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Clinical Trial
. 2010 Aug 31;5(8):e12412.
doi: 10.1371/journal.pone.0012412.

Psychometric evaluation of the altered states of consciousness rating scale (OAV)

Erich Studerus  1 , Alex Gamma, Franz X Vollenweider
Affiliations
Clinical Trial

Psychometric evaluation of the altered states of consciousness rating scale (OAV)

Erich Studerus et al. PLoS One. .

Abstract

Background: The OAV questionnaire has been developed to integrate research on altered states of consciousness (ASC). It measures three primary and one secondary dimensions of ASC that are hypothesized to be invariant across ASC induction methods. The OAV rating scale has been in use for more than 20 years and applied internationally in a broad range of research fields, yet its factorial structure has never been tested by structural equation modeling techniques and its psychometric properties have never been examined in large samples of experimentally induced ASC.

Methodology/principal findings: The present study conducted a psychometric evaluation of the OAV in a sample of psilocybin (n = 327), ketamine (n = 162), and MDMA (n = 102) induced ASC that was obtained by pooling data from 43 experimental studies. The factorial structure was examined by confirmatory factor analysis, exploratory structural equation modeling, hierarchical item clustering (ICLUST), and multiple indicators multiple causes (MIMIC) modeling. The originally proposed model did not fit the data well even if zero-constraints on non-target factor loadings and residual correlations were relaxed. Furthermore, ICLUST suggested that the "oceanic boundlessness" and "visionary restructuralization" factors could be combined on a high level of the construct hierarchy. However, because these factors were multidimensional, we extracted and examined 11 new lower order factors. MIMIC modeling indicated that these factors were highly measurement invariant across drugs, settings, questionnaire versions, and sexes. The new factors were also demonstrated to have improved homogeneities, satisfactory reliabilities, discriminant and convergent validities, and to differentiate well among the three drug groups.

Conclusions/significance: The original scales of the OAV were shown to be multidimensional constructs. Eleven new lower order scales were constructed and demonstrated to have desirable psychometric properties. The new lower order scales are most likely better suited to assess drug induced ASC.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Final confirmatory factor analysis model with completely standardized loadings and error variances.
Numbers in brackets are the 95% confidence intervals for the estimates. Covariances between factors were freely estimated and are shown in Table 3.
Figure 2
Figure 2. Known-group validities of the original and new OAV scales.
Error bars represent standard errors.
See this image and copyright information in PMC

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