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Journal of Cognitive Psychotherapy: An International Quarterly
Volume 22, Number 4 • 2008
©
2008 Springer Publishing Company 291
DOI: 10.1891/0889-8391.22.4.291
Introduction to the Special Issue on
Interoceptive Exposure in the Treatment
of Anxiety and Related Disorders: Novel
Applications and Mechanisms of Action
Sherry H. Stewart, PhD
Dalhousie University, Halifax, NS, Canada
Margo C. Watt, PhD
Saint Francis Xavier University, Antigonish, and Dalhousie University, Halifax, NS, Canada
Interoceptive exposure (IE) involves having an individual repeatedly induce and experience
feared arousal-related sensations (e.g., shortness or breath, heart palpitations, dizziness) as
a means of reducing the fear of those sensations. IE exercises such as hyperventilation, chair
spinning, and breathing through a straw have been demonstrated effective in the treatment
of panic attacks and panic disorder, both as part of a broader cognitive-behavioral program
and as a stand-alone intervention. This article introduces a special issue of the Journal of
Cognitive Psychotherapy focusing on cutting-edge findings on novel applications of IE in
the treatment of anxiety and related disorders and research that begins to investigate IE’s
mechanisms of action. We set the stage for the following series of six original articles by
first providing a historical review of the use of IE in cognitive-behavioral treatments of
panic. We then provide a brief overview of the various theoretical perspectives that can
be applied to understanding the mechanisms of action of IE in reducing fear of fear:
conditioning, cognitive restructuring, emotional processing, self-efficacy, and emotional
acceptance. Finally, we provide a brief overview of the articles included in the special issue.
This special issue should prove helpful to cognitive-behavioral therapists in improving and
expanding their use of IE in clinical practice. The issue also should stimulate additional
research on the mechanisms of action of IE to ultimately permit refinement of treatments
for anxiety and related disorders and, it is hoped, enhance the efficacy of cognitive-
behavioral psychotherapy.
Keywords: interoceptive exposure ; mechanism of action; panic disorder; anxiety disorder;
conditioning; cognitive restructuring
A commonly used technique in the cognitive-behavioral treatment of panic disorder is
interoceptive exposure (IE). IE refers to having patients repeatedly induce and experience
their feared physical sensations (e.g., shortness or breath, heart palpitations, dizziness) as
a means of reducing their fear of those sensations (Craske, Barlow, & Meadows, 2000; Schmidt
292 Stewart and Watt
et al., 2000). For example, the therapist might have the patient hold his or her breath to elicit
feelings of suffocation, spin around rapidly to induce vertigo, or breathe through a narrow straw
to elicit the sensation of “air hunger” (Meuret, Ritz, Wilhelm, & Roth, 2005). IE exercises have
been demonstrated effective in the treatment of panic attacks and panic disorder, both as part of
a broader cognitive-behavioral program (e.g., Barlow, Gorman, Shear, & Woods, 2000) and as a
stand-alone intervention (e.g., Craske, Rowe, Lewin, & Noriega-Dimitri, 1997). In the context of
panic treatment, IE strategies are intended to direct patients to attend to the feared sensations, to
challenge their catastrophic cognitions, and to accept their anxiety experiences so that the sensa-
tions of physiological arousal no longer provoke panic and avoidance behavior (Otto, Powers, &
Fischmann, 2005).
H ISTORY OF IE
IE has been a component of treatments for panic disorder for half a century, although its role
in these treatments has not always been appreciated. For example, Wolpe (1958) included CO
2
inhalations in his early anxiety reduction procedures, the original idea being that the inhalations
induced relaxation and thereby promoted the reciprocal inhibition of anxiety. Alternatively,
Barlow (2002) suggested that these inhalations may have reduced anxiety by exposing the panic
patients to their feared anxiety sensations within the safety of the therapist’s office. Bonn, Har-
rison, and Rees (1971) reported on the effects of lactate infusions administered to 33 patients
with “intractable, non-situational anxiety” (i.e., what we would consider panic disorder today).
Although none of the patients reported an exact reproduction of their “natural” panic attacks,
the treatment did result in a significant decline in “morbid anxiety” levels—a decline that was
maintained at 6 weeks posttreatment. Bonn et al. were especially impressed that patients’ levels
of phobophobia (i.e., “fear of fear” or anxiety sensitivity) were substantially reduced posttreat-
ment. The authors interpreted this as evidence that the lactate infusions led to “interruption of
a pathogenic somato-psychic sequence which had helped to maintain the anxiety neurosis”
(p. 470). Subsequent research found that administering graduated CO
2 inhalations was more
effective in reducing fear of arousal-related sensations than a medication intended to suppress
panic-like symptoms (Griez & van den Hout, 1986).
Other researchers similarly employed techniques that might be considered as IE exercises.
For example, Orwin (1973) used running to successfully treat eight patients with agorapho-
bia. Patients were required to run or walk briskly until breathless, at which point they were to
approach their feared agoraphobic situation. Orwin speculated that the anxiety response was
inhibited at a physiological level by competition from an already activated autonomic system
trying to cope with the urgent metabolic needs of vigorous physical activity. An alternative expla-
nation, of course, is that the running produced the same sensations associated with panic and
repeated exposure resulted in the reduction of fear of those sensations. More recent studies have
provided further support for the role of physical activity as a type of IE exercise. Broocks et al.
(1998) found that physical exercise alone was effective in reducing anxiety and panic symptoms
in patients with panic disorder. Physical exercise also has been found to reduce anxiety sensitivity
(fear of anxiety-related sensations) in nonclinical samples (e.g., Broman-Fulks, Berman, Rabian,
& Webster, 2004; Smits et al., 2008 ). Anxiety sensitivity is a known risk factor for anxiety and
related disorders (Taylor, 1999). Indeed, one article in this issue (Sabourin et al.) discusses the
effectiveness of running as a component in a brief cognitive-behavioral intervention designed to
reduce anxiety sensitivity in nonclinical participants.
Goldstein and Chambless (1978) have been credited as being the first to formally sug-
gest that repeated exposure to feared sensations, or IE as they labeled this technique, might
be an effective way of reducing the fear of physical sensations in panic disorder (see Antony,
Ledley , Liss, & Swinson, 2006). Over the intervening years, IE has come to be recognized as an
Interoceptive Exposure Introduction 293
important component of empirically validated treatments for various anxiety-related disorders.
Some even consider this an essential component of treatment for certain anxiety-related disor-
ders. For example, Barlow (1988) states that “when learned alarms are involved in an anxiety
disorder [as in panic disorder], it may be essential to prevent escape from somatic cues associ-
ated with panic” (p. 314). A number of studies have demonstrated that IE is effective in treating
panic disorder (e.g., Barlow et al., 2000; Craske et al., 1997; Taylor, 2000). Recent research, how-
ever, indicates that IE may be a useful therapy component in treating other disorders, including
posttraumatic stress disorder (Otto et al., 2003; Wald, this issue; Wald & Taylor, 2005, 2007),
claustrophobia (Telch et al., 2004), social phobia (Plotkin, 2002), hypochondriasis (Walker &
Furer, this issue), chronic pain (Shipherd, 2006), and certain forms of substance use disorder
(Zvolensky, Lejuez, & Kahler, 2003; Zvolensky, Yartz, Gregor, Gonzalez, & Bernstein, this issue).
What all these conditions seem to hold in common with panic disorder is an elevated fear of
arousal sensations—or high anxiety sensitivity (Taylor, 1999).
IE’S MECHANISM(S) OF ACTION
The precise mechanism by which exposure operates has been a topic of debate for at least 40
years. In the broader anxiety treatment field, as early as 40 years ago, it was suggested that the
effective ingredient across various fear reduction strategies involved repeated exposure to feared
stimuli (e.g., Bandura, 1969; Barlow, Leitenberg, Agras, & Wincze, 1969). Exposure was said
to exert its efficacious effects either via permitting habituation, allowing for extinction of the
learned fear response, and/or through fostering “reality testing” (Mavissakalian & Barlow, 1981).
Similarly, several different mechanisms of action have been proposed to account for the effective-
ness of IE: (a) conditioning (Bouton, 2002), (b) cognitive restructuring (Beck & Shipherd, 1997),
(c) emotional processing (Foa & Kozak, 1986), (d) social learning (self-efficacy; Bandura, 1983),
and (e) acceptance (Hayes, 2002). We briefly examine each of these perspectives, in turn, as they
apply to explaining how IE works.
Conditioning Model
The conditioning model of IE efficacy is predicated on fundamental learning principles. Accord-
ing to this model, fears are acquired via classical conditioning. Classical conditioning of fears
occurs when a previously neutral stimulus, event, or situation (i.e., conditioned stimulus [CS])
becomes associated with an inherently aversive event (i.e., unconditioned stimulus [UCS]), such
as a frightening episode of intense anxiety coming “out of the blue” (panic attack with attendant
intense physiological sensations). If anxiety-related sensations, such as dizziness or heart palpita-
tions (CS), are repeatedly paired with an intrinsically frightening event, such as an unexpected
panic attack coming out of the blue (UCS), then an individual might learn to fear (conditioned
response [CR]) the occurrence of anxiety-related sensations in the future (Forsyth & Eifert, 1996;
Rapee, 1987). After repeated pairings of the CS and UCS, the CS alone can trigger intense fear
(CR), and the person acquires a “fear of fear” or heightened anxiety sensitivity. In other words,
the intense fear becomes a CR to these harmless interoceptive stimuli. This is basically the process
outlined by Goldstein and Chambless (1978), who argued that classical conditioning explains
how low-level somatic sensations of anxiety or arousal effectively become CSs associated with
higher levels of anxiety or arousal (e.g., panic attacks).
Whereas classical conditioning explains how fear of arousal sensations may be acquired,
operant conditioning explains how the fear of these sensations is maintained. According to
the two-process theory (Rescorla & Solomon, 1967), anxiety CSs should increase or potenti-
ate instrumental responding that has been learned through negative reinforcement to allow for
avoidance or escape from aversive stimuli. In other words, once an intense fear response has
294 Stewart and Watt
been classically conditioned to anxiety-related sensations, the individual should try to avoid or
escape the anticipated intense fear response or panic attack by removing himself or herself from
the CS. For example, a person who is highly sensitive to anxiety-related sensations might learn
to avoid activities (e.g., exercise, sexual intercourse), situations, or emotions (e.g., intense anger)
that elicit these sensations. Avoidance of activities that elicit arousal-related sensations is known
as “interoceptive avoidance.” The tendency to engage in “safety behaviors” (Salkovskis, Clark, &
Gelder, 1996) such as interoceptive avoidance is reinforced by anxiety reduction via the process
of negative reinforcement. As Bouton, Mineka, and Barlow (2001) point out, whereas avoidance
and safety behaviors seem to “protect” the individual by eliminating the risk of danger, these
behaviors actually serve to protect the CR from extinction, thereby functioning to maintain the
fear of anxiety-related sensations.
From a classical conditioning perspective, IE’s mechanism of action is thought to occur via
the process of extinction. Extinction refers to “decrements in the strength of learned responses
through repetition of unreinforced responding” (Barlow, 1988, p. 289). Specifically, repeated
presentation of the CS in the absence of the UCS will result in extinction of the acquired fear
response. Since IE counters the anxiety-related action tendency of interoceptive avoidance by
strongly encouraging approach behavior, these exercises provide the conditions under which
extinction of the CR can take place. Patients undergoing IE repeatedly encounter their feared
arousal-related sensations without experiencing the feared consequences, allowing for classical
extinction to occur.
While extinction is an active process involving unlearning of the original CS–UCS relation-
ship or new learning (i.e., forming new associations of the CS with other nonintrinsically fright-
ening UCSs that replace the old learning), some argue that IE may simply work via allowing for
“habituation” of the fear response. Habituation refers to “a decline in fearful reactions . . . with
repetitive exposure to fear-provoking stimulation” (Barlow, 1988, p. 287). Basically, habituation
pertains to decrements in the strength of unlearned responses, while extinction involves decre-
ments in the strength of learned responses (Forsyth, Lejuez, & Finlay, 2000). While the habitua-
tion explanation has been criticized as being simply a description of process with little underlying
theory (e.g., Barlow, 1988), it has the advantage of describing how IE works to reduce fear of
anxiety sensations, even if this fear is inherited to some degree (e.g., Taylor, Jang, Stewart, & Stein,
2008) rather than being entirely learned (Watt, Stewart, & Cox, 1998 ).
Therapists sometimes teach anxiety control strategies that they instruct patients to apply
immediately after anxiety is induced via IE (Meuret et al., 2005). These strategies may be behav-
ioral (e.g., breathing retraining) or cognitive (e.g., coping self-statements; see next section). From
a conditioning perspective, such anxiety control strategies may be counterproductive when used
in combination with IE, as they may serve as “safety behaviors” or distractions that could retard
extinction by reducing exposure to the feared somatic sensations (Meuret et al., 2005).
Cognitive Restructuring Model
In contrast to the conditioning model that highlights the importance of extinction in the suc-
cessful reduction of fear following repeated exposure to feared stimuli (e.g., Foa, 1979; Rudes-
tam & Bedrosian, 1977), the cognitive model suggests that factors such as particular thought
patterns are more important (e.g., deSilva & Rachman, 1981; Rachman & Levitt, 1988). More
specifically, a cognitive model of IE’s mechanism of action would suggest that repeated expo-
sure to feared anxiety-related sensations is effective because it presents the anxious individual
with information that disconfirms irrational beliefs that cause and maintain anxiety. In other
words, IE provides the individual with an opportunity to learn that there is little to fear from
increased arousal. Via IE exercises, they have the opportunity to learn that there are no aversive
or untoward consequences to experiencing arousal-related sensations. In cognitive terms, their
Interoceptive Exposure Introduction 295
“outcome expectancies” regarding the catastrophic consequences of experiencing anxiety-related
sensations are disconfirmed through IE (Seligman & Johnston, 1973). Not only does IE allow
for challenging of catastrophic cognitions associating such bodily sensations with danger, but
it also allows for the development of alternative, more positive cognitions regarding the out-
comes of experiencing such sensations. Such learning opportunities are normally missed since
panic patients and those with high anxiety sensitivity typically avoid arousal-inducing activities
(Beck & Shipherd, 1997; Beck, Shipherd, & Zebb, 1997).
From a cognitive perspective, IE operates by providing opportunities for challenging irratio-
nal cognitions. To facilitate this cognitive change, as mentioned earlier, therapists sometimes teach
cognitive anxiety control strategies that they instruct patients to apply during IE trials (Meuret
et al., 2005). From the cognitive restructuring perspective, such strategies should be helpful in
improving the therapeutic outcome of IE. Those who attribute change from IE to extinction of
a classically conditioned fear response tend not to use such cognitive control strategies because
of concerns that they may be countertherapeutic, as discussed in the previous section. However,
in some applications of IE, such cognitive anxiety control strategies are applied very directly and
explicitly. For example, in the Sabourin et al. (this issue) study, high anxiety–sensitive partici-
pants were first taught cognitive restructuring in a therapy session prior to the introduction of
IE, and then they were actively encouraged to apply their cognitive restructuring skills during the
IE trials. In other applications of IE, cognitive restructuring might be encouraged more indirectly
or implicitly. For example, in the Wald (this issue) study, the patient was not taught any cognitive
coping techniques for dealing with her anxiety-related sensations. Yet she was asked to identify
and rate a positive and a negative cognition associated with the induced sensations on each IE
trial to allow the researchers to track decreases in negative outcome expectancies and increases in
positive outcome expectancies associated with the feared arousal sensations across IE trials. Thus,
Wald’s patient was indirectly encouraged to examine her irrational cognitions during the IE tri-
als, which might have facilitated cognitive restructuring by making the patient more aware of her
negative expectancies and of healthier, more adaptive interpretations of her arousal sensations.
It is possible that the conditioning model best applies in accounting for some individuals’
change in response to IE, while cognitive restructuring best applies in the case of other individu-
als’ change process. For example, Beck and Shipherd (1997) identified two distinct subtypes of
patient response patterns to IE; habituators and nonhabituators. Beck et al. (1997) replicated
these findings in a subsequent study and were prompted to conclude that there may be two path-
ways of therapeutic change for IE. One process involves habituation of fear; the other pathway
involves an absence of habituation but, nonetheless, results in a positive outcome. To account for
these findings, Beck et al. proposed that cognitive restructuring may mediate this second type of
response and account for the positive effects of IE in a subset of cases.
Emotional Processing Model
A third model of IE efficacy, one that includes aspects of both the conditioning and the cognitive
restructuring models, is Foa and Kozak’s (1986) emotional processing model of fear reduction.
Emotional processing refers to the modification of memory structures that underlie emotions
(Foa & Kozak, 1986). Following from Lang’s (1979) bioinformational model, fear is conceptual-
ized as an associative network that includes information about (a) the feared stimulus situation;
(b) the individual’s verbal, physiological, and overt behavioral responses to the situation; and
(c) aspects of the meaning of the fear for the individual. In the case of fear of arousal sensations,
this associative network might include (a) information about feared sensations (e.g., rapid heart-
beat, dizziness), (b) information about the individual’s tendency toward escape and avoidance of
such sensations (e.g., interoceptive avoidance), and (c) aspects of meaning of the feared sensations
(e.g., catastrophic beliefs that the sensations portend serious physical illness or even death). An
296 Stewart and Watt
individual’s fear structure is stored in memory and recalled on exposure to any of its elements.
For example, if an anxiety-sensitive person experiences arousal-related sensations, such as pal-
pitations after drinking a strong cup of coffee, this exposure would activate all elements of the
fear structure.
Successful emotional processing requires that two conditions be satisfied. First, the fear
structure must be adequately activated. According to Foa and Kozak (1986), fear activation is
more effective if there is a close match between the fear structure (containing propositions about
stimuli, responses, and their meaning) and the information presented. Second, information
incompatible with elements of the fear structure must be made available and cognitively pro-
cessed. By definition, IE satisfies both these conditions. IE exercises trigger the feared sensations
(e.g., breathlessness, heart palpitations), and, insofar as no catastrophic consequences follow
(e.g., fainting, heart attack), IE provides corrective, disconfirming information that leads to an
uncoupling of the fear structure elements. From the perspective of emotional processing theory,
cognitive or behavioral anxiety control strategies may be countertherapeutic when combined
with IE since such control strategies may interfere with adequate activation of the fear structure.
And combining IE with arousal-dampening drugs such as benzodiazepines might be counter-
therapeutic for similar reasons (Wardle, 1990; Westra & Stewart, 1998).
Foa and Kozak (1986) contended that habituation was the operative mechanism underlying
successful emotional processing. They argued that short-term physiological habituation leads to
dissociation of response elements from stimulus elements of the fear structure. This results in
diminished arousal, which facilitates integration of corrective information about the meaning of
the feared stimuli and responses. This, in turn, leads to reduced avoidance behavior and gradual
modification of irrational beliefs about the feared stimuli. As applied to explaining the efficacy of
IE in the treatment of fear of arousal sensations, repeated exposure to the sensations would first
lead to habituation of fear in response to the sensations. The resultant decreased arousal would
facilitate integration of corrective information about the nonthreatening nature of arousal sensa-
tions available from the outcome of the IE trail. This would allow for reductions in the intero-
ceptive avoidance response in future and would permit an eventual shift in irrational beliefs that
arousal-related sensations are dangerous across IE learning trials.
Social Learning Model
An alternative account for the effectiveness of IE in reducing fear of arousal sensations is
Bandura’s (1983) self-efficacy model. Self-efficacy refers to the individual’s conviction that he
or she is able to effectively cope with a situation. In the case of anxiety sensitivity, this would be
an individual’s expectancy that he or she is able to cope with arousal-related sensations when
they occur. In the case of panic disorder, this specific form of self-efficacy is referred to as “panic
self-efficacy,” which refers to the patient’s perceived ability to cope with or control the perceived
danger of panic attacks (Telch, Brouillard, Telch, Agras, & Taylor, 1989; Williams & Falbo, 1996).
According to the social learning model, it is the perceived lack of self-efficacy that induces fear
during potentially aversive situations (Bandura, 1988). For someone with panic disorder or high
levels of anxiety sensitivity, the social learning model asserts that self-perceived inability to cope
when experiencing arousal sensations accounts for the fear that he or she experiences when fac-
ing somatic sensations of anxiety, such as rapid heart beat or shortness of breath. In terms of
its role in therapeutic change, research indicates that increases in panic self-efficacy accompany
reduction of panic severity via cognitive-behavioral treatment (Bouchard et al., 1996; Côté,
Gauthier, Laberge, Cormier, & Plamondon, 1993).
According to Bandura (1994), the most potent source of self-efficacy is previous personal
experience with success or mastery experiences. Outcomes interpreted as successful, such as
behavioral mastery of fear-inducing situations, serve to enhance self-efficacy. IE may well provide
Interoceptive Exposure Introduction 297
the opportunity for personal mastery of encountering and coping with (rather than avoiding)
arousal-related sensations. Coping strategies aimed at mastery have been found to be highly
effective in improving self-efficacy when they are combined with exposure procedures (Jones &
Menzies, 2000).
In contrast to the conditioning and emotional processing models where cognitive or behav-
ioral anxiety control strategies are seen as potentially countertherapeutic, the self-efficacy model
suggests that such anxiety control techniques may have a beneficial role in fear reduction when
applied in combination with IE. In this case, such control strategies would allow the individual
to master facing arousal-related sensations with less anxiety than would otherwise have been the
case. The experience of being relatively free from anxiety in the presence of the phobic stimulus
(in this case, the feared arousal-related sensations) has been shown to improve perceived self-
efficacy, thereby contributing to fear reduction (Oliver & Page, 2008).
The self-efficacy perspective points to another crucial target of anxiety treatment, according
to experts such as Barlow (1988)—namely, a sense of control. Barlow (1988) has suggested that
a sense of uncontrollability is at the core of the complex cognitive-affective structure of anxiety.
More specifically, anxious individuals perceive themselves as lacking control. In the case of an
individual who fears anxiety-related sensations, this element presents as a perception that one
lacks control over the feared sensations. From this perspective, IE may work by altering percep-
tions of control. More specifically, IE may provide the opportunity for the individual to learn that
he or she can exert some degree of control over the anxiety-related sensations when they occur.
This would seem to be particularly the case when IE is accompanied by the individual practic-
ing anxiety control strategies that he or she has learned earlier in therapy. From this perspective,
what is learned during IE trials is that events are not out of control. That is, whether unwanted
physiological arousal occurs or not, the individual learns that he or she is in control of his or her
world (Barlow, 1988).
Acceptance Model
Recent theoretical models of anxiety emphasize the importance of acceptance of negative
emotional states and associated somatic sensations and cognitions (e.g., Hayes, 2002). Such
acceptance-based models contend that individuals who can accept and tolerate arousal-related
sensations without the need to escape them or change them should be less vulnerable to anxiety
pathology than those who feel the need to use cognitive or behavioral strategies to escape such
internal sensations (Hayes, Wilson, Gifford, Follette, & Strosahl, 1996). Empirically, a lack of
emotional acceptance has been shown to be a particular problem for patients with panic disor-
der (Campbell-Sills, Barlow, Brown, & Hofmann, 2006) and for nonclinical individuals high in
anxiety sensitivity (Eifert & Heffner, 2003). More recent research suggests that anxiety sensitivity
may interact with emotional acceptance. Specifically, Kashdan, Zvolensky, and McLeish (2008)
showed that anxious arousal and worry were elevated in anxiety-sensitive individuals when such
individuals were also low in acceptance of emotional distress.
In terms of psychotherapeutic implications, this model suggests that if anxiety-sensitive peo-
ple can be taught to emotionally accept aversive anxiety-related sensations, emotional states, and
associated thoughts, they may be able to forestall the escalation of problematic anxiety reactions
(Kashdan et al., 2008). It is here that the cognitive restructuring and emotional acceptance posi-
tions most clearly diverge in that the targets of treatment are very different. From the cognitive
perspective, low acceptance of anxiety implies that the person has negative beliefs about anxiety,
and it is these beliefs that are the focus of change strategies in anxiety treatment. In contrast, the
emotional acceptance position argues that acceptance of negative emotional states and sensations
should facilitate cognitive change. Theoretically, emotional acceptance allows anxiety-sensitive
people to attend to the current situation (e.g., to attend to rather than distract themselves from
298 Stewart and Watt
or avoid their feared anxiety-related sensations). This allows for a more realistic appraisal of the
level of threat posed by the arousal sensations rather than automatically reacting to the sensations
in a catastrophic manner.
In applying such acceptance-based models to understanding the mechanism of action of IE,
repeated exposure to arousal-related sensations over IE trials might allow the anxiety-sensitive
individual the opportunity to learn to accept rather than fight their feared somatic, cognitive,
and affective sensations. From an acceptance-based perspective, IE allows for challenging of
automatic negative evaluations of normal emotional reactions and sensations and disconfirma-
tion of beliefs that it is unhelpful to be in direct contact with these undesirable emotions and
sensations (Kashdan et al., 2008). In this respect, the acceptance-based perspective holds much in
common with the cognitive restructuring position outlined earlier. However, it is specifically the
change in cognitions around the unacceptability of the emotions and sensations that is thought
to mediate therapeutic benefit of IE from the acceptance-based position. Finally, this perspective
would suggest that IE works by directly countering high anxiety–sensitive people’s tendencies to
deliberately attempt to control or monitor their negative emotions and associated sensations due
to concerns about the harmful consequences of these sensations (Kashdan et al., 2008). Clearly,
those adopting an acceptance-based position would not advocate the combining of anxiety con-
trol strategies with IE techniques. The use of anxiety control strategies would be seen as feeding
into high anxiety–sensitive people’s tendencies to inflexibly attempt to escape or control rather
than accept their anxious emotions and associated somatic sensations.
Mechanism of IE Action: Conclusions
To recap, several theoretical positions can be applied to understand how IE is helpful in the
treatment of panic and related disorders. Possible mechanisms of IE action include extinc-
tion or habituation, cognitive restructuring, emotional processing, self-efficacy or an enhanced
perception of control, and emotional acceptance. These models differ in whether they contend
that accompanying IE with cognitive or behavioral anxiety control strategies should be helpful
or harmful: the conditioning, emotional processing, and emotional acceptance models predict
potentially countertherapeutic effects of adding in control strategies, while the cognitive restruc-
turing and self-efficacy models predict enhanced IE efficacy in reducing fear of arousal sensa-
tions when IE is accompanied by the practice of anxiety control strategies. The evidence to date
does not allow elimination of any of these proposed mechanisms of action for IE’s efficacy, and
additional research is needed to tease apart which mechanism(s) best explain(s) how repeated
exposure to arousal-related sensations works in reducing fear of these sensations. Better under-
standing the mechanism(s) of action underlying the effectiveness of IE would permit refinement
of treatments for panic and related disorders and, it is hoped, enhance treatment efficacy.
T HE CURRENT SPECIAL ISSUE
This special issue comprises a set of articles that examine some exciting and promising new
applications of IE in the treatment of anxiety and related disorders and that begin to explore
the mechanisms of action of IE in the treatment of fear of anxiety sensations. We begin with a
paper by Brigitte Sabourin and her colleagues (this issue) wherein they describe the role of IE in
a novel early intervention for high anxiety–sensitive individuals. This intervention has previously
been shown to reduce anxiety sensitivity (Watt, Stewart, Birch, & Bernier, 2006; Watt, Stewart,
Conrod, & Schmidt, 2008; Watt, Stewart, Lefaivre, & Uman, 2006). Sabourin et al.’s article focuses
on process data collected throughout the course of the IE sessions, representing a first step in
identifying IE’s mechanisms of action. Next, an article by James Lickel, Elizabeth Nelson, Athena
Interoceptive Exposure Introduction 299
Hayes Lickel, and Brett Deacon (this issue) describes the results of an experimental study that
examined IE in the treatment of depersonalization and derealization. This clinically useful article
identifies which IE exercises are most beneficial in reducing these specific anxiety-related symp-
toms. The next article, by Jaye Wald (this issue), illustrates a novel application of IE as a prelude
to traditional trauma-related exposure therapy in the treatment of posttraumatic stress disorder
(PTSD). Wald’s contribution demonstrates the utility of this approach via a case study of a PTSD
patient with substantial comorbidity (i.e., panic, depression, and chronic pain). A subsequent
article by Michael Zvolensky, Andrew Yartz, Kristin Gregor, Adam Gonzalez, and Amit Bernstein
(this issue) describes a novel treatment they have developed that emphasizes IE in the treatment
of daily smokers with high anxiety sensitivity. Specifically, short periods of nicotine withdrawal
are utilized therapeutically as a form of IE to prepare anxiety-sensitive smokers for the more
prolonged and intensive arousal sensations they are likely to experience in the early phase of a
smoking cessation attempt. In the penultimate article, John Walker and Patricia Furer (this issue)
outline the use of IE in the treatment of hypochondriasis and other conditions involving signifi-
cant health anxiety. Finally, Michael Otto (this issue) provides an integrative discussion article in
which he reviews of a number of the core themes evident in the special series articles and where
he highlights research achievements thus far as well as future directions for inquiry. We hope that
this special issue will be helpful to cognitive-behavioral therapists in improving and expanding
their use of IE in clinical practice. We also trust that the issue will stimulate additional research
on the mechanisms of action of IE, using more complex methodologies such as multivariate
time-series analyses.
R EFERENCES
Antony, M. M., Ledley, D. R., Liss, A., & Swinson, R. P. (2006). Responses to symptom induction exercises in
panic disorder. Behaviour Research and Therapy, 44, 85–98.
Bandura, A. (1969). Principles of behavior modification. New York: Holt, Rinehart and Winston.
Bandura, A. (1983). Self-efficacy determinants of anticipated fears and calamities. Journal of Personality and
Social Psychology, 45, 464–469.
Bandura, A. (1988). Self-efficacy conception of anxiety. Anxiety Research, 1, 77–98.
Bandura, A. (1994). Regulative function of perceived self-efficacy. In M. G. Rumsey, C. B. Walker, & J. H.
Harris (Eds.), Personnel selection and classification (pp. 261–271). Hillsdale, NJ: Lawrence Erlbaum
Associates.
Barlow, D. H. (1988). Anxiety and its disorders: The nature and treatment of anxiety and panic. New York:
Guilford Press.
Barlow, D. H. (2002). Anxiety and its disorders: The nature and treatment of anxiety and panic (2nd ed.). New
York: Guilford Press.
Barlow, D. H., Gorman, J. M., Shear, M. K., & Woods, S. W. (2000). Cognitive-behaviour therapy, imi-
pramine, or their combination for panic disorder. Journal of the American Medical Association, 283,
2529–2536.
Barlow, D. H., Leitenberg, H., Agras, W. S., & Wincze, J. P. (1969). The transfer gap in systematic desensitiza-
tion: An analogue study. Behaviour Research and Therapy, 7, 191–197.
Beck, J. G., & Shipherd, J. (1997). Repeated exposure to interoceptive cues: Does habituation of fear occur
in panic disorder patients? Behavior Research and Therapy, 35, 551–557.
Beck, J. G., Shipherd, J. C., & Zebb, B. J. (1997). How does interoceptive exposure for panic disorder work?
An uncontrolled case study. Journal of Anxiety Disorders, 11, 541–556.
Bonn, J. A., Harrison, J., & Rees, W. L. (1971). Lactate-induced anxiety: Therapeutic application. British
Journal of Psychiatry, 119, 468–470.
300 Stewart and Watt
Bouchard, S., Gauthier, J., Laberge, B., French, D., Pelletier, M.-H., & Godbout, C. (1996). Exposure vs.
cognitive restructuring in the treatment of panic disorder with agoraphobia. Behaviour Research and
Therapy, 34, 213–224.
Bouton, M. E. (2002). Context, ambiguity, and unlearning: Sources of relapse after behavioral extinction.
Biological Psychiatry, 52, 976–986.
Bouton, M. E., Mineka, S., & Barlow, D. H. (2001). A modern learning theory perspective on the etiology of
panic disorder. Psychological Review, 108, 4–32.
Broman-Fulks, J. J., Berman, M. E., Rabian, B. A. & Webster, M. J. (2004). Effects of aerobic exercise on
anxiety sensitivity. Behaviour Research and Therapy, 41, 125–126.
Broocks A., Bandelow, B., Pekrun, G., George, A., Meyer, T., Bartmann, U., et al. (1998). Comparison of
aerobic exercise, clomipramine, and placebo in the treatment of panic disorder. American Journal of
Psychiatry, 155, 603–609.
Campbell-Sills, L., Barlow, D. H., Brown, T. A., & Hofmann, S. G. (2006). Effects of suppression and accep-
tance on emotional responses of individuals with anxiety and mood disorders. Behaviour Research and
Therapy, 44, 1251–1263.
Côté, G., Gauthier, J. G., Laberge, B., Cormier, H. J., & Plamondon, J. (1993). The cognitive-behavioral
treatment of panic disorder: A critical review of the research. Canadian Journal of Behavioral Science,
25, 45–63.
Craske, M. G., Barlow, D. H., & Meadows, E. A. (2000). Mastery of your anxiety and panic: Therapist guide
for anxiety, panic, and agoraphobia (MAP-3). San Antonio, TX: Graywind Publishing/The Psychological
Corporation.
Craske, M. G., Rowe, M., Lewin, M., & Noriega-Dimitri, R. (1997). Interoceptive exposure versus breathing
retraining within cognitive behavioural therapy for panic disorder with agoraphobia. British Journal of
Clinical Psychology, 36, 85–99.
deSilva, P., & Rachman, S. (1981). Is exposure a necessary condition for fear reduction? Behaviour Research
and Therapy, 19, 227–232.
Eifert, G. H., & Heffner, M. (2003). The effects of acceptance versus control contexts on avoidance of panic-
related symptoms. Journal of Behavior Therapy and Experimental Psychiatry, 34, 293–312.
Foa, E. B. (1979). Failure in treating obsessive-compulsives. Behaviour Research and Therapy, 17, 169–176.
Foa, E. B., & Kozak, M. J. (1986). Emotional processing of fear: Exposure to corrective information. Psycho-
logical Bulletin, 99, 20–35.
Forsyth, J. P., & Eifert, G. H. (1996). Systemic alarms in fear conditioning, I: A reappraisal of what is being
conditioned. Behavior Therapy, 27, 441–462.
Forsyth, J. P., Lejuez, C. W., & Finlay C. (2000). Anxiogenic effects of repeated administrations of 20%
CO
2 -enriched air: Stability within sessions and habituation across time. Journal of Behavior Therapy
and Experimental Psychiatry, 31, 103–121.
Goldstein, A. J., & Chambless, D. L. (1978). A reanalysis of agoraphobia. Behavior Therapy, 9, 47–59.
Griez, E., & van den Hout, M. A. (1986). CO
2 inhalation in the treatment of panic attacks. Behaviour
Research and Therapy, 24, 145–150.
Hayes, S. C. (2002). Acceptance, mindfulness, and science. Clinical Psychology: Science and Practice, 9,
101–106.
Hayes, S. C., Wilson, K. G., Gifford, E. V., Follette, V. M., & Strosahl, K. (1996). Experiential avoidance and
behavioral disorders: A functional dimensional approach to diagnosis and treatment. Journal of Con-
sulting and Clinical Psychology, 64, 1152–1168.
Jones, M. K., & Menzies, R. G. (2000). Danger expectancies, self-efficacy and insight in spider phobia. Behav-
iour Research and Therapy, 38, 585–600.
Kashdan, T. B., Zvolensky, M. J., & McLeish, A. C. (2008). Anxiety sensitivity and affect regulatory strategies:
Individual and interactive risk factors for anxiety-related symptoms. Journal of Anxiety Disorders, 22,
429–440.
Lang, P. J. (1979). A bio-informational theory of emotional imagery. Psychophysiology, 16, 495–512.
Interoceptive Exposure Introduction 301
Mavissakalian, M. R., & Barlow, D. H. (1981). Phobia: Psychological and pharmacological treatment. New
York: Guilford Press.
Meuret, A. E., Ritz, T., Wilhelm, F. H., & Roth, W. T. (2005). Voluntary hyperventilation in the treatment of
panic disorder: Functions of hyperventilation, their implications for breathing retraining, and recom-
mendations for standardization. Clinical Psychology Review, 25, 285–306.
Oliver, N. S., & Page, A. C. (2008). Effects of internal and external distraction and focus during exposure to
blood-injury-injection stimuli. Journal of Anxiety Disorders, 22, 283–291.
Orwin, A. (1973). The running treatment: A preliminary communication on a new use for an old therapy
(physical activity) in the agoraphobic syndrome. British Journal of Psychiatry, 122, 175–179.
Otto, M. W., Hinton, D., Korbly, N. B., Chew, A., Ba, P., Gershuny, B. S., et al. (2003). Treatment of phar-
macotherapy-refractory post-traumatic stress disorder among Cambodian refugees: A pilot study of
combination treatment with cognitive-behavior therapy vs. sertraline alone. Behaviour Research and
Therapy, 41, 1271–1276.
Otto, M. W., Powers, M. B., & Fischmann, D. (2005). Emotional exposure in the treatment of substance use
disorders: Conceptual model, evidence, and future direction. Clinical Psychology Review, 25, 824–839.
Plotkin, D. P. (2002). The effects of interoceptive exposure on fear reduction and return of fear in indi-
viduals with public speaking anxiety. Dissertation Abstracts International. B. The Physical Sciences and
Engineering, 62, 5387.
Rachman, S., & Levitt, K. (1988). Panic, fear reduction, and habituation. Behaviour Research and Therapy,
26, 199–206.
Rapee, R. M. (1987). The psychological treatment of spontaneous panic attacks: Theoretical conceptualiza-
tion and review of evidence. Clinical Psychology Review, 7, 427–438.
Rescorla, R. A., & Solomon, R. L. (1967). Two-process learning theory: Relationships between Pavlovian
conditioning and instrumental training. Psychological Review, 74, 151–183.
Rudestam, K. E., & Bedrosian, R. (1977). An investigation of the effectiveness of desensitization and flooding
with two types of phobias. Behaviour Research and Therapy, 15, 23–30.
Salkovskis, P. M., Clark, D. M., & Gelder, M. G. (1996). Cognition-behaviour links in the persistence of panic.
Behaviour Research and Therapy, 34, 453–458.
Schmidt, N. B., Woolaway-Bickel, K., Trakowski, J., Santiago, H., Storey, J., Koselka, M., et al. (2000). Dis-
mantling cognitive–behavioral treatment for panic disorder: Questioning the utility of breathing
retraining. Journal of Consulting and Clinical Psychology, 68, 417–424.
Seligman, M. E. P., & Johnston, J. (1973). A cognitive therapy of avoidance learning. In J. McGuigan & B.
Lumsden (Eds.), Contemporary approaches to conditioning and learning (pp. 69–110). New York: Wiley.
Shipherd, J. C. (2006). Treatment of a case example with PTSD and chronic pain. Cognitive and Behavioral
Practice, 13, 24–32.
Smits , J. A. J., Berry, A. C., Rosenfield, D., Powers, M. B., Behar, E., & Otto, M. W. (2008). Reducing anxiety
sensitivity with exercise. Depression and Anxiety, 25, 689–699.
Taylor, S. (1999). Anxiety sensitivity: Theory, research, and treatment of the fear of anxiety. Mahwah, NJ:
Lawrence Erlbaum Associates.
Taylor, S. (2000). Understanding and treating panic disorder: Cognitive-behavioural approaches. New York:
Wiley.
Taylor, S., Jang, K. L., Stewart, S. H., & Stein, M. B. (2008). Etiology of the dimensions of anxiety sensitivity:
A behavioral-genetic analysis. Journal of Anxiety Disorders, 22, 899–914.
Telch, M. J., Brouillard, M., Telch, C. F., Agras, W. S., & Taylor, C. B. (1989). Role of cognitive appraisal in
panic-related avoidance. Behaviour Research and Therapy, 27, 373–383.
Telch, M. J., Valentiner, D. P., Ilai, D., Young, P. R., Powers, M. B., & Smits, J. A. J. (2004). Fear activation and
distraction during the emotional processing of claustrophobic fear. Journal of Behavior Therapy and
Experimental Psychiatry, 35, 219–232.
Wald, J., & Taylor, S. (2005). Interoceptive exposure therapy combined with trauma related exposure therapy
for posttraumatic stress disorder: A case report. Cognitive Behaviour Therapy, 34, 34–40.
302 Stewart and Watt
Wald, J., & Taylor, S. (2007). Efficacy of interoceptive exposure therapy combined with trauma-related
exposure therapy for posttraumatic stress disorder: A pilot study. Journal of Anxiety Disorders, 21,
1050–1060.
Wardle, J. (1990). Behaviour therapy and benzodiazepines: Allies or antagonists? British Journal of Psychia-
try, 156, 163–168.
Watt, M. C., Stewart, S. H., Birch, C. D., & Bernier, D. B. (2006). Brief CBT for high anxiety sensitivity
decreases drinking and drinking problems: Evidence from a randomized controlled trial. Journal of
Mental Health, 15, 683–695.
Watt, M. C., Stewart, S. H., Conrod, P. J., & Schmidt, N. B. (2008). Personality-based approaches to treatment
of co-morbid anxiety and substance use disorder. In S. H. Stewart & P. J. Conrod (Eds.), Anxiety and
substance use disorders: The vicious cycle of comorbidity (pp. 201–219). New York: Springer Publishing.
Watt, M. C., Stewart, S. H., & Cox, B. J. (1998). A retrospective study of the learning history origins of anxi-
ety sensitivity. Behaviour Research and Therapy, 36, 505–525.
Watt, M. C., Stewart, S. H., Lefaivre, M-J., & Uman, L. S. (2006). A brief cognitive-behavioral approach to
reducing anxiety sensitivity decreases pain-related anxiety. Cognitive Behaviour Therapy, 35, 248–256.
Westra, H., & Stewart, S. H. (1998). Cognitive behavioural therapy and pharmacotherapy: Complementary
or contradictory approaches to the treatment of anxiety? Clinical Psychology Review, 18, 307–340.
Williams, S. L., & Falbo, J. (1996). Cognitive and performance-based treatments for panic attacks in people
with varying degrees of agoraphobic disability. Behaviour Research and Therapy, 34, 253–264.
Wolpe, J. (1958). Psychotherapy by reciprocal inhibition. Stanford, CA: Stanford University Press.
Zvolensky, M. J., Lejuez, C. W., & Kahler, C. W. (2003). Integrating an interoceptive exposure-based smoking
cessation program into the cognitive-behavioral treatment of panic disorder: Theoretical relevance and
case demonstration. Cognitive and Behavioral Practice, 10, 347 –357.
Acknowledgments. The first author was supported by an Investigator Award from the Canadian Institutes of
Health Research at the time this special issue was being prepared. She is currently supported through a Killam
Research Professorship from the Faculty of Science at Dalhousie University. Preparation of this manuscript and
editing of the special issue was supported in part through a research grant to the second author from the Social
Sciences and Humanities Research Council of Canada, Sport Canada Research Initiative. The authors would
like to acknowledge the contributions of Dr. Steven Taylor in reviewing and commenting on an earlier version
of the present article.
Correspondence regarding this article should be directed to Sherry H. Stewart, PhD, Department of Psychology,
Dalhousie University, Halifax, NS B3J 4J1, Canada. E-mail: sstewart@dal.ca