<.01), MED1 (C .11, n=60, p>.05), MED2 (C = .74, n=70, p<. 
01), HIGH1 (C =.18, n=60, p>.05), HIGH2 (C =.36, n=70, p<.01). These data 
suggest that the binaural-beat stimulation effected an initial change (increase) 
in four of the six participants (LOW1, LOW2, MED2, AND HIGH2).
The two participants who did not demonstrate a significant increase in theta 
activity during the two initial sessions were MED1 and HIGH1. As mentioned 
earlier, Participant MED1 demonstrated a significant downward intersession trend 
across all three sessions, most obvious in session-3. The explanation of this 
anomalous response is uncertain, but as described in the introductory section on 
binaural-beat sound stimulation, a number of factors influence the EEG 
frequency-following response. Factors of primary interest in relation to theta 
activity are internal feelings, attitudes, beliefs, and overall mood-state. As 
theta is related to an overall relaxed state, any negative affect related to 
these factors could adversely affect theta production. Participant HIGH1 also 
demonstrated the most significant response in session-3. Participant HIGHI 
reported previous experience with head injury and EEG measurements. This 
experience involved an automobile accident in which the participant was knocked 
unconscious some ten years previous. Reported results of EEG at that time 
indicated an "abnormal" pattern during the sleep state. The relationship of 
possible brainwave abnormalities to measured theta activity in response to 
binaural-beat stimulation is not known. However, there is the possibility that 
the theta response of participant HIGH1 was affected by this head injury.
An additional post-hoc analysis was utilized to provide a precise evaluation of 
the immediate effect of the binaural-beat sound stimulation within the framework 
of the Multiple Baseline design. In this analysis, within each susceptibility 
group, the 1 0-minute baseline recording periods of Participant LOW2, MED2, and 
HIGH2 were compared to the 5-minute baseline recording periods appended with 
5-minutes of the first stimulus session of Participants LOW1, MED1, and HIGH1. 
As previously stated, the participants within each susceptibility group assigned 
10-minute and 5-minute baseline recording periods all demonstrated no 
significant upward trends in theta activity during baseline recordings. An 
examination of the initial five-minute stimulation period following the baseline 
period for the participants assigned the 5-minute baseline % within each 
susceptibility group revealed the following C values; LOW1 (C =.72, n=16, 
p<.05), MED1 (C =.27, n=16, p>.05), HIGH1 (C = .25, n=16, p>.05). The 
corresponding Z values for each C value stated above follow. LOW1 (Z = 2.99); 
MED1 (Z = 1.12); HIGH1 (Z = 1.02). Participant LOW1 demonstrated a significant 
upward trend during the initial 5-minute stimulus period, and participants MED1 
and HIGH1 did not demonstrate a significant trend during the initial 5-minute 
stimulus period. As mentioned earlier, participants MED1 and HIGH1 did not 
demonstrate a significant increase in theta activity during the two initial 
sessions. In contrast, participant LOW1 demonstrated a significant increase in 
theta activity during all three stimulus sessions. These data highlight the 
power of individual differences in relation to theta brainwave activity. The 
observation that the initial recording of stimulus data seemed predictive of a 
differential theta activity response over time may be particularly important is 
this analysis. It may be that the significance of an initial theta activity 
response to binaural-beat sound stimulation is positively related to the 
significance of the theta activity response over time.
Hypothesis 3.
Increases in theta activity will be of greatest significance in the participants 
in the medium-hypnotizable group. The obtained unequal number of participants in 
each group, due to the exclusion of participant MED1 (this participant 
demonstrated a decrease in theta activity across stimulus sessions), presents 
difficulties in providing support for this hypothesis.
Participant MED2 demonstrated the highest significant overall increase in theta 
activity across the baseline and stimulus sessions primarily manifested in 
session-2 and session-3. Further support for this hypothesis is also indicated 
in the previously mentioned post-hoc analyses of (a) session-1 and session-2 
combined relative to baseline, and (b) session-3 comparison to baseline. In both 
analyses, participant MED2 demonstrated the highest significant overall increase 
in theta activity.
Hypothesis 4.
Increases in theta activity will be of least significance in the participants in 
the low-hypnotizable group, The observed unequal number of participants in each 
group, due to the exclusion of participant MED1 (this participant demonstrated a 
decrease in theta activity across stimulus sessions), also presents difficulties 
in providing support for this hypothesis. Even with this consideration, the 
observation that both participants LOW1 and LOW2 demonstrated the least 
significant overall increase in theta activity across the baseline and stimulus 
sessions suggests support for this hypothesis.
Conclusions
The findings of this study provide support for the efficacy of the binaural-beat 
sound stimulation process, pioneered by the Monroe Institute, in effecting an 
increase in theta brainwave activity. As mentioned earlier, the baseline and 
stimulus tapes differed only in the presence or absence of the binaural-beat 
stimulation (i.e., both contained pink sound and tones). Each participant 
demonstrated no significant upward trend in baseline recordings of theta 
activity. Thus, the observed trends in theta activity following introduction of 
the binaural-beat sounds allows one to state, with a good deal of certainty, 
that it is the effect of the binaural-beat sounds and not merely the passage of 
time, the measurement operation, or some other independent event that effected 
the observed increases in theta activity. During the post-session interviews, no 
descriptions of unpleasant experiences were reported, Individual reports of each 
stimulation session varied from profoundly insightful to pleasant and relaxing.
The single-subject experimental design used in this study allowed for 
examination of the effects of binaural beat stimulation on individual theta 
activity over time. With single-subject methodology there is no need to 
compromise the effects of stimulation on different subjects by averaging across 
groups as is done with group designs.
The data in this study relative to hypnotizability suggest support for the 
stability of hypnotic susceptibility over time and suggest support for previous 
data showing differential response to modification of hypnotizability relative 
to initial susceptibility level. This support is evident in the fact that no 
participant decreased in hypnotic susceptibility over time and in the 
differential participant responses across general hypnotic susceptibility 
levels. Surprisingly, the most significant increase in hypnotic susceptibility 
was observed in the participant with the most significant decrease in theta 
activity in response to the binaural-beat sound stimulation. Even though the 
significance of the decrease in theta activity for this participant was 
explained entirely by third session recordings, it is difficult to draw 
conclusions regarding the relationship of theta activity to hypnotic 
susceptibility when reviewing the findings of this study. Overall, this study 
indicates that theta activity is related to, but cannot uniquely explain, the 
variation in hypnotic susceptibility.
 Limitations. Although the single-subject experimental design used in this study 
provided a direct examination of individual responses over time, the design of 
this study is not without inherent limitations. For example, as the participants 
in this study are not representative of the general population, it would be 
difficult to generalize the findings of this study, even to a similar group of 
females. It is worth noting, however, that the issue of external validity, which 
often essentially relates to possible inconsistencies in the data due to small 
sample sizes, is tempered somewhat in this study by the adequate number of 
recorded data points within each subject.
The demographic data were collected post-hoc, and thus prevented the homogeneous 
selection of subjects based on such variables as previous experience with EEG 
recordings or head-injury. Also, data collected in intersession interviews was 
not recorded for further analysis. This is unfortunate, as information regarding 
the subjective experience of binaural-beat stimulation is meaningful not only in 
and of itself but could have provided data relating to the differential 
participant theta activity in response to binaural-beat sound stimulation 
observed in this study.
Future Research. 
In future related research with the use of binaural-beat stimulation, the time 
of exposure could be increased. An increase in exposure time could provide 
important data relating to modification of theta brainwave activity and hypnotic 
susceptibility. This could be easily accomplished by using a home-practice 
protocol, not unlike home-practice relaxation training commonly used in 
behavioral medicine settings with disorders such as migraine headaches. This 
type procedure would allow for extended stimulation periods in a true applied 
setting. Another possible line of research could involve the use of 
binaural-beat stimulation within background music during hypnotic procedures in 
an effort to increase participant response to hypnotic susceptibility evaluation 
measures. The use of "background support" via binaural-beat sound stimulation 
could also prove a valuable asset to clinical practitioners as well. Data from 
this study may also provide a foundation for subsequent group comparison designs 
directed toward the generalization of stimulation effects across larger groups 
of individuals.
References
Akpinar, S., Uleft, G. A., & Itil, T. M. (1971). Hypnotizability predicted by 
computer-analyzed EEG pattern. Biological Psychiatry, 3, 387-392.
Anch, A. M., Browman, C. P., Mitier, M. M. & Walsh, J. K. (1988). Sleep: A 
scientific perspective, 96-97. Englewood Cliffs: Prentice Hall.
Atwater, F. H. (1997). The Hemi-Sync Process. The Monroe Institute. 
http://www.monroeinstitute.org/research
Barabasz, A. & Barabasz, M. (1995). Attention deficit hyperactivity disorder: 
Neurological basis and training alternatives. Journal of Neurotherapy, Summer 
1995.
Barber,T.X. (1969). Hypnosis: A scientific approach. New York: Van Nostrand 
Reinhold.
Bates, B. L. (1994). Individual differences in response to hypnosis. In J. W. 
Rhue, S. J. Lynn, & I. Kirsch (Eds.), Handbook of Clinical Hypnosis (pp. 23-54). 
American Psychological Association, Washington D.C.
Bowers, K. S. (1979). Hypnosis and healing. Australian Journal of Clinical and 
Experimental Hypnosis, 7(3), 261-277.
Bowers, K. S. (1982). The relevance of hypnosis for cognitive-behavioral 
therapy. Clinical Psychology Review, 2(l), 67-78.
Brown, D. P. (1992). Clinical hypnosis research since 1986. In E. Fromm & M. 
Nash (Eds.), Contemporary Hypnosis Research (pp. 427-486). New York: Guilford 
Press.
Bruneau, N., Sylvie, R., Guerin, P., Garreau, B., & Lelord, G. (1993). Auditory 
stimulus intensity responses and frontal midline theta rhythm. 
Electroencephalography and Clinical Neurophysiology, 186, 213-316.
Christensen, L. & Mendoza, J. (1 986). A method of assessing change in a single 
subject: An alteration of the RC index. Behavior Therapy, 17, 305-308.
Crawford, H., & Gruzelier, J. (1 992). A midstream view of the 
neuropsychophysiology of hypnosis: Recent research and future direction. In E. 
Fromm & M. Nash (Eds.), Contemporary Hypnosis Research (pp. 227-266). New York: 
Guilford Press.
Dumas, R. A. (1977). EEG alpha-hypnotizability correlations: A review. 
Psychophysiology, 14, 431438
Diamond, M. J. (1989). The cognitive skills model: An emerging paradigm for 
investigating hypnotic phenomena. In N. P. Spanos & J. F. Chaves, Hypnosis: The 
cognitive-behavioral perspective (pp. 380-399). New York: Prometheus Books.
Empson, J. (1986). Human brainwaves: The psychological significance of the 
electroencephalogram. London: The Macmillan Press Ltd.
Freud, S. (1966). Hypnosis. In J. Strachery (Ed. and Trans.), The standard 
edition of the complete Psychological works of Sigmund Freud (Vol. 1, pp. 
103-114).
Galbraith, G. C., London, P., Leibovitz, M. P., Cooper, L. M., & Hart, J. T. 
(1970). EEG and hypnotic susceptibility. Journal of Comparative and 
Physiological Psychology, 72, 125-131.
Glisky, M., Tataryn, D., Tobias, B., Kihistrom, J., & McConkey, K. (1991). 
Absorption, openness to experience, and hypnotizability. Journal of Personality 
and Social Psychology, 60, 262-272.
Graffin, N. F., Ray, W. J., Lundy, R. (1995). EEG concomitants of hypnosis and 
hypnotic susceptibility. Journal of Abnormal Psychology, 104(l), 123-131. 
Hilgard, E.R. (1965). Hypnotic Susceptibility. New York: Harcourt, Brace & 
World.
Green, E., & Green, A. (1977). Beyond Biofeedback. Delacorte Press, Seymour 
Lawrence.
Hilgard, E. R. (1965). Hypnotic Susceptibility. New York: Harcourt, Brace & 
World.
Hilgard, E. R. (1973). A neodissociation interpetation of pain reduction in 
hypnosis. Psychological Review, 80, 396-411.
 
Hilgard, E. R. (1975). Hypnosis in the Relief of Pain. Los Altos, California: 
William Kaufman, Inc.
Hilgard, E.R. (1986). Divided consciousness: Multiple controls in human thought 
and action. (expanded ed.). New York: Wiley.
Ishihara, T., & Yoshii, N. (1972). Multivariate analytic study of EEG and mental 
activity in juvenile delinquents. Electroencephalography and Clinical 
Neurophysiology, 33, 71-80.
Jasper, H. H. (1958). Report of the committee on methods of clinical examination 
in electroencephalography. Electroencephalography and Clinical Neurophysiology, 
10, 370-375.
Kirsch, I., & Council, J. (1992). Situational and personality correlates of 
hypnotic responsiveness. In E. Fromm & M. Nash (Eds.), Contemporary hypnosis 
research (pp. 267-291). New York: Guilford Press.
Kirsch, I., & Lynn, S.J. (1995). The altered state of hypnosis: Changes in 
theoretical landscape. American Psychologist, 50(10), 846-858.
Krishef, C. H. (1991). Fundamental approaches to single subjects testing and 
analysis. Malabar, Florida: Krieger Publishing company.
Kurtz, R. M. & Strube, M. J. (1996). Multiple Susceptibility Testing: Is it 
Helpful? American Journal of Clinical Hypnosis, 38(3), 172-184.
Laurence, J. & Perry, C. (1988). Hypnosis, will, and memory: A psychological 
history. New York: Guilford Press.
Life Sciences Institute of Mind-Body Health (1995). 
http://www.cjnetworks.com/~Iifesci/index.html.
Lubar, J. F. (1991). Discourse on the development of EEG diagnostics and 
biofeedback for attention-deficit/hyperactivity disorders. Biofeedback and 
Self-Regulation, 10(8), 201-225.
Lubar, J. F., Swartwood, M. O., Swartwood, J. N., & O'Donnell, P. H. (1995). 
Evaluation of the effectiveness of EEG neurofeedback training for ADHD in a 
clinical setting as measured by changes in T.O.V.A. scores, behavioral ratings, 
and WISC-R performance. Biofeedback and Self Regulation, 20(l), 83-99.
Mizuki, Y., Tanaka, M., lsozaki, H., & Inanaga, K. (1980). Periodic appearance 
of theta rhythm in the frontal midline area during performance of a mental task. 
Electroencephalography and Clinical Neurophysiology, 49, 345-351.
Nadon, R., Hoyt, I., Register, P., & Kihistrom, J. (1991). Absorption and 
hypnotizability: Context effects reexamined. Journal of Personality and Social 
Psychology, 60,144-153.
Ochs, L. (1994). New lights on lights, sounds, and the brain. The Journal of 
Mind Technology, 11, 48-52.
Oster, G. (1973). Auditory beats in the brain. Scientific American, 229, 94-102.
Peniston, E. G. & Kulkosky, P. J. (1989). Alpha-theta brainwave training and 
beta-endorphin levels in alcoholics. Alcoholism: Clinical and Experimental 
Research, 13, 271-279.
Peniston, E. G. & Kulkosky, P. J. (1990). Alcoholic personality and alpha theta 
brainwave training. Medical Psychotherapy: An International Journal, 3, 37-55.
Peniston, E. G. (1990). EEG brainwave training as a bio-behavior intervention 
for vietnam combat-related PTSD. The Medical Psychotherapist, 6(2).
Peniston, E. G. & Kulkosky (1991). Alpha-theta brainwave neurofeedback for 
vietnam veterans with combat related post-traumatic stress disorder. Medical 
Psychotherapy: An International Journal, 4, 1-14.
Peniston, E. G., Marrinan, D. A., Deming, W. A. & Kulkosky, P. J. (1993). EEG 
alpha-theta brainwave synchronization in Vietnam theater veterans with 
combat-related post-traumatic stress disorder with alcohol abuse. Advances in 
Medical Psychotheragy: An International Journal, 6, 37-50.
Perlini, A. H., Spanos, N. P. (1991). EEG alpha methodologies and 
hypnotizability: A critical review. Psychophysiology, 28(5), 511-530.
Perry, C. (1977). Is hypnotizability modifiable? The International Journal of 
Clinical and Experimental Hypnosis, 25(3), 125-146.
Perry, C., Nadon, R., & Bufton, J. (1992). The measurement of hypnotic ability. 
In E. Fromm & M. Nash (Eds.), Contemporary hypnosis research (pp. 227-266). New 
York: Guilford Press.
Rossiter, T. R. & Vaque, T. J. (1995). A comparison of EEG biofeedback and 
psychostimulants in treating attention deficit /hyperactivity disorders. Journal 
of Neurotherapy, Summer 1995.
Ruzyla-Smith, P., Barabasz, A., Barabasz, M. & Warner, D. (1995). Effects of 
hypnosis on the immune response: B-cells, T-cells, helper and suppressor cells. 
American Journal of Clinical Hypnosis, 38(2), 71-79.
Sabourin, M. (1982). Hypnosis and brain function: EEG correlates of state-trait 
differences. Research Communications in Psychology, Psychiatry and Behavior, 7 
(2), 149-168.
Sabourin, M. E., Cutcomb, S. D., Crawford, H.J., & Pribram, K. (1990). EEG 
correlates of hypnotic susceptibility and hypnotic trance: Spectral analysis and 
coherence. International Journal of Psychophysiology, 10, 125-142.
Saxby, E. & Peniston, E. G. (1995). Alpha-theta brainwave neurofeedback 
training: An effective training for male and female alcoholics with depressive 
symptoms. Journal of Clinical Psychology, 51(5), 685-693.
Schacter, D. L. (1977). EEG theta waves and psychological phenomena: A review 
and analysis. Biological Psychology, 5, 47-82.
Shor, R. & Orne, E. C. (1962). The Harvard Group Scale of Hypnotic 
Susceptibility, Form A: Consulting Psychologists Press, Palo Alto, CA.
Soskis, D.A. (1986). Teaching self-hypnosis: An introductory guide for 
clinicians. New York: W. W. Norton & company.
Swann, R., Bosanko, S., Cohen, R., Midgley, R. & Seed, K. M. (1982). The brain - 
A user's manual, 92. New York: G. P. Putnam's Sons.
Tebecis, A. K., Provins, K. A., Farnbach, R. W., & Pentony, P. (1975). Hypnosis 
and the EEG: A quantitative investigation. Journal of Nervous and Mental 
Disease, 161, 1-17.
Telliegen, A., & Atkinson, G. (1974). Openness to absorbing and self altering 
experiences ("absorption"), a trait related to hypnotic susceptibility. Journal 
of Abnormal Psychology, 83, 268-277.
Tice, L. & Steingerg, A. (1989). A better world, a better you, 57-62. New 
Jersey: Prentice Hall.
Vogel, W., Borverman, D. M., & Wilson, A. (1977). EEG and mental abilities. 
Electroencephalography and Clinical Neurophysiology, 24, 166-175.
Waite, A. E.. (1960). Braid on hypnotism: The beginnings of modern hypnosis. New 
York: Julian. (Rev. ed. of Neurypnology, by J. Braid, 1843).
Weitzenhoffer, A.M. (1953). Hypnotism: An objective study in suggestibility. New 
York: Wiley.
Weitzenhoffer, A. M. & Hilgard, E. R. (1959). Stanford Hypnotic Susceptibility 
Scale, Forms A and B: Consulting Psychologists Press, Palo Alto, CA.
Weitzenhoffer, A. M. & Hilgard, E. R. (1962). Stanford Hypnotic Susceptibility 
Scale, Form C.: Consulting Psychologists Press, Palo Alto, CA.
Wickramasekera, I. (1979). A model of the patient at high risk for chronic 
stress related disorders: Do beliefs have biological consequences? Paper 
presented at the Annual Convention of the Biofeedback Society of America, San 
Diego, CA.
Wickramasekera, I. (1994). Psychophysiological and clinical implications of the 
coincidence of high hypnotic ability and high neurooticism during threat 
perception in somatization disorders. American Journal of Clinical Hypnosis, 
37(l), 22-33. 
Wickramasekera, I. , Pope, A. T., & Kolm, P. (1996 in press) Hypnotizability: 
Skin conductance level and chronic pain: Implications for the somatization of 
trauma. Journal of Nervous and Mental Disease.
 
   
            
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