Validation of the Spanish-language Cardiff Anomalous Perception Scale
Validation of the Spanish-language Cardiff Anomalous Perception Scale
William Tamayo-Agudelo 0 2 3
Mar??a J. Ja e?n-Moreno 2 3
Mar??a O. Le o?n-Campos 2 3
Jorge Holgu??n-Lew 1 2 3
Rogelio Luque-Luque 2 3
Vaughan BellID 2 3
0 Universidad Cooperativa de Colombia , Medell ??n, Colombia , 2 Division of Psychiatry, University College London, United Kingdom, 3 UGC Salud Mental, Hospital Universitario Reina Sof ??a , C o ?rdoba , Spain
1 Universidad de Antioquia , Medell ??n , Colombia
2 Editor: Eduardo Fonseca-Pedrero, University of La Rioja , SPAIN
3 Funding: VB is supported by a Wellcome Trust Seed Award in Science [200589/Z/16/Z] and the UCLH NIHR Biomedical Research Centre
The Cardiff Anomalous Perceptions Scale (CAPS) is a psychometric measure of hallucinatory experience. It has been widely used in English and used in initial studies in Spanish but a full validation study has not yet been published. We report a validation study of the Spanish-language CAPS, conducted in both Spain and Colombia to cover both European and Latin American Spanish. The Spanish-language version of the CAPS was produced through back translation with slight modifications made for local dialects. In Spain, 329 non-clinical participants completed the CAPS along with 40 patients with psychosis. In Colombia, 190 non-clinical participants completed the CAPS along with 21 patients with psychosis. Participants completed other psychometric scales measuring psychosis-like experience to additionally test convergent and divergent validity. The Spanish-language CAPS was found to have good internal reliability. Test-retest reliability was slightly below the cut-off, although could only be tested in the Spanish non-clinical sample. The scale showed solid construct validity and a principal components analysis broadly replicated previously reported three component factor structures for the CAPS.
Competing interests: VB is the recipient of a
Wellcome Trust Seed Award in Science [200589/Z/
16/Z]. JH-L has received honoraria for giving talks
fromSanofi and Janssen. The other authors have
The Cardiff Anomalous Perceptions Scale (CAPS) is a self-report psychometric measure of
hallucinatory experience that was first validated in 2006 [
] and was revalidated in a
subsequent replication study [
] and has been widely used since. Since its first publication it has
been used to examine the role of perceptual anomalies in paranoia [
], autism [
], psychosis in
], the rubber hand illusion [
], hypomanic personality traits [
] and trauma [
name but a few areas of application.
Perhaps the most widely investigated aspect of hallucinations is where they appear as a
component of psychosis [
]. Indeed, hallucinations can appear across the extended psychosis
phenotype and can range from benign perceptual alterations to intense and distressing
hallucinations with the latter more likely to be present in diagnosable psychiatric disorders [
CAPS was designed to measure a range of hallucinatory experiences not limited to those found
declared that no competing interests exist. We
would like to confirm that our declaration of
interest does not alter our adherence to PLOS ONE
policies on sharing data and materials.
in the psychosis-spectrum, including, for example, alterations to sensory intensity and
hallucinations from the neurological literature [
]. Nevertheless, it has been shown to be sensitive to
psychosis-spectrum hallucinations can distinguish unselected patients with psychosis from the
general population [
] and psychotic patients with hallucinations from those without
The CAPS has been translated and validated in Taiwanese [
], an initial validation study
has been conducted with a Spanish-language version using non-clinical participants in Spain
] and a factor analytic study using the Spanish-language scale has been conducted in
nonclinical participants in Colombia [
]. However, a full validation study of a Spanish language
version with both clinical and non-clinical participants has not yet been published.
This study reports a back translation and validation study of the Spanish-language Cardiff
Anomalous Perceptions Scale in both non-clinical participants and patients with psychosis,
conducted in both Spain and Colombia to cover both European Spanish and Latin American
All data, analysis scripts and copies of the questionnaires are freely available online at the
following resource: https://osf.io/ekwgb/
Translation and back translation
The CAPS was translated using the back translation method. The original English-language
version was translated into standard Spanish by an independent professional translator
following the conventions of the Royal Academy of the Spanish language (?Real Academia
Espa?ola?). Feedback on potential uncertainties in translation and translation decisions was
provided to the study authors. Subsequently, this initial Spanish-language version was
translated back into English by two bilingual mental health professionals and the original and
backtranslated English versions compared. The Spanish and back-translated English versions were
reviewed by an expert committee of the study authors. Due to differences in appropriate word
choice between European Spanish and Latin American Spanish, a decision was made to
produce two Spanish-language versions, based on local word preferences and different emphasis
in meaning. For example, item 24 in English reads ?Do you ever have the feeling of being
uplifted, as if driving or rolling over a road while sitting quietly?? The verb ?to drive? differs
between Spain (?conducir?) and Latin America (?manejar?) and so was changed for the local
versions. The overall changes were minor and the two versions were then compared and
judged to be equivalent in meaning. The scale was assessed by the research team in each
country for equivalent face and content validity in comparison to the original version in English.
Pre-testing was conducted through informally distributing the questionnaire to respondents
na?ve to the purpose of the study and receiving verbal feedback. No changes were made as a
result of this phase.
The study was cross-sectional in design and data was collected by different researchers in
Spain and Colombia. The relevant projects were reviewed and approved by ethics committees
in each country: in Spain, the Research Ethics Committee of El Hospital Universitario Reina
Sof??a, in Co?rdoba, and in Colombia, the Bioethics Committee of La Universidad Cooperativa
de Colombia?Medell??n campus. la Universidad Cooperativa de Colombia Written informed
consent was obtained from all participants before participation.
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Participants. Participants were recruited in four groups. Nonclinical and clinical
participants in Spain, and nonclinical and clinical participants in Colombia. All data was collected in
Spain?Nonclinical sample: 324 individuals in Spain (Co?rdoba) were invited to participate.
The participants were second-year medical students who had not yet received any teaching
related to psychiatry or mental health. Participants were asked not to participate if they had
any history of brain injury or psychotic illness. Participants who didn?t complete the full series
of questionnaires were excluded, leaving 319 participants in the final analysis. 99 were male
and 220 were female (mean age 20.1; SD = 2.4; range 18?38). Relationship status was reported
as single (N = 262), married (N = 2), divorced / separated (N = 1), and with partner (N = 54).
In line with the source of recruitment, all participants reported a university level education.
Participants were additionally asked to indicate if they had a personal history of mental health
issues (48 responded yes) and if they had a family history of mental health issues (55 responded
yes). Following the original study,[
] after 6 months, participants were invited to complete the
subset of questionnaires again of which data for 71 participants was collected. An initial
analysis of data from this sample was originally reported in Jae?n Moreno et al. [
Spain?Clinical sample: 40 patients with a clinical DSM-IV-TR diagnosis of schizophrenia
participated in the study from an acute inpatient ward and outpatient clinic in Spain
(Co?rdoba). Patients were not referred to the study if they were considered by the clinical team to
have cognitive impairment that might interfere with informed consent. The sample consisted
of 30 males and 10 females (mean age 32.5; SD = 5.60; range 21?39). Relationship status was
reported as single (N = 31), married (N = 5), divorced / separated (N = 1), and with partner
(N = 3). Education level was reported as primary education (N = 20), vocational training
(N = 5), university (N = 6), completed undergraduate degree (N = 8) and postgraduate level
(N = 1). All patients were taking antipsychotic medication at the time of participation and
were assessed using the Brief Psychiatric Rating Scale as part of their clinical admission using
the 0 to 6 scaling system [
] resulting in a mean score of 16.95 (SD = 8.05).
Colombia?Nonclinical sample: 209 individuals from the general population of Colombia
(Medell??n) participated in the study and were invited by distributing invitations to domestic
residences and offices in the city. After removal of incomplete data, 190 participants, were
retained for the final analysis. Participants were asked not to participate if they had a history of
psychiatric illness or traumatic brain injury. The sample includes 79 males and 111 females
(mean age 36.02; SD = 15.39; range 17?99). Relationship status was reported as single
(N = 98), married (N = 59), divorced / separated (N = 9), and with partner (N = 18), widower
(N = 5), and didn?t respond (N = 1). Education was not recorded for this sample. An initial
analysis of data from this sample was originally reported in Tamayo et al. [
Colombia?Clinical sample: A total of 21 patients, from an outpatient clinic for patients
diagnosed with schizophrenia in Colombia (Medell??n) participated in the study. The patients
were diagnosed by the clinical team using DSM-IV criteria. The sample includes 13 males and
8 females (mean age 40.43; SD = 11.31; range 22?63). Relationship status was reported as single
(N = 16), married (N = 4) and divorced / separated (N = 1). Education was not recorded for
this sample. All patients were taking antipsychotic medication at the time of participation.
Measures. All measures were presented in their Spanish-language version. Not all
measures were presented to all samples and where measures were not completed by all
participants, the specific groups to which they were presented are described below.
Cardiff Anomalous Perceptions Scale (CAPS): a 32-item self-report scale designed to
measure perceptual anomalies and hallucinatory experience that has already been validated in
English in clinical and nonclinical populations [
]. Each of the 32 items involves a question
related to a specific hallucinatory experience to which the participant can answer ?yes? or ?no?.
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If the participant answers ?yes? they are asked to rate how distressing, how intrusive and how
often the experience occurs on separate 1?5 rated Likert scales. The scale total is calculated as
the total number items responded to with ?yes? (possible range 0?32) and the subscale totals
are calculated as the total of the subscale items (possible range 0?160). The Spanish language
versions of the CAPS used in this study have been made freely available at the following link:
Revised Launay-Slade Hallucination Scale (RLSHS). A 12-item self-report scale that
measures the predisposition to hallucinatory experiences [
]. This was used in all samples except
the clinical sample from Spain. The validated Spanish-language version of the RLSHS was
used in this study [
Brief Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE-R): a self-report
scale designed to measure schizotypy [
]. The brief version has 40 items that require a ?yes /
no? response. It has four subscales with measure unusual experiences, cognitive
disorganisation, introverted anhedonia and impulsive nonconformity. Total and subscale scores and
calculated by summing the relevant affirmative answers. This was only used in the non-clinical
sample from Spain. The validated Spanish-language translation of the scale was used in this
Peters et al Delusions Inventory, 21 item version (PDI-21): a self-report scale designed to
measure delusional ideation and magical thinking [
]. It is scored in a similar way to the
CAPS with 21 questions that requires a ?yes / no? and three subscales that measure
preoccupation, conviction and distress which participants are asked to complete for each item that they
respond to with a ?yes? response. This was only used in the non-clinical sample from Spain.
The validated Spanish-language version of this scale was used in this study [
Analysis. All statistical analysis was completed using SPSS 25 and R version 3.4.4. Internal
reliability was calculated using Cronbach?s alpha and Omega [
]. Test-retest reliability was
calculated using a Pearson correlation in the non-clinical sample for Spain who completed the
scale twice. Discriminant validity was tested using an independent samples t-test by comparing
clinical and non-clinical groups from both countries. Convergent validity was tested by
comparing CAPS and RLSHS total score using a Pearson correlation coefficient in non-clinical
groups in both countries.
Due to the additional measures in the sample from Spain, convergent validity was
additionally tested in this non-clinical sample by comparing CAPS total and PDI-21 total using a
Pearson correlation. Convergent and divergent validity in the Spanish non-clinical sample by
comparing CAPS total and O-LIFE subscale scores using Pearson correlations with the
prediction than the CAPS would selectively correlate with the O-LIFE unusual experiences subscale
but only weakly or non-significantly with the other schizotypy subscales.
We also completed a 2x2 between-subjects ANOVA comparing CAPS Total score with two
factors, each with two levels: country (Spain vs Colombia) and clinical groups (clinical vs
nonclinical) to investigate whether there was an interaction between country and clinical group.
Finally, we conducted a principal components analysis extracting three factors following
the methods from the original validation study published in Bell et al. [
], using the CAPS
main items with direct oblimin rotation.
Means and standard deviations for scale scores are reported in Table 1. Kurtosis and skewness
for all variables are reported in the supplementary material in S1 Table. As expected, clinical
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CAPS = Cardiff Anomalous Perceptions Scale. RLSHS = Revised Launay Slade Hallucinations Scale. O-LIFE = Oxford-Liverpool Inventory of Life and Experiences.
PDI-21 = Peters et al Delusions Inventory. UE = Unusual experiences subscale. CD = Cognitive disorganisation subscale. IA = Introvertive anhedonia subscale.
IN = Impulsive nonconformity subscale.
groups scored higher than non-clinical groups on the total score and all subscales of the CAPS
in both the samples from Spain and Colombia.
In the sample collected from Spain, the Cronbach?s alpha for the non-clinical sample was 0.834
and the coefficient Omega was 0.837 (95% CI 0.81?0.86). In the data from Colombia, the
Cronbach?s alpha for the non-clinical sample was 0.869 and the coefficient Omega was 0.874
(95% CI 0.84?0.90). For the combined non-clinical sample from both countries the
Cronbach?s alpha was 0.848 and the coefficient Omega was 0.851 (95% CI 0.83?0.87). Overall, these
analyses indicate good evidence for internal reliability. Test-retest reliability examined using
Pearson correlation on 71 participants for the non-clinical sample from Spain over a six
month period was 0.61. A typical cut-off for test-retest reliability is 0.7 [
] and indicates a
test-retest reliability marginally below the cut-off.
Criterion-related evidence of validity
CAPS total score and subscale scores between clinical and non-clinical groups were compared
using two-tailed independent samples t-tests and all showed a significant difference in that
patients with psychosis scored significantly more on the CAPS than non-clinical groups.
All CAPS scores were significantly different between non-clinical participants and patients
with psychosis in the sample from Spain: CAPS total (t = 3.181, p = 0.002, d = 0.53), CAPS
distress (t = 6.507, p < 0.0001, d = 1.09), CAPS Intrusiveness (t = 7.399, p < 0.0001, d = 1.24),
CAPS frequency (t = 5.673, p < 0.0001, d = 0.95).
All CAPS scores were significantly different in the sample from Colombia: CAPS total
(t = 5.685, p < 0.0001, d = 1.32), CAPS distress (t = 7.225, p < 0.0001, d = 1.67), CAPS
Intrusiveness (t = 6.691, p < 0.0001, d = 1.55), CAPS frequency (t = 7.271, p < 0.0001, d = 1.68).
Similarly, all CAPS scores were significantly different in the combined sample: CAPS total
(t = 5.986, p < 0.0001, d = 0.81), CAPS distress (t = 9.509, p < 0.0001, d = 1.29), CAPS
Intrusiveness (t = 9.777, p < 0.0001, d = 1.33), CAPS frequency (t = 8.925, p < 0.0001, d = 1.21).
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These results demonstrate that CAPS scores distinguish between non-clinical groups and
patients with psychosis, indicating good discriminant validity.
Evidence of validity based on relationships with measures of other variables
Using non-clinical samples, CAPS total score significantly correlated with RLSHS score in
both the sample from Spain (r = 0.561, p < 0.0001) and the sample from Colombia (r = 0.406,
p < 0.0001) and the total sample (r = 0.443, p < 0.0001).
Additionally, data from the Brief O-LIFE scale was collected from the non-clinical sample
from Spain. CAPS total score correlated moderately with the O-LIFE unusual experiences
subscale (r = 0.5, p < 0.0001), weakly with the cognitive disorganisation subscale (r = 0.254,
p < 0.0001), weakly with the impulsive non-conformity scale (r = 0.216, p < 0.0001) and
weakly and non-significantly with the introvertive anhedonia scale (r = 0.088, p = 0.115).
PDI21 data was also collected in the non-clinical sample Spain and correlated significantly with
the CAPS total score (r = 0.569, p < 0.0001).
These results indicate that the CAPS shows convergent validity with scales that measure
similar hallucinatory, psychosis-related constructs and divergent validity from scales that
measure dissimilar constructs.
Interaction between countries and clinical groups
A two-way 2x2 between-subjects ANOVA was conducted on the CAPS main score. The first
factor was country (Spain vs Colombia), the second factor was clinical group (non-clinical vs
clinical). There was no main effect for country (F(1,566) = 1.272, p = 0.260, partial eta
squared = 0.002) indicating that overall CAPS scores were not significantly different between
Spain and Colombia. There was a main effect of clinical group (F(1,566) = 43.973, p < 0.0001,
partial eta squared = 0.072) in that participants with psychosis scored significantly higher than
participants in the non-clinical groups. There was a significant interaction (F(1,566) = 8.940,
p = 0.003, partial eta squared = 0.016) in that patients from Colombia scored above patients
from Spain, but members of the non-clinical population in Colombia scored below the
nonclinical population in Spain. When tested with post-hoc t-tests, the difference between
nonclinical populations in Spain and Colombia was significant (t = 2.953, p = 0.003) but the
difference between clinical populations was not (t = 1.870, p = 0.066). However, we note the
difference between non-clinical participants on CAPS main score although significant was small in
magnitude (a mean difference of 1.51 points).
Evidence of validity based on internal structure
Non-clinical samples from Spain and Colombia were combined for a principal components
analysis (PCA), meaning data from 509 non-clinical participants were entered into this
analysis. The Kaiser-Meyer-Olkin value was 0.856 and Bartlett?s Test of Sphericity reached statistical
significance, supporting the suitability of the data for this analysis. We completed a PCA using
direct oblimin rotation, requesting three factors based on the factor structure found in the
original validation study [
]. The three factors explained 29.33% of the total variance. The
factor loadings for items in the scale are displayed in Table 2.
The factor structure broadly replicated the original factor structure reported in Bell et al.
]. Two factors could be clearly interpreted as ?clinical psychosis? and ?chemosensation? and
despite one component showing a significant overlap of items with the Bell el al. [
lobe experience? scale, we were equivocal whether this was the best interpretation and this
may be better interpreted as ?non-clinical hallucinatory experience? factor.
6 / 11
We report a validation study of the Spanish-language version of the Cardiff Anomalous
Perception scale in both Colombia and Spain, finding that this translated version of the scale is
both reliable and valid. The CAPS showed good internal reliability, discriminant validity,
7 / 11
convergent and divergent validity, and broadly reproduced the same three component factor
structure as the original validation study. The test-retest reliability was marginally below the
level of acceptability but it was only possible to test it in the non-clinical population in one
One notable finding was an interaction between country and participant group, finding
that patients with psychosis from Colombia typically scored higher on the CAPS than patients
with psychosis from Spain, and the non-clinical population in Colombia typically scored lower
than the non-clinical population from Spain. However, when the CAPS main score for clinical
groups was tested with a direct post-hoc comparison, the difference between the patient
sample from Colombia and patient sample from Spain was not significant and the difference
between non-clinical groups, although significant, was of small effect. Given these results, we
suggest it is unlikely that this reflects a true population difference, although we note both age
differences (the non-clinical sample from Spain was markedly younger than the non-clinical
population from Colombia) and cultural differences may play a part in differences in
hallucinatory experience, and need to be investigated further to fully confirm the equivalence of
populations in this regard. However, the extent to which the CAPS measures similar constructs
across populations is best tackled using a measurement invariance analyses [
] and future
research should test this as an additional aspect of the scale?s validity across countries and
The principal components analysis broadly replicated the three-component solution first
reported in the original validation study [
]. In this original study, the three factors were
labelled ?clinical psychosis??reflecting experiences most associated with clinically diagnosable
psychosis spectrum disorders, ?temporal lobe experience??reflecting hallucinatory experiences
commonly associated with disturbances to the temporal lobe, such as temporal lobe epilepsy,
and ?chemosensation??which reflected alterations to the senses of taste and smell.
In this study, the ?chemosensation? factor was clearly replicated, as was a factor that seemed
to reflect experiences more common in psychosis. Although the remaining factor overlapped
considerably with the original ?temporal lobe experience? factor some of the characteristic
?temporal lobe? experiences were missing (e.g. items 24, 27). In retrospect, it may be that this
factor better represents ?non-clinical hallucinatory experiences? factor rather than temporal
lobe-related experiences per se. Notably, this original three factor solution was not replicated a
subsequent validation study of the CAPS [
] or in a study of non-clinical participants in
]. One marked difference between the studies that have found a three factor
solution and those that haven?t, is sample size?with positive studies including more than 300
participants, and negative studies including approximately 200 or less. One hypothesis is that the
factor structure of anomalous experiences measured by the CAPS is unstable and varies
between populations, another is that it is present but not detectable except with larger sample
sizes, suggesting it may be present but only weakly so.
It is also worth noting some limitations to this study. Although this study was conducted in
line with recommendations for cross-cultural and cross-language adaptation of self-report
], the most complete process has been described by Beaton et al.  and
involves two translators?one familiar with the construct being measured by the scale and one
na?ve to its psychometric purpose?to give the best chance of highlighting potential challenges
or subtleties in translation. In our study we used only one construct na?ve translator for the
initial translation that may have under-detected challenges in translation particularly where the
language intended to capture specific clinical phenomena, although the fact that separate
expert committees in Spain and Colombia checked and commented on the resulting
translation with respect to country specific language may have mitigated this to some extent. We also
note that the non-clinical sample in Spain consisted of medical students who may be
non8 / 11
typical in several respects in comparison to other members of the population?in terms of
education, cognitive ability, but perhaps most relevant to this study, high levels of stigma towards
mental health problems [
] potentially affecting how they responded to the items on the
scales. Finally, we tested test-retest reliability over a six-month time period based on the design
of the original validation study [
]. However, this retest period was arbitrarily selected in the
original study and it is possible that true variation in the presence and intensity of
hallucinations in the general population, as has been found in experience sampling studies of psychosis,
] may mean that a shorter time period is necessary for adequate test-retest reliability
Nevertheless, the data presented here provide good evidence that the Spanish-language
version of the CAPS is reliable and valid in both Spain and Colombia, when tested with a sample
that includes nonclinical participants and patients with psychosis.
S1 Table. SupplementaryInformation.
Conceptualization: William Tamayo-Agudelo, Mar??a J. Jae?n-Moreno, Jorge Holgu??n-Lew,
Rogelio Luque-Luque, Vaughan Bell.
Data curation: William Tamayo-Agudelo, Mar??a J. Jae?n-Moreno, Vaughan Bell.
Formal analysis: Mar??a O. Leo?n-Campos, Vaughan Bell.
Investigation: William Tamayo-Agudelo, Mar??a J. Jae?n-Moreno.
Methodology: William Tamayo-Agudelo, Mar??a J. Jae?n-Moreno, Mar??a O. Leo?n-Campos,
Jorge Holgu??n-Lew, Rogelio Luque-Luque, Vaughan Bell.
Project administration: William Tamayo-Agudelo, Mar??a J. Jae?n-Moreno, Jorge
Lew, Rogelio Luque-Luque, Vaughan Bell.
Resources: William Tamayo-Agudelo.
Writing ? original draft: William Tamayo-Agudelo, Mar??a J. Jae?n-Moreno, Mar??a O.
Campos, Vaughan Bell.
Writing ? review & editing: William Tamayo-Agudelo, Mar??a J. Jae?n-Moreno, Mar??a O.
Leo?n-Campos, Jorge Holgu??n-Lew, Rogelio Luque-Luque, Vaughan Bell.
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