Journal of Obsessive-Compulsive and Related Disorders 3 (2014) 265268

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Journal of Obsessive-Compulsive and Related Disorders

journal homepage: www.elsevier.com/locate/jocrd

Introduction: A global perspective on unwanted intrusive thoughts

David A. Clark a, Adam S. Radomsky b,n
a
b

University of New Brunswick, Canada

Concordia University, Canada

art ic l e i nf o

a b s t r a c t

Article history:
Received 15 January 2014
Received in revised form
9 February 2014
Accepted 11 February 2014
Available online 18 February 2014

Because of Rachman and de Silva's (1978) inuential research on normal and abnormal obsessions, it is
now a basic tenet of cognitive behavioral theories (CBT) that clinical obsessions have their origins in the
normal intrusive thought phenomena that characterizes the stream of consciousness. However much of
the empirical research on unwanted intrusive thoughts has utilized retrospective self-report questionnaires that have weak construct validity and the samples have been drawn primarily from Western
European and North American populations. To enhance the measurement precision and investigate the
universality of unwanted intrusions, a structured intrusive thoughts interview was developed and
administered to 777 nonclinical individuals drawn from 13 countries. The three papers in this special
issue present ndings based on this large data set. Together it was found that unwanted intrusive
thoughts are reported by the majority of individuals in all countries, that signicant cross-cultural
differences are apparent in primary intrusive thought content, that faulty appraisals and confrontational
control strategies are related to the distress of intrusions, and that the frequency of dirt/contamination,
doubt, and miscellaneous intrusions are specically related to obsessive compulsive symptom distress.
The authors discuss these ndings in terms of their consistency with predictions derived from the CBT
perspective on obsessions. The special issue concludes with a discussion paper by Professor Jack
Rachman, originator of the obessional intrusions concept.
& 2014 Elsevier Ltd. All rights reserved.

Keywords:
Unwanted intrusive thoughts
Obsessions
Cross-cultural differences
Cognitive behavioral theory of obsessions
OCD

1. Introduction
This year marks the 36th anniversary of Rachman and de Silva's
(1978) seminal article that introduced the concept of unwanted
intrusive thoughts as a potential etiological factor in the development of obsessive compulsive disorder (OCD). Their paper reported
on three studies that sought to determine whether healthy, nonclinical individuals experience unwanted thoughts, images or
impulses that are similar in content to clinical obsessions (i.e.,
thoughts of contamination, doubt, aggression, sexuality, etc.). In the
rst study based on an intrusive thoughts questionnaire 99/124 (80%)
nonclinical individuals reported fairly frequent unwanted thoughts or
images involving obsessional content, although they were considered
fairly easy to dismiss. The second study consisted of a detailed
interview of intrusive thoughts conducted on 40 nonclinical individuals and 8 patients with OCD. A list of 23 obsessions from the
clinical sample and 58 obsessive-like intrusions from the nonclinical
individuals were reproduced in the article and have since become the
basis of numerous self-report measures of intrusive thoughts.

n
Correspondence to: Department of Psychology, Concordia University, 7141
Sherbrooke St. West, Montreal, QC, Canada.
E-mail address: adam.radomsky@concordia.ca (A.S. Radomsky).

http://dx.doi.org/10.1016/j.jocrd.2014.02.001
2211-3649 & 2014 Elsevier Ltd. All rights reserved.

Comparison between the clinical and nonclinical samples revealed

similarities in thought content, although the OCD patients reported
greater frequency, discomfort and difculty controlling their obsessions. In the third study OCD patients and nonclinical participants
were asked to repeatedly form their obsession or intrusive thought.
Habituation was evident in both samples, although the nonclinical
group had more difculty forming their intrusion upon request than
the OCD patients. Although Rachman and de Silva's (1978) ndings
raised many questions about the nature of intrusive thoughts, it also
provided the rst empirical evidence that obsessions might have
their origins in the normal thought processes that characterize the
stream of consciousness.
The conceptual signicance of normal obsessions was subsequently emphasized in Rachman and Hodgson's (1980) text, Obsessions and Compulsions, which in many respects provides the
theoretical underpinnings for contemporary cognitive-behavioral
(CB) models of OCD. In their chapter entitled An Anatomy of Obsessions,
the occurrence of unwanted, unacceptable intrusive thoughts or
images initiated a process of faulty meta-cognitive appraisal and
control efforts that could spiral into the development of obsessions.
Later publications elaborating on a CBT model of obsessions and
compulsions also reiterated the occurrence of mental intrusions as a
key determinant in the pathogenesis of obsessions (e.g., Clark, 2004;
Freeston, Rhaume, & Ladouceur, 1996; Rachman, 1997, 1998;

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D.A. Clark, A.S. Radomsky / Journal of Obsessive-Compulsive and Related Disorders 3 (2014) 265268

Salkovskis, 1985, 1989). Today the universality of obsession-related

intrusive thoughts, images and impulses is a central tenet of CBT
explanations for the development of obsessions.
While the conceptual signicance of the Rachman and de Silva
(1978) publication cannot be overstated, their work has also had a
signicant impact on empirical research on unwanted intrusions.
In the last three decades research on intrusions has taken two
broad pathways; the most common approach is questionnaire
based, whereas the other is more experimental, examining the
impact of intentional mental control efforts on unwanted intrusive
thoughts. These two broad research pathways are represented in
the rst and third studies reported in the Rachman and de Silva
(1978) publication. Interestingly there has been little research that
has employed the interview format; a neglect that we think is
serious given the complexity of intrusive thoughts.
There are important conceptual and methodological weaknesses that have been raised with questionnaire and experimental
measurement of unwanted intrusive thoughts. Questionnaire
measures of intrusions present individuals with a predetermined
list of thought statements which respondents are then instructed
to rate for frequency of occurrence. However concerns have been
raised about the veridicality of these item responses (Brown &
Clark, 2014). When individuals indicate that they frequently
experience an unwanted intrusive thought by endorsing an item
statement, does this reect their actual memory of specic
thought occurrences, or might it reect an emotional state or
self-identity that is congruent with the item content (Glass &
Arnkoff, 1997)? In addition the content validity of many intrusive
thought questionnaires is problematic because they can contain a
broad range of negative thought content that often includes
general anxiety and depressive thought content (Clark & Purdon,
1995). As well the lists of intrusions are always predetermined so
how well these pre-established items represent the intrusive
thought content of specic individuals is doubtful. Rachman
(1981) has noted that unwanted mental intrusions are often quite
idiosyncratic and triggered by external cues. Questions have also
been raised about the specicity and discriminative validity of
intrusive thoughts questionnaires (Julien, OConnor, & Aardema,
2007). These are fundamental questions about the construct
validity of retrospective self-report of unwanted intrusions that
leave us uncertain about the interpretability of a high score on
such measures. When a person indicates that s/he frequently has
an intrusion (e.g., I have unwanted intrusive thoughts, images or
impulses of verbalizing something rude or embarrassing that
would hurt a person's feelings), is this based on memories of
actual thought occurrences, recalling times when feeling anxious
about one's verbal interaction, a single recent experience of
embarrassed verbalization, or a self-identity that acknowledges
you are the type of person who is concerned about your impact on
others? In sum questionnaires may not be the most accurate
method for assessing people's actual experience of unwanted
intrusive thoughts.
Unfortunately experimental approaches to the investigation of
unwanted mental intrusions and their control also have signicant
drawbacks. The rst problem is ecological validity. When an
individual is brought into a laboratory setting and asked to
produce an intrusive thought, it is no longer intrusive. The
intentional production of the thought is no longer unwilful and
so lacks generalizability to the spontaneous, unintended intrusions
that occur in the natural world. As well, a diffusion of responsibility occurs such that the participant can now attribute responsibility to the experimenter for the generation of the intrusion
rather than the self. This transfer of responsibility to the experimenter could signicantly affect the participant's appraisal of the
intrusive thought. Even if the intrusion is induced, difculties arise
because it may be difcult to ensure that the induction was

successful across all research participants. Finally, the control of

unwanted negative thoughts under controlled laboratory conditions for very brief time periods will be quite different from the
experience of repeated unwanted intrusions over an extended
period of time in a context-rich, everchanging naturalistic setting.
Thus the ndings derived from laboratory-contrived intrusive
phenomena raise questions about their relevance to the spontaneous, distressing intrusive thoughts, images and impulses that
can haunt individuals in their everyday life.

2. Current research objectives

The present research was initiated to address two major
shortcomings in the intrusive thoughts literature. From a methodological perspective, our rst objective was to explore the use of a
structured interview format to assess individuals' experience of
unwanted intrusive thoughts, images and impulses specically
related to the major themes of OCD; dirt/contamination, doubt,
harm/injury, sex, religion/morality, and minor or miscellaneous
themes. [Though not normally represented in obsessional fears,
we also assessed intrusive thoughts about being a victim of
violence because these thoughts may be common in nonclinical
populations]. The use of an interview would allow us to collect
qualitative data to ensure that participants reported on intrusive
thoughts relevant to OCD rather than a range of negative thoughts
that might be more relevant to worry, dysphoria or anger. In
addition the qualitative information would help interpret the
quantitative data on the phenomenology of intrusions and their
sequellae (see below). Trained interviewers were provided with
strict denitions and examples of obsession-relevant intrusive
thoughts and participants' responses were written down for
subsequent verication that the intrusion t the study criteria. In
addition the interview ensured that participants responded to the
six types of obsessive intrusive thoughts and the interviewer could
probe to ensure that participants really did experience an intrusion. Another advantage of the interview is that participants were
asked to describe specic instances of the unwanted intrusion.
This increased the likelihood that endorsement reected actual
thought occurrences rather than personal conjectures on the types
of thoughts a person experiences. Thus our intention was to
develop an interview that would provide a more accurate measurement of intrusive thought content highly specic to OCD.
A second objective of the interview method was to provide a
more comprehensive and detailed assessment of individual's
appraisal and perceived control of their most distressing intrusive
thought. First, general ratings of frequency, distress and control
were collected on the six OCD-relevant intrusions. Then individuals selected their most distressing intrusion and detailed ratings
of several appraisal and control constructs were obtained. This
part of the interview utilized an endorsement approach with
participants providing their own ratings on appraisal and control
dimensions. Six point rating scales were used so individuals could
rate their level of agreement to specic questions about their
appraisal of the most distressing intrusion and frequency of using
various mental control strategies. Our intent was to provide the
participant with appraisal statements that accurately reect the
most common evaluative constructs in contemporary CBT theories
of OCD, while keeping them broad enough to encompass a wide
range of intrusive phenomena.
In addition to these methodological considerations, we also
wanted to investigate the cross-cultural expression of unwanted
intrusive thoughts. The universality of unwanted intrusive
thoughts is a central assumption of CBT theories of obsessions
(Rachman, 2003). However, there are no published studies that
have compared the occurrence of unwanted intrusions across

D.A. Clark, A.S. Radomsky / Journal of Obsessive-Compulsive and Related Disorders 3 (2014) 265268

a diverse range of countries with varying social and cultural

traditions. The majority of studies have documented the occurrence of intrusions in North American or Western European
countries. A primary goal of the current research was to compare
individuals' experience of obsession-relevant intrusive thoughts
across several countries using the same assessment methodology
that would allow a direct test of cultural inuences on intrusions.
Our intention was to conduct the rst large-scale international
study of unwanted intrusive thoughts in nonclinical individuals.
This would provide the most direct test of the universality of
unwanted mental intrusions.

3. History and development

The idea for an international/cross-cultural study of OCD-related
intrusions was rst raised at one of the nal meetings of the
Obsessive Compulsive Cognitions Working Group (OCCWG) in
Chambery, France in 2006. A cross-cultural working group was formed, initially consisting of OCCWG members (but later expanded).
This group drafted a preliminary version of a structured interview for
intrusive thoughts called the International Intrusive Thoughts Interview Schedule (IITIS). Initial elements of the IITIS included a carefully
worded introductory section in which a variety of examples and
denitions of obsessional intrusions were provided, as well as a
number of content-related sections, asking about intrusions related
to contamination, aggression, doubt, blasphemy, immorality, sex,
victimization, and miscellaneous intrusions. The early IITIS incorporated questions about frequency, distress and challenges associated
with dismissing intrusions, appraisals/interpretations of intrusions,
and control strategies used by individuals to try to get rid of or
otherwise manage their intrusions.
The rst meeting of a newly constituted research group called
the Research Consortium on Intrusive Fear (RCIF) took place in
Barcelona, Spain in 2007, at which point the membership was
expanded beyond the OCCWG. In addition to continued drafting of
IITIS elements, discussions at this meeting also began to include
issues associated with translation and back-translation, training
guidelines, and elements associated with study design (e.g.,
measures, samples, protocols, etc.). Successive drafts of the IITIS
unfolded over the next few years, largely in light of problems that
emerged with meaning and nuance during initial translation
exercises. These were incrementally resolved, and once a nal
version of the IITIS was obtained, a standardized translation/backtranslation protocol was adopted by all authors. The IITIS (now in
its 6th version) in English was translated by a team at each nonEnglish-speaking site containing at least one person familiar with
research on OCD and intrusive thoughts. This produced translated
versions of the IITIS in nine languages (English, Cantonese, French,
Greek, Hebrew, Italian, Persian, Spanish, and Turkish). Each translated version was then back-translated to English by a separate
team, and the back-translated versions were then sent to D. Clark
and A. Radomsky for review. There were very few differences
between the English IITIS and back-translated versions. Some of
the more interesting differences that emerged were associated
with the fact that some languages/cultures do not have a simple
term or expression for intrusive. These issues were resolved
collaboratively, and often involved a particular version of the IITIS
using a phrase to convey the meaning of particular constructs
rather than a specic word. Importantly, the phrase employed was
assessed to determine if it mirrored the internal experience of
those in the relevant culture/country. Whenever such issues arose,
pivotal importance was placed on having the different linguistic
versions of the IITIS be both equivalent to each other, and meaningful within the person's cultural context. These attributes were
conrmed by fully bilingual members of the RCIF at each site (for a

267

list of translators, consult the author list of the empirical articles in

this issue).
An initial pilot study of the IITIS, Version 6 was conducted
between February and May, 2011; some of the primary questions
we hoped to address included: Are unwanted intrusive thoughts
normative human experiences across countries and cultures? Are
there differences in the nature and types of intrusions reported
across countries and cultures? Data from this initial piloting were
presented and discussed at a meeting of the RCIF in Cordoba, Spain
in 2011. At that meeting and shortly thereafter, new sites were
added (e.g., Buenos Aires, Sierra Leone), and it was agreed that
each site would collect additional data (to a requested total of
approximately 50 nonclinical participants per site). Nearly all of
these data were in place by the most recent meeting of the RCIF in
Montreal in 2012, during which analysis and dissemination plans
were developed, and strategies to complete data collection were
discussed.

4. The special issue

This special issue on cross-cultural expressions of unwanted
intrusive thoughts consists of three papers that report on several
ndings from the same international study using the IITIS (v.6).
The research group consists of 19 researchers from 13 countries
who administered the IITIS (v.6) to 777 nonclinical individuals
along with self-report measures of OCD symptoms, beliefs and
negative affect.
Due to the wealth of information contained within this dataset,
and the many research questions we hoped to address, this special
issue contains three papers designed to highlight different aspects
of our ndings. The rst paper by Radomsky et al. (2014) addresses
the question of whether or not unwanted intrusive thoughts, images
and impulses are as common in an international context as they have
previously been found to be in British or North American samples.
This aspect of our work focused on providing information about the
nature of intrusions and appraisals reported by participants;
between-country comparisons of the frequency and content of
unwanted intrusive thoughts are highlighted. In the second paper
Molding et al. (2014) hierarchical linear modeling was utilized to
examine cross-cultural differences in the relationship between
appraisals and control of individuals' most distressing intrusive
thoughts. The latter were categorized into repugnant (i.e., harm/
injury, religious/immoral, sexual) and non-repugnant (i.e., contamination/dirt, doubt, victim of violence) intrusions. Specically, we
sought to understand the degree to which theoretically derived
appraisals were predictive of intrusive phenomenology, and how
these relationships, if shown, vary from site to site and across
different categories of intrusions. The third study by Clark et al.
(2014) examined the relationship between unwanted intrusive
thoughts and obsessional symptoms. We felt this to be important
as very little work has been conducted to elucidate the connections
between intrusive phenomenology and OCD symptoms, much less in
an international context.
This special issue on a global perspective on unwanted intrusive thoughts concludes with a commentary by Professor Jack
Rachman. Professor Rachman can be considered the founder of
intrusive thoughts, at least in reference to OCD, and so it is tting
that he should situate the current ndings within the historical
context of intrusions and cognitive-behavioral approaches to OCD.

Acknowledgments
We are grateful for nancial support for this research provided
by an International Opportunities Fund Grant awarded to

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D.A. Clark, A.S. Radomsky / Journal of Obsessive-Compulsive and Related Disorders 3 (2014) 265268

Drs. Clark and Radomsky from the Social Sciences and Humanities
Research Council of Canada (Grant #861-2009-0076) and to
Adriana del Palacio-Gonzalez for assistance during the data
collection phase of the research.
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