The current status of systematic desensitization

Cltntcal

Printed

Psyhologl Raww. Vol. 1. pp. 149- 179, 1981 in the USA. All nghts reserved.

0272-73?l@/81~020149-31502.0010 Copvright C 1981 Pergamon Press Ltd.

THE CURRENT STATUS OF SYSTEMATIC DESENSITIZATION F. Dudley McGlynn, Wallace L. Mealiea, Jr. and Denise L. Landau University of Fkxida

ABSTRACT. This article k a selective reiriez of the09 and research irz systematic desertsitization over the last two decades. First, several models that purport to explain therapeutic desensitization effects are reviewed. Then, the literatures pertaining to expectancy effects and relaxation effects in desensitization are reviewed and their implications for the several expkznatoly models are noted. Fina&, the outstanding methodological problems in nonclinkal desensitization research are discussed. The state of the09 in desensitization is confusing. The research done heretofore is unimpressive. However, valuable methodological lessolnchave been learned, and we are now, for the first time, in a reasonably good position to study carefully the ejyects of desensitization treatments.

Along with operant technology, the technique of systematic desensitization (Wolpe, 1958) ushered in the behavior therapy movement. The psychological literature about the technique is truly very large. In this paper we address several subsets of this literature in an effort to articulate a cohesive picture of desensitization theory and research over the past two decades. We set the stage for the bulk of the narrative by describing briefly the desensitization procedure and by discussing briefly the question of clinical efficacy. We then describe several of the various theories that purport to explain, wholly or partially, “why desensitization works,” and review two representative subsets of experimental research on theoreticaliy germaine treatment variables. Finally, we discuss the evolution of desensitization research methodology and describe contempol-ary approaches to the various problems of experimental validity.

Send requests for reprints to F. Dudley McGlynn, University of Florida College of Dentistry, Box J-424, Gainesville, Florida 32610. 149

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F. i)udley ‘~cGl~?~n,WallaceL. J\ifealiea,Jr. and Denise L. Landau

THE DESENSITTIZATION PROCEDURE Systematic desensitization based on relaxation (Wolpe. 1973) is used to provide anxious individuals with opportunities for nonanxious imaginal “exposure” to increasingly aversive forms of the cue stimuli for their anxieties. Aside from procedures used to assess antecedents and consequences of the patient’s anxious responsivity, the technique entails three basic steps. First, the patient is trained in the skill of muscular relaxation using “progressive relaxation” exercises patterned after those developed by Jacobson (cf. Berstein k Borkovec, 1973). Second, the patient and therapist construct one or more desensitization hierarchies: lists of clinically focal aversive cue descriptions that proceed in smaI1 increments from minimally to intensely frightening situations and/or activities. Third, the therapist instructs the patient to practice muscular relaxation and simultaneously to visualize at his or her own pace the increasingly aversive scenes within the hierarchy. Sometimes the therapist encourages the patient to track the imaginal hierarchy in vivo bv performing calmly in real life the same activities or confrontations that are hierarchically represented. Detailed analyses of the fine grain of clinical desensitization treatments are beyond the scope of this paper. Several valuable sources for this kind of information are available (e.g.. Goldfried 8c Davison, 1976; Marquis, Morgan, & Piaget, 1971; McGlynn, 19iS; Wolpe, 1973).

For the purposes of this paper the clinical efficacy of desensitization is accepted more or less uncritically. While recognizing that the Protestantism of the early behavior therapy movement spawned some extravagant claims, one cannot deny realistically the fundamental success of the method. The list of fears to which desensitization has been applied includes at least the following: injury, disaster, death, illness, atomic holocaust, heart attack, animals, storms. water, birds, insects, reptiles, airplanes, automobiles, injections, laboratory dissections, hospitals, ambulances, sanitary napkins, heterosexual interactions, social situations, childbirth, and authority figures. The list of sometimes anxiety-related disorders to which the technique has been applied includes the following: impotence, urinary urgency, homosexuality, repetitive handwashing, anorexia nervosa, asthma, speech disturbances, nightmares, insomnia, exhibitionism, chronic diarrhea, and auditory hallucinations. For the most part, literature reviews and retrospective studies of clinical cases have painted a picture of reliable success (cf. Hain, Butcher, & Stevenson, 1966; Lazarus, 1963; Marks & Gelder, 1965; Mever SCCrisp, 1966). Paul’s (1969a. 1969b) reviews of desensitization outcome stiil constitute the definitive works. He reviewed 55 case reports and uncontrolled group studies and 19 controlled experiments representing the work of over 90 therapists with nearly 1.OOO clients. He concluded that “The findings were overwhelmingly positive, and for the first time in the history of psychological treatments. a specific therapeutic package reliably produced measurable benefits for clients across a broad range of problems.” There is no reason in 1981 to chaflenge Paul’s verdict.

THEORIESIN DESENSITIZATION Problems in Desensitize tion Theory Even though most therapists agree that systematic desensitization is reliably anxiety reducing, there remains no consensus at all about why or how this anxiety reduction occurs. In fact, an uncritical survey of the various desensitization theories would yield a confusing array of conceptually diverse and empirically contradictory formulations. There are, of course, a great many factors responsible for the theoretical confusion over therapeutic desensitization effects. M’e will discuss three major sources of confusion by way of setting the tone for our discussion of the theories themselves. The Legacy of Learning Theory. The experimental psychology of learning during the 1930s and ’40s was a collage of theoretical systems, each of which sought to accommodate the available data better than could its competitors (see Guthrie, 1935; Hull, 1943; Tolman, 1932). There was not much disagreement at the level of experimental results. The major facts of behavior acquisition, extinction, generalization, discrimination, and the like were, with a few exceptions, consensually endorsed. Nonetheless, there was spirited argument at the seemingly basic levels of “what” was being learned, “what” was being unlearned, etc. Hull spoke of phvsiological “habits.” Tolman spoke of sign-Gestalt expectancies. Guthrie spoke of SR bonds. When Wolpe (1958) turned to experimental learning theory for explanations of his early results, he inherited inadvertently this legacy of controversy. By choosing to couch his ideas in the construct language of Hull he invited rejoinders in the languages of Guthrie and Tolman. Once Wolpe’s formulations gained some notoriety, these rejoinders did not take long to appear. Guthrie’s language was used in Davison’s (1968) assertion that desensitization is a “counterconditioning” process. Tolman’s language was used in Wilkins’ (1971) contention that desensitization effects are mediated partially by the patient’s “expectancy” of a successful therapy outcome. The Psychotherapy Environment. The field of psychotherapy during the 1950s and ’60s also was a collage of theoretical systems, each of which sought to make more sense than its competitors. Lazarus (1967), in a delightful paper, noted Harper’s list of 36 psychotherapy systems, adding that the list was incomplete. There was not much disagreement at the level of data in the psychotherapy field either. With the notable exception of the nondirective-client centered-experiential psychotherapy movement, data did not play a robust role in theoretical development. From such a variegated and uncritical psychotherapy zeitgeist, it was inevitable that some would seize on opportunities to explain Wolpe’s impressive results by recourse to their own preferred psychotherapv theories. Thus, the effects of desensitization were said to depend on the “therapeutic relationship” (Glover, 1959), on the adventitious psychodvnamic accompaniments of desensitization treatments (Weitzman, 1967), and the like.

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WaticzceL. Mealiea. Jr. and Denise L. Landau

Empirical Probierns. In the late 1960s and early ’70s there appeared scores of experiments intended to address the theoretical questions made outstanding by the experimental lineage and clinical matrix of Wolpe’s formulations. Is muscular relaxation necessary to therapy success? Must the imaging instructions proceed along a graduated, increasingly noxious hierarchy? Must the patient be permitted to govern his or her own rate of progress along the imaginal hierarchy? What will happen if you tell to-be-desensitized subjects that treatment will succeed or fail? What wiI1 be the effects of desensitizing operations when the recipient of them does not know they constitute an anxiety-therapy technique? Will training in muscular relaxation serve to diminish steady-state levels of autonomic flow or serve to attenuate the magnitudes of autonomic responses to stressful stimulation? Will training in muscular relaxation speed the rate of GSR habituation to a repetitive phobic stimulus? Unfortunately, the substantive yield from these scores of studies has been confusing and contradictory. Most of the questions raised have been answered in more than one way. To the extent that confusion has existed at the data level, theorists have been free to “‘pick and choose” experimental support for the diverse explanatory formulations offered by learning and psychotherapy theory. Even though for these reasons and others the state of desensitization theory is not as tidy as we wouid Iike, some accounts of “why desensitization works” have gained relative ascendency. Among the major theories are those based on reciprocal inhibition (Wolpe, 1958), on habituation (Lader & Mathews, 1968), on counterconditioning (Davison, 1968). on extinction (Wilson & Davison, 197 I), and on socialcognitive factors (Wilkins, 1971). We will begin our narrative by examining each of these models in turn.

Theories OFDesensitization Effects Reciprocal Inhibition and Habituation. According to the theory of reciprocal inhibition, systematic desensitization reduces anxiety by causing the cues for the anxiety to become cues for its inhibition. Neurotic anxiety basically is comprised of conditioned sympathetic responses to real and imagined aversive circumstances. The occurrence of sympathetic responsivity during aversive imaging can be reciprocally 1906j by the parasvmpathetic correlates of muscular reinhibited (Sherrington, 1938) provided that the imaging is done gradually and at the laxation (Jacobson. imager’s own pace. When reciprocal inhibition of the sympathetic response does occur during aversive imaging, the act of imaging acquires its own anxiety-inhibiting capability. This occurs through the action of conditioned inhibition (Hull, 1943) based on reciprocal inhibition. Then via a neurally mediated generalization process similar, and even more aversive. imaging responses begin to carry their own conditioned inhibition as well. Finally, after a time, the real-life referents of the aversive imaging become generalized conditioned inhibitors of the sympathetic responses they once excited. According to the theory of habituation, systematic desensitization reduces anxiety by promoting the habituation of sympathetic responses to clinically focal cue stimuli. Neurotic anxiety again is comprised of conditioned sympathetic responses to peripheral and imaginal circumstances. The occurrence of sympathetic responsivity during aversive imaging can be made to habituate over the course of repeated

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imaging trials in much the same way that an orienting response habituates over the course of repetitive novel-stimulus presentations. The maximal habituation theory of therapeutic desensitization effects (Lader & Mathews, 1968) holds specifically that: (I) the magnitudes of GSR’s to phobic stimuli habituate over the course of repeated imaging trials; (2) the speed of GSR habituation during desensitization is facilitated by muscular relaxation or other factors that minimize arousal; and (3) somehow the rate of GSR habituation during repeated imaging responses is significant in terms of clinical-treatment outcomes. The dual-process theory of habituation (Groves & Thompson, 1970) was rendered into a second habituation theory of desensitization by Watts (1979). It holds specifically that: (1) the magnitudes of GSR’s to phobic stimuli habituate over the course of repeated imaging trials; (2) this habituation, in turn, is the additive habituation, and “sensitization”; and consequence of two decremental processes(3) the speed of GSR habituation during desensitization is facilitated by muscular relaxation or other factors that maximize the sensitization component of the habituation phenomenon. Counterconditioning dncf f~tinction. According to the model of counterconditioning, systematic desensitization reduces anxiety by causing the cues for the anxiety to become cues for behavior other than anxiety (but not necessarily for behaviors that “inhibit” anxiety). In the counterconditioning model, neurotic anxiety would be comprised of conditioned autonomic and behavioral responses to specific stimulation. The display of emotional behaviors during conditioned aversive stimulation can be prevented by the occurrence of “other” behaviors provided that the conditioned aversive stimuli are introduced gradually and at the subject’s own pace (Guthrie, 1935). When such response substitution does occur during conditioned aversive stimulation, the conditioned emotional stimuli begin to call forth the other behaviors instead of the emotional ones. This “counterconditioning” of emotionality is said to occur via the “postremity” principle (Voeks, 1950): a type of recency principle according to which stimuli call forth the “movements” with which they were last associated (see Guthrie, 1935). As a model for describing orthodox clinical desensitization effects, the counterconditioning formulation simply holds that, following treatment, muscular relaxation is the response called forth by those imaged and real cues that heretofore had occasioned emotional arousal and/or behaviors. Other nonemotional responses could have been used equally well during desensitization (i.e., muscle-tension exercises, sitting quietly, and could have served equally well to supplant the emotional ones). According to the model of ciassical extinction, systematic desensitization reduces anxiety by promoting the extinction of conditioned emotional responses to clinically focal cue stimuli. In terms of a general extinction model, neurotic anxiety would be comprised of conditioned autonomic and behavioral responses to specific stimulation The display of emotional behaviors during conditioned aversive stimulation can be observed to diminish over the course of repeated, unreinforced conditioned stimulus presentations. When such “extinction” does occur, the once conditioned emotional stimuli have lost their ability to elicit emotional responsiveness. As a model for describing orthodox clinical desensitization effects, the extinction paradigm holds, simply, that after treatment, those imaged and real cues that heretofore caused emotional responses no longer are able to do so. The role, if

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F. Dudley ,~fcGlynn, Wallace L. Mealieu. Jr. and Dmise L. Landau

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by muscular

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Cognitive-Social Reinforcement Theory. Using an admixture of cognitive and reinforcement formulations, Wilkins (197 1) offered a fairly elaborate theory of therapeutic desensitization effects. He began by asserting that the only important client activity in desensitization is the imaging of clinically focal material “not necessarily arranged into a hierarchy and not necessarily concomitant to muscle relaxation” (p. 3 11). Within this simple procedural specification the following events were said to contribute to fear reduction: (1) the therapist fosters an expectation of therapeutic gain in the patient: (2) the therapist praises the patient for small improvements: (3) the treatment regimen provides the patient with three different sources of information to the effect that he or she is getting better; (4) the treatment regimen teaches the patient to control aversive imaging voluntarily: (5) systematic desensitization provides for learning via the covert self-modeling of nonemotional responses and their contingencies. Other Desensititation Keories. Marks (1975) reviewed a massive amount of literature and concluded that the effects of systematic desensitization reflect no more than the operation of exposure to conditioned aversive cues. Thus was originated the so-called “exposure theory” of therapeutic desensitization outcomes. Actually, however. the exposure theory is not an explanation of therapeutic desensitization effects. Rather, it is simply a hypothesis concerning the necessary and sufficient procedural ingredients within the technique. The therapeutic effects of the exposure remain to be explained (e.g., as extinction, as counterconditioning, as habituation). Lang (1979) has provided a fascinating theory concerning the place of imagery theory of emoin emotional experience and expression. This “bio-informational holds, first, that conceptual networks in the brain are created by tional imagery” encoding together the stimuli and responses that occur during the course of emotional learning. It holds, secondly, that these conceptual networks are encoded as not as iconic representations. Finally, it holds that these “propositional structures,” propositional structures in the brain subsequently regulate both the visceral and motoric expression of emotion. One of the manv implications of Lang’s formulation is that the clinical changes wrought by desensitization mirror alterations in the visceral and motor “response propositions” newly encoded centrally, along with the propositional versions of clinically focal stimuli. Though in an early stage of de” has received noteworthv exvelopment, Lang’s theory of the emotional “image 1980). It holds the perimental support (Lang, Kozak, Miller, Levin, & M&lean. promise of major advances in theorizing about systematic desensitization. Schachter (1964) proposed that the quality of an emotion was the conjoint product of the individual’s general level of physiological arousal and of his or her specific cognitive-perceptual interpretations of its meaning. t’alins (1956) reported experimental ,results suggesting that clinical effects of systematic desensitization might reflect the fact that patients who find themselves relaxing during aversive imagery come to re-interpret the aversiveness of the imaginal material. This type of thinking also is imbedded in Wilkins’ (197 1) more general theory. During the 1960s and ‘7Os, Bandura and his students popularized the importance

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of vicarious processes in the learning and unlearning of human behavior in general and in the acquisition and elimination of fear in particular (cf. Bandura, 1969; Bandura & Walters, 1963). in the latter case. they demonstrated unambiguously that fearful avoidance can be reduced via the observation of someone else performing aversive activities calmly and without adverse consequences (Bandura, Grusec, & Menlove. 1967). BY extending the concepts of vicarious learning processes into the realm of imagination. it is possible to speak of “covert modeling” influences (Kazdin, 1973). Thus, a theory is possible in which desensitization effects are yields from vicarious fear extinction during the covert self-modeling of competent. unpunished performances. Thinking along these lines is also imbedded in Wilkins’ (197 1) more general theory. Yates (19’75) pointed out that social reinforcement of approach responses can be used to overcome fearful avoidance and that room exists within orthodox clinical desensitization for operation of therapeutic social reinforcement processes. Bandura (1977) argued persuasively that a sense of “self-efficacy” is involved causall) in diverse types of therapeutic behavior change. Self-efficacy theory might, therefore, be a necessary constituent of a truly comprehensive desensitization theory. We have noted already that desensitization effects have been explained in terms produced of the psychotherapeutic relationship and in :erms of adventitiously psychodynamics.

SOME IElATED RESEARCH From our narrative, it is obvious that a “comfortable” theory of desensitization effects can be found by clinicians and researchers of diverse systematic persuasions. We have noted also some of the many experimental questions emanating from the crowded theoretical arena and have alluded both to the massive size of the relevant literature and to problems of factual contradictions within it. In the next two sections of our paper we review selectively two subsets of the desensitization literature: (1) instructionaliexpectancy effects in desensitization, and (2) the “role of relaxation” in desensitization. The literature on expectancy factors was chosen because it is the most cohesive single body of work related to cognitive desensitization theory. The literature on relaxation effects within desensitization was chosen because it interfaces, albeit complexly, with each of the other four explanatory desensitization models. Within each review we proceed by describing a few prototypical or representative experiments and by relating their results generally to other findings in the literature. Our descriptions of experimental methods should set the stage for discussing methodological issues later on. Our descriptions of the experimental results will be examined for any implications they might have for the “major” theories presented. Expectancy Effects in Desensitization None should have been surprised when, in the late 196Os, behavior therapy researchers turned their attention to the roles that might be played by placebo factors in the success of desensitization. Healing based on faith and on the expectation of cure had been recognized for hundreds of years as central to the helping arts

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and Denise L. Landau

(Shapiro, 1971). In the psychotherapy fiterature of the early 1960s there existed several correlational studies of expectancy effects on psychotherapy outcomes (cf. Goldstein, 1962). In the behavior therapy literature of the middle 1960s a call was being issued for broadened explanations of desensitization effects; explanations not based on quasi-mechanical learning formulations (e.g., Breger & McGaugh, 1965). By the end of the decade, Klein. Dittmann, Parloff, and Gill (1969) seriously raised the possibility that the confident optimism of hehavior therapists such as Wolpe and Lazarus might be the basis of successful desensitization treatments. Experimental studies of expectancy effects on desensitization outcomes have taken three basic forms. We will begin by describing the prototypical experiments of each type. The results of experiments on expectancy effects have been inconclusive. We will provide an overview of them. The current status of desensitization expectancy research is uncertain. We will address this subject as well. Many experiments have been reported in which the effects of desensitization are simply compared to those of a theoretically inert “placebo” treatment. Some writers (e.g., Lick & Bootzin, 1975) have included these in reviews of the desensitization-expectancy literature. We will not do so. Simple treatment versus placebo comparisons are not experimental studies of expectancy phenomena because expectancies are not (inferentialIy) manipulated. We will. however, discuss the desensitization versus placebo Iiterature in our paper, when later we turn to methodological considerations. The Prototypical Experiments. Leitenberg, Agras, Barlow, and Oliveau (1969) reported the first experiment dealing with the effects of “therapeutically oriented instructions” on desensitization outcomes. The subjects were college students who reported fear of snakes in response to a questionnaire item and who displayed motoric avoidance during a behavioral walkway task. One group of them received an imaginal and in vivo desensitization treatment after having been told they were in a therapy experiment. Another group received the same imaginal and in vivo desensitization regimen after having been told they were in a physiology experiment. unambiguously, the experimental fear changes were greater for the therapeutically oriented students than for the physiologically oriented students. In the Leitenberg et al. (1969) experiment, the independent variable of instructional content was confounded with another potentially outcome-influencing variable: therapist praise for reports of fear reduction during in vivo desensitization trials. The greater fear reduction seen among therapeutically-oriented subjects might have been unrelated to the instructional content variable or it might have depended on the concurrent operation of differential therapist praise and the instructional manipulation. Therefore, Oliveau, Agras, Leitenberg, Moore, and Wright (1969) subsequently performed a second and very similar experiment in which the variable of therapeuticallv-versus physiologically-oriented instructions was crossed with the variable of praise versus no praise for reported in vivo improvement. In this experiment the unilateral and interacting effects of therapist praise on desensitization impact were largely ruled out. There were significant main effects for the pretreatment instructional manipulation. The phenomenon of instructional control over desensitization was established. The studies were to become prototypes. McGlynn, kfealiea, and Nawas (1969) reported the first experiment dealing with the effects of “therapy-outcome instructions” on the impact of desensitization. The

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subjects again were college students who reported fear of snakes in response to a questionnaire and who displayed motoric snake avoidance during a walkway performance. One group of them received an imaginal desensitization therapy, having been told it was a treatment and that it ought to work. Another group received virtually the same imaginal desensitization, having been told only that it was a treatment. Ko mention was made of its anticipated effect. Unambiguously, the experimental measures of fear changed more among the optimistically instructed subjects than among those who heard only that a therapy was being studied. In the McGlynn, Mealiea, and Nawas (1969) study, subjects had either been told to anticipate success from the therapy or the+y.had not been told to anticipate anything. What would happen if a third condition were added in which subjects were told to anticipate therapy failure? The first (then) reasonably well done experiment to look at all three instructional sets simultaneously was reported by McGlynn and Mapp (1970). The pessimistic outcome orientation did not impede desensitization as seen under the neutral therapy set. However, on this occasion the optimistic outcome orientation did not enhance it either. None of the instructional variations affected the fear reduction wrought by desensitization. Konetheless, these studies became prototypical and spawned a sizable literature (see Wilkins, 1973). A third general approach to the experimental study of expectancy effects in desensitization involved use of false feedback about subjects’ physiological responsivity. This literature overlaps both of the first two and is not clearcut procedurally. In some studies making use of false physiological feedback manipulations, effects of desensitization have been compared with those of elaborate placebos based on the provision of bogus physiologic “data.” Marcia, Rubin, and Efran (1969), for example, used snake- and spider-fearful subjects to compare desensitization with a “t-scope placebo.” Placebo subjects presumably were deceived into believing that their unconscious physiological reactions to tachistoscopic snake or spider pictures had diminished over a series of eight sessions. As was the case with simple desensitization versus placebo comparisons, experiments like that of Marcia, Rubin, and Efran are really “anti-experiments” with respect to expectancy constructs. They attempt to eqwtte demand/expectancy influences for “real” and “bogus” treatments, not vary them. In other studies making use of false physiologica feedback manipulations. experiments have superimposed faise physiologic “data” onto otherwise uniform desensitization treatments. The types of feedback displays, the exact “message” carried by the feedback and the timing of the feedback periods all have varied considerably in this group of studies. McGlynn (1972), for example, presented his (snake fearful college student) subjects with bogus physiograph records before their experimental desensitization treatment. Subjects were expected to believe the records showed them to be uniquely suitable (or uniquely unsuitable) for the treatment they were about to receive. Fishman (197@), for another example, presented his (socially anxious college student) subjects with bogus oscilloscope configurations after every other treatment session. These subjects were expected to believe that they were succeeding (or failing) in the treatment they were receiving. Howlett and Nawas (1971), for a third example, presented their snake fearful subjects with bogus oscilloscope configurations after the desensitization treatment had been completed. Their message was that treatment had (or had not) been successful. The commonality in this group of investigations is the visual display of bogus biofeedback

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to “back up” variations in instructions. The results of these particular back experiments were uniformly negative save for the lone finding and Nawas of a feedback effect within self-reported snake-fear data.

bogus feedby Howlett

Overview of Lx~ectanc~~ Oukomes. The first half of the 1970s brought the seemingly inevitable debate over cognitive versus S-R approaches in behavior therapy. So-cailed “expectancy effects” in desensitization experiments came to be important because they were treated (naively) as direct support for the validity of cognitive formulations about treatment outcome. A half dozen or so major reviews of the literature appeared in the span of three years. The consensus among reviews of the desensitization-expectancy literature can be summed up in two sentences. When experiments vary therapeutically-oriented versus therapeutically-irrelevant (misleading) instructions, differences in the selfreported and behavioral effects of desensitization can be produced with fair reliability. When experimenters vary anticipated-outcome instructions, differences are much more difficult to produce and probably cannot be produced at all without the action of some other important variable. Several reviewers offered post hoc interpretations of why both varieties of instructional manipulation sometimes did and sometimes did not affect experimental treatment outcomes. After one very careful survey of the literature, Wilkins (1973) noted that instructional effects on desensitization outcomes always occurred in studies done by nonblind experimenters and never occurred in studies done by blind experimenters. -Apparently, experimenters were inadvertentiy able to produce an experimental effect they could not have produced deliberately. After another very careful review of the various papers, Borkovec (1973) described systematicaliy different subject-selection procedures for studies reporting versus not reporting instructional effects. If relatively nonstringent criteria had been used, then instructional effects had been seen. If relatively stringent selection criteria had been used. then instructional effects on desensitization outcome had not been produced. Other post hoc hypotheses about boundary disputes within the expectancy literature occurred as well. Maybe the instructional manipulation failed to work in some experiments because subjects “really” had therapeutic orientations despite exposure to nontherapy instructions. Maybe the production of i~lstructional effects required both condition-aware experimenters and relariveiv nonstringent subjectselection criteria. Despite considerable interest in the problem. consensus has vet to emerge on how to produce (or avoid producing) instructional effects in analogue desensitization experiments. Wilkins’ (1973) notion that the effect depends on conditionaware experimenters has, for example, been challenged bv a report of instructional effects in a blind experiment (Rosen, 1974). Borkovec’s (lW3) analysis in terms of differential subject-selection criteria rests on two untested assumptions: (I) that the differing selection criteria actually produced populations of subjects with different fear levels; and (2) that the different fear levels thus produced have unequal responsivity to experimental demands for posttreatment improvement. The view that subjects sometimes do not “believe” nonth~rap~ instructions is tautological in the absence of belief data apart from treatment outcome measures. Of course, when such independent belief data are sought a methodological Pandora’s box is opened.

Insofar as the experimental boundaries of instructional influence on desensitization have yet to be delineated. means by which instruct.ions exert their influence must be uncertain as well. Nonetheless, a sizable group of experiments has searched for the mechanism(s) of instructional influence on experimental desensitization outcomes. Illustrative approaches to explaining instructional regulation o\‘er desensitization were reviewed carefully by Lick and Bootzin (1975). Possibly. therapeutically-oriented’~nstructions generate some sort of positive affect that, in turn, facilitates counterconditioning. Possibly, therapeutically-oriented instructions prompt increased compliance with therapy regimens and/or increased likelihood of in vivo exposure trials. Maybe therapeutically-oriented instructions create differentially powerful experimental demands for demonstrable improvement during posttreatment assessment. Conceivably, therapeutic instructions operate directly via affecting some cognitive or physiological process inherent within desensitization. What does ail of this mean for Wilkins’ (1971) social-cognitire theory of desensitization outcomes? The language used by Wilkins clearly places his theory into the anticipated-outcome domain of experiments (McGlynn & Mapp, 1970) rather than into the domain of therapy knowledge (Leitenberg et al., 1969). To that extent, weight of the evidence argues against Wilkins’ assertion that benefits result from fostering expectations of therapeutic gain. ,4t the same time, effects on desensitization outcomes of differential anticipated-outcome instructions have not been studied systematically in interaction with several other causal factors Wilkins talked about (e.g., praise for small improvements or redundant information-feedback of therapeutic progress). Further, as we note-again later on, there were major and widespread methodological problems with virtually all of the relevant experimental research: problems that most likely precluded reasonable tests of Wilkins’ formulations.

Desensitization and Expectancy Current Status. Research on expectancy effects in desensitization no longer appears in the mainstream literature of the behaviortherapy movement. Like most questions in psychology, it did not pass from the scene because it had been answered. Rather, like an occasional “old soldier,” it just faded away, pushed from the field by newer and more interesting questions. One probable cause of disinterest was the fall into disrepute of analogue desensitization research methodology, the orthodox forms of which had typically been used in studies of instructional effects. Probably, too, emergence of so-called cognitive behavior therapy provided competing interests. The paradigms described here are now obsolete except for use of bogus biofeedback in instructional displays. Outcomes of the experiments no longer are viewed as very’ important to behavior therapy. When these paradigms became demonstrably obsolete, importance of the resulting experimental data was diminished. One could. of course, formulate experimental tests of the various post hoc hypotheses about instructional-effect boundaries in snake-fear desensitization studies. For example, one could use both blind and nonblind experimenters and/or differentially stringent subject selection rules in the same experiment. Similarly, having pinned down experimental variance sources in studies of boundary conditions, one could address experimentally the problem of explaining the instructional effect itself. One might, in time, articulate a cohesive theory of instructional effects in snake-desensitization studies. Nonetheless, the empirical generalizations

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Wt&zce L. Mcaliea, Jr. and Denise L. Landau

that were produced by the once orthodox desensitization analogue were of highly dubious meaning. Hence, further study of instructional effects within orthodox analogue experiments is of doubtful propriety. Still, any effects that instructional differences have on desensitization outcomes would be worth knowing about, both theoretically and clinically. Formalizing the problem of how instructional effects are produced might, in addition, forestall naively mentalistic interpretations in terms of expectancies. Also, as we will propose later, analogue research methods now exist that are sufficiently meaningful to make such research substantively worthwhile. Hence, methodologically contemporary studies of instructional effects in desensitization should still be viewed as potentially valuable.

From the vantage point of the patient, the elemental description of the desensitization procedure offers four components that, unilaterally or in concert, might be responsible for the observed treatment effects. These are: constructing the to-bevisualized hierarchy of clinically focal scenes. practicing progressive muscular relaxation; visualizing the previously constructed hierarchy while concurrently relaxing and “tracking” the imaginal hierarchy in viva by exhibiting topographically equivalent naturalistic performances. The quest for experimental precision prompted researchers early on to employ standardized hierarchies for all experimental subjects. Because individualized hierarchies were not typically used, the hierarchy construction component of the desensitization procedure was rarely studied as a causal variable. For reasons that have not been articulated, the patient’s in vivo tracking of imaginal rehearsal also has been largely ignored as a causal variable. In retrospect, this omission is, of course, most unfortunate because “exposure” figures prominently as a therapeutically important variable (Marks, 1955). Nonetheless, existing studies of component-procedure effects within desensitization typically have addressed only the roles of muscular relaxation, of graduated aversive-scene imaging, and of the pairing of these activities. Analogue Research with Human Subjects. Thirty or so papers report experiments in which fearful human subjects were used to study the “role of relaxation” within desensitization. Most of the experiments were based on the so-called “sequential dismantling strategy” (Lang, 1969) in which the effects of complete treatments are compared with the effects of subtotal treatments and/or of individual procedural components. Some of the experiments were based on a model-testing strategy in which attempts were made to evaluate particular conceptualizations of relaxation effects. Roughly two-thirds of the studies used as dependent-variable measures self-reports of fear and/or motoric avoidance of a feared target, usually a nonpoisonous snake. Ten or so studies incorporated ps~chophysiologicai dependent measures, usually recorded during the experimental-treatment sessions. By describing an illustrative few of these 30 experiments, we will address the substantive issue and, at the same time, chronicle an interesting methodological evolution. The first major experiment attempting to delineate the role of relaxation in desensitization was reported by Davison (1968). In that now classic experiment. one group of snake-fearful college-student subjects was exposed to experimental

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desensitization (i.e., one session of muscular relaxation training, then up to nine sessions of abbreviated relaxation instructions paired with instructions to visualize a Z&item snake desensitization hierarchy}. A second group of snake-fearful students received instructions to visualize the same hierarchy but did not receive either preceding muscular relaxation training or concurrent relaxation instructions. A third group did receive relaxation exercises before and during instructed visualizations, but the “scenes” they imagined were unrelated to the themes of snakes and fear. As compared to pre- and postexperimental fear changes among a (fourth) group of untreated subjects, only fear changes produced by experimental desensitization were significant. Neither graded hierarchy visualization by itself nor relaxation paired with snake-irrelevant imagery produced signi~cantly reduced behavioral or self-reported fear. The Davison (1968) paper is probably the most frequently cited source of support for those who assert that successful desensitization requires inclusion of relaxation components. Unfortunately, the results are not representative of extant research on the issue. One major competing result, for example. was reported by McGlynn (1973). Three experimental treatments in the McGlynn experiment were similar to those in the Davison study. One group of snake-fearful students received three sessions of muscular relaxation training followed by six sessions of abbreviated relaxation paired with instructions to visualize a ZO-item snake-approach hierarchy. The second group of fearful students received instructions to visualize the same hierarchy but received no experience with preceding or concurrent relaxation instructions. The third group of subjects did receive advance relaxation training and brief relaxation paired with imagery instructions, but the imagery instructions were unrelated to snakes. In a modification of Davison’s design, a fourth group of subjects received “neither component” treatment (i.e., they received no relaxation and, for six sessions, they visualized snake-irrelevant scenes). A fifth group served as untreated controls. When the effects of the four treatments on reported and motoric fear indices were evaluated with two (relaxation vs. no relaxation) x two (snake scenes vs. irrelevant scenes) factorial variance analyses, only the main effects for imagery content were signifcant. Subjects who visualized the snake-approach hierarchy showed significantly greater pre- to posttreatment improvement than did subjects who visualized snake-irrelevant pastoral material. Relaxation had no unilateral or interacting effect on reported or behavioral fear reduction. The Davison (1968) and McGlynn (1973) experiments are illustrative of 15 or so “dismantling” studies in which self-report and behavioral fear measures were used to compare effects of desensitization with effects of muscular relaxation alone and/or with the effects of guided imagery alone. Taken together their results also are representative. Success with imaginal desensitization sometimes did and sometimes did not require the combination of graded imagery with relaxation training. Because statistical success with experimental desensitization sometimes did and sometimes did not require relaxation training and because the two outcomes were treated (naively) as criteria1 support for rival theoretical explanations of therapeutic desensitization effects, considerable attention was paid to the fine-grain experimental differences between the two sets of studies. When relaxation bar had an important infIuence on experimental desensitization effects: (1) experimenters rather than subjects have controlled progress along the imaginal hierarchy; (2) numbers of experimental-treatment sessions have been relatively few; and (3) durations of aversive imagery per hierarchy item have been relatively short. Seem-

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ingly. in the dismantling studies. relaxation has been important only when the parameters of instructed visualization did not themselves produce attenuation of arousal during the imagery. While the sequential dismantling strategy can be adapted to the study of gradedvisualization treatment effects with and without relaxation, it is not suited to the problem of temporal contiguity. Assuming that imaginal exposure (or other) parameters can be found that show relaxation to be important, must relaxation occur simultaneously with imaginal rehearsal ot might one be able to relax during some periods and visualize the hierarchy at other times. Even though this question has potentially important implications for some theories of desensitization, only a half dozen papers have discussed it. An illustrative experiment on the imagery-relaxation contiguity issue was reported by Aponte and Aponte (197 1). Casing test-anxious students as subjects and self-reported test-anxiety measures as dependent variables, they compared four conditions. Subjects in one condition received relaxation training and group-administered, standardized systematic desensitization along a 22-item imaginal hierarchy. Subjects in a second condition received identical treatment except that the temporal contiguity between relaxation and hierarchy visualization was disrupted by introducing relaxation into each session only after imaginal rehearsal had been completed. Subjects in a third condition received muscular relaxation alone (i.e., they had no experience with imagery instructions either during or after relaxation exercises). Subjects in a fourth condttion served as untreated controls. The results obtained by Aponte and Aponte (197 1) were somewhat unrepresentative of similarly produced data, in that group preprogrammed desensitization seemingly exerted ICSSoverall influence on self-reported test anxiety than did the procedure that incorporated hierarchy visualization followed by relaxation. Most comparisons of contiguous versus non-contiguous relaxation effects in desensitization have resulted in equivalent change for the two procedures (cf. Nawas, Mealiea, & Fishman, 1971). Ten experiments attempting to delineate the role of relaxation in desensitization have incorporated psychophysiological assessment techniques somewhere within their procedures. Use of psychophysiological assessment eliminates several of the dangers of research with obtrusive self-report and behavioral dependent variables. Fot this reason, and severai others, application of psychophysiology to experimental research in desensitization is a significant development. In some instances psychophysiological assessment has been added to experiments that otherwise were fairly orthodox in methodology. Exemplary of these early psychophysiological studies is an experiment reported by Waters, McDonald, and Koresco (1972). Forty rat-avoidant female volunteer students were selected with orthodox self-report and behavioral walkway measures. Twenty of these students then were exposed to one session of relaxation training and to one session .in which they relaxed very briefly and then observed and visualized a hierarchical series of slides depicting mastery performances of the behavioral walkway test. The other twenty students received the same treatment except that all references to relaxation were deleted. Results obtained bv Waters, McDonald. and Koresco (1972) accorded pretty well with those obtained In most of the orthodox dismantling studies. The effects OF hierarchical imaging were equivalent with and without muscular relaxation. This was true in terms of treatment-efftciencv measures (such as numbers of discomfort

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signals during the session) and in terms of treatment-outcome measures such as intra-session skin resistance, intra-session skin potential, and posttreatment avoidance of a caged rat. In some instances psychophysiological assessment has been incorporated into experiments that reflect methodological advances at other levels as well as that of measurement. An illustrative contemporary experiment was reported by O’Brien and Borkovec (1977). In that experiment. 43 volunteer female subjects were used who reported at least “some” fear of being with a member of the opposite sex. They were first exposed to a heterosocial performance test with a male confederate, during and after which self-reported, behavioral, and psychophysiological measures of shyness were obtained. Subjects in a systematic desensitization group then received one session of imagery and relaxation training followed by three sessions of experimental desensitization along a standardized Is-item heterosocial interaction hierarchy_. Subjects in a non-contiguous relaxation group received one corresponding sesston of imagery and reIaxation training followed by three sessions that began with appropriate hierarchical imaging and ended with (separate) muscular relaxation. Subjects in a hierarchy-only group received one (control) session of pleasant imagery rehearsal followed by three sessions that began with pleasant imagery instructions and ended with appropriate hierarchical imaging. Along with subjects in an untreated group, each of the subjects then repeated the heterosocial performance and again provided the self-report, behavioral, and psychophysiological measures of shyness. Analyses of self-report and behavioral shyness measures revealed essentially no treatment effects within the best measures used in the O’Brien and Borkovec (1977) study. More importantly, analyses of heart-rate data recorded before and during the pre- and posttreatment heterosocial performances showed relatively high posttreatment heart rates for hierarchy-only subjects, at least during the anticipatory period. Subjects who had received muscular relaxation training either concurrently with or after hierarchical visualization showed less anticipatory heart-rate responsivity than did unrelaxed subjects who visualized the hierachy. While this resuh is interpretatively marginal, it accords well with data from some of the orthodox experiments. Taken as a whole, the human subject analogue experiments seem to say the following things: (1 f graduated aversive-imagery training with some “presentation” parameters can be therapeutic by itself; (2) procedural parameters do exist for which relaxation is necessary to achieve therapeutic results: (3) procedural parameters might exist for which graduated imaging produces “sensitization” (Wolpe, 1973).

Analogue Research with Animal Subjects. A massive literature describes experiments in which aversively constrained animal subjects were used to test hypotheses related to the role of relaxation in desensitization (for representative reviews, see Adams & Hughes, 1976; Wilson & Davison, 1971). The greater majority of these experiments bear on the problems of desensitization in only a post hoc way. They were undertaken to examine some other issue, such as the comparative properties of extinction and countercondjtionjng~ and incidentally they provided data related to relaxation effects in desensitization. Hoytiever, several animal-subject experiments have been set up a priori to produce a procedural analogue of systematic desensitization and to study an anxiety-competing response within it.

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An experiment reported by Delprato (1973) is representative of the several efforts to produce and study systematic desensitization with animal subjects. Fiftyone rats first acquired a noise-discriminated two-way shuttle avoidance of an aversive shock. Ten of the rats then were “treated” with systematic desensitization to the noise cue. While ingesting food pellets, they were exposed to a hierarchy of increasingly loud noise signals. Each of these was either escaped and therefore repeated or tolerated. This, then, led to an advance to the next loudness level. Ten other rats then were treated with a graduated exposure procedure that was identical to desensitization save that food was not being ingested during the graduated noiseexposure trials. A third group of rats was treated with a fairiy standard extinctiontraining procedure. They were treated as were the graduated exposure subjects but were exposed to the full intensity noise stimulus on all extinction occasions. Three control conditions were also used to examine the effects of apparatus exposure, of food ingestion per se, and of housing conditions during the study. After treatment with one of the experimental or control procedures, the 51 rats were run in a posttreatment extinction test. Twenty-five discriminated, non-shock avoidance extinction trials were conducted just like the acquisition trials, except that each was terminated when the rat failed to avoid within the warning interval. Results of the Delprato (1973) experiment were somewhat surprising. Rats that received “systematic desensitization” showed significantly more escape responses during the 25 extinction trials than did either rats that received graduated exposure to the noise cue or those that received extinction training with the full acquisitionintensity stimulus. The latter two groups showed substantial avoidance extinction and did not differ from each other. The extinction behavior of the systematic desensitization group did not show avoidance extinction and did not differ from the behavior of three groups of control animals that had not been exposed to the noise cue during the “treatment” phase of the experiment. Taken together, data suggested that the “competing response ” had interfered with the otherwise therapeutic effects of exposure to the noise signal. In general, the same result was produced by Delprato and Jackson (I973) during an experimental comparison of counterconditioning versus aversive-stimulus exposure as “treatments” for peripherally cued suppression of appetetively reinforced lever pressing. Also representative of a priori desensitization experiments using animals as subjects are two studies reported by Wilson (1973). In the first experiment 64 rats acquired a noise-discriminated one-way shuttle avoidance of an aversive shock. Each was then exposed for 15 nonshock trials to one of eight “treatments” generated by a three-factor design, in which the variables were: (1) opening versus blocking the avenue of escape from the fear compartment: (2) presenting versus withholding food from the fear compartment; and (3) exposure to increasingly loud versus full intensity noise signals. After treatment, the rats were exposed to a 60-trial, nonshock avoidance-extinction test using the training intensity noise cue and to a “residual fear” test in which the noise cue was sounded continuously. Duration of unforced time spent in the food-baited fear compartment was tallied. In terms of both the extinction-test data and the residual fear measure, Wilson’s (1973) results mirrored the superiority of “forced exposure” as a treatment ingredient. Rats whose avenues of escape were blocked during the 15 treatment trials improved more from their experimental therapy than did rats who were permitted to escape. This was true irrespective of the other experimental variations to which the rat was concurrently exposed. At the same time, however, the experimental

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analogue to systematic desensitization was the most effective of those treatments that did permit escape from the fear compartment during therapy. Following effectiveness of the blocked conditions in facilitating extinction was a combined graduated noise intensity plus food condition in which the rats controlled their exposure to the tonal cue. In Wilson’s first experiment, procedures that resulted in prolonged durations of unreinforced exposure to the no&e cue were generally more effective than were procedures resulting in minimal conditioned stimulus exposure. Possibly, therefore, the beneficial effects of feeding during graduated exposure were brought about by a simple, food-correlated increase in unreinforced exposure to the conditioned stimulus, not by the counterconditioning of anxiety-competing appetetive responses to it. To test this possibihtp, Wilson performed a second experiment. Thirty-two rats again first acquired a noise-discriminated one-way shuttle avoidance of an aversive shock. Each was then exposed for 15 nonshock trials to one of four treatments: (1) food-correlated forced exposure to graduated intensity tonal cues; (2) food-correlated unforced exposure to graduated intensity tonal cues: (3) forced exposure to the full intensity conditioned stimulus; and (4) unforced exposure to the full intensity conditioned stimulus. As in the first experiment, extinction over the course of 60 nonshock discriminated avoidance trials was most pronounced for the two treatments that had ensured exposure to the aversive conditioned stimulus by blocking the avenue of The two blocking treatments were better than was escape during therapy. food-correlated unforced exposure to graduated fear cues (systematic desensitization), even though a yoking-to-desensitization procedure had equated these three conditions vis % vis durations of exposure to the aversive conditioned stimulus. Again, however, systematic desensitization was more effective than was the (regular extinction) procedure in which the rats were able to escape the fear compartment during therapy. The results for residual fear measures were interpretively similar to those for discriminated avoidance extinction. The two forced-exposure treatments and the systematic desensitization treatment afforded greater residual-fear reduction than did unforced exposure to the full intensity conditioned stimulus (regular extinction). In general, Wilson’s two experiments showed that in an animal analogue of anxiety and behavior therapy, unreinforced exposure to the aversive conditioned stimulus produced the greatest abatement of discriminated avoidance, while long durations of exposure to it led to the greatest reductions in residual fear. The provision of food during exposure did have a facilitative effect on treatment outcome, but onlv under conditions where the animal was free to escape the aversive conditioned stimulus. Hence, the facilitative effect of food presentation during therapy was mediated by increases in unreinforced exposure to the conditioned stimulus that food availability brought about. When the results reported by Delprato f 1973) and Wilson (1973) are combined, the following general picture seems to emerge: (1) exposure to a conditioned aversive stimulus is necessary and sufficient for fear reduction; (2) therapeutic conditioned stimulus exposure can be either graded or ungraded in intensity; (3) food presentation during conditioned stimuius exposure can facihtate therapeutic exposure effects if it serves to increase the duration of unreinforced exposure: (4) food presentation during conditioned stimulus exposure also can impede therapeutic effects if it serves to interfere with “functional” exposure to the aversive cue; (5)

the presentation of food during the conditioned stimulus does not seem to provide the conditioned stimu!us with reliable power to occasion anxiety-competing appetetive responses. In general, this picture is consistent with that of the large literature on eliminating animal avoidance {cf. Wilson 8e Davison, 1971). C~~n~~i Research wit/r ~syc~oneuro~c Patients. The somato-visceral correlates of muscular relaxation have been the subject of experimental study for one-half centurv. Physiological and behavioral effects of muscular relaxation in the context of cl&a1 desensitization treatments have been studied off and on foe the Iast 20 vears. For our purposes we will restrict the following narrative to three ciinicaLexperimenta1 investigations in which muscular relaxation served as an independent variable and clinically anxious patients served as subjects. In one ciinical experiment, Woipe and Flood (1970) compared GSR’s during hierarchical imaging among patients who were and were not concurrently relaxed. GSR’s were recorded for four sessions during each of which there were five increasingly aversive imaging trials. For patients who were relaxed during their aversive imaging, and only for these patients, GSR’s were seen to decline in size over the four sessions. Also for the reiaxed patients only. magnitudes of GSR’s during imaging arranged themselves according to hierarchical locations of particular imaging instructions. Finally. there was the unexpected result that GSR’s during initial imaging trials were higher for relaxed than for unrelaxed patients. X major clinical-experimental study of relaxation effects in desensitization was conducted by Gillan and Rachman (1974) in the context of a comparison between desensitization and psychotherapy as treatments for phobic neuroses. Their subjects were 32 multiphobic outpatients selected by psychiatric interview and by fulfillment of various demographic and psychiatric-status criteria. Their psychotherapists were six psychiatrists, each of whom had at least six months of psychotherapy experience. The behavior therapist was a clinical psychologist with one year of supervised training in desensitization treatments. Then- assessment instruments were: (1) therapist, patient, and independent ratings for the intensities of phobia, anxiety, depression, and other psychological complaints; (2) the Eysenck Personaiity Inventory measures of extraversion, neuroticism, and “tying”; and (3) measures of exposure durations, physical proximit)i’, and subjective fear during behavioral avoidance tests (where possible) with clinically focal stimuli. Blocks of four phobic patients matched approximately on phobia intensity and duration were assigned randomly across four treatment conditions: (1) systematic desensitization; (2) graded imaging without relaxation; (3) psychotherapy; or (4) control for nonspecific treatment influences. The desensitizaa “pseudotherapy” tion regimen was limited to 30 sessions; numbers of sessions received by subjects in the other three conditions were determined bv yoking to desensitization within blocks. unfortunately, some important details of the four experimental treatments are missing. The patients allotted to the desensitization group received conventional treatment. After construction of suitable hierarchies the phobic items were presented for rehearsal in imagination while the patients were in a relaxed state. The patients in the pseudotherapy group.. were given the same instruction and training in muscle relaxation as those in the desensitization group. In the remaining sessions they were given fifteen minutes of deep relaxation and then asked to imagine a series of unrelated, neutral stimuli. During the last

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half hour of each treatment session, the therapist encouraged them to discuss non-anxietvevoking aspects of their lives. The rule throughout these sessions was that no phobic situation was to be imagined or discussed. If the patient referred to his phobia the therapist had to steer the conversation away from the subject.. . . The third group.. consisted of patients who were presented with phobic hierarchy items in the usual style of desensitization treatment but were not given preliminary training‘in relaxation and were not relaxed during each treatment session. In other words, they progressed up the hierarchy of fearful items in the usual wav, but without relaxation instructions or training. The patients allotted to psychotherapy received individual sessions from one of six psychotherapists. The treatment consisted of a combination of insight therapv and rational therapy. (Gillan & Rachman, 1954. p. 394)

The various assessment procedures were employed before, immediately after, and three months following treatment. On patient and independent phobia ratings, those who received desensitization and those who received graded imaging improved more than did those who received pseudotherapy or psychotherapy. On the therapist’s phobia ratings, there was a similar picture aside from some “drift” in the psychotherapist’s ratings. On the therapist’s ratings of depression, patients who received either desensitization or graded imaging were seen as less depressed than were the other patients, after treatment and again at follow up. Patient ratings of general anxiety followed the same pattern. Meaningful results were not obtained from the context of behavioral avoidance tests owing to extreme diversity in phobic stimulation. The authors summarized their major results as follows. “Overall, systematic desensitization (with relaxation) was the most effective of the four methods both at posttreatment and at follow up. However, it was not always superior to desensitization administered without relaxation. In fact, this form of treatment, consisting of graded and gradual presentations of hierarchy items in imagination, proved to be highly effective” (p. 399). In addition to studying the contribution of muscular relaxation to desensitization outcomes, Gillan and Rachman (1974) availed themselves of the opportunity to study the relevance of habituation via a vis those outcomes. Measures of skin conductance and fluctuation were taken while the patients attended to a series of 20 discrete auditory stimuli. Habituation data were not found to relate meaningfully to any of the clinical-outcome measures. A third cljnical-experimental study related to relaxation effects in “desensitization” was conducted by Wroblewski, Jacob, and Rehm (1977). Subjects were 27 dentally fearful males and females obtained from university classes and newspaper advertisements in a large metropolitan area. They were chosen because they failed to make an appointment for dental work during a pretreatment behat-ioral avoidance of dentistry test. Their dental anxiety before and after treatment was measured by the behavioral test, with self-reports on both a 14-item Dental -4nxiety Scale and a 40-item Fear Survey Schedule, and by subject and dentist responses to telephone questions about dental care during the three weeks following treatment. Subjects assigned to a symbolic modeling plus muscle relaxation group first were exposed to the reciprocal inhibition treatment rationale and to tape-recorded relaxation training. During each of the following five sessions they were exposed to relaxation instructions and then to videotaped items from a standard 19-item hierarchy showing progressively more frightening dental occurrences. Subjects assigned to a symbolic modeling (only) condition first were exposed to an extinction treatment rationale. During each of the remaining sessions thev were exposed to

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the same hierarchically ordered videotapes. Subjects assigned to an attention placebo condition first were exposed to a “learning theory” treatment rationale. During each of the remaining sessions they were exposed to a videotaped social history interview and to a videotaped dental chair that was empty. In contrast to the results reported by Gillan and Rachman (1974), data obtained by Wroblewski et al. (1977) portrayed a vital role for muscular relaxation. The terminal response within the laboratory test of dental avoidance behavior was performed by seven of the nine subjects, who had received symbolic modeling plus relaxation, and by only one subject in each of the other two conditions. Similarly, seven of the symbolic modeling plus relaxation subjects successfully underwent dental treatment without aid of nitrous oxide during the three weeks fo!lowing treatment. Two subjects in the symbolic modeling without relaxation group did so, as did only one subject in the attention-placebo condition. When the results reported by Wolpe and Flood (1970), Gillan and Rachman (1974) and Wroblewski et al. (1977) are combined, the substantive yield is contradictory. The role of relaxation was minimal in the desensitization treatment of heterogeneously phobic outpatients and critical in the symbolic modeling treatment of dentally anxious college students and newspaper respondents. Because these their divergent experiments differed in so many ways. speculation concerning outcomes might be imprudent. Later, however, we will speculate that greatly differing numbers of therapy sessions might well have been important. Data reported by Wolpe and Flood (1970) do document a diminution in sympathetic responding during aversive imaging that empirically is associated with concurrent muscular relaxation. However, they used only a Few clinical-patient subjects, their results were presented only graphically, and there were some unexpected features in their data. To summarize the clinical results in brief: (1) there do exist conditions under which graduated aversive imaging is clinically therapeutic in its own right; (2) there also exist conditions under which graduated aversive imaging must be paired with relaxation in order to be clinically therapeutic; (3) when relaxation effects on desensitization outcomes do occur they might reflect relaxation influences within the physiology of imaging. Overview of the Role of Relaxation. In our review of research on relaxation effects in desensitization we have included analogue experiments with nonclinical human subjects, analogue experiments with aversively constrained animal subjects, and clinical studies with anxious patients. Each of these data sources has its own strengths and weaknesses. None can stand without some form of corroboration from the others. Within all three research paradigms, there are studies in which simple exposure to aversive-cue stimuli (Marks, 1975) has served to attenuate fearful responsiveness. However, it seems also that “simple exposure” is therapeutic only when the other experimental variables concurrently promote low states of visceral and motor arousal. In human-subjects analogues, for example, exposure effects have occurred when there were long imaging durations and when subjects explicitly controlied analogues. in their own progress along the imaginal hierarchy. In animal-subject turn, exposure effects have occurred when there were long functional conditioned stimulus exposure durations without aversive reinforcement. In clinical research with anxious patients, exposure effects were seen within the experimental variables used by Gillan and Rachman (1974). These included between 20 and 30 sessions of imaging.

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Within all three paradigms there are studies also in which muscular relaxation or some other behavior was necessary before exposure to aversive cues would attenuate emotionality. In human-subject analogues, muscular relaxation was necessary when there were brief image durations and when experimenters governed subjects’ progress along the imaginal gradient. In animal-subject analogues, appetetive responding was necessary when otherwise the animal would have avoided long durations of conditioned stimulus exposure. In the Wroblewski et al. (1977) study, using persons genuinely fearful of dentistry, relaxation was necessary when only six treatment sessions were used. Our review is highly selective but hopefully it is not biased. Our conclusion is that some duration of nonanxious exposure to aversive stimulation constitutes the functional therapeutic basis of desensitization and that varied experimental and clinical parameters exist for which muscular relaxation sometimes will and sometimes will not be needed to make nonanxious exposure possible. The general view of therapeutic desensitization as resting on nonanxious exposure will be recognized as really amounting to a procedural specification like Marks’ (1975) “exposure” theory. It is not an explanatory model. Indeed, it would run the risk of tautolo~ used in that way. It adds to Marks’ simple ‘*exposure” specification, the procedural addendum that patients must somehow be made nonanxious while confronting aversive cues. Also in common with Marks’ theory, the general view of therapeutic desensitization as resting on nonanxious exposure does little to arbitrate between the major peripheral S-R desensitization models. Both “simple” nonanxious exposure effects and nonanxious exposure effects based on relaxation can be explained in terms of extinction from unreinforced exposure to the conditioned stimulus and in terms of counterconditioning derived from the learning of new behaviors in its presence. Similarly, the notion of nonanxious exposure fails to arbitrate definitively between the conditioned inhibition and habituation formulations. (However, the former concept handles therapeutic effects from simple nonanxious exposure less satisfactorily than does the latter.) The choice among classical learning models for explaining nonanxious exposure effects within desensitization obviously will rest on considerations other than gross empirical ones. The general view of orthodox desensitization as resting on nonanxious exposure effects likewise has few differential implications for the more contemporary theoretical approaches. It accords in genera1 with both self-efficacy theory (Bandura, 1977) and with the bio-informational-theory (Lang, 1979) of how desensitization effects might take place. The nonanxious exposure model of therapeutic desensitization obviously is very vague. Such vagueness is necessary, however, because of the crude empirical picture that results when confirmation is sought within all three major sources of data. Hopefully, the vagueness will be heuristic also. Refinements in theory can only accompany refinements in reliable data. Fortunately, behavior therapy researchers have learned a good deal about their craft during the last 20 years. It is to some of the outstanding issues of research methodology that we now turn our attention. METHODOl.OClCAL tSSUESIN DESENSlWAllON

RESEARCII

Progress in behavior therapy can be anticipated only if valid conceptual principles and/or trustworthy empirical generalizations are available to serve as guideposts for clinical practices. In the early days of the behavior-therapy movement the

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ultimate availability of sound theories and accurate empirical propositions was never questioned. Behavior therapy, after all, was experimental! As time has passed. however, trustworthy empirical generalizations have not been forthcoming. As is exemplified in the case of desensitization, significant probeims have been encountered in the production of meaningful data. As we have seen, data that can be used to conceptualize desensitization effects and/or guide clinical practice are available from three general sources: experimental studies of aversively constrained animals; clinical studies of psychoneurotic patients; and experimental studies of nonpatient humans. Studies of aversively conditioned animals are not wholly without potential value because they can suggest avenues for human research, they can confirm existence of presumably fundamental processes imbedded within desensitization treatments, and they afford a unique opportunity to mute anxious responsivity under controlled circumstances. However, the issue of phyletic discontinuity is a compelling one that places a priori limits on the extent to which animal data can guide clinical work. Clinical studies with psychoneurotic patients are of obvious value in documenting the global clinical efficacy of desensitization. Indeed, the study of real patients is the only way clinical efficacy can be shown. However, the contexts and conduct of clinical deser,sitization treatments leave uncontrolled a large number of potentially influential variables and hence will not suffice for careful experimental work. Further, ethical constraints of professional practice preclude some valuable research tactics (e.g., use of “placebo” treatments). The history of human-subject analogue research has been a scientific horror story based on the theme of rudely violated validity. Hence, the entire literature on expectancy effects in desensitization is suspect, ,4 major portion of the literature on relaxation is suspect as well, in the absence of corroboration from clinical and/ or animal studies. Yet the methodological problems associated historically with human-subject analogues are not inherent as are the problems with animal studies. Nor are they contextually imposed as are the major problems with clinical investigations. Rather, they have been caused by widespread methodological naivete within the academic arm of the behavior-therapy movement. . Because their problems potentially can be redressed, analogue studies with nonpatient human subjects might offer our best hope for producing empirical generalizations that are both clinically meaningful and experimentally derived. .4ccordingly, we will end our paper by discussing validity of experimental research in which nonpatient human populations serve as subjects. ‘il’e will devote most of our attention to the topic of external validity as it has seen the liveliest discussion we will characterize briefly the contemporary of late. After doing so, however, human-subject analogue vis h vis the desiderata for internal validity.

External

Validity in Analague

Research

The methodological evolution in analogue desensitization research has been fairly straightforward. It began, not surprisingly, in experiments by Peter J. Lang and his colleagues (Lang & Lazovik, 1963; Lan,,D Lazovik, & Reynolds, 1965; Lazovik & Lang, 1960). In those experiments, self-reports of snake fear and avoidance of a non-poisonous snake during a behavioral task were used to study the fear reducing

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impact of desensitization administered to college students. These experiments were benchmarks because they offered hope of a truly experimental study of clinical behavior-change tactics, complete with controls for nonspecific factors and with objective measures of outcome. Following the experiments of Lang and his group, Paul (1966) presented his classic study of desensitization versus psychotherapy in the treatment of publicspeaking anxiety. Paul’s paper functioned to strengthen the belief that experimental therapy-outcome research was possible and to prompt more interest in desensitization (and, indeed. in behavior therapy as a whole). Lang’s early studies ultimately spawned hundreds of experiments in which preand posttreatment measures of snake fear among college students were used to evaluate the effects of desensitization and/or alternative behavioral-influence packages and/or procedural variations within orthodox treatment regimens. The behavior therapy literature during the late 1960s and early ’70s was, in fact, inundated with so-called “snake desensitization” studies. The seeds for the downfall of the snake-fear research paradigm were being sown during its heyday. Cooper, Furst, and Bridger (1969) raised the external validity issue by arguing that “studying the treatment of snake fears may .be irrelevant to the understanding of treatmg clinical neuroses.” This view was based mostly on their finding that two snake-fearful students were cured with a “control” treatment. Hence, they were too easily changed to be representative of clinically psychoneurotic patients. It was bolstered as well by recalling other instances of easy cures for snake fears and by citing an earlier paper (Marks & Gelder, 19661, in which presumptive differences between animal phobias and other phobias had been described. The Cooper et al. (1969) argument was rebutted capably by both Bates (1970) and Levis (1970). Bates (1970) rejoined that the “control treatment used by Cooper et al. actually included active therapeutic ingredients. Hence they had not shown their snake-fearful subjects to have been unrepresentatively easy to treat. He argued cogently also that no data existed about the external validity of analogue findings to work with clinical patients. Levis (1970) contended that most analogue research was not undertaken with the goal of producing generalizations directly relevant to the clinic. On the contrary, laboratory studies were typically used as experimentally controlled “vehicles to obtain information about various treatment manipulations, to develop ideas or hypotheses, to clarify theoretical issues, or to check the validity of previous findings” (p. 36). Levis noted also that the Marks and Gelder (1966) paper used as support by Cooper et al. did not actually report a comparison of college versus patient populations. The series of papers just reviewed might well have gone unnoticed were it not for the publication of a to-be-influentiai critique of analogue research methodology by Bernstein and Paul (197 if. These authors took as a point of departure the assertion that “therapy anaiogue studies become relevant for clinical practice only when generalization from the laboratory to the clinical setting is possible” (p. 226). They then argued their position on how such external vaiidity can be achieved ‘6 . . . the generality of particular conclusions from experimental analogues to the real-life behavior modification context must be a function of the degree to which the variables studied in the laboratory share the essential characteristics of the variables in the clinical context” (p. 226). Finalh, they enumerated a large number of “common analogue research errors” having to do with subject and therapist

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selection, anxiety measurement, and experimental treatment procedures. Among the orthodox analogue methods collectively dubbed as errors were: (1) failure to obtain subjects who demonstrate anxiety responses with the essential characteristics of the responses seen in the clinical context; (2) recruiting experimental subjects with offers of incentives other, than anticipated relief from anxiety; (3) assessing anxiety solely or primarily with demand-reactive locomotor and psychomotor tests; and (4) failing to represent experimentally all of the principles upon which the originally proposed desensitization treatment was based. The obvious intent of the Bernstein and Paul (197 1) paper was to husband the experimental-analogue approach by redressing its errors and by offering suggestions for its improvement. The short-run effect of their paper was quite the opposite. Orthodox analogue research with systematic desensitization all but disappeared from the mainstream behavior therapy literature. When substantive research disappeared from the literature, it was replaced by methodologically oriented experimentation directed toward the external-validity question. Some investigators challenged and examined the empirical assertions that formed the bases of the Bernstein and Paul (1971) critique. McGlynn, Puhr, Gaynor, and Perry (1973a), for example, studied the critical assertion that snake-fearful college students do not show physiological responsivity when they are confronted with live snakes. Other investigators granted arbitrarily the empirical claims made within the critique and set about to redress major methodological errors while retaining snake fear among college students as the dependent-variable domain. McGlynn, Williamson, and Davis (1973133, for example, attempted to increase the fear levels of snake-aversant experimental participants by altering fundamentally the orthodox conditions of behavioral avoidance testing. (In brief, subjects were chosen who avoided a snake during a walkway task despite an explicit positive incentive for snake-approach behavior.) Other investigators granted the various problems of external validity in snake-fear research and set about to articulate and study more meaningful domains of target behaviors. Borkovec, Stone, O’Brien, & Kaloupek (1974), for example, evaluated heterosocial shyness as a therapy research target. Experimental work of the sort just described showed, by and large, that the doubts voiced by Bernstein and Paul (197 1) were well founded. Many of the snakefearful college students used as subjects in orthodox studies were only minimally fearful. Some were not fearful at all. The behavioral and self-reported “fear” changes used to assess desensitization effects were usually not pure fear changes. Rather, they were, in some degree, the effects of purposeful compliance with “experimental demands” (Orne, 1962) for signs of improvement. Bernstein and Paul were correct in other particulars as well. During the decade of the 1970s some sharpening of the issues involved in external validation took place and several systematic validation strategies were proposed. We now turn to these developments as we consider current approaches to external validity, their problems and their prospects. General Approaches to External Validity. The external validity of analogue research is at issue when one is discussing the extent to which empirical generalizations produced by the analogue hold also over clinical states of affairs. To be sure, external validity issues involved in analogue desensitization research are not separate from those along the experimental-clinical interface generally. As such, a

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large literature exists that could be brought to bear on our discussion (see especially Bachrach, 19623. However, only three systematic approaches are influential within the contemporary zeitgeist. As we have noted, Bernstein and Paul (19fl) argued that external validity in analogue research is determined by the degree to which laboratory variables share “essential characteristics” with real-life behavior modification contexts. This clinicmatching approach to external validity probably is the most prominent one currently. Kazdin (1978) has called for an empirical approach to solving the problems of external validity. “The relation between an analogue study and generality to clinical situations.. . itself is an area of research” (p. 684). Whether any particular analogue characteristic works against (or for) clinical-external validity can be known only by studying clinically the relevance of that characteristic to treatment outcomes. Bandura 11978) proposed a threefold program of research. 4t the most basic level would be highly controlled research on the fundamental mechanisms of behavior change. At a second level would be nonclinical research on therapy prototypes suggested by results from the basic investigations. At a third level would be clinical research on diverse applications of the prototypes vis P vis particular types of conditions. The basic processes studied in highly controlled investigations might have different “appearances” than do the same basic processes encountered clinically. Hence, external validity is not an issue in evaluating research at the most basic level. Seemingly, the problem of external validity is solved by circumvention. These general formulations are not without arguable deficiencies. The clinicmatching strategy of Bernstein and Paul obviously presupposes knowledge of the clinic that we do not have. (Some of their r~ommendations also pose threats to internal validity.) Kazdin’s empirical approach similarly presupposes some research that we cannot do. Bandura’s threefold program runs aground of the externalvalidity issue when initial clinical-research trials are justified by results from the nonclinical studies of therapy prototypes. At the same time, however, levels at which these issues are currently being portrayed point to two potentially viable approaches. The behavioral community now agrees that all experiments are “analogues” of the naturalistic occurrences which they serve to reproduce (Adams & Hughes, 1976; Kazdin, 1978). The analogue desensitization study is not a special case. The external validity of any experimental procedure constitutes a continuum of judgment, not a binary classification. The external validity of an entire analogue desensitization experiment, in turn, is a product of successive con~nuum judgments involving various procedures {i.e., subject and therapist selection, experimental treatments, anxiety assessments: cf. Bernstein & Paul, 1971; Kazdin, 1978). Armed with the sharpened perspective that external validity in analogue research is a complex matter of successive judgments, we can pian our experimental procedures so as to match known clinical characteristics when it is possible to do so without violating internal validity. Likewise, we can prompt clinicians to validate our empirical claims in those instances where clinical research is feasible, In time this approach might produce analogue research with meaningful external validity vis 9 vis clinical treatments (Borkovec % O’Brien, 1976). Possibly, however, circumvention is the best long run “solution” to the problem of external validity in analogue research. ,4n “analogue” study is by definition suspect of external invalidity at the level of raw experimental variables. Its purpose,

17-f

F. Dudley AClcGlynn, Wallace L. Aklealiea, Jr.

and Denise L. Landau

therefore, cannot be solely the production of clinically valid empirical propositions. The future of the analogue research enterprise might well rest in the articulation of experimental purposes that are meaningful in the known absence of direct external validity.

/ntema/ Validity in Analogue Research When desensitization researchers employ demand reactive measures and obtrusive assessment contexts, the global fear changes associated with experimental participation might reflect conjoint influence from: (1) enduring effects of specific desensitizing operations; (2) enduring but “nonspecific” effects of attention, concern and the like: and (3) temporary effects of “experimental demands” (Orne, 1962) for particular types of performances and psychological “pulls” that are imbedded within laboratory contexts and procedures. For reasons that have never been articulated, influences of nonspecific therapy effects and of temporary demand effects always have been viewed conjointly as demand-placebo influences. Practically speaking then, an analogue desensitization experiment is internally valid to the extent that accurate discriminations are made between the specific effects of desensitizing operations and the nonspecific effects of the experiments in which those operations are imbedded. The problem of internal validity could have been generally approached by developing dependent measures that were not demand reactive (e.g., Borkovec, et al., 1974). The problem of internal validity also could have been approached by developing procedures for unobtrusive assessment (e.g., Lick 8c Unger, 1977). For seemingly good reasons, however, researchers have chosen knowingly to use reactive measures and obtrusive measurement settings. Hence, the “control” of demand-placebo effects has involved measuring, rather than eliminating them and, in turn, sifting them away from “active” therapy influences. The psychological placebo-control strategy originated in psychotherapy research (Thorne, 1952). It was introduced into behavior-therapy analogue research by Lang, Lazovik, and Reynolds (1965) and popularized by Paul (1969c). It has been further refined in the interim and has become the orthodox approach to sifting out nonspecific effects in fear-therapy studies. It involves a comparison within which the effects of desensitization are pitted against those of a nontherapy procedure conducted by the same experimenter, in the same context. for the same period of time. In effect. the nontherapy results serve as measures of demandplacebo effects within the experimental context and, simultaneously, as estimators of the demand-placebo variance within global desensitization outcomes. Because nontherapy results are treated as pure demand-placebo variance, it is important that demand-placebo treatments be arguablv devoid of any procedure that could be construed as specifically therapeutic. In the early days of analogue desensitization research, the requirement of theoretical inertness in placebo treatments had been insufficiently stressed and hence was infrequently met. (Often some potentially therapeutic form of muscular relaxation was included in nontherapy treatments.) More recently, experimental papers have appeared in which the problem of placebo inertness is handled reasonablv well (e.g.. Borkovec, 19i2). While the problem of developing theoretically inert demand-placebo control treatments is not as straightforward as it appears to be (O’Leary & Borkovec, 1978). it

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does not at this time pose a major obstacle to internally valid laboratory experimentation. Because results from a nontherapy procedure are used to estimate component demand-placebo variance within the global results of desensitization, it is important that the demand impact of the two experimental “treatments” be at least arguably similar, For internal validity purposes, then, experimenters must set about to equate treatment and placebo procedures with respect to demand-placebo impact. (This is, of course. why simple comparisons between treatments and placebos are “antiexperiments” with respect to the expectancy construct.) Again, in the early days of analogue research this consideration was ignored or it was treated lightly. When researchers later did address it (e.g., Borkovec & Nau, 1972), they found that, by and large, the early placebo treatments did not have demand-placebo impacts as robust as those of the experimental desensitization packages with which thev were compared. As a consequence virtually all of the orthodox analogue experiments suffer from suspect internal validity. in response to the reliable finding of insufficient demand-placebo impact within orthodox placebo treatments there has been some dialogue about alternative means of controlhng for demand-placebo influence (i.e., means not entailing the use of placebo treatments). A second response to the finding of routinely insufficient demand-placebo impact within our control treatments has been dialogue about how to retain the “sifting” strategy by developing better nontherapy regimens. A third response to this same finding has been fine grain dialogue concerning the desiderata for measuring demand-placebo influences. .4s a convergent result of developments along these lines, we are now in a position to construct high impact nontherapy procedures and to compare, at least crudely, the demand-placebo impacts of placebos versus desensitization regimens. Overall, we seem to be a little farther along with the internal validity issues than with the external validity ones. Experiments already have been reported in which the fearreducing effects of clearly (theoretically) inert placebo treatments have been compared to those of demonstrably, if crudely, demand-equivalent behavior therapy procedures (cf. McGlvnn, Kinjo, % Doherty, 1978). The critical issues and work to be done have been articulated most carefully in a seminal paper by Kazdin and Wilcoxon ( 1976). EPILOGUE Our peers might well conclude that we tried to do too much in this paper, that our coverage was incomplete, that our empirical foci were biased, and that our conclusions are too general. It is true that massive amounts of relevant hterature were virtually ignored (i.e., basic studies on the extinction of emotionality in rats, studies of the psychophysioIogy of muscular relaxation in general, papers on the complex and, as yet, only grossly described multi-channel nature of anxiety, etc.). What we have tried to do, however, is provide a cohesive picture of theory and research in desensitization: a picture that is broad in scope and general in content but that, at the same time, is sufficiently concrete to provide a “researcher’s eye” view of some real experimental events. For the time being the “major” models of desensitization effects can be viewed as functionall) equivalent insofar as each calls for the occurrence of nonanxious exposure during therapy trials. Arguments over the major explanatory models of

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L. Meab.ea,

Jr.

and Denise L. Landau

desensitization effects probably are, in fact, best viewed as rooted in history, not in data. Real theoretical advance might occur with the empirical fleshing out of the habituation theory in one of its forms (e.g., Watts, 1979). There is little likelihood that data will influence arguments over extinction versus counterconditioning. As we have said, real theoretical advance might well come also from pursuing (very carefully) the implications of self-efficacy theory (Bandura, 1977) or those of Lang’s (1978) conception of the emotional image. Heretofore, we have not been able to show convincingly that a subject’s expectancy of therapeutic success serves to facilitate that success. Virtually all of our experimental research is suspect, however, because of both external and internal validity problems. Heretofore, we have been able to show that fear reduction seems to depend on a therapeutically provided history of nonanxious exposure. This interpretation is vague and doubtless oversimplified, but it is the only statement justifiable when, in the spirit of scientific caution, confirmation is required from all three relevant domains of data. The problem of external validity has been a vexing one to systematic desensitization researchers. It is now on the way toward being dealt with satisfactorilv: either by solution or by circumvention. We are far enough along to do substantive research while, at the same time, keeping an eye toward additional methodological improvement. The problem of internal validity has been solved from a practical vantage point, though there is room for refinement in our measures of demandplacebo impact. We might need further dialogue on exactly what we mean when we say a nontherapy procedure is “theoretically inert.” The classical empirical questions of desensitization research have not been answered squarely. They are not unanswerable but rather were addressed prematurely. Experimental techniques now exist that make us want to ask them again. REFERENCES Adams, H. E., & Hughes. H. H. Animal analogues of behavioral treatment procedures: A critical evaluation. In M. Hersen, R. M. Eisler, & P. M. Miller (Eds.), Progress tn behavior rnodzficatzon: I’& 3. New York: .4cademic Press, 1976. Aponte. J. F., & Aponte, C. E. Croup preprogrammed systematic desensitization without the simultaneous presentation of aversive scenes with relaxation training. Behavtour Research and Therapy, 197 1, 9, 337-346. Bachrach, A. J. Expenmental found&tons of clintcal psyhology. New York: Basic Books, 1962. Bandura, A. Principb of behavior modificatton. New York: Holt. Rinehart, SC Winston, 1969. Bandura, A. Self-efficacy: Toward a unifying theory of behavioral change. Psychologxal Revtew, 1977. 84, 191-215. Bandura. A. On paradigms and recycled ideologies, Co,qnztive Therapy and Research, 197s. 2. 105- 117. F. L. Vicarious extinction of avoidance behavior. Jovrntli of Bandura, A., Grusec, J. E., & Menlove. Personality and Social Psychology, 1967, 5, 16-23. Bandura, A., & Walters. R. H. Social learnzng and personali development. New York: Holt, Rinehart 8c Winston, 1963. Bates, H. D. Relevance of animal-avoidance analogue studies to the treatment of clinical phobias: A rejoinder to Cooper, Furst, and Bridger. Jovnal ofAbnonna1 Pqrholoa. 1970. 75, 12- 14. Bernstein, D. .A.. & Borkovec, T. D. Progressne relaxatton rrainzng: .4 manual f‘Or the helpnq proj>sstorLy. Champaign, Ill.: Research Press, 1973. Bernstein, D. A., & Paul, G. L. Some comments on therapy analogue research with small ammal “phobias.” Journal of Buhavzor Therap? and Experimrntal P.yhza@, 1971. 2, 225-237. Borkovec, T. D. Effects of expectancy on the outcome of svstematic desensitization and implosive treatments for analogue anxietv. Behavtor Therapy. 1972. 3, 29-40.

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