Assessing Anomalous Perceptual Experiences in Nonpsychiatric Individuals and Outpatients with Psychosis in Taiwan: An Investigation Using the Cardiff Anomalous Perceptions Scale (CAPS)

Abstract

The Cardiff anomalous perceptions scale (CAPS) has been recently designed for the assessment of anomalous perceptual experiences in the general population, and includes dimensions that measure distress, intrusiveness, and frequency. The purpose of this study was to assess the psychometric properties of a Taiwanese version of the CAPS. The English version of the CAPS was translated into Taiwanese (CAPS-T) and the latter was applied to this study. We administered the questionnaire to a consecutive sample of 192 participants with (n = 106; clinical group including schizophrenia and affective psychosis) or without psychotic disorders (n = 86; non-clinical group). In addition to the CAPS-T, the Taiwanese version of the brief psychiatric symptom rating scale (BSRS) measured the severity of the psychopathology. We also tested the psychometric properties of the CAPS-T including construct validity, internal consistency, test-retest reliability, and convergent and discriminative validity. Overall, the CAPS-T showed good construct validity, internal consistency, and stability over time and correlated significantly with the psychoticism subscale of the BSRS. As predicted, the mean differences in CAPS-T scores between participants with or without a psychotic disorder were significant. Convergent and discriminative validity were satisfactory. A score of 5 was found to the best threshold in discriminating between clinical and non-clinical samples. Our findings indicate that the Taiwanese version of the CAPS is a reliable and valid instrument to measure the multidimensionality of perceptual anomalies in general and appears to complement the clinical measures of psychosis proneness in Taiwan.

Factor structure and age invariance of the Cardiff Anomalous Perceptions Scale (CAPS) in healthy older and younger adults.

“…In the current study, Factor 1 comprised items predominately related to changes in the perception of smell, taste, body image, and touch perception (sometimes referred to as body-centered senses ; Postmes et al, 2014; Riva, 2018). Previous analyses of the CAPS have frequently identified a “chemosensation” factor—comprising items assessing olfactory and gustatory experiences (Bell et al, 2006; Kao et al, 2013; Tamayo-Agudelo et al, 2019)—that clearly shares some similarities with our Factor 1. However, given the current factor analysis includes items beyond changes in the experience of smell and taste, one potential interpretation of this factor is that it more broadly captures anomalous body-centered self-experiences .…”

“…Overall, the items within this factor capture more severe distortions in everyday perceptions and frank hallucinations, experienced in external space and/or involving other (nonself) agents. Previous factor analyses of the CAPS have identified a clinical psychosis factor—comprising items assessing experiences commonly linked to clinically diagnosable psychosis disorders (Bell et al, 2006; Bell et al, 2011; Debbané et al, 2011; Kao et al, 2013; Tamayo-Agudelo et al, 2019)—that also shares strong similarities with our Factor 2. However, the clinical significance of this factor is unclear, and labeling it in this way also implies that the anomalous self-experiences described in Factor 1 are not clinically significant (which also remains unknown).…”

“…Importantly, in addition to the varying number of factors found in previous research, there is also evidence of inconsistency in the factor loadings for the indicators of similarly labeled factors (see in the online supplemental material). For example, although a “clinical psychosis” factor has frequently been found in previous research, it has considerable variation in item composition across studies, such as: Items 3, 5, 7, 10, 11, and 31 (Bell et al, 2006); Items 2, 4, 6, 7, 8, 11, 12, 13, 14, 28, 31, and 32 (Bell et al, 2011); Items 2, 3, 4, 8, 11, 12, 13, 22, 24, and 29 (Debbané et al, 2011); Items 3, 7, 11, 13, and 31 (Kao, Wang, Lu, & Liu, 2013); and Items 2, 11, 12, 13, 28, 31, and 32 (Tamayo-Agudelo et al, 2019). Furthermore, there are a number of problems in previous factor analytical studies of the CAPS that prevent researchers from replicating these previous factor structures, such as not being able to confidently determine which items belong in which factor/s (see in the online supplemental material).…”

Validation of the Spanish-language Cardiff Anomalous Perception Scale

“…The CAPS has been translated and validated in Taiwanese [13], an initial validation study has been conducted with a Spanish-language version using non-clinical participants in Spain [14] and a factor analytic study using the Spanish-language scale has been conducted in non-clinical participants in Colombia [15]. However, a full validation study of a Spanish language version with both clinical and non-clinical participants has not yet been published.…”