See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/230878361
Construct Validity of Three Depersonalization Measures in
Trauma-Exposed College Students
Article in Journal of Trauma & Dissociation · October 2012
DOI: 10.1080/15299732.2012.678470 · Source: PubMed
CITATIONS
READS
17
843
3 authors, including:
Christy A Blevins
Frank Weathers
Overton Brooks VA Medical Center
Auburn University
9 PUBLICATIONS 3,081 CITATIONS
113 PUBLICATIONS 28,870 CITATIONS
SEE PROFILE
All content following this page was uploaded by Frank Weathers on 23 May 2016.
The user has requested enhancement of the downloaded file.
SEE PROFILE
This article was downloaded by: [Auburn University]
On: 25 October 2012, At: 10:21
Publisher: Routledge
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Journal of Trauma & Dissociation
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/wjtd20
Construct Validity of Three
Depersonalization Measures in TraumaExposed College Students
a
a
Christy A. Blevins MS , Frank W. Weathers PhD & Elizabeth A.
Mason PhD
a
a
Department of Psychology, Auburn University, Auburn, Alabama,
USA
Accepted author version posted online: 05 Apr 2012.Version of
record first published: 18 Sep 2012.
To cite this article: Christy A. Blevins MS, Frank W. Weathers PhD & Elizabeth A. Mason PhD (2012):
Construct Validity of Three Depersonalization Measures in Trauma-Exposed College Students, Journal
of Trauma & Dissociation, 13:5, 539-553
To link to this article: http://dx.doi.org/10.1080/15299732.2012.678470
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation
that the contents will be complete or accurate or up to date. The accuracy of any
instructions, formulae, and drug doses should be independently verified with primary
sources. The publisher shall not be liable for any loss, actions, claims, proceedings,
demand, or costs or damages whatsoever or howsoever caused arising directly or
indirectly in connection with or arising out of the use of this material.
Journal of Trauma & Dissociation, 13:539–553, 2012
Copyright © Taylor & Francis Group, LLC
ISSN: 1529-9732 print/1529-9740 online
DOI: 10.1080/15299732.2012.678470
Construct Validity of Three
Depersonalization Measures
in Trauma-Exposed College Students
CHRISTY A. BLEVINS, MS, FRANK W. WEATHERS, PhD,
and ELIZABETH A. MASON, PhD
Downloaded by [Auburn University] at 10:21 25 October 2012
Department of Psychology, Auburn University, Auburn, Alabama, USA
Depersonalization is a type of dissociation characterized by feelings
of unreality and detachment from one’s sense of self. Despite
a history rich in clinical description, the construct of depersonalization has proven difficult to define and measure. Available
measures vary substantially in content, and all have relatively
limited psychometric support. In this study the content validity,
internal consistency, and convergent and discriminant validity of 3 depersonalization measures were compared in a sample of 209 trauma-exposed college students. Measures were the
Dissociative Experiences Scale (E. M. Bernstein & F. W. Putnam,
1986), Cambridge Depersonalization Scale (CDS; M. Sierra & G. E.
Berrios, 2000), and Multiscale Dissociation Inventory (MDI; J.
Briere, 2002). All 3 measures exhibited adequate to high internal
consistency for the depersonalization–derealization items. Based
on D. Westen and R. Rosenthal’s (2003) procedure for quantifying
construct validity, the CDS and MDI demonstrated the best fit with
the predicted pattern of correlations with measures of other constructs. The CDS and MDI also demonstrated the strongest evidence
of content validity. Overall, the results most strongly support the
use of the CDS and MDI for assessing depersonalization in this
population.
KEYWORDS depersonalization, dissociation, construct validity,
self-report
Received 20 October 2011; accepted 1 March 2012.
Address correspondence to Christy A. Blevins, MS, Auburn University, 226 Thach Hall,
Auburn, AL 36849. E-mail: cat0011@tigermail.auburn.edu
539
Downloaded by [Auburn University] at 10:21 25 October 2012
540
C. A. Blevins et al.
Depersonalization is a type of dissociation characterized by feelings of unreality and detachment from one’s sense of self that often leads to significant
distress and impairment (Hunter, Phillips, Chalder, Sierra, & David, 2003).
Associated symptoms include emotional numbing, altered perceptions of the
physical self, loss of sense of agency, altered perceptions of autobiographical memories, heightened self-awareness, and altered visual perceptions
(Sierra & Berrios, 2001). It is important to note that individuals experiencing
depersonalization are not considered delusional or psychotic (Hunter et al.,
2003).
Although once considered rare, depersonalization is in fact commonly
observed in a variety of settings. The lifetime prevalence of transient depersonalization symptoms ranges from 26% to 74% in student and nonclinical
populations, and clinically significant symptoms are reported by 1%–2% of
community samples and 42%–91% of psychiatric inpatients (Hunter, Sierra, &
David, 2004). When symptoms of depersonalization become persistent or
recurrent and are associated with significant distress or impairment, a diagnosis of depersonalization disorder may be warranted (American Psychiatric
Association, 2000). Although the prevalence of depersonalization disorder
has been estimated as relatively low, depersonalization as a dimensional construct is frequently described in the general population (e.g., Hunter et al.,
2004).
Since its introduction in the literature more than 100 years ago, investigators have extensively described the clinical features of depersonalization
and proposed a number of conceptual models (see Sierra & Berrios, 1997,
for a full discussion). Currently, the most comprehensive conceptualization
of depersonalization is what Sierra and Berrios (1998) characterized as a
neurobiological model. This model, which has been supported in a growing
number of studies (e.g., Phillips et al., 2001; Sierra et al., 2002), postulates that
depersonalization is a hardwired biological response involving simultaneous
emotion inhibition and heightened vigilance. Depersonalization evolved to
help individuals cope with life-threatening situations in which they have no
control over their surroundings and the source of danger is unknown. In such
situations, in which the typically adaptive fight-or-flight response may not be
feasible, the “freezing” response of depersonalization may increase one’s
chances of survival by inhibiting potentially disorganizing emotional arousal
and increasing vigilant alertness, thereby enabling the individual to scan the
environment for important information. When this response becomes generalized to situations not involving a threat to life, the result is a disturbing
experience that combines an enhanced sensory clarity with a sudden lack of
emotional feeling.
Despite increasingly well-articulated theoretical models and a growing empirical literature on depersonalization (Sierra & Berrios, 2001), the
transition from clinical description to operational definition and scientific
investigation has proven difficult. First, depersonalization is a subjective
Downloaded by [Auburn University] at 10:21 25 October 2012
Journal of Trauma & Dissociation, 13:539–553, 2012
541
experience with no characteristic behavioral manifestations (Radovic &
Radovic, 2002) and thus is assessed primarily through self-report. Second,
individuals use ambiguous language to describe their depersonalization
experiences, such as “unreal” and “as if,” which poses a number of semantic difficulties (Radovic & Radovic, 2002). Third, depersonalization overlaps
with derealization. Although the Diagnostic and Statistical Manual of Mental
Disorders, Fourth Edition, Text Revision (DSM–IV–TR) distinguishes between
derealization, defined as “an alteration in the perception or experience of
the external world so that it seems strange or unreal” and depersonalization,
defined as “alteration in the perception or experience of the self so that one
feels detached from, and as if one is an outside observer of, one’s mental
processes or body” (American Psychiatric Association, 2000, p. 822), there
is no conclusive evidence that the two phenomena are distinct (Sierra &
Berrios, 2001). Indeed, Dugas, who coined the term depersonalization in
the late 1800s, recognized the essential equivalence of these two terms: “[In
depersonalization] the individual feels a stranger amongst things, or if one
prefers, things appear strange to him” (as translated by Sierra & Berrios,
1996, p. 456). Evidence from factor analytic studies has empirically supported this lack of distinction (Briere, Weathers, & Runtz, 2005; Stockdale,
Gridley, Balogh, & Holtgraves, 2002). For example, Briere et al. (2005) conducted a factor analysis of the Multiscale Dissociation Inventory (MDI) and
found that depersonalization and derealization scale items loaded onto one
factor, suggesting that depersonalization and derealization represent a single
underlying dimension.
Given these challenges, it is not surprising that a consensus definition of
depersonalization has not emerged, which thus hinders the development of
psychometrically sound measures. Several measures have been developed,
but they vary substantially in content and therefore assess either somewhat
different constructs or different aspects of the same construct. Furthermore,
none has been extensively validated. To address these concerns, the present
study examined the content validity, internal consistency, and convergent
and discriminant validity of three self-report measures of depersonalization: the Dissociative Experiences Scale (DES; Bernstein & Putnam, 1986),
Cambridge Depersonalization Scale (CDS; Sierra & Berrios, 2000), and MDI
(Briere, 2002).
Predicted patterns of correlations were based on a literature review
that indicated significant associations between depersonalization and anxiety
(e.g., Cox & Swinson, 2002), obsessive-compulsive disorder (e.g., Simeon,
Stein, & Hollander, 1995; but see Sierra & Berrios, 2000), posttraumatic stress
disorder (PTSD; e.g., Bremner, Steinberg, Southwick, Johnson, & Charney,
1993), depression (e.g., Mula, Pini, & Cassano, 2007), borderline personality
disorder (e.g., Zanarini, Ruser, Frankenburg, & Hennen, 2000), somatization
and conversion (e.g., Spitzer, Spelsberg, Grabe, Mundt, & Freyberger, 1999),
and schizotypy (e.g., Watson, 2001; but see Simeon, Guralnik, Knutelska, &
542
C. A. Blevins et al.
Downloaded by [Auburn University] at 10:21 25 October 2012
Nelson, 2004). In the context of current theory and empirical findings, the
following hypotheses were posited:
Hypothesis 1: Internal consistency. Scores on the three depersonalization
measures will demonstrate high internal consistency (α ≥ .80).
Hypothesis 2: Convergent validity. Scores on the three depersonalization measures will demonstrate strong convergent validity, correlating
highly (r ≥ .80) with one another.
Hypothesis 3: Discriminant validity. Following convergent correlations,
scores on the depersonalization measures will correlate (a) most
strongly (r = .50–.60) with other types of dissociation and closely
related constructs such as depression, borderline personality disorder, and facets of the schizophrenia spectrum; (b) moderately (r =
.40) with related constructs such as anxiety and traumatic stress; (c)
weakly (r = .20) with obsessive-compulsive and paranoia symptoms,
constructs less related to depersonalization but potentially associated
through their correlation with anxiety; and (d) near zero (r = .10) with
mania and antisocial personality features, constructs least theoretically
related to depersonalization.
METHOD
Participants
Participants were 209 undergraduates (81 male, 126 female, 2 unreported)
enrolled in psychology courses at a large southeastern university who completed the study for extra credit. Participants were recruited using flyers that
described the study as involving the assessment of stressful life events. The
sample was predominantly Caucasian (n = 165; 79%) or African American
(n = 28; 13%). Mean age was 19.9 years (SD = 2.0). To be included in
the final analyses, participants were required to endorse at least one event
that met Criterion A1 for PTSD in the DSM–IV–TR (American Psychiatric
Association, 2000). Trauma-exposed participants were selected based on the
relationship between trauma and dissociation and to reduce restriction of
range resulting from the floor effect typically found on measures of psychopathology in nonclinical samples. The present study focused on the
assessment of depersonalization as a dimensional construct and not as a
taxon.
Measures
Measures were administered as part of a larger battery that included a
demographics form, three measures of health beliefs and behaviors not relevant to the present study, the three depersonalization measures (DES, CDS,
Downloaded by [Auburn University] at 10:21 25 October 2012
Journal of Trauma & Dissociation, 13:539–553, 2012
543
and MDI), the Life Events Checklist (LEC), and the Personality Assessment
Inventory (PAI).
The DES is a 28-item measure of disturbances in identity, memory, and
awareness; depersonalization; and absorption. Respondents rate symptom
frequency from 0% to 100% in increments of 10%. The DES does not define
a time period for symptom assessment. Although the DES was created as a
general dissociation measure, several factor analytic studies have identified
three subscales: amnesia, absorption, and depersonalization (for a review,
see Stockdale et al., 2002). In the present study, the 6-item depersonalization
subscale (Items 7, 11, 12, 13, 27, and 28) identified in Carlson et al.’s (1991)
original factor analysis of the DES and used in most subsequent studies was
analyzed. The DES has been found to have strong psychometric properties
(Bernstein & Putnam, 1986; van IJzendoorn & Schuengel, 1996). Although
most of these studies apply to the DES as a whole and are not specific to
the depersonalization subscale, available psychometric evidence for the DES
depersonalization subscale supports its internal consistency (.84–.87) and
temporal stability (.84–.92; Dubester & Braun, 1995) as well as its criterionrelated validity, in that DES depersonalization scores were able to predict
depersonalization disorder diagnosis (Simeon, Smith, Knutelska, & Smith,
2008).
There are several limitations to the DES as a measure of depersonalization, all having to do with content validity (see Haynes, Richard, &
Kubany, 1995). First, the content validation process for the DES was not
explicitly described, so there is insufficient information as to how depersonalization was defined and how items were matched to key aspects of the
construct. Second, the depersonalization subscale used in most DES studies includes an item assessing auditory hallucinations, which is inconsistent
with current conceptualizations of depersonalization that require symptoms
to be nonpsychotic (Hunter et al., 2003). Third, DES depersonalization items
represent more extreme forms of depersonalization, such as out-of-body
experiences, and underrepresent less extreme phenomena associated with
depersonalization.
The CDS is a 29-item measure of depersonalization. Respondents rate
items on separate scales for frequency (0 = never to 4 = all the time) and
duration (1 = few seconds to 6 = more than a week) and report symptoms
that have occurred in the past 6 months. The CDS was developed partly in
response to the reliance of existing measures on overly narrow definitions of
depersonalization. To address this issue, the authors defined depersonalization as a syndrome including not only feelings of unreality and detachment
but also emotional numbing, heightened self-observation, and perceptual
distortions. The initial item pool for the CDS was based on a comprehensive literature review and Sierra and Berrios’s (1998) neurobiological model.
An effort was made to represent both extreme (e.g., “I have the feeling
of being outside my body”) and more subtle (e.g., “I feel detached from
Downloaded by [Auburn University] at 10:21 25 October 2012
544
C. A. Blevins et al.
memories of things that have happened to me—as if I had not been involved
in them”) phenomena.
Initial reliability and validity evidence for the CDS supports its
psychometric merit. The CDS has been found to demonstrate excellent
internal consistency (.89) and split-half reliability (.92) as well as good
criterion-related validity in that CDS scores were able to differentiate individuals with depersonalization disorder from individuals with anxiety and
temporal lobe epilepsy (Sierra & Berrios, 2000). The utility of the CDS in
nonclinical populations is limited to a few studies using an abridged version
of the CDS in a German general population (e.g., Michal et al., 2009) and
several small healthy control groups (e.g., Sierra et al., 2002).
The MDI is a 30-item measure that assesses six types of dissociation:
disengagement, depersonalization, derealization, emotional constriction,
memory disturbance, and identity dissociation. Respondents rate symptom
frequency on a 5-point scale (1 = never to 5 = very often) and report
symptoms that have occurred in the past month. Raw scale scores are calculated by summing the five item scores for each scale, which may then
be converted to standardized T scores. The MDI was standardized using
university, clinical, and community samples. Briere (2002) found evidence
of good reliability and validity for the MDI. Internal consistency coefficients
for the MDI depersonalization and derealization scales ranged from .77 to
.93 across the three samples. In addition, the MDI depersonalization and
derealization scales demonstrated good criterion-related validity in that MDI
scores predicted PTSD diagnosis.
The major limitation of the MDI is the lack of additional psychometric
studies, with only one such study currently in the literature (Briere et al.,
2005). Another limitation concerns the splitting of depersonalization items
(e.g., “Feeling like you didn’t belong in your body”) and derealization items
(e.g., “Suddenly things around you not feeling real or familiar”) into separate
scales. Given the lack of support for distinguishing depersonalization and
derealization (as previously discussed; see Briere et al., 2005), and given
that the DES depersonalization subscale and the CDS include both types of
items, the MDI depersonalization and derealization items were combined
into a single scale for all analyses in the present study. A final limitation of
the MDI is that the content validation process for the scales was not fully
described, and thus it is not clear how the initial item pool was created or
how items were mapped onto scales.
The LEC, the self-report trauma assessment of the Clinician-Administered
PTSD Scale (Blake et al., 1995), is a list of 17 categories of potentially
traumatic events. Respondents indicate whether they have experienced, witnessed, or learned about or were never exposed to each type of event.
If participants endorsed at least one LEC category, they identified the
worst event and completed several items assessing whether that event
met DSM–IV–TR Criterion A1 for PTSD. The LEC demonstrated adequate
Journal of Trauma & Dissociation, 13:539–553, 2012
545
Downloaded by [Auburn University] at 10:21 25 October 2012
psychometric properties in an undergraduate sample (Gray, Litz, Hsu, &
Lombardo, 2004).
The PAI (Morey, 2007) is a 344-item multiscale inventory that assesses
a broad range of psychopathology and personality traits. The PAI scales
have been found to have consistently high internal consistency and test–
retest reliability. In addition, support for the validity of the clinical scales has
been demonstrated in numerous correlational and criterion-group studies
(Morey, 2007). The following PAI scales and subscales were analyzed in the
current study: Inconsistency, Infrequency, Negative Impression Management,
Conversion, Anxiety, Obsessive-Compulsive, Traumatic Stress, Depression,
Mania, Paranoia, Schizophrenia, Identity Problems, and Antisocial Features.
Procedure
Measures were administered online in a university computer lab. After
providing informed consent, participants completed a demographics form,
followed by the LEC. Depersonalization measures were administered in random order within one block, and the health measures were administered in
random order within a second block. The presentation of the two blocks
was also randomized. The PAI was always administered last.
A total of 277 participants completed the questionnaire session.
Of those, 68 were excluded based on (a) an index event that did not
meet Criterion A1 (n = 28), (b) an invalid PAI profile as indicated by
an Inconsistency score ≥73 T or an Infrequency score ≥75 T (n = 38;
Morey, 2007), or (c) having completed only the demographics questionnaire and no other measure (n = 2). Therefore, the final sample consisted
of 209 participants.
Data Analyses
Missing data were analyzed using PASW 18 software. Missing data were
considered missing completely at random and were addressed by multiple
imputation, following guidelines in Enders (2010). Twenty complete data
sets were generated and pooled. The results discussed here were based on
the pooled data set.
Descriptive statistics and internal consistency coefficients for all measures were examined. Next, zero-order correlations were calculated to
evaluate convergent and discriminant relationships among the DES, CDS,
MDI, and PAI. Finally, statistics developed by Westen and Rosenthal (2003)
were used to investigate construct validity by examining the extent to which
the observed pattern of correlations matched the pattern of correlations
predicted by theory.
Westen and Rosenthal’s (2003) procedure is based on contrast analysis and permits the evaluation of specific hypotheses regarding patterns
546
C. A. Blevins et al.
of correlations. The first statistic, r alerting-CV , reflects the degree to which the
ordering of predicted versus obtained correlations is consistent. The second
statistic, r contrast-CV , is a more stringent test of the fit between the predicted and
obtained correlations that takes into account sample size, median intercorrelations among criterion, and the magnitudes of correlations between target
and criterion measures. In calculating r contrast-CV , we used Poythress et al.’s
(2010) procedure to convert Z scores into t values.
RESULTS
Downloaded by [Auburn University] at 10:21 25 October 2012
Descriptive Statistics and Internal Consistency
Descriptive statistics are presented in Table 1. Mean depersonalization and
dissociation scores were somewhat higher than scores found in previous
studies using student and other nonclinical samples (e.g., Briere, 2002; van
IJzendoorn & Schuengel, 1996). Consistent with the first hypothesis, the
CDS and the MDI depersonalization scale exhibited high internal consistency
(αs = .93 and .90, respectively), and the DES depersonalization scale exhibited adequate internal consistency (α = .75). Inter-item correlations were
analyzed as an additional index of internal consistency. In general these fell
in the recommended range of .15 to .50 (Clark & Watson, 1995) for all three
measures, with a range of .12 to .61 (M = .33) for the DES, .09 to .67 (M =
.34) for the CDS, and .21 to .69 (M = .49) for the MDI.
Correlation Analyses
Convergent and discriminant correlations are shown in the left side of
Table 2. Consistent with the second hypothesis, the highest correlations
were found for the convergent correlations among the depersonalization
measures, which ranged from r = .63 (p < .01) between the DES and
CDS to r = .82 (p < .01) between the CDS and MDI. Consistent with the
third hypothesis, somewhat weaker but still strong correlations were found
between the three depersonalization measures and other dissociation measures, with rs ranging from .42 to .52 for the DES, .53 to .68 for the CDS,
and .51 to .73 for the MDI. Furthermore, moderate correlations were found
between the depersonalization measures and Identity Problems, Anxiety,
Conversion, and Traumatic Stress, with rs ranging from .31 to .37 for the
DES, .40 to .46 for the CDS, and .42 to .50 for the MDI. Finally, the weakest correlations were found between the depersonalization measures and
Obsessive-Compulsive, Mania, and Antisocial Features, with rs ranging from
.16 to .25 for the DES, .22 to .28 for the CDS, and .22 to .31 for the MDI.
A few discriminant correlations were higher than expected, specifically the correlations between each of the depersonalization measures and
Journal of Trauma & Dissociation, 13:539–553, 2012
547
TABLE 1 Descriptive Statistics for the DES, CDS, MDI, and PAI
Downloaded by [Auburn University] at 10:21 25 October 2012
Measure
DES
Depersonalization/
Derealization
Absorption
Amnesia
CDS
MDI
Depersonalization/
Derealization
Disengagement
Emotional
Constriction
Memory Disturbance
Identity Dissociation
PAI validity scale
NIM
PAI clinical scales
SOM-C
ANX
ARD-T
ARD-O
DEP
MAN
PAR
SCZ
BOR-I
ANT
No. of
items
Possible
range
Observed
range
M
SD
α
28
6
0–100
0–100
9–52
5–70
20.8
13.7
9.3
7.6
.90
.75
16
6
29
0–100
0–100
0–290
7–67
6–57
0–226
26.2
13.6
25.9
12.4
8.1
28.4
.87
.66
.93
10
10–50
10–42
14.1
5.4
.90
5
5
44–125
46–131
44–125
46–131
73.7
60.0
18.2
18.1
.86
.91
5
5
45–172
47–283
45–159
47–224
66.8
54.8
22.1
21.2
.80
.78
9
44–144
44–92
50.8
9.8
.68
8
24
8
8
24
24
24
24
6
24
43–114
34–103
41–99
25–89
35–111
25–103
29–112
32–124
36–89
36–115
43–105
34–96
41–99
30–86
35–101
29–86
36–86
33–92
36–86
38–90
48.8
55.6
55.5
50.6
54.0
54.0
54.9
49.4
57.8
57.0
9.0
11.7
13.3
11.7
12.3
11.4
11.0
11.1
11.3
11.2
.79
.91
.89
.66
.91
.84
.85
.85
.65
.83
Notes: N = 209. T scores derived from a trauma-exposed adult community standardization sample are
reported for MDI Disengagement, Emotional Constriction, Memory Disturbance, and Identity Dissociation
scores. T scores derived from a census-matched standardization sample are reported for the PAI scales.
Raw scores are reported for the DES scales, the CDS, and the MDI Depersonalization/Derealization
scale. DES = Dissociative Experiences Scale; CDS = Cambridge Depersonalization Scale; MDI =
Multiscale Dissociation Inventory; MDI Depersonalization/Derealization = MDI Depersonalization and
Derealization Scales combined; PAI = Personality Assessment Inventory; NIM = Negative Impression
Management; SOM-C = Conversion; ANX = Anxiety; ARD-T = Traumatic Stress; ARD-O = ObsessiveCompulsive; DEP = Depression; MAN = Mania; PAR = Paranoia; SCZ = Schizophrenia; BOR-I = Identity
Problems; ANT = Antisocial Features.
Schizophrenia (rs = .51–.61) and Paranoia (rs = .34–.41). To examine
the influence of negative response bias, we computed partial correlations,
controlling for Negative Impression Management, and report them in parentheses in Table 2. After we controlled for Negative Impression Management,
the associations between the depersonalization measures and PAI scales
that remained significant included DES with Schizophrenia (r = .24); CDS
with Depression, Identity Problems, and Schizophrenia (rs = .24–.33); and
MDI with Depression, Identity Problems, Schizophrenia, Anxiety, Traumatic
Stress, and Mania (rs = .18–.34).
548
C. A. Blevins et al.
TABLE 2 Predicted and Observed Correlations Between Depersonalization Measures and
Criterion Measures, Raw λs, and Integer Values of Raw λs
Predicted correlations and λs
Observed correlations
Downloaded by [Auburn University] at 10:21 25 October 2012
Criterion
variable
DES-DP/DR
CDS
MDI-DP/DR
MDI-ECON
MDI-DENG
DES-ABS
MDI-MEMD
MDI-IDDIS
DES-AMN
PAI-DEP
PAI-BOR-I
PAI-SCZ
PAI-ANX
PAI-SOM-C
PAI-ARD-T
PAI-ARD-O
PAI-PAR
PAI-MAN
PAI-ANT
DES-DP/DR
r(pr)
.63∗
.73∗
.52∗
.42∗
.51∗
.52∗
.51∗
.47∗
.43∗
.32∗
.51∗
.35∗
.31∗
.37∗
.16∗
.34∗
.25∗
.25∗
(.48∗ )
(.62∗ )
(.42∗ )
(.26∗ )
(.37∗ )
(.36∗ )
(.33∗ )
(.35∗ )
(.13)
(.10)
(.24∗ )
(.10)
(–.02)
(.08)
(.00)
(.03)
(.11)
(.12)
CDS
r(pr)
.82∗
.66∗
.58∗
.60∗
.68∗
.53∗
.55∗
.56∗
.46∗
.61∗
.40∗
.42∗
.44∗
.22∗
.40∗
.28∗
.22∗
(.72∗ )
(.59∗ )
(.43∗ )
(.47∗ )
(.56∗ )
(.31∗ )
(.43∗ )
(.27∗ )
(.24∗ )
(.33∗ )
(.11)
(.06)
(.10)
(.05)
(.05)
(.13)
(.06)
MDI-DP/DR
r(pr)
.71∗
.64∗
.62∗
.73∗
.61∗
.51∗
.56∗
.45∗
.60∗
.45∗
.42∗
.50∗
.22∗
.41∗
.31∗
.23∗
(.66∗ )
(.52∗ )
(.51∗ )
(.63∗ )
(.44∗ )
(.37∗ )
(.28∗ )
(.25∗ )
(.34∗ )
(.20∗ )
(.08)
(.21∗ )
(.05)
(.09)
(.18∗ )
(.08)
Predicted
r
Raw
λs
Raw λs as
integers
.80
.80
.80
.60
.60
.60
.50
.50
.50
.50
.50
.50
.40
.40
.40
.20
.20
.10
.10
.34
.34
.34
.14
.14
.14
.04
.04
.04
.04
.04
.04
−.06
−.06
−.06
−.26
−.26
−.36
−.36
3
3
3
1
1
1
0
0
0
0
0
0
−1
−1
−1
−3
−3
−4
−4
Notes: N = 209. Partial correlations, controlling for PAI Negative Impression Management, are
reported in parentheses. DES-DP/DR = Dissociative Experiences Scale, Depersonalization/Derealization
Scale; CDS = Cambridge Depersonalization Scale; MDI-DP/DR = Multiscale Dissociation Inventory,
Depersonalization and Derealization Scales; MDI-ECON = MDI Emotional Constriction Scale; MDIDENG = MDI Disengagement Scale; DES-ABS = DES Absorption Scale; MDI-MEMD = MDI Memory
Disturbance Scale; MDI-IDDIS = MDI Identity Dissociation Scale; DES-AMN = DES Amnesia Scale; PAI =
Personality Assessment Inventory; DEP = Depression; BOR-I = Identity Problems; SCZ = Schizophrenia;
ANX = Anxiety; SOM-C = Conversion; ARD-T = Traumatic Stress; ARD-O = Obsessive-Compulsive;
PAR = Paranoia; MAN = Mania; ANT = Antisocial Features.
∗
p < .01.
Effect Size Indices r alerting-CV and r contrast-CV
Predicted correlations and λ values used to compute r alerting-CV and r contrast-CV
are shown on the right side of Table 2. The results of these analyses are
shown in Table 3. Large values for r alerting-CV and r contrast-CV were found for
the DES depersonalization scale, the CDS, and the MDI depersonalization
scale (r alerting-CV = .88, .88, and .90, respectively; r contrast-CV = .70, .78, and .83,
respectively). This suggests substantial correspondence between theoretical
predictions and observed correlations. The 95% confidence interval around
the DES r contrast-CV effect size did not overlap the MDI confidence interval. This
suggests a weaker match between predicted and observed correlations for
the DES than for the MDI. Neither of the other two comparisons of r contrast-CV
effect size confidence intervals were non-overlapping.
Journal of Trauma & Dissociation, 13:539–553, 2012
549
Downloaded by [Auburn University] at 10:21 25 October 2012
TABLE 3 Effect Size Statistics r alerting-CV and r contrast-CV for
Depersonalization Measures
Quantity
DES-DP/DR
CDS
MDI-DP/DR
r alerting-CV
r contrast-CV
95% CI
From
To
Z contrast
t contrast
pcontrast
.88
.70
.88
.78
.90
.83
.62
.76
11.68
13.92
<.001
.72
.83
13.98
18.07
<.001
.78
.87
15.43
21.19
<.001
Notes: DES-DP/DR = Dissociative Experiences Scale,
Depersonalization/Derealization Scale; CDS = Cambridge
Depersonalization Scale; MDI-DP/DR = Multiscale Dissociation
Inventory, Depersonalization and Derealization Scales; CI =
confidence interval.
DISCUSSION
In this study, the psychometric properties of three depersonalization measures were examined in trauma-exposed college students. First, scores on
the three measures exhibited adequate (DES) to strong (CDS and MDI) internal consistency as indicated by coefficient alpha and satisfactory internal
consistency as indicated by inter-item correlations. Second, all three measures demonstrated substantial convergent validity. However, the strongest
convergent correlation was between the CDS and MDI, which was stronger
than the correlation between the DES and either the CDS or MDI. Third,
the results generally support the discriminant validity of the depersonalization measures. The DES, CDS, and MDI correlated most strongly with
other measures of dissociation; less strongly with measures of moderately
related constructs, such as anxiety and PTSD; and least strongly with measures of relatively unrelated constructs, such as mania and antisocial features.
Finally, the high degree of congruence between the predicted and observed
patterns of correlations was reflected in large effect size indices r alerting-CV
and r contrast-CV . The MDI depersonalization scale demonstrated the best match
between predicted and observed correlations, followed by the CDS, then the
DES depersonalization scale.
Content validity was also examined. Because the CDS is based on a comprehensive literature review and clear theoretical model, its items appear to
provide the best coverage of the depersonalization construct, including core
and associated symptoms. Items on the MDI depersonalization and derealization scales reflect a narrower definition of depersonalization, and coverage is
limited primarily to core symptoms of feelings of unreality and detachment.
Items on the DES depersonalization scale appear to underrepresent the full
construct, focusing primarily on more extreme forms of detachment. In sum,
Downloaded by [Auburn University] at 10:21 25 October 2012
550
C. A. Blevins et al.
the MDI and CDS demonstrate better content validity, internal consistency,
convergent validity, and construct validity as measured by rcontrast-CV . Thus,
overall the findings most strongly support the use of the MDI and CDS as
measures of depersonalization in this population.
This study has several limitations. First, data are based on self-report
and thus are subject to response biases. The possible effects of inconsistent,
careless, and random responding were addressed by excluding participants
who exceeded the recommended cutoffs on PAI scales measuring these
response styles. In addition, we examined the effects of negative impression
management by calculating partial correlations between the depersonalization measures and all other measures, controlling for the PAI Negative
Impression Management scale. Second, Westen and Rosenthal’s (2003) procedure requires a priori selection of external correlates. Although a variety
of relevant variables were used in this study, the findings might have differed with the selection of alternative correlates. Third, participants were a
nonclinical sample. Although an effort was made to increase variability on
measures of psychopathology by including participants with self-identified
trauma exposure, participants were likely relatively well adjusted overall.
Consistent with this concern, the distributions of scores does not extend to
the full possible range. Nonetheless, there does not appear to be a significant
restriction of range, and the obtained correlations closely fit the predicted
size and pattern. Furthermore, one aim of this study was to contribute to
the available evidence of the validity of the depersonalization measures in
a nonclinical population. Given the reported prevalence of depersonalization in normal individuals (Hunter et al., 2004), establishing evidence for
the appropriate use of self-report depersonalization measures outside of a
clinical setting is an important step in student and community research.
Given the limited number of available psychometric studies of depersonalization measures, this study contributes to the literature by examining
the convergent and discriminant validity of three depersonalization measures and by generalizing findings to a nonclinical sample. The pattern of
convergent and discriminant validity coefficients supports the conceptualization of depersonalization as a unique type of dissociation. In light of this
finding, measures assessing specific types of dissociation (e.g., the CDS) or
multiple types of dissociation (e.g., the MDI) may be considered more useful than global measures of general dissociation. As noted by Briere et al.
(2005), the assessment of specific dissociative symptoms allows for more
accurate information and specific clinical intervention. Detailed data from
well-validated measures of depersonalization provide clinicians with a useful
tool in creating treatment goals and tracking treatment progress.
Depersonalization is a distressing condition that may lead to fears of
loss of control, functional impairment due to disturbances in early attentional and perceptual processing (Guralnik, Schmeidler, & Simeon, 2000),
and interpersonal stress due to a profound sense of emotional disconnection.
Journal of Trauma & Dissociation, 13:539–553, 2012
551
Downloaded by [Auburn University] at 10:21 25 October 2012
When comorbid with other disorders, depersonalization is associated with
greater clinical severity and poorer response to treatment (Mula et al., 2007).
Simeon (2004) suggested that depersonalization may be underdiagnosed for
several reasons, including clinicians’ unfamiliarity with the construct and
the reluctance of individuals experiencing depersonalization to discuss their
symptoms because of their fear of being perceived as crazy by others and
difficulty describing the symptoms. Completing a measure that describes
such depersonalization experiences may alone be therapeutic to individuals struggling to articulate their experience. For these reasons, the continued
process of construct validation of depersonalization measures is warranted
to enhance scientific understanding of depersonalization, provide clinicians
with a validated instrument to screen for depersonalization, and facilitate the
development of empirically supported interventions.
REFERENCES
American Psychiatric Association. (2000). Diagnostic and statistical manual of
mental disorders (4th ed., text rev.). Washington, DC: Author.
Bernstein, E. M., & Putnam, F. W. (1986). Development, reliability, and validity of a dissociation scale. Journal of Nervous and Mental Disease, 174,
727–735.
Blake, D. D., Weathers, F. W., Nagy, L. M., Kaloupek, D. G., Gusman, F. D., Charney,
D. S., & Keane, T. M. (1995). The development of a clinician-administered PTSD
scale. Journal of Traumatic Stress, 8, 75–90.
Bremner, J. D., Steinberg, M., Southwick, S. M., Johnson, D. R., & Charney, D. S.
(1993). Use of the Structured Clinical Interview for DSM-IV dissociative disorders for systematic assessment of dissociative symptoms in posttraumatic stress
disorder. American Journal of Psychiatry, 150, 1011–1014.
Briere, J. (2002). Multiscale Dissociation Inventory professional manual. Odessa, FL:
Psychological Assessment Resources.
Briere, J., Weathers, F. W., & Runtz, M. (2005). Is dissociation a multidimensional
construct? Data from the Multiscale Dissociation Inventory. Journal of Traumatic
Stress, 18, 221–231.
Carlson, E. B., Putnam, F. W., Ross, C. A., Anderson, G., Clark, P., Torem, M., . . .
Braun, B. G. (1991). Factor analysis of the Dissociative Experiences Scale: A
multicenter study. In B. G. Braun & E. B. Carlson (Eds.), Proceedings of the
Eighth International Conference on Multiple Personality and Dissociative States
(p. 16). Chicago, IL: Rush.
Clark, L. A., & Watson, D. (1995). Constructing validity: Basic issues in objective scale
development. Psychological Assessment, 7, 309–319.
Cox, B. J., & Swinson, R. P. (2002). Instruments to assess depersonalizationderealization in panic disorder. Depression and Anxiety, 15, 172–175.
Dubester, K. A., & Braun, B. G. (1995). Psychometric properties of the Dissociative
Experiences Scale. Journal of Nervous and Mental Disease, 183, 231–235.
Enders, C. K. (2010). Applied missing data analysis. New York, NY: Guilford Press.
Downloaded by [Auburn University] at 10:21 25 October 2012
552
C. A. Blevins et al.
Gray, M. J., Litz, B. T., Hsu, J., & Lombardo, T. W. (2004). Psychometric properties
of the Life Events Checklist. Assessment, 11, 330–341.
Guralnik, O., Schmeidler, J., & Simeon, D. (2000). Feeling unreal: Cognitive
processes in depersonalization. American Journal of Psychiatry, 157, 103–109.
Haynes, S. N., Richard, D. C. S., & Kubany, E. S. (1995). Content validity in
psychological assessment: A functional approach to concepts and methods.
Psychological Assessment, 7, 238–247.
Hunter, E. C. M., Phillips, M. L., Chalder, T., Sierra, M., & David, A. S.
(2003). Depersonalization disorder: A cognitive-behavioural conceptualisation.
Behavior Research and Therapy, 41, 1451–1467.
Hunter, E. C. M., Sierra, M., & David, A. S. (2004). The epidemiology of depersonalization and derealisation—A systematic review. Social Psychiatry and
Psychiatric Epidemiology, 39, 9–18.
Michal, M., Wiltink, J., Subic-Wrana, C., Zwerenz, R., Tuin, I., Lichy, M., . . . Beutel,
M. E. (2009). Prevalence, correlates, and predictors of depersonalization experiences in the German general population. Journal of Nervous and Mental
Disease, 197, 499–506.
Morey, L. C. (2007). Personality Assessment Inventory professional manual (2nd ed.).
Odessa, FL: Psychological Assessment Resources.
Mula, M., Pini, S., & Cassano, G. B. (2007). The neurobiology and clinical significance of depersonalization in mood and anxiety disorders: A critical reappraisal.
Journal of Affective Disorders, 99, 91–99.
Phillips, M. L., Medford, N., Senior, C., Bullmore, E. T., Suckling, J., Brammer, M.
J., . . . David, A. S. (2001). Depersonalization disorder: Thinking without feeling.
Psychiatry Research: Neuroimaging, 108, 145–160.
Poythress, N. G., Lilienfeld, S. O., Skeem, J. L., Douglas, K. S., Edens, J. F., Epstein,
M., & Patrick, C. J. (2010). Using the PCL-R to help estimate the validity of two
self-report measures of psychopathy with offenders. Assessment, 17, 206–219.
Radovic, F., & Radovic, S. (2002). Feelings of unreality: A conceptual and phenomenological analysis of the language of depersonalization. Philosophy,
Psychiatry, and Psychology, 9, 271–279.
Sierra, M., & Berrios, G. E. (1996). A case of depersonalization. History of Psychiatry,
7, 451–461.
Sierra, M., & Berrios, G. E. (1997). Depersonalization: A conceptual history. History
of Psychiatry, 8, 213–229.
Sierra, M., & Berrios, G. E. (1998). Depersonalization: Neurobiological perspectives.
Biological Psychiatry, 44, 898–908.
Sierra, M., & Berrios, G. E. (2000). The Cambridge Depersonalisation Scale: A new
instrument for the measurement of depersonalisation. Psychiatry Research, 93,
153–164.
Sierra, M., & Berrios, G. E. (2001). The phenomenological stability of depersonalization: Comparing the old with the new. Journal of Nervous and Mental Disease,
189, 629–636.
Sierra, M., Senior, C., Dalton, J., McDonough, M., Bond, A., Phillips, M. L., . . . David,
A. S. (2002). Autonomic response in depersonalization disorder. Archives of
General Psychiatry, 59, 833–838.
Simeon, D. (2004). Depersonalization disorder: A contemporary overview. CNS
Drugs, 18, 343–354.
Downloaded by [Auburn University] at 10:21 25 October 2012
Journal of Trauma & Dissociation, 13:539–553, 2012
553
Simeon, D., Guralnik, O., Knutelska, M., & Nelson, D. (2004). Dissection of schizotypy and dissociation in depersonalization disorder. Journal of Trauma &
Dissociation, 5(4), 111–119.
Simeon, D., Smith, R. J., Knutelska, M., & Smith, L. M. (2008). Somatoform
dissociation in depersonalization disorder. Journal of Trauma & Dissociation,
9, 335–348.
Simeon, D., Stein, D. J., & Hollander, E. (1995). Depersonalization disorder and
self-injurious behavior. Journal of Clinical Psychiatry, 56, 36–39.
Spitzer, C., Spelsberg, B., Grabe, H., Mundt, B., & Freyberger, H. J. (1999).
Dissociative experiences and psychopathology in conversion disorders. Journal
of Psychosomatic Research, 46, 291–294.
Stockdale, G. D., Gridley, B. E., Balogh, D. W., & Holtgraves, T. (2002).
Confirmatory factor analysis of single- and multiple-factor competing models
of the Dissociative Experiences Scale in a nonclinical sample. Assessment, 9,
94–106.
van IJzendoorn, M. H., & Schuengel, C. (1996). The measurement of dissociation
in normal and clinical populations: Meta-analytic validation of the Dissociative
Experiences Scale (DES). Clinical Psychology Review, 16, 365–382.
Watson, D. (2001). Dissociations of the night: Individual differences in sleeprelated experiences and their relation to dissociation and schizotypy. Journal
of Abnormal Psychology, 110, 526–535.
Westen, D., & Rosenthal, R. (2003). Quantifying construct validity: Two simple
measures. Journal of Personality and Social Psychology, 84, 608–618.
Zanarini, M. C., Ruser, T., Frankenburg, F. R., & Hennen, J. (2000). The dissociative
experiences of borderline patients. Comprehensive Psychiatry, 41, 223–227.
View publication stats