Responsibility and perfectionism in OCD: an experimental study
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BEHAVIOUR
RESEARCH AND
THERAPY
PERGAMON Behaviour Research and Therapy 37 (1999) 239±248
Responsibility and perfectionism in OCD: an experimental
study
Catherine Bouchard, JoseÂe RheÂaume, Robert Ladouceur *
Universite Laval, Ecole de Psychologie, Ste-Foy Quebec G1K 7P4, Canada
Received 17 July 1998
Abstract
Cognitive models of obsessive±compulsive disorder (OCD) suggest a number of dierent variables
that may play a role in the development and maintenance of obsessive compulsive symptoms [Freeston,
M. H., RheÂaume, J., & Ladouceur, R. (1996) Correcting faulty appraisals of obsessional thoughts.
Behaviour Research and Therapy, 34, 433±446]. This study's aim was to verify the eect of perfectionism
and excessive responsibility on checking behaviors and related variables. Twenty-four moderately
perfectionistic subjects (MP) and 27 highly perfectionistic subjects (HP) were submitted to a
manipulation of responsibility (low and high). After each manipulation, they had to perform a
classi®cation task during which checking behaviors were observed. Results indicate that more checking
behaviors (hesitations, checking) occurred in the high responsibility condition than in the low
responsibility condition for subjects of both groups. After executing the task in the high responsibility
condition, HP subjects reported more in¯uence over and responsibility for negative consequences than
MP subjects. These results suggest that high perfectionistic tendencies could predispose individuals to
overestimate their perceived responsibility for negative events. Furthermore, perfectionism could be
conceived as playing a catalytic role in the perception of responsibility. Results are discussed according
to cognitive models of OCD. # 1999 Elsevier Science Ltd. All rights reserved.
Keywords: Perfectionism; Responsibility; Obsessive±compulsive disorder; Cognitive models
1. Introduction
Behavior therapy is faced with some limits for the treatment of obsessive±compulsive
disorder (OCD). Almost 25% of patients refuse this type of treatment and approximately
25% do not bene®t from it (Foa, Steketee, Grayson, & Doppelt, 1983). Cognitive therapy
* Corresponding author. Tel.: +1-418-656-396; Fax: +1-418-656-3646; E-mail: robert.ladouceur@psy.ulaval.ca
0005-7967/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved.
PII: S 0 0 0 5 - 7 9 6 7 ( 9 8 ) 0 0 1 4 1 - 7240 C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248 is considered as an alternative or as a complement to traditional behavioral treatments (e.g. van Oppen & Arntz, 1994; van Oppen et al., 1995; Freeston et al., 1996). In these circumstances, it is important to know and understand the cognitive variables that are involved in OCD in order to ®nd eective ways of correcting cognitive distortions. Dysfunctional perfectionism and excessive responsibility have been identi®ed as part of the ®ve main cognitive variables associated with OCD (McFall & Wollersheim, 1979; Freeston et al., 1996); the other principal variables being overestimation of the importance of thoughts, overestimation of danger and the belief that anxiety caused by thoughts is unacceptable. Recent de®nitions of responsibility and perfectionism contribute to our understanding of the role these variables play in OCD. Excessive or in¯ated responsibility has been de®ned as the belief which is pivotal to bring about or prevent subjectively crucial negative outcomes. They may be actual, that is, having consequences in the real world and/or at a moral level (Salkovskis et al., 1996). This de®nition has been empirically supported using a semi- idiographic questionnaire (e.g. RheÂaume, Ladouceur, Freeston, & Letarte, 1995) as well as with experimental manipulations of responsibility (e.g. Ladouceur et al., 1995; Ladouceur, RheÂaume, & Aublet, 1997). The unidimensional de®nition of perfectionism used in this study is: `the belief that a perfect state exists that one should try to attain' (Pacht, 1984). According to this perspective, which is particularly pertinent in the study of OCD (RheÂaume, Freeston, Dugas, Letarte, & Ladouceur, 1995), perfection does not exist and the attempt to attain this perfect state would be associated with psychopathology. Hamachek (1978) points out that perfectionism can be a positive personality trait and distinguishes between sane and pathological perfectionism. The Perfectionism Questionnaire was devised to measure this construct with respect to the distinction between functional and dysfunctional perfectionism. The criterion and convergent validity of this instrument were established with questionnaire (RheÂaume, Freeston, & Ladouceur, 1995) and behavior manipulation studies (RheÂaume et al., 1995b). In the past few years, the concept of excessive responsibility has received a lot of attention (Cottraux, 1990; Rachman, 1993; RheÂaume, Ladouceur, Freeston, & Letarte, 1994; Tallis, 1994; van Oppen & Arntz, 1994; RheÂaume et al., 1995c). Salkovskis (1985, 1989) made a great contribution to this theory by proposing a theoretical model whereby an excessive sense of responsibility is at the core of OCD. According to this model, obsessional patients would appraise intrusive thoughts as a function of possible harm to themselves or others. This excessive sense of responsibility would produce automatic negative thoughts, and discomfort would arise. The individual would then attempt to reduce the anxiety through cognitive neutralization or compulsive behavior (e.g. checking repetitively). Many studies support this model. In a number of clinical studies, the presence of an excessive sense of responsibility was observed in OC patients (Salkovskis, 1989; van Oppen et al., 1995; Ladouceur, LeÂger, RheÂaume, & DubeÂ, 1996). Furthermore, questionnaire studies comparing OC patients to control subjects support the existence of a link between responsibility and OC-type behaviors (Freeston, Ladouceur, Gagnon, & Thibodeau, 1992, 1993; RheÂaume et al., 1995a). Finally, two recent experimental studies manipulated the level of perceived responsibility. Lopatka and Rachman (1995) succeeded
C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248 241 in changing the perceived responsibility for negative consequences in thirty compulsive checkers. As expected, the lowering of responsibility was associated with a signi®cant drop in discomfort and need to check. Lastly, two studies experimentally manipulated responsibility in nonclinical subjects (Ladouceur et al., 1995, 1997). Results showed that checking behaviors were more frequent in the group receiving high responsibility instructions compared to controls. On the other hand, although it has been suggested for many years that perfectionism also plays a key role in OCD (Hamachek, 1978; Burns, 1980; Pacht, 1984; Rasmussen & Eisen, 1989), this variable has not yet been fully studied. At the clinical level, Ladouceur et al. (1996) observed that perfectionism was a common characteristic in a group of OC patients without manifest compulsions, while responsibility was clearly less apparent in those same subjects. Correlational studies have shown a signi®cant link between perfectionism and OC symptoms (Hewitt & Flett, 1991; Hewitt, Flett, & Turnbull, 1992). Furthermore, two correlational studies using the Maudsley OC symptom checklist with analogue subjects have shown that participants with OC tendencies were more perfectionistic than noncompulsive individuals (Frost, Steketee, Cohn, & Griess, 1994) and were also more perfectionistic than nonanxious controls (Gershuny & Sher, 1995). Finally, in a recent experimental study using a variety of tasks with nonclinical subjects, dysfunctional perfectionists obtained higher scores on the Padua Inventory and performed more poorly in precision and decision making tasks compared to functional perfectionists. These results support the link between perfectionism and OC symptoms (RheÂaume et al., 1995b). At this point in time, the links between perfectionism and responsibility remain obscure. Studies conducted by RheÂaume et al. (e.g. RheÂaume et al., 1995a; RheÂaume, Ladouceur, & Freeston, 1998) have shown that responsibility and perfectionism are good independent predictors of OC symptoms. Nonetheless, little is known about the nature of the relationship between these two important factors. Considering the recent developments in cognitive therapy (e.g. van Oppen et al., 1995; Ladouceur et al., 1996; Freeston et al., 1997), it appears necessary to investigate how perfectionism and responsibility are linked together and to OC symptoms, in order to develop speci®c cognitive interventions adapted to this population. The aim of the current study is to explore the links between perfectionism and excessive responsibility. This relationship will be studied by increasing and lowering perceived responsibility in subjects showing dierent degrees of perfectionism. We will verify if perfectionism, together with an excessive sense of responsibility, has an impact on the appraisal of intrusions and whether they predispose individuals to show OC tendencies. It is expected that highly perfectionistic subjects will show more OC-type behaviors and will attribute more responsibility to themselves than moderately perfectionistic subjects. In the high responsibility condition, we should observe, for both groups, more OC-type behaviors than in the low responsibility condition. Furthermore, this increase in checking and other related behaviors should be more marked in highly perfectionistic subjects than in moderately perfectionistic subjects.
242 C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248 2. Method 2.1. Participants Fifty-one adults from a nonclinical population participated in the study (41 women, 10 men, mean age 23.3 years). Subjects were recruited through questionnaire studies conducted in university classes. Subjects participating in the study were eligible for a draw prize of CAN$50. In order to increase the credibility of the task, subjects were not to be psychology students and not to have already participated in a laboratory study. Subjects were selected on the basis of their scores on the PQ. Two groups were formed: the highly perfectionistic group (HP), composed of subjects whose scores ranked over the 90th percentile on the perfectionistic tendencies scale of the PQ and the moderately perfectionistic group (MP), composed of subjects whose scores ranked under the 40th percentile on this scale. Three subjects were excluded due to the fact that they did not believe the manipulation context. 2.2. Procedure Subjects of both groups participated in an individual 35 min session. The experimenter brie¯y explained the procedure which consisted of performing a classi®cation task two times and completing a questionnaire. He explained that the session would be recorded on video for research purposes. The task consisted of classifying 50 drug capsules (10 kinds, ®ve of each) previously emptied of their active substances and ®lled with sugar into 12 semitransparent bottles. Subjects had to pick one capsule at a time and put each type of capsule in a dierent bottle aligned in front of them. If they believed that they made a mistake, Ss could check and move the capsules during the task. Subjects were instructed to proceed as fast as possible while completing the task as best as they could. 2.3. Manipulation of responsibility 2.3.1. Low responsibility The subject was asked to do the task a ®rst time as a simple practice. Moreover the experimenter explained to the subject that his personal results had no importance because it was only a practice trial. After receiving these low responsibility instructions the subject completed the task a ®rst time while the experimenter was out of the room. 2.3.2. High responsibility The experimenter then explained to the subject that our research group was specialized in the perception of colors and had been mandated by a pharmaceutical company for a project concerning the exportation of a medication for a virus which was presently very widespread in a Southeast Asian country. Moreover, the subject was told that, as this region was very poor and its population poorly educated, there was a need for developing a system of colors that would make the distribution of medication safer for the inhabitants. The subject was also told that he had great responsibility in the project, because his results in the classi®cation of capsules could directly in¯uence the manufacturing of the medication. Moreover, it was
C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248 243 essential that he completed the task as seriously as possible in order to prevent serious harm and completed the task with the high responsibility instructions in mind. After the task was completed, the experimenter counted the mistakes while the subject completed the retrospective questionnaire on the classi®cation task. Finally, the experimenter debriefed the subject, explained the real goals of the study and asked him to sign a ®nal consent form if he still accepted that his results be used for analyses. 2.4. Instruments The Perfectionism Questionnaire (PQ; RheÂaume et al., 1995c) contains 64 items divided into three subscales: (1) perfectionistic tendencies (10 items, a = 0.82), (2) domains aected by perfectionism (30 items, a = 0.88) and (3) negative consequences of perfectionism (24 items, a = 0.96). The PQ has good construct and convergent validities (RheÂaume et al., 1998). This instrument is used to form the groups. The retrospective questionnaire on the classi®cation task is a slightly modi®ed version of the retrospective questionnaire used in the Ladouceur et al. (1995) study. It contains 10 questions evaluating responsibility and subjective variables. 2.5. Manipulation checks The mean score of the HP and MP groups on the perfectionistic tendencies subscale of the PQ were compared to determine wether the groups were signi®cantly dierent on this dimension. 2.6. Responsibility variables Four questions of the retrospective questionnaire evaluated perception of the probability and the severity of negative consequences, the in¯uence of the subject over these consequences, and perceived responsibility. Since the intrasubject design of the current study did not allow for a manipulation check measure to be introduced after the LR condition, we compared the mean scores for the responsibility variables for the HR condition to those obtained in the study of Ladouceur et al. (1995) in order to support the ecacy of the responsibility manipulation. 2.7. Dependent behavioral variables Five behavioral variables were measured: (1) hesitations, de®ned as close examination of a capsule for more than 2 s or by a movement of the Ss hand between two dierent pill bottles for at least 2 s; (2) checking, de®ned as picking up the bottle to look inside or emptying the content of the bottle into the palm of the hand; (3) modi®cations, referred to as any change, addition or withdrawal of one or more capsules from a given pill bottle; (4) number of errors made; and (5) time to complete the task. An inter-judge agreement was established for each of these behavioral measures (see Ladouceur et al., 1995, 1996).
244 C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248
2.8. Dependent subjective variables
The subjective variables were evaluated with the retrospective questionnaire: (1) doubt, (2)
preoccupation with errors, (3) need to check, (4) desired additional time to check and (5)
anxiety.
3. Results
3.1. Manipulation checks
A t-test on the integrity variable revealed a signi®cant dierence between the HP group and
the MP group on their score on the perfectionistic tendencies subscale of the PQ (t = 19.88,
p < 0.0001). The HP group reported signi®cantly more perfectionistic tendencies than the MP
group. The two groups also diered on their score on the negative consequences subscale of
the PQ (t = 5.19, p < 0.0001), the HP group reporting signi®cantly more negative
consequences related to their perfectionistic tendencies than the MP group.
3.2. Responsibility variables
Table 1 presents the mean scores of both groups for responsibility variables: probability and
severity of possible negative consequences and perceived in¯uence and responsibility for these
consequences. A Manova conducted on these variables revealed a signi®cant group eect
(F(4,46) = 5.15; p < 0.002). After completing the task in the high responsibility condition,
subjects from the HP group reported more in¯uence and responsibility for possible negative
consequences than Ss from the MP group.
3.3. Dependent behavioral variables
Table 2 presents the mean scores of both groups for behavioral variables. A Manova on the
®ve behavioral variables revealed a signi®cant intragroup eect (responsibility) (F(5,44) = 5.25;
p < 0.0008), but no group (perfectionism) nor interaction eects. Subsequent Anovas indicated
Table 1
Responsibility variables (HR condition)
Variables MP group HP group
M S.D. M S.D. F
Severity 5.58 1.56 6.48 2.26 2.66
Probability 4.67 1.43 4.70 1.88C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248 245
Table 2
Dependant behavioral variables
Variables Low responsibility condition High responsibility condition HR/LR
MP group HP group MP group HP group
M S.D. M S.D. M S.D. M S.D. F
Hesitations 17.67 8.85 16.88 11.28 21.87 10.09 19.11 11.92 7.73*
Checking 4.04 5.08 3.50 4.37 5.75 5.37 6.15 6.55 10.34*
Modi®cations 2.58 2.60 1.31 1.19 1.88 1.39 1.46 1.58246 C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248 Analyses con®rm that the identi®cation of two levels of perfectionism was successful since the HP group reported signi®cantly more perfectionistic tendencies and negative consequences associated to these tendencies than the MP group. It also appears that the experimental manipulation of responsibility was successful. Indeed, when we compare the mean scores in the HR condition (HP and MP groups combined) to those obtained in the study of Ladouceur et al. (1995), respectively, results are comparable for all four responsibility variables. Analyses conducted on the responsibility variables reveal that the HP group perceived more in¯uence and responsibility for negative consequences than the MP group. On a subjective level, HP subjects were therefore more aected by an increase in responsibility than less perfectionistic subjects. This result suggests that perfectionism may predispose individuals to feel responsible. Highly perfectionistic individuals would react more strongly in a situation of increased responsibility, perceiving more personal in¯uence on the situation than they actually have. On the other hand, we notice that the HP group does not perceive greater probability nor severity of negative consequences than the MP group. In previous manipulation studies, signi®cant dierences were obtained on these variables (Ladouceur et al., 1995, 1997). This result is therefore puzzling. It is possible that this result is nonsigni®cant simply due to a lack of power; a tendency was observed for the gravity variable. It is also possible that the relationship between perfectionism and responsibility only aects the perception of having a pivotal role in the situation and not the appraisal of the consequences themselves; the evaluation of consequences being independent of perfectionism. Results concerning the number of errors and the time to complete the task, partially con®rm the intragroup dierences hypothesis. Both groups made less mistakes and took more time to complete the task in the high responsibility condition compared to the LR condition. This con®rms the eect of responsibility at a behavioral level. Concerning the subjective variables, no dierence was observed for doubt, need to check, anxiety or desired additional time to check. These results discon®rm the hypothesis of subjective dierences between groups. This could be due to the simplicity of the task and to the fact that subjects could check as much as they wished, which left little room for a persistence of doubt or need to check. The absence of signi®cant behavioral dierences between groups is surprising considering that signi®cant intergroup dierences were found on other levels. A ®rst hypothesis that could explain this absence of dierence concerns the assignment of subjects. The score of the MP group on the negative consequences subscale appears higher than would normally be expected. Surprisingly, these subjects who report being only slightly perfectionistic on the perfectionistic tendencies subscale also report suering a great deal from the negative consequences associated to perfectionism (see RheÂaume et al., 1995b). If these MP subjects present a high degree of dysfunction, they would clearly distinguish themselves less from HP subjects, which would explain the similar checking behavior of the two groups in the classi®cation task. Another hypothesis is the fact that the manipulation of responsibility was too powerful. Indeed, it was expected that the HP group would check more than the MP group, especially in the high responsibility condition. It is possible that this was not observed due to a ceiling eect: the increase in responsibility was so marked that both groups increased their checking rate to a maximum, leaving no room for a distinction between groups. It is therefore possible that the optimal way to use such a manipulation is with random groups (Stevens, 1980); indeed, the
C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248 247 present experimental protocol (2 2) did not reach the necessary power to study a perfectionism responsibility interaction on the behavioral level. The overall results suggest a link between checking behavior and the perception of in¯ated responsibility and show a relation between perfectionistic tendencies and an increased perception of responsibility and personal in¯uence. These results have important implications for the cognitive models of OCD. They suggest that perfectionism, when it reaches a dysfunctional level, could predispose the individual to overestimate his or her own responsibility for negative events, which in turn could potentially contribute to an increase in checking behavior. Increased responsibility has the eect of increasing checking behavior, and furthermore, perfectionism could be conceived as playing a catalytic role in the perception of responsibility. Acknowledgements This study was conducted while the ®rst author was supported by the Fonds pour la Recherche en Sante du QueÂbec and while the third author received grants from the Medical Research Council of Canada and the Fonds de Recherche en Sante du QueÂbec. References Burns, D. (1980). The perfectionist's script for self-defeat. Psychology Today, November, 34±51. Cottraux, J. (1990). Therapie cognitive des obsessions-compulsions. Encephale, 16, 347±353. Foa, E. B., Steketee, G. S., Grayson, J. B., & Doppelt, H. G. (1983). Treatment of obsessive±compulsives: when do we fail? In E.B. Foa & P.M.G. Emmelkamp (Eds.), Failures in behavior therapy (pp. 10±33). New York: Wiley and Sons. Freeston, M. H., Ladouceur, R., Gagnon, F., & Thibodeau, N. (1992). Intrusive thoughts, worry and obsessions: empirical and theor- etical distinctions. Paper presented at the World Congress of Cognitive Therapy, Toronto. Freeston, M. H., Ladouceur, R., Gagnon, F., & Thibodeau, N. (1993). Beliefs about obsessional thoughts. Journal of Psychopathology and Behavioral Assessment, 15, 1±21. Freeston, M. H., Ladouceur, R., Gagnon, F., Thibodeau, N., RheÂaume, J., Letarte, H., & Bujold, A. (1997). Cognitive behavioral treatment of obsessive thoughts: a controlled study. Journal of Consulting and Clinical Psychology, 65, 405±423. Freeston, M. H., RheÂaume, J., & Ladouceur, R. (1996). Correcting faulty appraisals of obsessional thoughts. Behaviour Research and Therapy, 34, 433±446. Frost, R., Steketee, G., Cohn, L., & Griess, K. E. (1994). Personality traits in sub clinical and nonobsessive compulsive volunteers and their parents. Behaviour Research and Therapy, 32, 47±56. Gershuny, B. S., & Sher, K. J. (1995). Compulsive checking and anxiety in a nonclinical sample: dierences in cognition, behavior, personality and aect. Journal of Psychopathology and Behavioral Assessment, 17, 19±38. Hamachek, D. E. (1978). Psychodynamics of normal and neurotic perfectionism. Psychology, 15, 34±52. Hewitt, P. L., & Flett, G. L. (1991). Perfectionism in the self and social contexts: conceptualization, assessment and association with psychopathology. Journal of Personality and Social Psychology, 60, 456±470. Hewitt, P. L., Flett, G. L., & Turnbull, W. (1992). Perfectionism and multiphasic personality inventory (MMPI) indices of personality disorder. Journal of Psychopathology and Behavioral Assessment, 14, 323±335. Ladouceur, R., LeÂger, EÂ., RheÂaume, J., & DubeÂ, D. (1996). Correction of in¯ated responsibility in the treatment of obsessive±com- pulsive disorder. Behaviour Research and Therapy, 34, 767±774. Ladouceur, R., RheÂaume, J., Freeston, M. H., Aublet, F., Jean, K., Lachance, S., Langlois, F., & De Pokomandy-Morin, K. (1995). Experimental manipulation of responsibility: an analog test for models of obsessive±compulsive disorder. Behaviour Research and Therapy, 33, 937±946.
248 C. Bouchard et al. / Behaviour Research and Therapy 37 (1999) 239±248 Ladouceur, R., RheÂaume, J., & Aublet, F. (1997). Excessive responsibility in obsessional concerns: a ®ne-grained experimental analysis. Behaviour, Research and Therapy, 35, 423±427. Lopatka, C., & Rachman, S. J. (1995). Perceived responsibility and compulsive checking: an experimental analysis. Behaviour Research and Therapy, 33, 673±684. McFall, M. E., & Wollersheim, J. P. (1979). Obsessive±compulsive neurosis: a cognitive behavioral formulation and approach to treat- ment. Cognitive Therapy and Research, 3, 333±348. Pacht, A. R. (1984). Re¯ections on perfection. American Psychologist, 39, 386±390. Rachman, S. J. (1993). Obsessions, responsibility and guilt. Behaviour Research and Therapy, 31, 149±154. Rasmussen, S. A., & Eisen, J. L. (1989). Clinical features and phenomenology of obsessive±compulsive disorder. Psychiatric Annals, 19, 67±72. RheÂaume, J., Freeston, M. H., Dugas, M., Letarte, H., & Ladouceur, R. (1995a). Perfectionism, responsibility and obsessive±com- pulsive symptoms. Behaviour Research and Therapy, 33, 785±794. RheÂaume, J., Freeston, M. H., Ladouceur, R., Bouchard, C., Gallant, L., Talbot, F., & VallieÁres, A. (1995b). Perfectionism and obses- sive±compulsive type behaviors. Paper presented at the 29th annual Congress of the Association for the Advancement of Behavior Therapy, Washington, DC. RheÂaume, J., Freeston, M. H., & Ladouceur, R. (1995, July). Functional and dysfunctional perfectionism: construct validity of a new instrument. Paper presented at the 1st annual World Congress of Behavioral Cognitive Therapy, Copenhagen. RheÂaume, J., Ladouceur, R., Freeston, M. H., & Letarte, H. (1994). In¯ated responsibility and its role in OCD. II. Psychometric stu- dies of a semi-idiographic measure. Journal of Psychopathology and Behavior Assessment, 16, 265±276. RheÂaume, J., Ladouceur, R., Freeston, M. H., & Letarte, H. (1995c). In¯ated responsibility in obsessive±compulsive disorder. I. Validation of an operational de®nition. Behaviour Research and Therapy, 33, 159±169. RheÂaume, J., Ladouceur, R. & Freeston, M. H. (1998). The prediction of obsessive±compulsive symptoms: new evidence for multiple cognitive vulnerability factors, submitted for publication. Salkovskis, P. M. (1985). Obsessional±compulsive problems: a cognitive behavioural analysis. Behaviour Research and Therapy, 23, 571±583. Salkovskis, P. M. (1989). Cognitive behavioural factors and the persistence of intrusive thoughts in obsessional problems. Behaviour Research and Therapy, 27, 677±682. Salkovskis, P. M., Rachman, S. L., Ladouceur, R., Freeston, M. H., Taylor, S., Kyrios, M., & Sica, C. (1996). De®ning responsibility in obsessional problems. In Proceedings of the Smith College Women's Room after the Toronto Cafeteria. Stevens, J. P. (1980). Power of the multivariate analysis of variance tests. Psychological Bulletin, 88, 728±737. Tallis, F. (1994). Obsessions, responsibility and guilt: two case reports suggesting a common and speci®c etiology. Behaviour Research and Therapy, 32, 143±145. van Oppen, P., & Arntz, A. (1994). Cognitive therapy for obsessive±compulsive disorder. Behaviour Research and Therapy, 32, 79±87. van Oppen, P., de Haan, E., van Balkom, A. J. L. M., Spinhoven, P., Hoogduin, K., & van Dyck, R. (1995). Cognitive therapy and exposure in vivo in the treatment of obsessive compulsive disorder. Behaviour Research and Therapy, 33, 379±390.
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