Behm. Rcs. Thu. Vol. 32. No. 4, pp. 403-410, 1994 Copyright IC 1994 Elsevier Science Ltd

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OBSESSIVE rNTR~SIVE THOUGHTS IN NONCLINICAL SUBJECTS. PART II. COGNITIVE APPRAISAL,

EMOTIONAL RESPONSE AND THOUGHT CONTROL STRATEGIES

CHRISTINE PURDON and DAVID A. CLARK*

Department of Psychology, University of New Brunswick, Fredericton, N.B., Canada E3B 6E4

(Received 23 Aprii f99.3)

Summary-This second part of the study reports on the appraisal and thought control responses of 270 students to their most upsetting intrusive thought. Multiple regression analysis revealed that belief that one could act on the intrusive thought and perceived uncontrollability of the thought were the two most important predictors of the frequency, or persistence of the distressing intrusion. Intrusions rated as very difficult to control were also associated with increased belief that one could act on the intrusion, avoidance of situations that may trigger the intrusion, reduced success with one’s most typical thought control strategy and higher thought frequency. Based on the Padua Inventory Total score, high and low obsessional Ss were selected. Highly obsessional jndividuals reported more unwanted obsessive intrusive thoughts and rated their thoughts as significantly more frequent and believable than low obsessive individuals. The type of thought control strategy typically used was not a factor in thought frequency and controllability, nor did it differentiate between high and low obsessional groups. The results are discussed in terms of Salkovskis’ cognitive model of obsessions and intrusive thoughts.

INTRODUCTION

As noted in our first paper (Purdon & Clark, 1993), Salkovskis (1985, 1989) postulates two processes that are crucial to the increased frequency and saliance of unwanted intrusive thoughts, images and impulses. First, he notes that the manner in which an individual appraises or evaluates an unwanted intrusive thought is a major determinant of the persistence of the intrusion. If, for example, unwanted intrusive thoughts are evaluated by individuals as indicative that they may cause harm to self or others, then this will lead to a heightened sense of personal responsibility toward self and others, which, in turn, will directly increase the perceived discomfort and unacceptability of the intrusion. Furthermore, other negative evaluative processes may indirectly contribute to the persistence of the intrusion by reinforcing the mood disturbance (e.g. dysphoria, anxiety) often associated with unwanted negative intrusive thoughts (Salkovskis, 1985, 1989).

According to Salkovskis, appraisals of responsibility lead to the second key factor in the persistence of unwanted intrusive thoughts. Since the discomfort associated with the intrusion is heightened because of the exaggerated sense of personal responsibility, the individual feels compelled to perform an overt or covert response in order to avert harm to others occasioned by the intrusion (Salkovskis, 1985, 1989). The production of such a neutralizing or thought control response has three consequences for the persistence of unwanted intrusions: first, there is a temporary reduction in discomfort associated with the intrusion which, in turn, acts as a negative reinforcement for the neutralizing response; second, a sensitization process occurs whereby the neutralizing response actually increases the salience of the target intrusion by boosting its attentional priority; and, finally, the production of a thought control response to the unwanted intrusion paradoxically reinforces or validates the individual’s initial dysfunctional belief that this intrusive thought signifies the possibility of harm to self or others (Salkovskis, 1989). In sum, appraisals of responsibility and the accompanying thought control or neutralization efforts lead to an escalation and intensification of the unwanted mental intrusion.

*To whom all correspondence should be addressed.

BRT x2,- 403

404 CHRISTINE PUKDON and DAVID A. CLARK

Over the last few years a number of studies, conducted primarily on nonclinical samples, have shown that appraisal processes are integral to understanding the frequency and controllability of unwanted negative intrusive thoughts, images and impulses. Evaluative dimensions such as unpleasantness, unacceptability, disapproval, guilt, belief, and perceived harm have been positively associated, to a greater or lesser extent, with increased frequency and/or reduced control of unwanted intrusive thoughts (Clark, 1992; Clark & de Silva, 1985; Edwards & Dickerson, 1987; England & Dickerson, 1988; Freeston, Ladouceur, Gagnon & Thibodeau, 1992a; Freeston, Ladouceur, Thibodeau & Gagnon, 1992b; Niler & Beck, 1989; Parkinson & Rachman, 198 1; Rachman & de Silva, 1978; Reynolds & Salkovskis, 1991). However, across studies considerable disagreement exists on which of the appraisal dimensions are most salient to the persistence of unwanted intrusions. Niler and Beck (1989) for example, found that perceived guilt was a significant unique predictor of unpleasant intrusive thoughts. In a later study, Reynolds and Salkovskis (1991) failed to replicate this result, instead finding that depressive and anxious symptoms, but not guilt, were the best predictors of intrusive thoughts. Parkinson and Rachman (1981) found that unpleasantness was significantly related to the controllability of intrusive phenomena, while England and Dickerson (1988) concluded that unpleasantness was not a significant factor in the controllability of intrusive thoughts.

More recently, a few studies have focused more specifically on the role of appraisals of responsibility in the frequency and controllability of negative intrusive thoughts. In two studies appraisals concerning responsibility formed a separate dimension in the factor structure of intrusive thoughts measures (Bouvard, Mollard, Cottraux & Guerin, 1989; Freeston, Ladouceur, Thibodeau & Gagnon, 1991~). In another important study, Freeston, Ladouceur, Gagnon and Thibodeau (1991a) developed a questionnaire that directly assesses beliefs about intrusive thoughts. They found that Ss who had high disapproval of their intrusive thoughts also endorsed more responsibility beliefs and reported more anxious, depressive and obsessional symptoms. In a second study, scores on an evaluative dimension which included perceived responsibility emerged as the only significant predictor of obsessional symptoms (Freeston et al., 1992b). However, positive results have not always been reported for responsibility ratings. When obsessive-compulsive disorder (OCD) patients and normals were compared on a number of dimensions related to their experience of unwanted intrusive thoughts, OCD patients did not report significantly higher ratings on belief of personal responsibility (Freeston, Ladouceur, Gagnon & Thibodeau, 1991 b). Gener- ally, results from these studies indicate that perceived responsibility is an important appraisal dimension in the frequency and controllability of unwanted intrusive thoughts. How this dimension relates to other evaluative dimensions of intrusive thinking is still a matter for further investigation.

Empirical support for the role of neutralizing responses in the persistence of unwanted intrusions is not as strong, in part due to the small number of studies that have directly investigated this construct. Freeston et ul. (1991~) found that unwanted intrusions which elicited a neutralizing control response were rates significantly higher on disapproval, guilt, and perceived responsibility than intrusions involving no effortful response. Salkovskis and Dent [cited in Salkovskis (1989)] found a significant relation between beliefs of responsibility and tendency to neutralize in a nonclinical sample. Freeston et al. (1992a) found that normal neutralizers (i.e. nonclinical Ss who often use neutralizing strategies to control their intrusive thoughts) endorsed significantly more obsessional beliefs about responsibility than Ss who did nothing in response to their intrusions. Furthermore, OCD patients do report a greater tendency to neutralize their unwanted intrusive thoughts than nonclinical Ss (Freeston et al., 1992a; Rachman & de Silva, 1978), although in the former study, clinical obsessionals did use a variety of mental control strategies apart from neutralizing. In sum, too few studies have directly investigated Ss’ thought control responses to unwanted intrusive thoughts to draw firm conclusions on whether certain control strategies lead to greater increases in intrusive thoughts over others.

As we have seen, empirical support has been encouraging, but by no means consistent, for the role of appraisal dimensions and thought control strategies in the persistence of unwanted intrusive thoughts, images and impulses. This lack of consensus may be due, in part, to the broadly based measures used in many studies to assess intrusive phenomena. As discussed in our first paper, most research on intrusive thoughts considers thoughts with any content appropriate for inclusion in their studies. Consequently, depressive and anxious negative automatic thoughts as well as truly

Obsessive intrusive thoughts 405

obsessive-like, ego-dystonic intrusive thoughts are included in most intrusive thoughts measures (Purdon & Clark, 1993). However, it may be that Ss’ evaluations of highly unacceptable ego-dystonic thoughts involving loss of control over aggressive and sexual urges (i.e. content typical of clinical obsessions) will differ from their evaluations of more ego-syntonic cognitions dealing with personal loss, failure and threat (i.e. the negative automatic thoughts characteristic of anxiety and depressive states). Also, researchers have often relied upon aggregate ratings across many different types of cognitive stimuli rather than asking Ss to evaluate their response to their single most upsetting intrusion.

The purpose of the present study was to investigate Ss’ cognitive, emotional, and thought control responses to their most upsetting intrusive thought, image or impulse using a questionnaire designed to assess exclusively obsession-like material. Three questions guided this part of the study:

(a) Which appraisal dimensions play a significant role in the frequency and controllability of intrusive cognitions?

(b) Does the type of thought control strategy used influence the frequency or controllability of the intrusion?

(c) Do obsession-prone individuals differ from nonobsessionals in their apraisal of and response to upsetting intrusive thoughts?

METHOD

Subjects and procedure

This was described in Part I of the study (Purdon & Clark, 1993).

Dependent measures

Padua Inventory. The Padua Inventory (PI) is a 60-item self-report measure of obsessional ideation and compulsive behaviour (Sanavio, 1988). A summary of the psychometric status of this instrument is presented in Part I of this study (Purdon & Clark, 1993).

Obsessional Intrusions Inventory (OZZ). The 011 is a 52-item self-report inventory designed to assess the frequency of and cognitive/emotional response to intrusive thoughts that are exclusively obsession-like in nature. Item development and validation of the 011 frequency scale is presented in Part I of this study.

After completing the 52-item checklist of obsessive intrusive thoughts (Part I of the 011), Ss were, in Part II, requested to examine their item endorsements and choose the single most upsetting intrusive thought which they have experienced. This intrusive thought was then rated along several evaluative dimensions using a 5-point rating scale from ‘not at all’ to ‘very’. The appraisal dimensions consisted of: (a) upset; (b) unpleasantness; (c) guilt; (d) avoidance of situations that may trigger the intrusion; (e) uncontrollability; (f) unacceptability; and (g) belief that the intrusive thought could occur in real life. Ss were also presented with a list of 10 thought control strategies (Freeston et al., 1991~) and asked to indicate which strategy they most often use in response to this upsetting intrusive thought (see Table 2). Ss were also asked to make a final rating on the degree of success they had in removing their most upsetting intrusive thought using the thought control strategy endorsed in the previous question.

RESULTS

Descriptive analysis

All Ss were able to select an intrusive thought from the 011 checklist which represented their most upsetting unwanted intrusive thought. All Ss reported that they found at least one of their intrusive thoughts upsetting. However, some Ss did not complete the second part of the 011 because of time constraints. As a result, the original N of 293 was reduced to 270 in the analyses to follow.

Of the 52 items comprising the 011, 45 were endorsed by at least 1 S as their most distressing intrusion. However, the item frequency distribution for selection of Ss’ most upsetting intrusive thoughts was flat, with the majority of items selected by less than 3% of the sample. In fact, the

406 CHRISTINEPURDON and DAVID A. CLARK

Table I. Correlation coefficients of cognitive/emotional response to most upsetting intrusive thought

2 3 4 5 6 1 8 9

I Avoidance 0.32 0.36 0.25 0.27 0.21 0.04 0.07 0.33

2. Unpleasantness 0.64 0.09 0.33 0.12 0.01 0.05 0.37

3. upset 0.17 0.39 0.21 0.09 0.14 0.38

4. Uncontrollability 0.02 0.47 -0.31 0.34 -0.10

5. Guilt -0.14 0.04 - 0.06 0.43

6. Belief -0.18 0.29 -0.14

7. Thought control success -0.17 0.12

8. Frequency -0.11

9. Unacceotabilitv

All correlations >O. I I significant, P < 0.05.

4 011 items most often selected were: “running the car off the road” (6%); “leaving the heat or stove on thereby causing an accident” (10%); “having sex with an unacceptable person” (11%); and “engaging in activity contrary to one’s sexual preference” (8%). Furthermore, there were no significant differences between men and women in the type of item selected as their most upsetting intrusion, or in the appraisal ratings and thought control strategies associated with the intrusion.

Appraisal ratings and thought control strategies

Table I presents the zero-order correlations between the 8 appraisal ratings of Ss’ most upsetting intrusive thought. Most of the correlations between ratings were quite low, indicating considerable independence amongst the appraisal dimensions included in this study. The one exception to this was the high correlation between unpleasantness and upset. Since upset may be confounded with the defining criteria for selecting the target intrusion, we decided to exclude this rating from further analyses. The frequency of Ss’ most upsetting intrusive thought correlated with only two other appraisal dimensions, uncontrollability and, to a lesser extent, belief that the intrusion could be acted upon in real life. Uncontrollability, on the other hand, was moderately correlated with avoidance, belief, and decreased success in utilizing one’s typical thought control strategy.

Table 2 presents the number of Ss who endorsed each thought control strategy as their most typical means of removing the distressing intrusion. Once again one sees considerable diversity across the sample in the thought control strategies endorsed. The most popular thought control responses (“reasoning with one’s self in an attempt to prove the intrusive thought is irrational” and “distracting one’s self by thinking something pleasant”) were endorsed by only 22% or less of the sample. Control strategies which clearly qualify as covert neutralizing responses (such as thinking another thought or performing a behaviour that counters the effects of the intrusion), were endorsed as Ss’ most typical control strategy by less than 12% of the sample. Interestingly, very few Ss (7%) indicated that they did nothing in response to their most upsetting intrusive thought.

Because of the low endorsement rates on a number of the thought control categories, the data were collapsed into more general categories thereby allowing further analysis. The 10 control strategies were recategorized into 6 groups: (i) distraction (overt and covert distraction); (ii) neutralizing (overt and covert neutralizing and saying a prayer); (iii) reassurance (reassuring self and seeking reassurance from others); (iv) reasoning with self; (v) saying ‘stop’ to self; and (vi) doing nothing.

Table 2. Endorsement rates for typical thought control strategies used to suppress the most upsettmg

intrusive thoueht

Typical thought control strategy

I. Reason with self, trying to prove thought is irrational

2. Distract self by thinking something pleasant

3. Think of another thought that counters effect of ( - ) thought

4. Distract self by doing something

5. Perform behaviour that counters effect of thought

6. Say ‘stop’ to myself

7. Do nothing

8. Reassure self all is okay

9. Seek reassurance from others that thought has not come true

IO. Say a prayer

n

59

46

33

31

29

27

I9

II

9

6

% (N = 270)

22

I7

I2

II

II

IO

7

4

3

Obsessive intrusive thoughts 407

Table 3. Means, standard deviations, and standardized discriminant function coefficients of appraisal ratings for high and low obsessional groups

Low obsessional High obsessional

Appraisal ratings Man SD MeaIl SD SDFC”

Frequency 1.7 0.8 2.tY 0.9 0.61 Belief 0.5 0.7 I .3*** I.2 0.54 Avoidance 0.9 I.1 I E*** 1.4 0.30 Uncontrollability 0.8 0.9 1:5** I.1 0.12 Unpleasantness 2.0 1.2 2,s I.2 0.18 Guilt 1.2 1.3 I .9’ 1.5 0.32 Thought control success 2.7 1.0 2.1* 1 .o 0.25 Unacceptability 1.4 1.3 1.9 1.5 0.00

“Standardized d~scrimin~nt function co&cients. *P CT 0.05; **P < 0.01; ***p < 0.001.

MultipEe regression analyses of appraisal and control strategies

In order to determine which variables were associated with the persistence of Ss’ most upsetting intrusive thought, a standard multiple regression analysis was performed with frequency as the dependent variable (DV). Thought control strategies and appraisal ratings were entered simul- taneously as predictors. The 6 control strategies were first dummy coded with ‘do nothing’ as the comparison group. The multiple R (0.38) was highly significant [ic(12,280) = 3.93, P < O.OOl] with 14% of the variance accounted for by the predictors. Based on the magnitude of the squared semi-partial correlation (sr 2), the only significant unique predictors to emerge in this analysis were the appraisal ratings of uncontrollability (sr 2 = 0.04, P < 0.007) and belief that the intrusive thought could be acted upon in real life (sr 2 = 0.02, P < 0.02).

A second standard multiple regression analysis was performed with the uncontrollability rating as the DV. The control strategies were dummy coded as before and all variables were entered on one step. Once again the multiple R (0.60) was highly significant [F(l2,280) = 13.23, P < 0.000~~ with 36% of the variance in uncontrollability ratings accounted for by the predictors. Belief that the intrusion could be acted upon in real life was the strongest unique predictor of thought uncontrollability (sr 2 = 0.09, P < O.OOOl), followed by success in using one’s most typical thought control strategy (sr * = 0.05, P < O.OOOl), then avoidance of situations that might trigger the intrusion (sr . , ’ = 0 03 P --c O.OOl), and finally the frequency of the intrusion (sr 2 = 0.03, P < 0.001).

High us low obsessional groups

We were also interested in dete~ining whether there were individual differences in Ss’ response to their most upsetting intrusive thought, image or impulse. For example, are individuals with obsessional tendencies more likely to have difficulties with their most upsetting intrusive thought than nonobsessional persons? To address this question, Ss who scored within the bottom 25th percentile on the PI were classified as a low obsessional group (PI scores ranged from 2 to 27, with a mean total score of 17.9, SD = 6.33, n = 61). Individuals scoring within the top 25th percentile of the PI Total score were considered to be high on obsessional tendencies (PI scores ranged from 58 to 150, with a mean of 78, SD = 18.37, n = 67).

Table 3 presents the means and standard deviations for both groups on each of the 8 appraisal ratings. A one-way multivariate analysis of variance was performed on the 8 appraisal ratings with GROUP (high vs low obsessionality) as the independent variable. A significant main effect of GROUP was found [F(8,117) = 8.22, P < O.OOl]. Univariate F-tests indicated that the high obsessional group obtained significantly higher ratings than the low obsessional Ss on frequency, belief, avoidance, unpleasantness, uncontrollability, guilt, and thought control success. Interpret- ation of the standardized discriminant function coefficients revealed that frequency and belief that the intrusive thought could be acted upon were the most important appraisal ratings in distinguishing the high obsessional from the low obsessional group.

Finally, to determine if high and low obsessional individuals differed in their most typical control response to the upsetting intrusion, a 2 x 6 chi-square analysis was performed between group and thought control strategies. The chi-square failed to attain significance, indicating no significant differences between high and low obsessional individuals in the typical thought control strategy used in response to their most upsetting unwanted intrusive thought.

408 CHRWINE PARDON and DAVID A. CLARK

DISCUSSION

In response to the three questions posed for this study, we found that the extent to which individuals believed that their most upsetting intrusive thought could lead to unacceptable behaviour in real life was closely related to both the frequency and persistence of the intrusion as well as its perceived uncontrollability. The stronger one believes that he/she could act on the intrusion, the more persistent and less controllable the intrusive thought. This finding is consistent with Salkovskis’ (1985, 1989) view that perceived responsibility for harm or danger occurring to self or others is a critical factor in the escalation of unwanted intrusive thoughts, images and impulses. Although we did not directly assess the extent to which Ss assigned personal responsibility to the intrusion, nevertheless we can assume that our belief rating is relevant to the Salkovskis’ responsibility construct. If Ss believe they could act on their upsetting intrusion, then they will no doubt feel a greater sense of responsibility for possible harm or danger resulting from the intrusive thought. Obviously, further empirical work is needed to establish the relationship between belief ratings in the possibility that one could act on an intrusive thought, and an increased sense of personal responsibility. At the very least, our findings are consistent with previous studies showing that belief is an important appraisal dimension in unwanted intrusive thoughts.

The second major finding of this study concerns individual differences in Ss’ experience of unwanted intrusive thoughts. We found that nonclinical Ss who obtained elevated scores on a measure of obsessional symptoms reported more unwanted intrusive thoughts than Ss who reported few obsessional symptoms. * Furthermore, these obsessional individuals rated their most upsetting intrusive thought as significantly more frequent, unpleasant, guilt-inducing and difficult to control than low obsessional individuals. These high-scoring Ss also reported greater efforts to avoid cues that might trigger the intrusion, stronger belief that they could act on the intrusion, and less success in utilizing their most typical thought control strategy in efforts to suppress the upsetting intrusive thought. Interestingly, the high and low obsessional groups did not differ in terms of which thought control strategy was endorsed as their most typical response to the intrusion. Having said this, it is clear from our discriminant function that the frequency of the most upsetting intrusion and degree to which Ss believed the intrusion could be acted upon in real life were the most important differences between high and low obsessional individuals. Once again, we see here the emergence of belief as a central appraisal rating in the experience of persistent unwanted intrusive thoughts. These results suggest that one important reason why highly obsessional individuals may have more frequent and uncontrollable obsessive intrusive thoughts is their stronger belief that they could act on the intrusion. This, of course, would be consistent with Salkovskis’ (1985, 1989) view that an increased sense of responsibility is the most important appraisal dimension behind the persistence of intrusions and clinical obsessions.

On the other hand, it appears that the characteristic control response of highly obsessional individuals to their unwanted, distressing intrusive thoughts is not that unusual or unique, but rather these individuals experience less success in utilizing these control strategies than low obsessional individuals. Our results support Salkovskis and others who contend that the relative failure of highly obsessional individuals to control their unwanted obsessive intrusive thoughts is due to the exaggerated appraisal of harm and personal responsibility these individuals place on their mental intrusions. The findings, however, do not support Salkovskis’ view that neutralizing or the way in which obsessional individuals try to suppress their intrusive thoughts contributes to the persistence of the obsession. Rather we found little difference between high and low obsessional individuals in the most typical thought control strategy used to suppress the upsetting intrusion. In addition, type of thought control strategy did not emerge as a significant predictor of frequency or uncontrollability in our total sample analysis, a finding also noted by Parkinson and Rachman (198 1). However, it may that differences would be evident if high and low obsessional SS

*Analysis of the 011 Total scale for men indicated that the scores for the highly obsessional group were significantly higher than those of the low obsessional group [F(1,51) = 44.5, P < O.OOl]. In the women’s sample, comparison with the low obsessional group revealed that the total scores for both 011 subscales were significantly higher in the high obsessional group [F(1,99) = 34.63, P <O.OOl and F(1,99) = 63.70, P < 0.001 for the Sex/Aggression and Dirt subscales, respectively].

Obsessive intrusive thoughts 409

participated in an actual thought supression experiment with their most upsetting intrusive thought as the supression target. Clearly, this is an important area for further research.

Two additional findings are worthy of mention. First, it is apparent that unwanted, obsessive intrusive thoughts, images and impulses are fairly idiosyncratic. This point was previously made by Parkinson and Rachman (1981) in their earlier studies on intrusive thoughts. In our study, there was a wide spread in Ss’ selection of their most upsetting intrusion. We did not find a most typical, or common persistent intrusive thought. This, of course, presents a special challenge for researchers interested in this phenomena. It is clear that we must use either individually tailored cognitive assessment strategies, or ensure that our self-report checklists of intrusive thoughts are sufficiently inclusive to capture most of the obsessive intrusive thought content individuals experience.

A second finding of note is that we obtained relatively low correlations between our appraisal ratings. This differs from previous studies where high intercorrelations amongst appraisal dimensions have been reported (Clark, 1992; Clark & de Silva, 1985). It may be that the lower intercorrelations result from the fact that Ss were responding to their most upsetting intrusion. In past studies, we investigated Ss’ appraisals across an aggregate of intrusive thoughts, only a few of which would be relevant to any one person. Given the idiosyncratic nature of intrusive thoughts, we would argue that researchers interested in studying intrusions as an analogue to clinical obsessions should focus on Ss’ response to their most frequent or distressing intrusive thought. As noted in a previous study, Ss’ response to low frequency or largely irrelevant intrusive thoughts may differ significantly from their response to their most upsetting or frequent cognitive intrusion (Clark & Nicki, 1989).

Finally, we found that our appraisal ratings accounted for twice as much variance in the uncontrollability ratings as compared to the frequency of the most upsetting intrusion. Also, appraisal ratings other than frequency emerged as significant predictors of uncontrollability. These results suggest that appraisal may be more influential in affecting the uncontrollability of Ss’ personally most upsetting intrusive thought rather than directly affecting the persistence of this intrusion. However, as in past research, we did find a strong relationship between uncontrollability and frequency (Clark & de Silva, 1985; Edwards & Dickerson, 1987; Niler & Beck, 1989; Parkinson & Rachman, 1981). Turner, Beidel and Stanley (1992) concluded that uncontrollability and unacceptability may be the central characteristics that distinguish normal and abnormal obsessive intrusive thoughts. Thus, it may be that the impact of exaggerated appraisal on the persistence of unwanted obsessive intrusive thoughts is mediated through decreased controllability of these phenomena.

In conclusion, we found that the extent to which individuals believed their most upsetting intrusive thought might happen in real life was a significant predictor of the frequency and perceived uncontrollability of the intrusion. Furthermore, this belief rating also emerged as one of the important variables distinguishing highly obsessional analogue subjects from low obsessional controls. Our findings are consistent with the cognitive behavioural model of obsessions proposed by Salkovskis which contends that dysfunctional beliefs involving exaggerated harm and personal responsibility are crucial in the persistence of unwanted intrusive thoughts and obsessions. We are continuing research in this area as a means of understanding why some individuals present with persistent and uncontrollable intrusive thoughts, images and impulses.

Acknowledgements-Partial support for this research was obtained by a grant from the New Brunswick Mental Health Commission awarded to the second author. The research was conducted in fulfilment of the thesis requirements for a Masters of Arts degree from the University of New Brunswick. Portions of this study were presented at a Symposium on “Unwanted Intrusive Thoughts in Clinical and Nonclinical Subjects” at the World Congress for Cognitive Therapy, Toronto, 1992.

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