Elsevier

Comprehensive Psychiatry

Volume 58, April 2015, Pages 198-204
Comprehensive Psychiatry

Factor structure and temporal stability of the Vancouver Obsessional Compulsive Inventory–Mental Contamination Scale (VOCI-MC) and psychometric properties of its Italian version

https://doi.org/10.1016/j.comppsych.2014.12.017Get rights and content

Abstract

Objective

The Vancouver Obsessional Compulsive Inventory–Mental Contamination Scale (VOCI-MC) is a self-report instrument that assesses symptoms of mental contamination. The aim of this study was to investigate the psychometric properties of the Italian version of the VOCI-MC in non-clinical and clinical samples.

Method

Factor structure, internal consistency, temporal stability, construct and criterion validity were investigated in 541 participants from the general population, 120 participants diagnosed with OCD and 31 participants diagnosed with other anxiety disorders (OAD). For some of these analyses, our OCD sample was subdivided into those with contamination-related symptoms and concerns (n = 39) and those whose OCD excluded concerns related to contamination fear (n = 81). Exploratory and confirmatory factor analyses supported the expected one-factor structure of the VOCI-MC both in non-clinical and OCD sample.

Results

VOCI-MC scores showed good internal consistency, temporal stability, construct validity and criterion validity. In particular, the VOCI-MC successfully discriminated between those with OCD who reported contamination-related concerns and all other groups of participants.

Conclusion

These findings suggest that the Italian version of the VOCI-MC retains the adequate psychometric properties of the original, provide preliminary evidence of its one-factor structure and temporal stability, and suggest that it can be confidently used as an assessment tool of mental contamination symptoms in both clinical and research settings.

Introduction

Traditionally, contamination fear in obsessive-compulsive disorder (OCD) has been conceptualized with a focus on physical contaminants, which were perceived to be threatening as a result of direct contact [1]. However, as Fairbrother and Rachman [2] pointed out, there is more than one type of dirtiness, and it has been recognized that individuals may also feel dirty, and experience an associated urges to wash, in the absence of direct contact with a contaminant. The concept of “mental contamination” (MC) was first described by Rachman [1] and refers to feelings of internal dirtiness and urges to wash that arise in the absence of contact with a physical source of contamination.

The main differences between the “internal sense of dirtiness” stemming from mental contamination and the ordinary “external dirtiness” associated with contact contamination include the nature of the contamination process (resulting from physical contact vs. occurring in the absence of direct contact), the effectiveness of washing (washing is helpful when the contaminant is physical, but ineffective when it is not), the perceived source (a known and tangible source for contact contamination vs. an intangible and obscure source for mental contamination), the nature of the source (inanimate dirty/harmful substances for contact contamination vs. usually human persons for mental contamination), the vulnerable individual (self and others for contact contamination vs. uniquely self for mental contamination), and the range of contamination provocations (dirt, germs or harmful substances vs. thoughts, memories, betrayal, etc.) [1].

A preliminary study of the prevalence of mental contamination in a clinical sample of patients with obsessive-compulsive symptoms found that 10% of participants reported mental contamination in the absence of contact contamination, 15% reported contact contamination in the absence of mental contamination, and 36% experienced both mental and contact contaminations. These findings demonstrated that mental contamination is a construct that overlaps with, but is distinct from, contact contamination [3].

After a pioneering study involving sexual assault victims [2], a series of experiments [4], [5], [6], [7], [8] tested this phenomenon in a laboratory setting involving non-clinical participants in an imagined non-consensual sexual experience (‘dirty kiss scenario’). Several factors (e.g. immoral behavior, imagined physical dirt, betrayal, appraisals associated with responsibility, violation, and immorality) were shown to exacerbate and amplify feelings of contamination and the urge to rinse or wash [4], [5], [8], [9]. Furthermore, an additional experiment has demonstrated that mental contamination can be evoked by the recall of unwanted memories associated with betrayal and immorality, which do not involve physical violation [10]. Similarly, imagining wearing clothing that belongs to undesirable and immoral people leads to feelings of contamination and to washing behavior [11]. This experimental support for the construct of mental contamination provides a basis for elucidating potential treatment targets and important aspects of phenomenology; that said, a valid and reliable assessment tool is necessary to study mental contamination sufficiently.

The Vancouver Obsessional Compulsive Inventory–Mental Contamination Scale (VOCI-MC) was designed by Rachman [12] to capture ‘symptoms’ of mental contamination and to help researchers and practitioners to assess and understand this phenomenon. This self-report questionnaire is composed of twenty items, based on the theory of mental contamination [1] and on clinical observations, and rated on a five-point Likert-type scale ranging from 0 (not at all) to 4 (very much), with higher scores indicating higher levels of mental contamination. Sample items include “Some people look clean, but feel dirty” and “Having an unpleasant image or memory can make me feel dirty inside”.

The psychometric properties of the VOCI-MC have been investigated in a recent study [13] conducted on a sample of 57 participants diagnosed with OCD, divided into a contamination-symptoms subgroup and a subgroup who did not report any contamination related concerns. The study included also an unselected sample of 410 undergraduate students and a fourth group of 24 participants diagnosed with other anxiety disorders. Results showed that the VOCI-MC had excellent internal consistency across all four groups (Cronbach's alphas of .94, .97, .96 and .93 for the OCD contamination group, OCD non-contamination group, anxious controls and student controls, respectively). The VOCI-MC was significantly correlated (.45  r's  .87, p's <. 001) with the Contamination Sensitivity Scale (CSS) [12] and the Contamination Thought-Action Fusion Scale (CTAF) [12], two self-report measures used to assess levels of distress associated with feelings of contamination and the fusion between thoughts, feelings and behaviors associated with contamination. Convergent validity was also confirmed by the strong associations (.61  r's  .76, p's < .001) between the VOCI-MC and the Contamination Subscale of the Vancouver Obsessional Compulsive Inventory (VOCI) [14]. Importantly, the scale was not significantly associated with depression scores providing evidence of divergent validity. Finally, the VOCI-MC successfully discriminated between those who reported contamination-related concerns and all other groups of participants. Although there were limitations of this recent study – e.g., the factor structure of the VOCI-MC was not explored – it demonstrated the ability of the VOCI-MC to discriminate between those with contamination-related OCD symptoms and other forms of psychopathology, as well as to distinguish between mental contamination and contact contamination symptoms.

Given the lack of Italian measures designed to assess mental contamination symptoms, the aim of the present study was to investigate the psychometric properties of the Italian version of the VOCI-MC and to overcome some limitations of the previous study. Because the factor structure and temporal stability of the scale have never been explored, we ran both exploratory and confirmatory factor analyses to provide evidence of its factor structure, and investigated the stability of VOCI-MC scores over time in a subset of our non-clinical sample. We also explored internal consistency and construct validity, in both clinical and non-clinical samples, and tested the ability of the VOCI-MC to discriminate between OCD participants with contamination-related symptoms and all other participants.

Section snippets

Participants

The total study sample consisted of 692 adults, including 120 diagnosed with OCD, 31 diagnosed with other anxiety disorders (OADs) and 541 non-clinical participants recruited from the general population (GP).

Non-clinical participants lived in Florence urban and suburban areas and responded to advertisements requesting potential volunteers for psychological studies. To be included in the study, they had to be at least 16 years old, have at least a primary school education. Although the absence

Factor analyses

The Keyser-Meyer-Olkin (KMO) measure of the sampling adequacy was .93, indicating that the correlation matrix was suitable for factor analysis [36]. Bartlett's test of sphericity [37] was significant, which also suggested that factor analysis was suitable.

The scree-plot suggested that eigenvalues began to level off after one factor (first five observed eigenvalues: 8.47, 1.34, 1.17, .98, .91). Also PA suggested to extract one factor when the mean percentile was considered and one again when the

Discussion

Given the lack of tools for assessing mental contamination in Italy, the present study evaluated the psychometric properties of the Italian version of the VOCI-MC in a large community sample and in two clinical samples, and aimed to provide preliminary evidence of its factor structure and temporal stability.

Exploratory and confirmatory factor analyses supported a one-factor measurement model of the VOCI-MC items in both non-clinical and OCD samples, although the fit indices in the clinical

References (43)

  • D.S. Thordarson et al.

    The Vancouver Obsessional Compulsive Inventory (VOCI)

    Behav Res Ther

    (2004)
  • R.P. Mattick et al.

    Development and validation of measures of social phobia scrutiny and social interaction anxiety

    Behav Res Ther

    (1998)
  • A. Radomsky et al.

    Subtyping OCD: prospects and problems

    Behav Ther

    (2005)
  • S. Rachman

    Betrayal: a psychological analysis

    Behav Res Ther

    (2010)
  • C. Elliott et al.

    Feelings of mental contamination evoked by imagined role as a perpetrator of a non-consensual sexual act: replication in men

  • M. Lee et al.

    The induction of mental and contact contamination

    Clin Psychol

    (2013)
  • S. Rachman

    Vancouver Obsessional Compulsive Inventory (VOCI-MC)

    (2005)
  • T.A. Brown et al.

    Anxiety disorders interview schedule adult version (ADIS-IV):client interview schedule

    (1994)
  • American Psychiatric Association

    Diagnostic and statistical manual of mental disorders (4th ed. Text Revision)

    (2000)
  • O. Behling et al.

    Translating Questionnaires and Other Research Instruments: problems and solutions (Sage University Papers Series on Quantitative Applications in the Social Sciences, series no. 07–131)

    (2000)
  • E.B. Foa et al.

    The obsessive-compulsive inventory: development and validation of a short version

    Psychol Assess

    (2002)
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