Cognitive Behaviour Therapy Vol 35, No 3, pp. 138–147, 2006
Inferential Confusion and Obsessive Beliefs in
Obsessive-Compulsive Disorder
Frederick Aardema1, Kieron P. O’Connor1 and Paul M. G. Emmelkamp2
1
Centre de Recherche Fernand-Seguin, Montréal, Québec, Canada, and 2University of
Amsterdam, Department of Clinical Psychology, Amsterdam, The Netherlands
Abstract. The goal of the present study was to investigate whether inferential confusion could
account for the relationships between obsessional beliefs and obsessive-compulsive disorder (OCD).
The Inferential Confusion Questionnaire and the Obsessive Beliefs Questionnaire were administered
to a sample of 85 participants diagnosed with OCD. Results showed that the relationship between
obsessive beliefs and obsessive-compulsive symptoms decreased considerably when controlling for
inferential confusion. Conversely, the relationship between inferential confusion and obsessivecompulsive symptoms was not substantially affected when controlling for obsessive beliefs. Since
inferential confusion has an overlap with overestimation of threat, a competing hypothesis for the
results was investigated. Results indicated that inferential confusion was factorially distinct from
overestimation of threat, and that the independent construct of inferential confusion remains
significantly related to obsessive-compulsive symptoms when controlling for anxious mood. These
results are consistent with the claim that inferential confusion may be a more critical factor in
accounting for OCD symptoms than are obsessive beliefs and appraisals. Key words: obsessivecompulsive disorder; inference-based approach; inferential confusion; reasoning; beliefs.
Received August 3, 2005; Accepted February 2, 2006
Correspondence address: Frederick Aardema, Centre de Recherche Fernand-Seguin, 7331 Hochelaga,
Montréal, Québec, H1N 3V2, Canada. Tel: +514-251-4015; Fax: +514-251-2617. E-mail: faardema
@crfs.rtss.qc.ca
Contemporary cognitive models of obsessivecompulsive disorder (OCD) tend to focus on
specific beliefs and appraisals in the development and maintenance of this disorder. The
emphasis on specific beliefs and appraisals
operating in OCD is derived directly from
Beck’s cognitive specificity hypothesis, which
holds that different psychological disorders
are characterized by different dysfunctional
beliefs (Beck, 1976). The application of Beck’s
model of psychopathology has found its most
systematic application to OCD in the work of
Rachman (1997) and Salkovkis (1985, 1989),
who hold that it is not the unwanted intrusive
cognition that leads to distress and compulsive behaviours, but how the person appraises
these thoughts in terms of personal significance or responsibility. Since then, the main
focus of these appraisal models of OCD has
# 2006 Taylor & Francis ISSN 1650-6073
DOI 10.1080/16506070600621922
been to identify other specific obsessivecompulsive beliefs proposed to be relevant to
OCD (see Taylor, 2002).
The application of Beck’s model of psychopathology to OCD is based on several studies
that have shown obsessions to be similar
in content to intrusive cognitions occurring in
the normal population. The similarity in
content between intrusions and obsessions
would suggest that intrusive cognitions are
not the essential element in the development
of OCD, but rather, it is how the person
appraises these thoughts as dictated by
specific dysfunctional beliefs (Rachman &
DeSilva, 1978; Salkovskis & Harrison, 1984).
However, this argument regarding the normal
nature of obsessions in terms of content may
have been taken too far (Clark & O’Connor,
2004). Rachman and Hodgson (1980) already
VOL 35, NO 3, 2006
noted that a conceptualization of obsessions
as intrusive cognitions was unsatisfactory, and
while there may be similarities in content
between intrusive cognitions and obsessions,
there may be differences in the particular way
that they arise. In particular, there may be
important differences in the form and context
of obsessions, which highlights the role of
important processes operating in OCD that go
beyond cognitive content considerations
(O’Connor, 2002; Julien & O’Connor, 2005).
An inference-based approach (IBA) to
OCD (Aardema & O’Connor, 2003;
O’Connor & Robillard, 1995, 1999) identifies
a characteristic reasoning process associated
with the occurrence of obsessions and, as
such, is more concerned with the form and
context of the obsession rather than its
(ab)normal content. This is not a "general
deficit model" where obsessions are solely the
result of any particular cognitive dysfunction;
rather, the IBA holds that the obsessional
doubt, finds its justification in a wide variety
of idiosyncratic narratives that contain inductive reasoning processes peculiar to OCD
(O’Connor & Robillard, 1999). As such, the
"intrusions" in OCD ("maybe my hands are
contaminated"; "maybe I drove over someone
with my car") inherit their persistence and
reality value from reasoning processes associated with their occurrence rather than being
the result of a specific belief.
A central reasoning process that has been
identified by the IBA model as relevant to the
occurrence of obsessions is inverse inference.
Inverse inference refers to an inverse type of
reasoning where the person does not start out
with the senses in reaching a conclusion ("I see
there is mud on the floor, so people may have
walked over it with dirty shoes"), but instead
comes to infer a remote possibility without
any actual indication of it being present or
even in contradiction to what is seen or sensed
("People may have walked with muddy shoes
on the floor, therefore the floor is dirty").
Another reasoning process closely related to
inverse inference is a distrust of the senses.
Often, obsessional doubts justify disregarding
the senses in favour of going deeper into
reality (e.g. "Even though my senses tell me
nothing is there, I know by my intelligence
that there is"), which in fact negates or ignores
reality in favour of a hypothetical (and
completely subjective) possibility. These
Inferential confusion and obsessive beliefs in OCD
139
reasoning processes, which lead a person with
OCD to treat the obsessional doubt as a real
probability, have broadly been termed "inferential confusion" (O’Connor, Aardema &
Pélissier, 2005).
Empirical investigations into OCD have so
far found encouraging evidence for a role of
"inferential confusion" operating in OCD.
Psychometric studies have consistently shown
substantial relationships between inferential
confusion and obsessive-compulsive symptoms in non-clinical and clinical samples
(Aardema, Kleijer, Trihey, O’Connor, &
Emmelkamp, 2006; Aardema, O’Connor,
Emmelkamp, Marchand, & Todorov, 2005;
Emmelkamp & Aardema, 1999). Therapy
specifically targeting inference processes in
OCD leads to equivalent or greater improvement than "conventional" cognitive behaviour
therapy (CBT) and exposure in vivo and
response prevention (O’Connor et al., 2005).
In addition, successful treatment outcome for
OCD was found to be associated with changes
in inferential confusion even if inference
processes were not directly targeted in an
OCD sample receiving CBT (Aardema,
Emmelkamp, & O’Connor, 2005). Finally,
experimental studies have highlighted the
importance of reasoning processes operating
in OCD, which leads people with OCD to
replace certainty with doubt (Pélissier &
O’Connor, 2002).
The IBA model is not incompatible with an
appraisal-based approach to OCD, whose
primary concern is with the interpretation of
the intrusion guided by specific obsessive
beliefs. However, an inference and appraisal
approach seem to target different stages in the
obsessional sequence (Clark & O’Connor,
2004). Inference processes are primarily associated with the occurrence of obsessions
whereas OCD relevant appraisals by definition occur in the aftermath of obsessions. In
fact, the IBA model conceptualizes the
initial "intrusion" in OCD as an inference
about a possible, but improbable state of
affairs, which comes about as the result of
inferential confusion – a completely subjective
inferential process that negates current reality
(O’Connor, 2002). This intrusion may subsequently be appraised, but the appraisal model
considers the occurrence of obsessional intrusions as a "given" phenomenon that requires
little further explanation. However, if indeed
140
Aardema, O’Connor and Emmelkamp
inferential processes are relevant to the form
and context of intrusions, it is quite possible
that the relationship between obsessional
beliefs and obsessive-compulsive symptoms
can be accounted for by inference processes.
For example, an obsession such as "I might
have driven over someone with my car" may
logically result in a need for certainty, elevated
responsibility, attempts at control, and to give
the thought importance; if this thought is
experienced as realistic due to a confusion
between reality and possibility (i.e. inferential
confusion). In other words, if I really was
convinced that, because I left the light on, the
apartment block would burn down and everybody’s belongings and lodgings destroyed, it
would seem realistic to feel anxious, guilty and
responsible. As such, it has been suggested
that some obsessive-compulsive beliefs and
appraisals may follow logically and naturally
from the intensity and reality value of the
primary obsessional intrusion (Aardema &
O’Connor, 2003). Deductive abilities seem
intact in OCD (Pélissier & O’Connor, 2002;
Reed, 1977), and hence valid deductive conclusions may be drawn from a faulty inductively generated premise.
Due to the theoretical foundations of the
appraisal model (i.e. intrusions as normal
phenomena) overestimation of threat is generally also considered solely in the aftermath
of intrusions. For example, the person has the
intrusion "I may harm my child" and subsequently interprets this as "I am in danger of
doing it" (Sookman, Pinard, & Beck, 2001,
p. 112). However, considering more enduring
anomalous processes as responsible for the
initial intrusion would be theoretically incoherent for the appraisal model of OCD (which
considers such intrusions as normal), whilst
the IBA model has less issue with the notion
that a cognitive bias towards overestimation
of threat may play some role in the initial
occurrence of intrusions and in deciding their
content. In particular, for the IBA model the
personalised content of the initial threatening
intrusion (e.g. "I may have left the front door
open") could be primed by a self-referent
theme preceding its onset (e.g. "I’m just the
sort of person who could leave front doors
open"). Yet, the IBA model would be particularly interested in the reasoning processes by
which this (mis)perception of threat comes
about. In particular, it would argue that the
COGNITIVE BEHAVIOUR THERAPY
perception of threat in OCD is characterized
by inferential confusion where the person
generates the obsessional inference (or threat)
in the absence of sense data to support it.
Hence, it would argue that even if obsessions
are often characterized by overestimation of
threat (i.e. "I’m in danger") it is the element of
inferential confusion ("I am in danger even
though I see and sense nothing to support it")
that constitutes the unique obsessional element.
Regardless of the exact causal mechanisms
involved in the obsessional sequence, the
question arises as to what extent obsessive
beliefs are related to OCD symptoms independently of inferential confusion. Several
studies have found support for a relationship
between inferential confusion and obsessivecompulsive symptoms while controlling for
competing cognitive domains as well as
negative mood states (Aardema, Kleijer et al.,
2006; Aardema, O’Connor et al., 2005;
Emmelkamp & Aardema, 1999). However,
whether or not the relationship of obsessive
beliefs with OCD symptomatology is independent of levels of inferential confusion
remains as yet un-investigated.
The goal of the present study was to
establish whether inferential confusion could
account for most of the relationships between
obsessional beliefs and obsessive-compulsive
symptoms. In line with our theoretical formulation, we expected that most of the
relationships between belief domains and
obsessive-compulsive symptoms could be
accounted for by inferential confusion. In
addition, a priori, we addressed a competing
hypothesis that it is not inferential confusion,
which accounts for the relationship between
obsessive-compulsive beliefs and symptoms,
but level of anxiety and overestimation of
threat.
Method
Recruitment and participants
Participants in the study were recruited under
the auspices of the OCD research program
already in place at Centre de Recherche
Fernand-Seguin. (For full details of sample
characteristics see Aardema, O’Connor et al.,
2005.) This recruitment included face-to-face
diagnostic interview, and administration of a
semi-structured interview (Brown, Di Nardo,
VOL 35, NO 3, 2006
& Barlow, 1994; Goodman et al., 1989). The
total sample comprised 85 participants diagnosed with OCD (54 female, 31 male). The
average age for the entire group was 37.6
years (SD511.9; range 17–59 years).
Education levels were: 23.8% secondary education, 31.7% college education and 40%
university education. The marital status was:
43.5% single, 28.6% married or cohabiting,
and 12.7% separated or divorced.
Measures
All participants were administered and completed the questionnaires described below.
Inferential Confusion Questionnaire (ICQ;
Aardema, O’Connor
et al., 2005). This
questionnaire measures several key aspects
of inferential confusion, as formulated by
O’Connor and Robillard (1995). Items reflect
a tendency to distrust the senses and inverse
inference, where the person infers a state of
affairs in reality without any actual indication
of it being present or even in contradiction to
what is seen or sensed. The items of the ICQ15 are scored on a 5-point scale: 15strongly
disagree, 25disagree, 35neutral, 45agree,
55strongly agree. Previous research has
found the ICQ to be reliable (a50.85;
Aardema, O’Connor et al., 2005).
Padua Inventory Washington University
Revision (PI-R; Burns, Keortge, Formea, &
Sternberger, 1996). This is a comprehensive
39-item self-report inventory of obsessions
and compulsions, based on the original
version of the Padua Inventory (Sanavio,
1988). Items are rated on a 5-point scale
Inferential confusion and obsessive beliefs in OCD
(05not at all typical to 55very typical). The
PI-R content dimensions relevant to OCD: (1)
Obsessional
thoughts
(7
items), (2)
Contamination (10 items), (3) Checking (10
items), (4) Dressing/grooming (3 items) and
(5) Obsessional impulses (9 items). The total
scale (a50.95) and the subscales are reliable
(a50.75–0.91; Burns et al., 1996).
Obsessive Belief Questionnaire (OBQ-44;
Obsessive Compulsive Cognitions Working
Group (OCCWG), 2005). This instrument
has been developed collaboratively by the
Obsessive Compulsive Working Group. The
OBQ-44 is a shortened version of the OBQ-87
(OCCWG, 2003) whose scales have been
derived through factor-analyses as opposed to
the rationalistic generated scales of the OBQ87. It consists of 3 scales, namely (1)
Responsibility/Overestimation of Threat, (2)
Tolerance for Uncertainty/Perfectionism, and
(3) Importance of Thoughts/Control of
Thoughts. The subscales are reliable (a50.89–
0.93; OCCWG, 2005). For the current study,
the OBQ-87 version was administered, and
scored as OBQ-44, unless indicated otherwise.
Beck Anxiety Inventory (BAI; Beck,
Epstein, Brown, & Steer, 1988). This is a 21item anxiety symptom checklist rating symptom intensity for the last week on a 0–3 scale
(a50.91, Beck et al., 1988).
Results
Descriptive statistics showing means and
standard deviations of the questionnaires for
the entire sample are shown in Table 1.
Table 1. Means and standard deviations of the ICQ, OBQ-44 and symptom measures (n585).
ICQ
OBQ44-Total
Responsibility/Overestimation of Threat
Tolerance for Uncertainty/Perfectionism
Importance of Thoughts/Control of Thoughts
Padua Revised-Total Score
Thoughts about harm
Impulses about harm
Contamination
Checking
Dressing/grooming
Beck Anxiety Inventory
141
M
SD
49.1
188.4
66.8
78.2
43.4
63.2
10.7
3.5
18.0
21.4
5.7
20.3
12.0
53.8
25.0
20.8
17.1
24.0
6.1
4.8
11.1
9.5
4.0
13.2
142
COGNITIVE BEHAVIOUR THERAPY
Aardema, O’Connor and Emmelkamp
Table 2. Intercorrelations of the ICQ and OBQ belief domains (n585).
OBQ44-T
RT
PC
ICT
ICQ
0.90***
0.84***
0.82***
0.57***
RT
PC
–
0.60***
0.64***
0.71***
–
–
0.55***
0.29**
ICT
–
–
–
0.41***
pv0.05, ** pv0.01, *** pv0.001. OBQ44-T5Obsessional Beliefs Questionaire-44 Total Score;
RT5Responsibility/Threat; PC5Perfectionism/Intolerance of uncertainty; ICT5Importance given to
thoughts/Control of thoughts; ICQ5Inferential Confusion Questionnaire.
Intercorrelations between the ICQ and
OBQ-44 subscales
We calculated interrelations between the ICQ
and OBQ-subscales to establish the level of
overlap between the different cognitive
domains. Correlations are shown in Table 2.
As expected, the relationships between the
various cognitive domains are quite strong.
The interrelationships between the OBQ belief
subscales range from 0.55 to 0.64, and not
surprisingly, are highly correlated with the
OBQ total score. The ICQ shows discriminant
validity
with
the
OBQ
subscales
Perfectionism/Certainty and Importance/
Control of Thoughts, but is strongly related
to the OBQ subscale Responsibility/Threat
estimation. The magnitude of these intercorrelations indicates that zero order correlations
alone would not be conclusive in determining
which cognitive domain best accounts for the
variance in obsessive-compulsive symptoms.
Zero-order and partial correlations of
the ICQ and OBQ-44 with obsessivecompulsive symptoms
The main purpose of the present study was to
establish whether inferential confusion could
account for the relationship between OBQ-44
belief domains and obsessive-compulsive
symptoms. A powerful method to establish
whether the relationship between variables is
accounted for by a third variable is the
calculation of partial correlations, which
represents the relationship between 2 variables
with the effects of a third variable removed (or
held constant) (see Nunnally & Bernstein,
1994). If the partial correlation between 2
variables decreases substantially relative to
the zero-order correlation then this relationship is said to be accounted for (although not
necessarily explained) by a third variable.
We calculated zero-order and partial correlations (between brackets) between the OBQ
belief domains and obsessive-compulsive
symptoms, while controlling for inferential
confusion (see Table 3). Additionally, for
comparison purposes we calculated the
zero-order and partial correlations (between
brackets) between inferential confusion and
obsessive-compulsive symptoms while controlling for obsessive beliefs.
The results confirmed our expectations that
inferential confusion can largely account for
the relationship between OCD beliefs and
obsessive-compulsive symptoms. While zeroorder correlations of the OBQ-44 beliefs with
obsessive-compulsive symptoms are substantial, these relationships decreased considerably when controlling for inferential
confusion. However, a few significant relationships remain when controlling for inferential confusion. The subscale Perfectionism/
Certainty remained significantly related to the
total score of the PI-R total and the subscale
checking compulsions. As well, the subscale
Importance/Control of thoughts remained
significantly related to obsessions about harm.
In contrast to these results, the relationship
between inferential confusion and obsessivecompulsive symptoms when simultaneously
controlling for all of the 3 OBQ belief
domains showed a far less dramatic decrease.
Most of the relationships between inferential
confusion and obsessive-compulsive symptoms remained substantial and significant
when controlling for obsessive beliefs.
Controlling for overestimation of threat
and anxiety
Inferential confusion as measured by the ICQ
has an overlap with the construct of overestimation of threat (Aardema, O’Connor,
Emmelkamp, Marchand, Todorov, 2005).
VOL 35, NO 3, 2006
Inferential confusion and obsessive beliefs in OCD
143
Table 3. Zero-order correlations and partial correlations (in parentheses) of inferential confusion and OBQ
belief domains with obsessive-compulsive symptoms (n585).
(Controlled for ICQ)
OBQ44-T
PI-R Total
Zero-order correlations
Controlled
PI-R Obsessions
Zero-order correlations
Controlled
PI-R-Impulses
Zero-order correlations
Controlled
PI-R Checking
Zero-order correlations
Controlled
PI-R Contamination
Zero-order correlations
Controlled
PI-R Dressing
Zero-order correlations
Controlled
RT
PC
ICT
ICQ (Controlled
for OBQ
domains)
0.48***
(0.18)
0.47***
(0.06)
0.39**
(0.27)*
0.34*
(0.09)
0.52***
(0.43)***
0.57***
(0.24)*
0.61***
(0.20)
0.32**
(0.10)
0.50***
(0.33)*
0.72***
(0.46)***
0.18
(0.10)
0.29*
(0.20)
0.20
(0.11)
0.10
(20.16)
0.26*
(0.06)
0.25*
(0.11)
0.32**
(0.03)
0.19
(20.02)
0.34**
(0.06)
0.34**
(0.26)*
0.28*
(0.01)
0.28*
(20.07)
0.22*
(0.08)
0.19
(20.09)
0.11
(20.20)
0.29**
(0.19)
0.21
(0.01)
0.08
(20.03)
0.38***
(0.36)***
0.12
(0.14)
pv0.05, ** pv0.01, *** pv0.001. OBQ44-T5Obsessional Beliefs Questionaire-44 Total Score;
RT5Responsibility/Threat; PC5Perfectionism/Intolerance of uncertainty; ICT5Importance given to
thoughts/Control of thoughts; ICQ5Inferential Confusion Questionnaire; PI-R5Padua Inventory Revised.
Thus, it could be argued that some of the
results in the present study were attenuated by
the overlap between the ICQ and overestimation of threat. In particular, the overlap
between overestimation of threat and inferential confusion may be responsible for the
ability of inferential confusion to account for
the relationship between obsessive beliefs and
obsessive-compulsive symptoms. We examined this possibility by first investigating
whether the item set of the ICQ could be
empirically distinguished from overestimation
of threat through factor analyses.
We performed a principal component analyses on the items of the ICQ and the original
OBQ-87 subscale overestimation of threat,
followed by varimax rotation in order to
extract 2 independent factors. The rationale
for using the original OBQ-87 overestimation
of threat scale was to ensure an adequate
representation of items reflecting overestimation of threat (in line with the hypothesis)
rather than the mixed scale of the OBQ-44
consisting of both responsibility and overestimation of threat items. Results indicated 1
large first factor with an eigenvalue of 11.0
explaining 38.0% of the variance, followed by
a second factor with an eigenvalue of 2.3
explaining an additional 7.9% of variance.
Subsequent factors had eigenvalues of respectively 1.8, 1.5, 1.2, 1.1 and 1.0. Thus,
examination of the scree plot indicated support for extraction of 2 factors.
Factor loadings on a 2-factor solution after
varimax rotation are shown in Table 4.
Salient loadings (>0.40) are shown in bold.
As can be seen in Table 4, the first factor
mostly contained highest loadings from the
items of the ICQ, whereas the items of the
overestimation of threat scale had most of
their highest loadings on the second factor.
Only 1 item of the ICQ had its primary
loading on the construct of overestimation of
threat (ICQ item 5), and only 3 items from the
overestimation of threat scale had their
primary loading on the construct of inferential
confusion (OBQ item 6, 39, 52). An additional
2 items of the overestimation of threat scale
had secondary loadings (w0.40) on the
construct of inferential confusion (OBQ items
68, 79). None of the items of the ICQ had
secondary loadings on the construct of overestimation of threat.
In order to determine whether the varimax
rotation was truly reflective of the underlying
factor structure we also performed an oblique
144
Aardema, O’Connor and Emmelkamp
COGNITIVE BEHAVIOUR THERAPY
Table 4. Factor loadings after varimax rotation with abbreviated item content.
Factor 1:
Inferential
Confusion
ICQ9
ICQ8
ICQ12
ICQ11
ICQ10
ICQ1
ICQ15
ICQ2
ICQ7
ICQ13
ICQ6
ICQ14
OBQ39
ICQ3
OBQ6
ICQ4
OBQ52
OBQ82
OBQ40
OBQ50
OBQ80
OBQ61
OBQ79
OBQ16
OBQ30
OBQ72
ICQ5
OBQ68
OBQ9
There are many invisible dangers
Even without proof my imagination convinces me otherwise
My imagination makes me lose confidence in what I perceive
Knowing a problem exists without visible proof
Just a thought is enough proof of danger
More convinced about what might be than what is seen
Reacting to something that might be as if it is happening
Inventing dangers that might be without seeing
Idea of danger without obvious reason
In spite of evidence, feeling that danger will occur
Something not safe, because things are not as they appear
More afraid of unseen than seen
Avoiding serious problems requires constant effort
Knowing there’s danger without feeling the need to look
I think things around me are unsafe
One can never know something is safe on appearances
I believe the world is a dangerous place
When things go wrong it’s likely to have terrible effects
Small things turn into big problems in my life
Not taking precautions increases the risk of an accident
When things go well, something bad will follow
I’m more likely than others to cause harm
Ordinary experiences in my life are full of risk
Minor annoyances seem like disasters to me
Bad things are more likely to happen to me than others
Harmful events will happen unless I’m careful
Thinking there is danger and taking precautions
Even when I’m careful, I often think bad things will happen
I am more likely to be punished than others
0.73
0.71
0.66
0.65
0.65
0.64
0.64
0.58
0.58
0.57
0.56
0.56
0.56
0.53
0.52
0.43
0.41
0.09
0.02
0.33
0.09
0.03
0.42
0.16
0.28
0.35
0.28
0.46
0.33
Factor 2:
Threat
Estimation
0.01
0.25
0.30
0.17
0.38
0.21
0.33
0.29
0.29
0.30
0.24
0.02
0.45
0.08
0.45
0.17
0.22
0.81
0.69
0.69
0.81
0.67
0.65
0.64
0.63
0.58
0.57
0.53
0.48
Salient loadings (w0.40) are indicated in bold. OBQ5Obsessional Beliefs Questionaire; ICQ5Inferential
Confusion Questionnaire.
rotation. Oblique rotation resulted in very
similar findings. with only 2 items of the
inferential confusion questionnaire having
their highest loading on a second factor
representing the construct of overestimation
of threat, and none of the items of the
overestimation of threat subscale having their
highest loading on the first factor representing
the construct of inferential confusion. Thus,
these results established that the construct of
inferential confusion could be clearly separated from overestimation of threat through
factor analyses. Moreover, since both factors
came about through varimax rotation (and so
were uncorrelated), the independent correlation of each factor with OCD symptoms
should reveal whether the ICQ still accounted
for the relationship between OBQ belief
domains without any overlap with overestimation of threat.
We calculated the correlations between
each of the independent factors derived
through varimax rotation (using factor-scores)
and obsessive-compulsive symptoms. Both
overestimation of threat and inferential confusion were independently related to obsessive-compulsive symptoms. The construct of
inferential confusion was independently significantly related to the PI-R total score
(r50.41; pv0.001), obsessions about harm
(r50.60; pv0.001) and washing compulsions
(r50.39; pv0.001). No significant relationships were found with the other subscales of
the PI-R. The construct of overestimation of
threat was independently significantly related
to the PI-R total score (r50.44; pv0.001),
VOL 35, NO 3, 2006
Inferential confusion and obsessive beliefs in OCD
obsessions about harm (r50.47; pv0.001),
obsessional impulses (r50.24; p50.03) and
checking compulsions (r50.39; pv0.001). No
significant relationships were found with the
other subscales of the PI-R.
Since overestimation of threat appears to be
independently related to obsessive-compulsive
symptoms these results do not exclude the
possibility that the ability of inferential confusion to account for the relationships
between OBQ belief domains and obsessivecompulsive symptoms may in part have been
caused by its overlap with overestimation of
threat. However, it can be questioned whether
this second factor actually represents overestimation of threat. Overestimation of threat
is often considered to be a general vulnerability factor in anxiety disorders (Beck,
Emery & Greenberg, 1985), and as such, this
factor may be more representative of anxious
mood rather than form a particular cognitive
bias. In order to test this hypothesis we
calculated the relationship between overestimation of threat (using factor-scores) and
obsessive-compulsive symptoms while controlling for anxious mood (BAI). Results of
these partial correlational analyses showed
that the construct of overestimation of threat
only remained significantly related to checking compulsions (r50.27; p50.02), while no
significant relationships remained with any of
the other obsessive-compulsive symptoms. In
contrast, the construct of inferential confusion
remained significantly related with obsessivecompulsive symptoms overall (r50.26;
p50.03), obsessions about harm (r50.48;
pv0.001) and washing compulsions (r50.26;
p50.03) when controlling for anxious mood.
Therefore, the competing hypothesis that
overestimation of threat may be responsible
for the ability of inferential confusion to
account for the relationship between beliefs
and obsessive-compulsive symptoms is not
supported.
Discussion
The main goal of the present study was to
establish whether inferential confusion could
account for most of the relationships between
belief domains and obsessive-compulsive
symptoms. Results indicated that inferential
confusion accounted substantially for the
relationships between obsessive-compulsive
145
beliefs and obsessive-compulsive symptoms.
In contrast, the relationship between inferential confusion and obsessive-compulsive
symptoms remained substantial when controlling for obsessive beliefs. Hence, these results
provide support for the view that the relationship between obsessive beliefs and obsessivecompulsive symptoms can be accounted for
by inferential confusion.
A competing hypothesis, which attributed
the current results to the overlap between
inferential confusion and overestimation of
threat, was not supported. After separating
the shared variance of both constructs with
obsessive-compulsive symptoms, and controlling for anxious mood, inferential confusion
was significantly related to several obsessivecompulsive symptoms, while most of the
relationships between overestimation of threat
and obsessive-compulsive symptoms disappeared. In other words, overestimation of
threat was found not to be a viable competing
hypothesis for the current results. Rather, it
appeared that the independent relationship
between overestimation of threat and obsessive-compulsive symptoms was due to an
overlap of overestimation of threat with
anxious mood.
It should be noted that these results do not
provide evidence for any causal mechanisms
proposed to be operating in OCD according
to an inference-based approach. However, the
results are consistent with our contention that
obsessive-compulsive beliefs logically follow
from the inferential confusion process associated with the occurrence of "intrusions" or
obsessions. Cognitive elaboration via appraisal of intrusions or obsessions may certainly
reinforce obsessive-compulsive symptoms.
Rachman (2003) has recently drawn attention
to the role of appraisals in generating fearful
contexts for the obsession to occur, and
resulting in its increased persistence and
frequency. However, the present results seem
to indicate that inferential confusion may be a
more critical factor in accounting for most
OCD symptoms than obsessive beliefs and
appraisals.
It should be recognized that multidimensional studies investigating the relationship
between cognitive measures with obsessivecompulsive symptoms remain a challenge,
since partial correlations cannot completely
eliminate all competing hypotheses. For
146
Aardema, O’Connor and Emmelkamp
example, the current study did not control for
depressive mood, which has been found to
account for a portion of the variance in some
obsessive-compulsive symptoms (Emmelkamp
& Aardema, 1999). While inevitably alternative explanations for the current results
remain, it should be noted that the current
study addresses a variety of competing
hypothesis in an attempt to isolate cognitive
domains that are often confounded with each
other. In this regard, a recent study investigating an even larger number of statistically
independent cognitive domains and their
relationship OCD symptoms as well as controlling for both anxiety and depression has
continued to highlight the importance of
inference processes operating in OCD
(Aardema, Radomsky, O’Connor & Julien,
in press). However, further research is needed
to determine the relative contribution of
inferential confusion and diverse negative
mood states, such as depression, in explaining
the relationships between obsessive-compulsive beliefs and obsessive-compulsive symptoms. As well, there may be other cognitive
variables operating in OCD outside of both
belief domains and inferential confusion, and
current results remain tentative due to the
limitations of correlational data.
While the importance of psychometric
investigations should not be underestimated
(Taylor, 2002) causal pathways in the development and maintenance of OCD will ultimately need to be addressed through more
experimental designs directly manipulating
variables. In particular, the inferential confusion model would predict that people with
OCD would be more affected than (non)clinical controls by subjective possibilitybased information that negates reality-based
information. This would account for the
persistence and occurrence of obsessional
inferences in the absence of (or despite) proof
to the contrary. In particular, studies that link
such experimental and psychometric data
could more concretely address current limitations.
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