The Effect of Energy Psychology on Athletic Performance:
A Randomized Controlled Blind Trial
Dawson Church, PhD 1 2
This study investigated whether the most widely practiced form of Energy
Psychology, called Emotional Freedom Techniques (EFT), could affect athletic
performance. It evaluated whether a single brief EFT treatment for performance stress
could produce an improvement in two skills for high-performance men’s and women’s
college basketball teams at Oregon State University. The treatment group received a
brief EFT session while the control group received a “tips and techniques reading”
(TTR). Performance was measured on free throws and vertical jump height. Basketball
players who received the EFT intervention scored an average of 21% better
individually in free throws after treatment than the control group, while the control
group scored an average of 17% lower (p<0.028). However, there was no statistically
significant difference between the groups in their percent change in jump height.
When analyzed separately, there was a trend for females in the EFT condition to have
better performance on both free throws and jump height than females in the control
group. These findings suggest that EFT performed as an intervention during the
course of an athletic event may reduce performance stress, and improve individual
player function for free throws, and is thus worthy of further study. This study was
limited by the small sample size and short duration of the intervention.
Keywords: Stress, performance, Emotional Freedom Techniques (EFT), anxiety, sport.
1 Research Director, Association for Comprehensive Energy Psychology (ACEP)
2 Chair, Epigenetic Medicine Institute (EMI)
There have been numerous studies of the effect of Emotional Freedom
Techniques (EFT) and other Energy Psychology (EP) therapies for various
psychological conditions, including depression, anxiety, phobias, and posttraumatic
stress disorder (PTSD) (Feinstein, 2008a). However, no prior study has examined the
effect of EP on healthy and high-performing individuals. This study investigated
whether EFT could make a difference in elite athletes by treating any stress or anxiety
that might underlie their performance.
EFT was developed Gary Craig as an abbreviation of the methods used in
Thought Field Therapy or TFT, an earlier Energy Psychology method which used
elaborate diagnostic and treatment protocols (Callahan, 1987). Craig came to the
conclusion that EFTs brief and standardized protocol could treat most of these
problems without the need for lengthy diagnoses, and organized these points into a
easily-administered method (Feinstein, et al. 2005). EFT may be self-administered, but
may also be administered by a coach or therapist (Church, 2008a).
There are several hundred clinical reports at the EFT web site (Craig, 2008), and
studies have found the technique effective for several types of psychological distress,
such as anxiety (Rowe, 2005) and phobias, (Wells, et. al, 2003, Lambrou, et. al., 2003).
Most of these studies use a single session of EFT, and the effects of EFT have been
found to hold over time (Rowe, 2005, Wells, et. al., 2003). No negative side effects have
been reported (Feinstein, 2008a). Clinical reports also suggest that by reducing
emotional trauma, EFT can have an effect on physical conditions including joint pains,
allergies, chronic fatigue syndrome, rashes, arthritis, colds, flu, and toothaches
(Feinstein, et. al. 2005, Church, 2007b). A randomized blind clinical trial has found
EFT to be effective for fibromyalgia (Brattberg, 2008).
There is considerable debate as to the mechanisms of action of EFT and other
Energy Psychology therapies. Craig and other proponents of EFT believe that the
method is effective because it makes use of “energy meridians” corresponding to the
endpoints of the acupuncture meridians described by traditional Chinese medicine
(Gallo, 1999). However, other authors have advanced more conventional hypotheses
to explain the efficacy of Energy Psychology, including:
• The deactivation of the arousal of the amygdala and other fight-or-
flight structures in the brain that occurs during traumatic recall
• The semiconductive properties noted in connective tissue when a
piezoelectric stimulus is produced by manual stimulation (Oschman,
• Stimulation of the rapid reuptake and resynthesis of stress hormones
such as cortisol (Church, 2008b)
• Changes in the secretion of neurotransmitters such as serotonin and
dopamine (Feinstein, et. al. 2005).
• Termination of the alarm response in the Sympathetic Nervous
System, and replacement with a relaxation response in the
Parasympathetic Nervous System (Lane, 2006).
• The release of serotonin in the prefrontal cortex of the brain (Ruden,
More research is required to determine whether one of these physiological
factors, or a combination of them, comprises the active mechanism of EFT and other
Energy Psychology therapies. While their objective mechanisms cannot be determined
without further study, their subjective evidence base comes from the self-reports of
those utilizing these therapies, and the case histories of clinicians. Participants in the
published studies summarized by Feinstein (2008a) typically report large drops in their
pain and distress levels for one or more of their perceived causes of anxiety, a decrease
in stress, and an improvement in performance.
The present study was designed to determine if EFT could be used successfully
on athletes to improve performance, either in a team context or individually, and
measure changes in a way that both insured methodological quality and provided a
replicable experiment. Participants were members of the Oregon State University
men’s and women’s basketball teams. The opportunity to study basketball athletes at
Oregon State University grew out of the successful use of EFT by the baseball team,
some members of whom had learned EFT two years prior (The Oregonian, 2007). The
game of basketball chosen because psychological stress has been demonstrated to
affect free throw performance (Whitehead, 1996), and empirical measurements can be
obtained in a compressed time frame.
Analysis has shown that accurately performed free throws are one of the most
critical factors in winning basketball games (Trninić, 2002), leading to performance
stress on players being asked to perform this maneuver. Free throws have been used in
more than two dozen studies reported in the Pubmed database to measure the effects
of treatments such as Cognitive Behavioral Therapy (CBT) on athletic performance.
In this study, the EFT treatments were administered under randomized
controlled blind conditions, as described below. The goal of the study was to examine
the effect of EFT on two specific skills relating to the game of basketball: percent of
free throws, and jump height. The primary hypothesis being tested was whether EFT
would mitigate the performance effects of stress, thus improving athletic performance.
Participants and Procedures
The study was performed at Oregon State University with the men and women’s
basketball teams, and data gathering took place during the course of a single week. A
total of 26 players participated, 14 male and 12 female. The men and women reported
at a designated time, and informed consent was obtained. The woman’s team study
was done in a single afternoon, while the men’s team was studied in a morning of the
same week. The head coach for each team was briefly present at the start of each
session, but did not address the team or stay to observe the study. The men’s team had
four assistant coaches, who were present for the duration of the study. No assistant
coaches were present for the women’s study. To provide for a blind placebo control,
the control group received an inspirational reading of tips and techniques (TTR)
written by a former college basketball coach.
All subjects performed their regular warm-up period, to eliminate any effect on
athletic performance of inadequate muscular preparation. The warm-up was of a
nature and duration standard to the teams, lasting approximately ten minutes and
consisting of stretches and running.
All subjects then performed six jumps on the jump pad, and ten free throws,
after which the subjects were randomized by an independent research assistant into
two matched groups: Team X and Team Y, based on the last three of the six vertical
jump height measurements. The player with the highest jump was assigned to Team
Y, the one with the next highest jump went into team X, and so on, until all the players
were distributed into one team or the other. In order to control for investigator
expectancy, the randomization of the teams and data recording done throughout the
study was done by research assistants without significant experience with EFT, though
they had heard of EFT, and of the author of the TTR reading.
The researchers measured the vertical height of the subjects’ jumps using a jump
pad, a device that electronically records and displays jump height. They also recorded
the number of successful free throws, before and after the session, and calculated the
percentage of improvement or decline. Both raw data and a statistical analysis are
provided in the Results section below.
Other members of the team observed the participants while the jumps and free
throws were being recorded. Prior research using free throws as a measure has
suggested that human performance changes when under the stress of observation by
others (Moore, 1993, Whitehead, 1996), and the observation by other team members
simulated that effect.
During the course of the testing, the two teams were at opposite ends of the
basketball court, and following randomization, they were instructed not to talk to each
other for the duration of the study. They were also instructed to practice free throws,
run, dribble, do vertical jumps, and generally stay warmed up for the duration of the
study. This was done to counteract any confounding effect due to body cooling
between measurements, and to simulate the fatigue over time that players might
experience during the course of an actual basketball game. The effects of fatigue on
both the muscular and nervous system, and the subsequent degradation of
performance during the course of a game, have been described by other researchers
(Kuipers, 1998, Williams,1995). Athletes were also instructed to drink as much water
as they needed, since dehydration has been shown in other studies to affect free throw
performance (Hoffman 1995, Dougherty 2006).
The free throw test consisted of ten throws to the basket from a mark on the
court called the free throw line. Players were familiar with this test. For the jump
height test, the Probotics jump pad (www.Probotics.org) was used to measure jump
height, and was located in the middle of the court, between the two teams. This pad
measures the player’s jump height by units that represent tenths of an inch (for
example, 265 units is equivalent to 26.5 inches). Vertical jump height is a selection
criterion for college basketball athletes, and all the athletes were familiar with the
jump pad procedure and measurement.
The experimental treatment consisted of approximately fifteen minutes of EFT,
while the control group received approximately fifteen minutes of TTR, performed in
a ten minute session and a five minute follow-up session. The time lapse between the
first test of the first participant and the last test of the last participant was
approximately two hours. Compressing the data gathering and treatment into two
hours was designed to approximate the time period of an actual basketball game.
For treatment, each of the teams was taken as a group to a different location in
the building. They were then told the nature of the intervention they were to receive,
with care being taken to maintain blindness. The first participants were randomly
selected from each team and the rest of the team members were asked to return to
their end of the basketball court and to “stay warm.” This was accomplished by the
performance of drills and impromptu games, in order to produce the same degree of
progressive muscle fatigue and performance degradation noted during regular games
(Busso, 1994, Bigland-Richie, 1984).
In both the experimental and control groups, treatments were then administered
individually. A participant was taken into a private office, and the first ten minute
treatment was administered. Participants then went back to the court, performed
three vertical jumps, and returned to the treatment room for an additional treatment
lasting approximately five minutes. After this, they returned to the court to perform
three final jumps and a post-treatment set of ten free throws. This process continued
until all team members were treated.
The experimental group received EFT according to the protocol below.
Therapists who performed EFT interventions had experience in using EFT for sports
performance. The control group received the tips and techniques reading, TTR, which
was written by a former college and professional basketball coach, Phil Pitino, and
read to them by a therapist or assistant coach. It covered topics such as setting high
personal standards, improving with practice, building self-confidence, positive
thinking, handling stress well, and the value of hard work (Success, 1998).
EFT is an exposure therapy that combines both cognitive and somatic elements.
In the first step of the EFT session, participants identify their degree of distress on an
11 point Subjective Units of Distress (SUD) scale (Wolpe, 1958, 1973). On the SUD
scale, zero represents no problem, and ten represents the most pressing experience of
the problem. In the case of physical pain, for instance, zero represents no pain, while
ten represents the most extreme pain imaginable. In the case of emotional pain, the
subject is asked to identify a point in the body particularly identified with the pain, and
to note its SUD score.
After deriving a SUD score, participants create a short verbal summary of the
problem they wish to change, and combine it with a statement of self-acceptance. In
EFT this is referred to as the “setup statement.” A setup statement pairs the problem
with acceptance, e.g., “Even though I have (this problem), I fully and completely accept
myself.” An example of a setup statement involving athletic performance is, “Even
though I worry that I’ll tear a hamstring if I jump to too high, I fully and completely
Following this brief cognitive element of the therapy, the somatic portion of the
treatment is administered, either by the individual or a therapist. This involves tapping
with the fingertips of one hand on twelve parts of the body, referred to as a “round” of
The first point is the fleshy outside edge of the hand, called, for convenience, the
“karate chop point.” The participant taps this portion of the opposing hand repeatedly,
while repeating the setup statement three times.
Next five points on the face are tapped about seven times: the inner terminus of
either eyebrow, the side of the eye socket, the center of the bony ridge below the eye,
the middle of the upper lip just below the nose, and the center of the chin.
Then two points on the torso are tapped: the junction of collarbone and sternum,
and the lowest rib under the arms.
Lastly, five points on the hand are tapped, the part of the cuticle of each finger
closest the body, with the exception of the ring finger, and finally the groove between
the bones of the last two fingers on the back of the hand.
After a round of tapping, subjects provide a second SUD score. Subjects typically
report a decrease in the distress associated with a negative emotion or traumatic event
after rubbing or tapping these points, e.g. “My anger was an eight but now it’s a three.”
Two or more applications of EFT may be used to further reduce the SUD score. In this
study, most participants completed one or two rounds of tapping in the first (ten
minute) session, and a single round in the second (five minute) session.
In interviews with the athletes during this study, it was determined that their
stress centered on issues involving their athletic and life problems, and that these
factors were self-perceived to be affecting their game. There were four treatment
targets for the EFT experimental group. Their “setup statements” focused on:
• Limiting beliefs about performance
• Anxieties in general
• Negative past experiences
• Muscle memory of past maximum achievement
Typical problems were tiredness, stress from facing exams, homework or poor
grades, and family conflicts. Some issues were general and global beliefs: “I’m a poor
athlete, but the team needs me because I shoot well.” Others were very specific, “My
upper body is strong, but my legs are weak. I’ve never been a good jumper.” Some were
from long ago, “My father went to jail when I was five, and I never saw him again,” and
others were from the present, “I’m worried about being here because I have a huge
amount of homework to finish today.” Thus a setup statement for a negative belief
might be: “Even though I have weak legs, I fully and completely accept myself.” A
setup statement for a desired condition might be, “My legs are powerful and strong.”
The goal of EFT treatment was to reduce the SUD level for one or more such
issues during the short course of treatment, reduce the impact of the identified
traumatic event, administer the somatic portion of treatment, and measure the results.
Alternatively, EFT was performed while imagining a positive desired outcome.
Data analysis was subsequently performed by an independent statistician blind to
the condition. The Raw Scores Table below shows the raw scores obtained in this
study, and the calculated percent change in free throws, as well as the percent change
in mean for the jumps. A data key is provided below; the EFT or experimental group is
designated “Exp” and the TTR or control group is designated as “Cont.” For both
groups, the women’s scores appear first.
Table 1: Raw Scores
Free Throw Results: T-tests were conducted on the percent change score for
free throws to determine whether there significant group differences. A statistically
significant difference was found (t(32)=-2.34, p<.028). The athletes treated with EFT
improved their free throw performance by an average of 20.8% (SD + 22.5%), while the
control group decreased by an average of 16.6% (SD + 53.0%).
Table 2: Male and Female Combined Free Throw Statistics
When the analyses were conducted within gender, there was a trend towards
significance for females (t(10)=-1.96, p<.078). Free throws increased an average of
2.6% (SD + 25.9%) in the female treatment group versus the control group. The
control group decreased an average of 22.2% (SD + 16.9%). There was no significant
difference between treatment groups for males (t(7.9)=-1.78, p<.114).
Table 3: Female Free Throw Statistics
Table 4: Male Free Throw Statistics
Jump Height Results: There was no difference between the treatment and
control groups on the percent change in jump height for males and females combined
(t(24)=-0.79, p<.47) and for males when analyzed separately (t(12)=-0.429, p<.68).
Table 5: Male and Female Jump Height Statistics
Table 6: Male Jump Height Statistics
However there was a trend towards significance for the females (t(5.9)=-2.13,
p<.078). Females in the treatment group showed close to no change in jump height
(decreased 0.73%, SD +1.2%), while females in the control group decreased 4.3% (SD
Table 7: Female Jump Height Statistics
Most studies of EFT and other forms of Energy Psychology have focused on
psychological distress. Conditions such as phobias and anxiety have been the object of
considerable examination and evaluation, and these therapies have been studied in
even extremes of distress such as holocaust victims in Rwanda and ethnic cleansing
victims in Kosovo (Feinstein, 2008b). However, no studies have yet been conducted of
the effects of EFT on athletic performance, even though the brief nature of this
intervention makes it more suited to application during stressful situations than
therapies that require a series of office visits. Such studies are timely, given the many
reports from coaches and athletes of EFT being applied in professional and college
level golf, baseball, and American football (Achenbach, 2007).
A limitation of this study is its small sample size. Performance changes by 6 of the
26 players accounted for most of the variation in results. To compensate for this
limitation, statistical measures intended to compensate for individual variance were
employed. When analyzing small samples, t-tests are used to account for degrees of
freedom in the sample size. The above results fall within the parameters of the
statistical tests chosen to analyze them. However, replication in larger subject
populations is required to see if these results are typical.
The results raise some additional questions. Why did vertical jump height not
improve to a statistically significant degree, while free throws did? Possible reasons
include player fatigue, player boredom, the passage of time, and the brevity of the
treatment. The therapists administering EFT expressed frustration at the brevity of
time available for treatment inherent in the research design. It is challenging for a
counselor or coach to both identify and treat a condition in a period as brief as ten
minutes, and it represents a further challenge to establish trust and rapport with a
stranger in that brief period of time. Any psychotherapy modality requires the
building of trust between therapist and client, and this takes time. Clients do not
usually open up with deep-seated emotional issues with a therapist until well into an
hour-long session, and sometimes not until several sessions have elapsed.
Another possible reason why jump height did not change significantly is that it
may be less dependent on emotional states, and more dependant on physiological
factors, such as physical conditioning, flexibility, and strength; while free throws may
be more affected by emotional factors, such as stress. There is evidence to suggest that
players with the ability to perform consistently under stress have better free throw
percentages (Whitehead, et. al., 1996).
For this reason, established therapies like Cognitive Behavioral Therapy or CBT
usually prescribe between 6 and 12 one-hour sessions to show results. A study using
CBT for jump height improvement found that as players moved from negative
cognitions such as the limiting setup statements above, to positive ones, their jump
height improved significantly (Hamilton, 1985). Another study of CBT also found
improvement in free throw percentages after treatment, though again, between 7 and
9 hours of treatment were required (Kearns, 1996). The quality of self-talk has also
been found to affect free throw scores (Theodorakis, 2001). All these studies used
courses of therapy much longer than the 15 minute format allowed by the current
study. The clinicians administering EFT during this study speculated that to have an
effect on jump height, they would have required longer therapeutic sessions, or even
The discharge of emotional trauma might have a positive effect on athletic
performance. The contrary hypothesis has been proposed: that athletes who are angry
and anxious may be able to funnel that energy to produce greater vigor during play.
However, the study of basketball teams has shown that emotional equilibrium and
calm judgment contribute to factors that determine success in basketball, such as
accuracy and sensitive teamwork (Trninić, 2002). Consistently good players are able to
perform well even under stress. The ability to discharge stress, and stay focused, allows
an athlete’s full skill set to come to bear on the athletic task at hand.
While athletes formed the subject pool of this study, other research finds that
EFT reduces stress in general populations as well. A study of 102 individuals (Rowe,
2005) demonstrated decreased scores on measures of anxiety, depression and other
conditions after EFT treatment. The results held up on six month followup. Outcome
studies of EFT in clinical settings have shown a large effect size, and efficacy in a wide
variety of psychological conditions (Feinstein, 2008a). For this reason, it is being
studied in many primary care settings, including two clinical trials in Britain’s National
Health Service; the unpublished preliminary results of these and other studies in
progress yield results consistent with Rowe’s findings (Church, 2008c).
Clinical reports, and accounts from coaches and athletes, show that EFT is widely
practiced in professional and college level golf, baseball, and American football. This
study indicates that a very brief application of EFT can increase certain measures of
performance in high-performing individuals, producing a large effect size in a
compressed time frame. The brevity of a typical treatment renders EFT suitable for
reducing stress during athletic performance. EFT appears to have similar effects on
both women and men. The use of EFT for stress reduction in sports warrants further
empirical evaluation. Further study is also required to determine if longer courses of
therapy with EFT produce changes in vertical jump height, or greater improvement in
free throw scores. The study of this therapy in healthy populations, and peak
performers, opens up new potential applications for Energy Psychology.
Thanks to psychiatrist and clinical psychologist colleagues who provided advice
on study design and on drafts of this paper: Daniel Benor, MD, David Feinstein, PhD,
John Freedom, CEHP, Phillip Friedman PhD, Richard Leskowitz, MD, Gregory
Nicosia, PhD, Jack Rowe, PhD, Norman Shealy, MD, PhD, and members of the ACEP
Research Committee. Special thanks to Greg Warburton, LPC, who arranged access to
the OSU teams, assisted in the study, and together with Stacy Vornbrock, LPC,
provided treatment. Thanks to Audrey Brooks PhD for data analysis, and to Leane
Roffey Line PhD for editorial assistance. Thanks to women’s basketball head coach
LaVonda Wagner, men’s basketball head coach Jay John, and OSU Director of
Athletics, Bob DeCarolis, for their cooperation in conducting this study.
Achenbach, J. (2007). Golfers “tap” into psychology. Golfweek, March 25:60.
Busso, H., et. al. (1994). Fatigue and fitness modelled from the effects of training on
performance. European Journal of Applied Physiology, 69(1):50-54.
Bigland-Ritchie, B., et. al. (1984). Changes in muscle contractile properties and neural
control during human muscular fatigue. Muscle & Nerve, 7(9):691-699.
Callahan, R. J. (1987). Successful psychotherapy by radio and telephone. International
Journal of Applied Kinesiology. Winter.
Brattberg, G. (2008). Self-administered EFT (Emotional Freedom Techniques) in
individuals with fibromyalgia: a randomized trial. Integrative Medicine, Aug/Sept.
Feinstein, D., et. al. (2005). The Promise of Energy Psychology. New York: Tarcher, 10.
Church, D. (2007). The Genie in Your Genes. Santa Rosa: Energy Psych Press, 227.
Church, D. (2008a). Using biological markers to measure psychological effects: a case
study using subjective and objective evaluations of Emotional Freedom Therapies (EFT)
for depression. Subtle Energies and Energy Medicine. In press.
Church, D.. (2008b). The effect of psychotherapy on stress biochemistry: A comparison
of EFT and CBT. Reported at ACEP Conference Albuquerque NM May. Clinical Trials
Church, D. (2008c). For a list of current studies, see
Craig, G. (2008). Cases searchable on www.Emofree.com
Dougherty, K. A., et. al. (2006). Two percent dehydration impairs and six percent
carbohydrate drink improves boys basketball skills. Medical Science & Sports Exercise,
Feinstein, D., et. al. (2005). The Promise of Energy Psychology. New York: Tarcher, 108.
Feinstein, D. (2008a). Energy psychology: a review of the preliminary evidence.
Psychotherapy: Theory, Research, Practice, Training. June.
Feinstein, D. (2008b) Energy psychology in disaster relief. Traumatology 141:1, March.
Gallo, F. P. (1999). Energy Psychology. (Boca Raton, FL: CRC Press), xi.
Hamilton, S. A., Fremouw, W. J. (1985). Cognitive-behavioral training for college
basketball free-throw performance. Cognitive Therapy and Research. 9(4):479-483.
Hoffman, J. R., et. al. (1995). The effect of water restriction on anaerobic power and
vertical jumping height in basketball players. International Journal of Sports Medicine,
Kearns, D. W., Crossman, J. (1992) Effects of a cognitive intervention package on the
free-throw performance of varsity basketball players during practice and competition.
Perceptual & Motor Skills, 75(3 Pt 2):1243-53.
Kuipers, H. (1998). Training and overtraining: an introduction. Medicine & Science in
Sports & Exercise, 30(7):1137-1139.
Lambrou, P. T., et. al. (2003). Physiological and psychological effects of a mind/body
therapy on claustrophobia. Subtle Energies & Energy Medicine, 14(3):239.
Lane, J. (2006). Wolpe not woo woo; counterconditioning not charlatanism: A
biochemical rationale for using acupressure desensitization in psychotherapy. Paper
presented at ACEP (Association for Comprehensive Energy Psychology) annual
conference, Virginia, May 2006.
Moore, J., Brylinksky, J. A. (1993). Spectator Effect on Team Performance in College
Basketball. Journal of Sport Behavior, Vol. 16.
The Oregonian (2007). In Corvallis, suddenly there came a tap ping. June 18.
Oschman, J. (2006). Trauma energetics. Journal of Bodywork and Movement Therapies,
Rowe, J. (2005). The effects of EFT on long-term psychological symptoms. Counseling
and Clinical Psychology Journal, 2(3):104.
Ruden, R. A. (2005). Neurobiological basis for the observed peripheral sensory
modulation of emotional responses. Traumatology. 2005;11(3):145-158.
Success (1998). Profile: Rick Pitino. October. 70.
Theodorakis, Y. (2001). Self-talk in a basketball shooting task. Perceptual & Motor Skills,
Trninić, S., et. al. (2002). Differences between winning and defeated top quality
basketball teams in final tournaments of European club championship. Collegium
Wells, S., et. al. (2003). Evaluation of a meridian-based intervention, emotional freedom
techniques (EFT), for reducing specific phobias of small animals. Journal of Clinical
Whitehead, R., et. al. (1996). Stress and performance: an application of Gray's three-
factor arousal theory to basketball free-throw shooting. Journal of Sports Science.
Williams, J. H., Klug, G. A. (1995). Calcium exchange hypothesis of skeletal muscle
fatigue: a brief review. Muscle & Nerve, 18(4):421-34.
Wolpe, J. (1958). Psychotherapy by Reciprocal Inhibition. (Stanford, CA: Stanford
Wolpe, J. (1973). The Practice of Therapy (2nd Ed). (New York: Pergamon Press).