4
.-tddicli~,c,B~,hoviors. Vol. 17. pp. 297-300. 1992 Printed in the USA. .A11 rights reserved. 0306~4603/92SS.O0 + .OO Copyright c’ 1992 Pergamon Press Ltd. BRIEF REPORT CUE EXPOSURE AND LEARNING THEORY RICHARD HAMMERSLEY University ofGlasgow Abstract - The implicationsare discussed for cue exposure treatment of four theoretical issues: (a) spontaneous recovery. (b) response competition, (c) generalization, and (d) the cognitive basis ofconditioning. It is suggested that practical cue exposure treatment will not be asstraight- forward as initial trials have suggested. Cue exposure is a promising treatment for drug and alcohol dependency [see the special section of Addictive Behaviors 15(4) 19901. The basic idea is that the drug user is exposed to stimuli previously associated with drug use, which evoke conditioned responses like those to actual drug-taking. These responses include signs ofarousal, pre- paratory physiological adjustments to compensate for the effects of the expected drug dose, drug-like responses, and self-reports,of craving for drugs. By exposure without subsequent drug-taking, the responses are gradually extinguished. The basic clinical idea is that in order to avoid drug use, it is necessary to learn to not take drugs in situ- ations where drug use previously would have occurred. This general approach makes a lot of sense and the rigorous experimental study of cue exposure is to be welcomed. This report will clarify some implications of learning theory for cue exposure treat- ment. The real treatment implications remain to be seen: Behavior therapy in general is highly successful despite the fact that it is often difficult to relate treatment practice to the behaviorist learning theory which supposedly underpins it (Erwin, 1978). THEORETICAL ISSUES The basic theoretical account Cue exposure assumes that the responses described above are classically conditioned. That is. as unconditioned responses they are responses to the unconditioned stimulus of the drug itself. By repetition, they become associated with a variety of conditioned stimuli vvhich are associated by time and place with the drug (for example, the smell of alcohol or the sight of injecting equipment). There are some problems with this simple account (O’Brien, Childress, McLellan, & Ehrman, 1990; Laberg, 1990; Powell et al., 1990). Also, it has long been known that classical conditioning is neither simple nor readily separable from operant conditioning (see Mowrer, 1960) or cognitive learning (see Davey, 1987). One problem which will not be discussed here is whether the conditioned responses are compensatory responses to the effects of the drug, or drug-like responses. They may well be a mixture of both (see Powell et al., 1990), and in terms of learning theory it does not matter because the mechanism of conditioning would be the same in either case. A Requests for reprints should be sent to Richard Hammersley, Behavioural Sciences Group, hledical Fac- ulty. UniLersity ofGlasgow, Glasgow GIZ 8QQ, UK. 297

Cue exposure and learning theory

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Page 1: Cue exposure and learning theory

.-tddicli~,c,B~,hoviors. Vol. 17. pp. 297-300. 1992 Printed in the USA. .A11 rights reserved.

0306~4603/92SS.O0 + .OO Copyright c’ 1992 Pergamon Press Ltd.

BRIEF REPORT

CUE EXPOSURE AND LEARNING THEORY

RICHARD HAMMERSLEY University ofGlasgow

Abstract - The implicationsare discussed for cue exposure treatment of four theoretical issues: (a) spontaneous recovery. (b) response competition, (c) generalization, and (d) the cognitive basis ofconditioning. It is suggested that practical cue exposure treatment will not be asstraight- forward as initial trials have suggested.

Cue exposure is a promising treatment for drug and alcohol dependency [see the special section of Addictive Behaviors 15(4) 19901. The basic idea is that the drug user is exposed to stimuli previously associated with drug use, which evoke conditioned responses like those to actual drug-taking. These responses include signs ofarousal, pre- paratory physiological adjustments to compensate for the effects of the expected drug dose, drug-like responses, and self-reports,of craving for drugs. By exposure without subsequent drug-taking, the responses are gradually extinguished. The basic clinical idea is that in order to avoid drug use, it is necessary to learn to not take drugs in situ- ations where drug use previously would have occurred. This general approach makes a lot of sense and the rigorous experimental study of cue exposure is to be welcomed.

This report will clarify some implications of learning theory for cue exposure treat- ment. The real treatment implications remain to be seen: Behavior therapy in general is highly successful despite the fact that it is often difficult to relate treatment practice to the behaviorist learning theory which supposedly underpins it (Erwin, 1978).

THEORETICAL ISSUES

The basic theoretical account Cue exposure assumes that the responses described above are classically conditioned.

That is. as unconditioned responses they are responses to the unconditioned stimulus of the drug itself. By repetition, they become associated with a variety of conditioned stimuli vvhich are associated by time and place with the drug (for example, the smell of alcohol or the sight of injecting equipment). There are some problems with this simple account (O’Brien, Childress, McLellan, & Ehrman, 1990; Laberg, 1990; Powell et al., 1990). Also, it has long been known that classical conditioning is neither simple nor readily separable from operant conditioning (see Mowrer, 1960) or cognitive learning (see Davey, 1987).

One problem which will not be discussed here is whether the conditioned responses are compensatory responses to the effects of the drug, or drug-like responses. They may well be a mixture of both (see Powell et al., 1990), and in terms of learning theory it does not matter because the mechanism of conditioning would be the same in either case. A

Requests for reprints should be sent to Richard Hammersley, Behavioural Sciences Group, hledical Fac- ulty. UniLersity ofGlasgow, Glasgow GIZ 8QQ, UK.

297

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29s RICH.iRD H.AblblERSLE\

second irrelevant problem is whether cue exposure extinguishes the conditioned response or the unconditioned response (Powell et al.. 1990). For cue exposure to drugs, it must be the latter because the unconditioned response to a drug is never manipulated; users are not given drugs and made to practice not feeling intosicated.

Setting these problems aside, we can turn to the four phenomena which cue exposure treatment should consider.

Spontaneous recovery Powell et al. ( 1990, pp 343-344) write: “The case for using esposure therapy to elim-

inate [my emphasis] such conditioned withdrawal is strong.” Thus, it is assumed that once extinction is achieved the user will no longer crave drugs upon exposure to the conditioned stimuli. Other authors appear to believe that extinction weakens the con- ditioned drug response in an approximately linear fashion.

Extinction is indeed the decreasing likelihood that the response will occur on presen- tation of the conditioned stimulus. but the response does not vanish from the behavior repertory. This is demonstrated by the well-known phenomenon of spontaneous recov- ery where after extinction to some criterion (say 100 trials without response), the response reappears occasionally when the conditioned stimulus is removed, then re- presented (see Hill, 1972). Furthermore, there are many influences on response prob- ability other than the number of extinction trials administered, some of which will be addressed below. Not only do old habits die hard, but they do not die at all; they merely lie dormant masked by new responses. Thus, some incidence of relapse is to be expected after cue exposure treatment.

Cue exposure should still reduce the frequency of conditioned drug responses, thus reducing the probability of relapse, but it will not eliminate craving or relapse. One log- ical supplement to future cue exposure treatment is that the user be taught how to deal with craving when it occurs, how to cope with relapse if it occurs, and how to accept both phenomena as normal parts of treatment, rather than as signs of treatment failure. This probably already occurs in practice (see Laberg, 1990). A second extension would be to re-administer the extinction procedure at intervals to reduce the probability of spontaneous recovery.

Response competition Extinction is not just the reduction of one response, or set of responses, but is in the-

ory the replacement of one response by another. In cue exposure experiments so far the drug user is not actively provided with alternative responses to conditioned drug responses (Laberg, 1990; O’Brien et al., 1990; Powell et al., 1990), although O’Brien’s team are considering this and it is recommended behavior therapy practice (Masters et al., 1987, p. 294). In current procedures, there is a risk that the user may substitute the conditioned drug response with a variety of alternatives from session to session, no one of which will be as strong the original conditioned response. This would make relapse more likely. It might be better for treatment if the user were provided with explicit alternative responses to conditioned drug responses which could be systemati- cally strengthened through practice. Preferably, these would be responses which were incompatible with conditioned drug responses (O’Brien et al.. 1990).

Generalization Classical conditioning does not occur arbitrarily. In order for a conditioned stimulus

to elicit the conditioned response, the setting of the stimulus must resemble that in

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Cue exposure and learning theon 299

which conditioning took place (see Masters et al., 1987, pp. 278-285). It is already appreciated that users are unlikely to generalize the extinction acquired in a laboratory or clinic to their everyday life (O’Brien et al., 1990). The obvious solution to this prob- lem is to extinguish conditioned drug responses in more realistic settings. There may be difficulties in applying this solution.

First, drugs are often used in a wide variety of settings and even with the most heroic therapist, the extinction of conditioned drug responses, setting by setting, may be unfeasible for all sorts of reasons. Will the therapist set up a simulated armed robbery so that the user can extinguish the urge to squander the money on drugs? A more prac- tical approach may be to utilize the concept of breadth of transfer. That is, cue exposure should be undertaken in as diverse a range of settings as possible in the hope that the learned extinction will generalize to all behavior settings, or at least as many as possible. For the broad generalization of learning, the diversity of settings may be more impor- tant than the extent to which particular settings resemble natural settings in the user’s life. Indeed, setting-specific extinction risks spontaneous recovery of conditioned drug responses when the user enters a novel setting.

Second, successful broad extinction will be more likely if it is possible to identify the key elements of settings which tend to lead to drug use. Obviously, direct exposure to drugs often leads to drug use (see Heather, Stallard, & Tebbutt, 199 1). which is why drug stimuli are often used in cue exposure studies. However, it is leaving things rather late to wait until a user is sitting cooking up heroin or holding a glass of vodka. The chain of behavior which leads to drug use must begin much earlier than that. Users report that places, people, kinds of event, emotions, and thoughts can all lead to relapse (Marlatt & Gordon, 1985). Indeed, part of the concept of drug dependency is that drugs are used in an exceptionally wide range of settings. At the extreme, for example, with a chain- smoker, almost everyfhing in everday life may cue conditioned drug responses. There is a need for cue exposure studies to explore cues other than those directly associated with drug use, As with the treatment of phobias, this would require tailoring cues more carefully to the individual.

A role for cognition? It has never been demonstrated satisfactorily that classical conditioning is relevant to

human learning. Classical conditioning only occurs in humans when they were aware of the association which they were supposed to form. That is, they could just as well be making the association cognitively (Dawson & Schell, 1987). Classical conditioning has also been demonstrated in cognition alone without any external stimuli (Davies, 1987). Thus, it is possible that the critical cues to drug use are primarily in the user’s mind rather than in the user’s environment. For example, Laberg (1990) reports that alco- holics show conditioned alcohol responses when merely told that they are going to receive alcohol. More generally, users may not automatically crave drugs upon expo- sure to some stimuli, but instead their cognitive interpretation of the stimuli may or may not elicit conditioned drug responses. For example, does the sight ofa bag of heroin in a corrupt policeman’s hand elicit conditioned drug responses, or anxiety? It seems reasonable that this depends upon whether the user believes that the officer is going to sell the drug to her, or plant it on her.

if cognitive interpretations of cues prove important, then this rather undermines the essential simplicity of cue exposure as a treatment. Instead, treatment starts to move back towards the more familiar, but less rigorous, ground of dealing with users’ feelings and beliefs (see Marlatt, 1990). To an extent, this is what happens in the practice of

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300 RICHARD HAMMERSLEY

behavior therapy. For example, the treatment of phobias by systematic desensitisation tends to begin, most unbehavioristically, with clients imagining situations which pro- voke mild fear: a snake phobic may imagine seeing a photograph of a snake. The treat- ment of obsessive behavior, which is cited as an inspiration for cue exposure in drug treatment, progresses similarly (Masters et al., 1987). If cue exposure develops upon similar lines [like Powell et al. (1990), except with less emphasis on pictures of drugs and drug paraphernalia], then it might begin by having users think about drugs, or sit- uations which incline them to use, without taking them. Once they could think about drugs without conditioned drug responses, then perhaps they would be ready to extin- guish conditioned drug responses in more tempting situations.

CONCLUSIONS

Cue exposure is a promising technique for the treatment of drug dependency. How- ever, its theoretical rationale has been put too simply. Its application as treatment will probably not be as straightfonvard as it might first appear, and, as treatment, cue expo- sure will probably end up being less radically behavioristic than it now seems. It will not be sufficient to extinguish conditioned drug responses to a variety of drug-related stim- uli in specific settings. Users must be prepared to deal with the spontaneous recovery of conditioned drug responses and should be taught alternative responses which are incompatible with conditioned drug responses. Conditioned drug responses should be extinguished in a wide range of settings so that considerable generalisation is achieved. Finally, the stimuli which elicit conditioned drug responses need to be studied in more detail with the aim ofconstructing a stimulus hierarchy. It may turn out that these stim- uli are basically cognitive, rather than environmental, in which case cue exposure will have more in common with current talking therapies than it appears at first sight.

REFERENCES

Dave!. G. (Ed.). (1987). Cognitiveprocesscs and Pavlovian conditioning in hm~ans. Chichester: Wiley. Davies, P. (1987). Conditioning. the basis of all psychological activity. In Wm. J. Baker, ht. E. Hyland. H.

Van Rappard. & A. W. Saats (Eds.), Current issues in theoretical psychology (pp. 23-35). Amsterdam: Elsevier.

Datvson, M. E., & Schell, A. M. (1987). Human autonomic and skeletal classical conditioning: the role of conscious cognitive factors. In G. Davey (Ed.), Cognitive processes and Pavlovian conditioning in h1tmnr7s (pp. 27-55). Chichester: Wiley.

Erwin, E. (1978). Behavior therapy: Scientific philosophical and moral foundations. New York: Cambridge University Press.

Heather, N., Stallard. A., & Tebbutt, J. (199 I). Importance of substance cues in relapse among heroin users: Comparison of two methods of investigation. Addictive Behaviors, 16,4 l-49.

Hill. W. F. (1972). Learning. A survey qfpsychological interpretations (2nd ed.). London: Methuen. Laberg. J. C. (1990). What is presented, and what is prevented. in cue exposure and response prevention with

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