The Adult Repetitive Behaviours Questionnaire-2 (RBQ-2A): A Self-Report Measure of Restricted and Repetitive Behaviours
The Adult Repetitive Behaviours Questionnaire-2 (RBQ-2A): A Self-Report Measure of Restricted and Repetitive Behaviours
Sarah L. Barrett 0 1 2 3
Mirko Uljarevic´ 0 1 2 3
Emma K. Baker 0 1 2 3
Amanda L. Richdale 0 1 2 3
Catherine R. G. Jones 0 1 2 3
Susan R. Leekam 0 1 2 3
0 Olga Tennison Autism Research Centre, Cooperative Research Centre for Living with Autism Spectrum Disorders (Autism CRC), School of Psychology and Public Health, La Trobe University , Bundoora 3086 , Australia
1 Wales Autism Research Centre, School of Psychology, Cardiff University , Tower Building, Park Place, Cardiff CF10 3AT , UK
2 & Sarah L. Barrett
3 Olga Tennsion Autism Research Centre, School of Psychology and Public Health, La Trobe University , Melbourne , Australia
In two studies we developed and tested a new self-report measure of restricted and repetitive behaviours (RRB) suitable for adults. In Study 1, The Repetitive Behaviours Questionnaire-2 for adults (RBQ-2A) was completed by a sample of 163 neurotypical adults. Principal components analysis revealed two components: Repetitive Motor Behaviours and Insistence on Sameness. In Study 2, the mean RBQ-2A scores of a group of adults with autism spectrum disorder (ASD; N = 29) were compared to an adult neurotypical group (N = 37). The ASD sample had significantly higher total and subscale scores. These results indicate that the RBQ-2A has utility as a selfreport questionnaire measure of RRBs suitable for adults, with potential clinical application.
Repetitive behaviours; Adults; Autism; Principal components analysis
Restricted and repetitive behaviours (RRBs) form one of
the core diagnostic criteria for autism spectrum disorder
(ASD; American Psychiatric Association 2013; World
Health Organization 1993). This class of behaviours,
driven by a desire for sameness and dislike of change (Kanner
1943), includes a wide range of motor and sensory
behaviours and restricted activities that are highly frequent in
their repetition and invariant in their manifestation. These
behaviours are also found in neurotypical (NT) individuals
and those with other developmental disorders and
neuropsychological conditions (for reviews see Langen et al.
2011; Leekam et al. 2011).
Caregiver interviews and questionnaires are the most
frequently used measures of RRBs. Observation measures,
while effective for measuring motor and sensory behaviours,
may be less sensitive for measuring less frequent restricted
behaviours (e.g., Harrop et al. 2014; Honey et al. 2012).
Factor analytic studies of RRBs using caregiver interviews
and questionnaires have identified two sub-groups; one
comprising repetitive sensory and motor behaviours such as
hand flapping and rocking (RSMB), and the other
comprising more abstract behaviours such as routines and
circumscribed interests, which are collectively referred to as
insistence on sameness (IS). This binary grouping has been
found in as many as eleven previous studies of individuals
with ASD (e.g., Bishop et al. 2006; Bishop et al. 2013;
Cuccaro et al. 2003; Georgiades et al. 2010; Lidstone et al.
2014; Mooney et al. 2009; Papageorgiou et al. 2008; Richler
et al. 2007; Richler et al. 2010; Shao et al. 2003; Szatmari
et al. 2006) and in studies of NT children (e.g., Evans et al.
1997; Leekam et al. 2007b).
However, other studies have identified alternative
solutions ranging from three to five different factors (e.g.,
Bishop et al. 2013; Honey et al. 2008; Lam and Aman
2007; Lam et al. 2008; Mirenda et al. 2010). Such
differences may be due to the use of RRB measures that are
different in terms of their scope and format, such as the
Repetitive Behaviour Scale-Revised (RBS-R; Bodfish et al.
1999) and the Autism Diagnostic Interview-Revised
(ADIR; Lord et al. 1994). For example, the RBS-R is a
questionnaire comprising questions about self-injurious
behaviours, which may form a separate factor (e.g., Bishop
et al. 2013; Mirenda et al. 2010). On the other hand, the
ADI-R is an interview that has been reported to
undersample RRBs (Lam et al. 2008).
In contrast to an extensive literature on RRBs in
children with ASD and in children with neurotypical
development, there is limited research on RRBs in adulthood.
Some factor analysis studies of RRBs in ASD have
included adults in their samples (e.g., Cuccaro et al. 2003;
Georgiades et al. 2010; Lam et al. 2008; Papageorgiou
et al. 2008; Shao et al. 2003). However, conclusions from
these studies about RRBs in adults are limited; either
because the samples span a limited age range, or because
the adult samples were not separated from the child
samples in the analysis. A minority of studies of ASD that have
directly compared RRB symptoms in adults with those in
children have found lower levels of RRBs in adults than in
children (Esbensen et al. 2009; Fecteau et al. 2003; Piven
et al. 1995). This pattern remains the same across the
subtypes of RRBs and is consistent across gender and
intellectual disability (ID), with the exception that motor
stereotypies do not reduce as much over time in adults with
comorbid ID (Esbensen et al. 2009). These findings
indicate that RRBs in adulthood may present differently than in
childhood, which has implications for clinical practice and
Caregiver-report methods such as the RBS-R are
suitable for use with adults. However, certain items may not be
applicable, such as items related to play behaviours and
toys. Furthermore, once an adult leaves home caregivers
may not be able to report as accurately on their behaviours.
Currently there are few self-report measures of RRBs
available that are suitable for adults. While there is a
selfreport interview of obsessive-compulsive symptoms, the
Yale-Brown Obsessive-Compulsive Scale (YBOCS;
Goodman et al. 1989), to our knowledge there are no
published self-report measures for the full range of RRBs
relevant to the diagnosis of ASD. RRBs and
obsessivecompulsive behaviours overlap but they do not capture the
same construct. For example, the YBOCS includes
questions about intrusive imagery, which is not a feature of
RRBs. The Autism-Spectrum Quotient (AQ; Baron-Cohen
et al. 2001) is a measure of autistic traits that includes items
related to RRBs (e.g., It does not upset me if my daily
routine is disturbed). However, factor analyses suggest that
the AQ does not provide an adequate or reliable assessment
of RRBs in NT adults (Kloosterman et al. 2011; Lau et al.
Therefore, in the current study we adapted and tested a
parent-report questionnaire to provide the first self-report
RRB questionnaire suitable for adults with ASD.
Following the pattern of previous research on RRBs in both NT
and ASD children, we assessed the questionnaire initially
in NT adults and then applied it to an ASD sample. In
contrast to research on RRBs in NT children, research on
the full range of RRBs in NT adults is sparse and limited to
particular behaviours such as pre-sleep rituals and
transition objects (Markt and Johnson 1993). Therefore, new
evidence on self-reported RRBs in NT individuals will
enable comparison with evidence from adults with ASD,
providing further insight into the presentation of these
behaviours in adults both with and without ASD. Beyond
comparison purposes, it would be useful to understand the
pattern of RRBs in an adult NT population. Furthermore,
given the increasing need by clinicians for briefer and more
streamlined methods for diagnosis, a self-report format for
eliciting information on RRBs in able adults has
application as a supplement to add information to other diagnostic
The Repetitive Behaviour Questionnaire-2 (RBQ-2;
Leekam et al. 2007b) is a twenty item questionnaire, with
items directly derived from a standardised clinical
interview tool, the Diagnostic Interview for Social and
Communication Disorders (DISCO; Wing et al. 2002). The
DISCO has good inter-rater reliability and discriminant
validity (Leekam et al. 2002; Maljaars et al. 2012; Nygren
et al. 2009) and shows strong agreement with outputs from
the ADI-R (Nygren et al. 2009) and Autism Diagnostic
Observation Schedule (ADOS; Maljaars et al. 2012). Items
from the DISCO and converging items from a
semistructured interview, the Repetitive Behaviours Interview
(RBI; Turner 1996, unpublished doctoral thesis), were
adapted into a questionnaire measure, the RBQ-2. The
RBQ-2 includes 20 RRB items; 13 identical items taken
from both interviews, five items unique to the DISCO and
two unique to the RBI (Leekam et al. 2007b).
The RBQ-2 was originally tested in a large sample
(N = 679) of NT two-year-olds (Leekam et al. 2007b).
There was satisfactory endorsement of all RRBs, and
exploratory factor analysis supported both a four- and
twofactor solution. The four-factor solution comprised:
repetitive motor movements, adherence to routine, restricted
interests, and unusual sensory interests. The two-factor
solution comprised RSMB, which corresponded to
repetitive motor movements and unusual sensory interests, and
IS, which corresponded to adherence to routine and
restricted interests. The reliability and validity of the
RBQ2 has since been further supported in NT 15-month-olds
(Arnott et al. 2010). Finally, the RBQ-2 has also been
assessed in children and adolescents with ASD (N = 120;
Lidstone et al. 2014). Reflecting Leekam et al.’s (2007b)
findings, principal components analysis (PCA) for this
ASD sample also resulted in two components: RSMB and
IS, with good internal consistency across the whole scale
(a = .86) and for both RSMB and IS (a = .79, a = .83,
respectively). Overall, the similarity of results across
studies, satisfactory endorsement of items and good
internal consistency support the construct validity of the RBQ-2
For the current research, the RBQ-2 was adapted into an
adult self-report questionnaire, the Adult RBQ-2
(RBQ2A). As the RBQ-2A has been adapted into a self-report
measure, it is only accessible to participants with sufficient
cognitive resources and verbal ability to complete the
questionnaire. Approximately half of children with ASD
are reported to have an IQ in the average range (e.g.,
Charman et al. 2011), suggesting that the RBQ-2A will be
accessible to a similar proportion of adults with ASD.
However, given the hetereogeneity of ASD, this represents
a potential limitation of the RBQ-2A. Nevertheless, there is
still need for a self-report measure of RRB for adults with
ASD for the reasons discussed earlier.
Two studies are reported here. In Study 1, to build upon
the findings with NT children, the RBQ-2A was
administered to a group of NT young adults. Consistent with the
majority of previous factor analytic research, PCA analysis
was used to identify factors and the internal consistency of
the measure was also assessed. In Study 2, the RBQ-2A
was administered to a sample of NT adults with a broader
age range and a sample with an ASD diagnosis to establish
whether the RRB scores in those with a diagnosis of ASD
was higher than those in the NT group. A secondary aim of
Study 2 was to assess whether the subscales derived from
Study 1 were reliable in a more representative sample.
For Study 1, the RBQ-2A was administered to a NT
university student sample and the structure of the RBQ-2A
assessed using principal components analysis (PCA). It was
expected that two components would emerge, as this
structure is the most consistent finding, and that they would
be broadly similar to that found in the original RBQ-2
(Leekam et al. 2007b; Lidstone et al. 2014). Its internal
consistency was also assessed using Cronbach’s alpha.
Finally, we also included the Autism-Spectrum Quotient
(AQ; Baron-Cohen, et al. 2001), which has been used
widely to assess the presence of a variety of autistic traits in
the general population (e.g., Hurst, Mitchell, Kimbrel,
Kwapil et al. 2007; Kloosterman et al. 2011; Stewart and
Austin 2009). It was expected that scores on the RBQ-2A
would be significantly correlated with scores on the AQ.
There were 163 UK university students (95 female, 67
male, 1 unreported) recruited, aged between 18 and
50 years (M = 21.32 years, SD = 4.67). Participants were
recruited via the university and social media. Psychology
undergraduates (N = 120) received course credits in
exchange for participation. Two participants scored at or
above the clinical cut-off of 32 on the AQ and were
removed from further analyses, resulting in a new sample
(N = 161) comprising 95 women, 65 men (1 unreported)
with a mean age of 21.28 years (SD = 4.69). The majority
(N = 136) were aged18–22 years.
The Adult Repetitive Behaviours Questionnaire-2
(RBQ2A): The original RBQ-2 caregiver questionnaire was first
adapted so that it could be used by adults in a self-report
format. The original RBQ-2 is sub-divided into five
sections as shown in Table 1. For three sections
(corresponding to items 1–6 and 13–19; responses are given on a
4-point scale, corresponding to never or rarely (1), mild or
occasional/one or more times daily (2), marked or notable/
15 or more times daily (3) and serious or severe/30 or more
times daily (4). The remaining items (7 to 12 and item 20)
are answered on a 3-point scale (see Table 1 for the
response options for each item). In previous studies, the
responses to these items are collapsed into a 3-point scale
to make means and standard deviations (SDs) comparable
across all items. The RBQ-2 may be scored in terms of
total mean score (ranging from 1 to 3).
The original RBQ-2 was adapted for use with adults by
editing the phrasing of questions. The phrase ‘‘does your
child’’ at the beginning of questions 1 to 19 was changed to
‘‘do you’’, and question 20 was changed from ‘‘what sort of
activity will your child choose if they are left to occupy
themselves?’’ to ‘‘what sort of activity will you choose if
you are left to occupy yourself?’’ Child-specific words such
as toys were either replaced with other similar concept
words (e.g., objects) or removed entirely from items 1, 2,
11 and 14. This edited version of the RBQ-2 was piloted
with a small group (N = 16; 8 male) with a mean age of
26.26 years (SD = 9.09 years). Even though the
questionnaire was only edited minimally, there was good
internal consistency for the scale (a = .73), a range of
responses (M = 1.51, SD = .24), and few participants
reported any difficulties with the questionnaire. This
Like to arrange items in rows or patterns?
Repetitively fiddle with items? (e.g. spin, twiddle, bang, tap, twist, or flick anything
Spin yourself around and around?**
Rock backwards and forwards, or side to side, either when sitting or when standing?***
Pace or move around repetitively (e.g. walk to and fro across a room, or around the same
path in the garden?)*
Make repetitive hand and/or finger movements? (e.g. flap, wave, or flick your hands or
Have a fascination with specific objects (e.g. trains, road signs, or other things?)
Like to look at objects from particular or unusual angles?*
Have a special interest in the smell of people or objects?
Have a special interest in the feel of different surfaces?*
Have any special objects you like to carry around?*
Collect or hoard items of any sort?
Play the same music, game or video, or read
the same book repeatedly?*
Insist on wearing the same clothes or refuse to
wear new clothes?*
Insist on eating the same foods, or a very small
range of foods, at every meal?*
Table 1 Study 1: frequencies, percentages, means and standard deviations of neurotypical participants’ responses to all twenty Adult Repetitive
Behaviour Questionnaire-2 items (N = 161)
Insist on things at home remaining the same? (e.g. furniture staying in the same
place, things being kept in certain places, or arranged in certain ways?)**
Get upset about minor changes to objects (e.g. flecks of dirt on your clothes,
minor scratches on objects?)
Insist that aspects of daily routine must remain the same?
Insist on doing things in a certain way or re-doing things until they ‘‘just
version of the RBQ-2A was not edited further before being
administered to the present sample.
The Autism-Spectrum Quotient (AQ): The AQ
(BaronCohen et al. 2001) is a self-report questionnaire assessing
the presence of autistic features in the general population,
(Baron-Cohen et al. 2001). It comprises 50 statements
based on the original triad of impairments (social
interaction, social communication and imagination; Wing and
Gould 1979), and other aspects of cognitive processing in
ASD. Each participant receives a score out of 50, with
higher scores indicating greater endorsement of autistic
traits. In most studies, a score of 32 is considered the
clinical cut-off for ASD as according to the original paper
(Baron-Cohen et al. 2001). Later research has
recommended a more stringent cut-off of 26 (Woodbury-Smith
et al. 2005). Here we chose to implement the the original
cut-off score of 32 in order to preserve sample size and
Procedure, Data Screening and Statistical Analyses
Ethical approval was obtained from the university’s School
of Psychology Ethics Committee, and informed consent
was obtained from the participants before they completed
the questionnaires. The online questionnaires were
presented on Google Documents, with the RBQ-2A presented
first followed by the AQ. The data were analysed using
To maintain consistency with previous research
(Leekam et al. 2007b; Lidstone et al. 2014) item 20 was
included in the total score but was removed before factor
analysis as its response scale differs to the other items
(Leekam et al. 2007b; see Table 1). In addition, for the
factor analysis stage only, items were removed before
analysis if 80% or more of the sample responded never
or rarely; this resulted in item 18 (clothing) being
excluded from the analysis. Responses were scored in
line with previous studies using a mean severity score
An initial PCA was run to obtain Eigenvalues for
each component. Components were extracted using
parallel analysis (Horn 1965) with the Monte Carlo PCA for
Parallel Analysis program. This is a more stringent
criterion for component extraction than Kaiser’s criterion or
the Scree plot (Tabachnick and Fidell 2014). Due to the
small sample size, we employed a relatively high cut-off
for determining what items were meaningfully associated
with a component; here the cut-off was .4 (as in
Honey et al. 2008; Szatmari et al. 2006) and
crossloading items were excluded. The internal consistency
for the whole scale and each of the resultant components
was also assessed by calculating Cronbach’s alpha (a)
Table 1 shows the endorsement, mean total scores and SD
for all 20 RBQ-2A items. For every item, at least 14.9 % of
the sample endorsed mild or occasional or higher. The
mean total score for all RBQ-2A items for the sample
(N = 161) ranged from 1 to 2.55 (M = 1.51, SD = .30).
The internal consistency of the whole scale was good
(Cronbach’s a = .83).
Principal Components Analysis (PCA)
Several participants had missing data (N = 13) across the
18 RBQ-2A items being included in the analysis. A
Missing Value Analysis was conducted on the dataset for these
18 items. As Little’s Missing Completely at Random test
was non-significant and the percentage of participants with
missing data was small (8.07 %) it was appropriate to
exclude these participants from the analysis (Tabachnick
and Fidell 2014).
The final sample used for the PCA comprised 148
participants (87 female, 60 male, 1 unreported) with a mean
age of 21.3 years (SD = 4.79; 22 participants were
23 years or older) and a mean total RBQ-2A score of 1.52
(SD = .30). The mean scores of the participants were
significantly positively skewed, as found in the analysis of
other RRB questionnaires. Age was also positively skewed
with five outliers. However, age was not significantly
correlated with RBQ-2A score (rs = .01, p = .88).
Therefore, to preserve variation and sample size these five
outliers remained in the PCA. Mean total AQ score was
13.82 (SD = 5.99), which was normally distributed.
Initial screening indicated that the assumptions of
sampling adequacy (Kaiser-Meyer-Olkin = .79),
multicollinearity and factorability were all met. The initial PCA
solution resulted in six components with eigenvalues
greater than one, explaining 62.03% of the variance.
Parallel analysis indicated that two components should be
retained, so the analysis was re-run specifying two
components. When running the PCA with oblique rotation
(Direct Oblimin), the correlation between the two
components was above .32, indicating oblique rotation should be
retained (Tabachnick and Fidell 2014).
This solution explained 35.83 % of the variance after
Direct Oblimin rotation. Table 2 shows the rotated item
loadings (from the pattern matrix), percentage of variance
explained and Cronbach’s alpha values for each of the
components. There were no cross-loading items, but four
items did not load sufficiently on to either component. The
first component corresponds approximately to RSMB but
with no sensory items; therefore it is named Repetitive
Motor Behaviours (RMB). The second corresponds to
insistence on sameness IS as in previous research. The
For the following analyses, non-parametric statistics were
used where the data were not normally distributed. Firstly,
the within-participant difference between sub-scale scores
was assessed. Mean total scores on both RMB and IS were
significantly positively skewed, although there were no
outliers. Table 2 shows the means, SDs, medians and
interquartile ranges (IQRs) of the two components. There
was a significant correlation between the two components
(rs = .35, p \ .001). A Wilcoxon’s signed ranks test
indicated that participants scored significantly more highly
on RMB than IS (Z = -2.79, p = .005). These results
indicate that there is a small but significant difference
between sub-scale scores.
Mean total score on the RBQ-2A was significantly and
positively correlated with mean total score on the AQ
(rs = .57, p \ .001), which remained significant when
removing two outliers on RBQ-2A (rs = .56, p \ .001).
Mean total AQ score was also significantly positively
correlated with both RMB (rs = .35, p \ .001) and IS
(rs = .54, p \ .001).
The aim of Study 1 was to develop and test the RBQ-2A as
a self-report measure of RRBs in NT adults. An existing
parent report measure of RRBs, the RBQ-2 (Leekam et al.
2007b), was adapted into an adult self-report measure and
administered to a university student sample. PCA resulted
in a two-component structure, one comprising motor
behaviours, RMB, and the other behaviours related to
routines and a preference for sameness, IS. As predicted,
scores on the RBQ-2A were also correlated with another
measure of autistic traits, the AQ (Baron-Cohen et al.
Table 2 Study 1: pattern matrix for principal components analysis of neurotypical data, percentage of variance explained, internal consistency
and descriptive statistics for each component
Rotated item loadings
Like to arrange items in rows or patterns?
Repetitively fiddle with items?
Spin yourself around and around?
Rock backwards and forwards, or side to side, either when sitting or when
Pace or move around repetitively
Make repetitive hand and/or finger movements?
Have a fascination with specific objects?
Like to look at objects from particular or unusual angles?
Have a special interest in the smell of people or objects?
Have a special interest in the feel of different surfaces?
Have any special objects you like to carry round?
Collect or hoard items of any sort?
Insist on things at home remaining the same?
Get upset about minor changes to objects?
Insist that aspects of daily routine must remain the same?
Insist on doing things in a certain way or re-doing things until they are ‘‘just
Play the same music, game or video, or read the same book repeatedly?
Insist on eating the same foods, or a very small range of foods, at every meal?
Bold denotes items that load on each factor (item loading [ .4)
The first component, RMB, is similar to RSMB found in
previous research with the RBQ-2 (e.g., Leekam et al.
2007b; Lidstone et al. 2014). Five of the six RMB items
consistently load onto the factor that in previous research
included motor and sensory items (RSMB), the exception
being item one, arranging objects. The major difference
between RMB found here and RSMB in previous research
is the lack of sensory items loading onto this component.
The second component corresponded to IS. This result was
more comparable to previous research using the RBQ-2 in
an ASD sample, with five items (13–17) loading in the
same way as in Lidstone et al.’s (Lidstone et al. 2014)
In summary, the components yielded by the present
PCA are similar to previous research with NT children and
autistic children using the RBQ-2, with the exception of
sensory items. Items two to six load onto RSMB in the
child version of the questionnaire (Leekam et al. 2007b;
Lidstone et al. 2014) and RMB in the present study, and
items 13 to 17 load onto IS across all three studies,
supporting the construct validity of the questionnaire.
The most probable reason for the difference between the
present PCA solution and previous research is that the
present sample comprised NT adults whereas previous
research examined NT children (Leekam et al. 2007b) and
children and adolescents with ASD (Lidstone et al. 2014).
Certain types of behaviours may be associated with
younger children or children with ASD rather than NT
adults. For example, mean scores on items 3 (spinning) and
11 (carrying around objects) were higher in NT children
(Arnott et al. 2010; Leekam et al. 2007b) than in the
present study. Moreover, autistic individuals show higher
levels of sensory symptoms than NT individuals (e.g.,
BenSasson et al. 2009; Kern et al. 2006; Leekam et al. 2007a;
Rogers and Ozonoff 2005) and these items were not well
endorsed by the present sample.
The different loading of certain items may also reflect
the fact that certain behaviours do not clearly fall into one
particular category. For example, eating a small range of
foods (item 19) formed part of IS in the present study but
has previously loaded on to RSMB (Lidstone et al. 2014) as
well as IS (Leekam et al. 2007b); eating a small range of
food may be a result of sensory issues or insistence on
sameness and is therefore conceptually related to both
There are some limitations in terms of the sample.
Firstly, the sample comprised only university students and
is therefore limited in age and IQ distribution. Second, it
might be considered that the size of the sample is relatively
small for PCA. However, the literature is equivocal
regarding the appropriate sample size for PCA and factor
analysis (e.g., Tabachnick and Fidell 2014; Williams et al.
2010) and the assumptions for PCA were met. Therefore,
the data were deemed suitable for analysis. Overall, the
results of Study 1 support the construct validity of the
RBQ-2A and suggest that it is useful as a self-report
questionnaire in an adult population.
In Study 1, the sample comprised young NT adults. In
Study 2, the RBQ-2A was administered to older NT adults
and to adults with ASD. It was hypothesised that the ASD
sample would score significantly higher than the NT group
on the RBQ-2A. This study also explored the reliability of
the subscales found in Study 1 in a more representative NT
sample. As all RBQ-2A items were administered, including
the sensory items that did not load on to the PCA in Study
1, this study also offered the opportunity to examine the
RBQ-2A sensory scores in ASD as compared with NT
Data were collected from two groups of adults who were
participating in a larger study of adults with ASD being
carried out in Australia. All participants completed a
screening questionnaire that included first language, ASD
diagnosis or family history of ASD, comorbid diagnoses,
other medical and health related diagnoses, employment
and marital status, living arrangements and medication. To
be accepted into the study, ASD adults needed to have a
confirmed clinical diagnosis of ASD (clinical reports were
provided), while NT adults all had an AQ score \26
(Woodbury-Smith et al. 2005). Any individual with a
diagnosis of schizophrenia was also excluded from the
study. Furthermore, NT adults were excluded if they had a
first degree relative with ASD, or if they had an anxiety or
mood disorder. All participants had at least average
intellectual ability (IQ [ 80) and the NT and ASD samples
were group-wise matched for Performance IQ (PIQ),
Verbal IQ (VIQ) and Full Scale IQ (FSIQ), as shown in
The ASD group (N = 29) comprised 15 women and 14
men aged 21.86 to 44.23 years (M = 34.27, SD = 6.29).
The NT group (N = 37) comprised 23 women and 14 men
aged 21.90 to 43.32 years (M = 30.75, SD = 6.21), with a
mean AQ score of 11.78 (SD = 4.41). For the NT group,
48.6 % were employed on a full time basis, 24.3 % worked
part-time, 24.3 % were students and 2.7 % were
unemployed. For the ASD group, 27.6% were employed full
time, 24.1 % worked part-time, 6.9 % were home keepers,
13.8 % were students and 27.6 % were unemployed. ASD
Table 3 Study 2: verbal IQ, performance IQ, and full scale IQ ranges, mean scores and standard deviations (SDs) and their correlations with
mean Adult Repetitive Behaviour Questionnaire-2 total scores for both neurotypical (NT) and autism spectrum disorder (ASD) groups
Correlation with RBQ-2A
Correlation with RBQ-2A
participants were recruited through various Australian
Autism Associations, the research centre’s Research
Participant Registry as well as flyers displayed at clinics
specialising in ASD. The NT participants were recruited
primarily through the School of Psychological Science
participant registry, social media, and flyers placed around
the university and in the general public. This study
received ethical approval from the university’s Human
Ethics Committee. Informed consent was obtained for all
As in Study 1, all participants completed the RBQ-2A and
the AQ as part of an online survey comprising several
As noted above, all ASD participants provided a copy of
their clinical report confirming their diagnosis. They were
also assessed using the Autism Diagnostic Observation
Schedule-Second edition (ADOS-2). The ADOS-2 (Lord
et al. 2012) is a semi-structured observation schedule that
is used clinically to diagnose ASD and confirm diagnoses
for research purposes. ADOS-2 data were available for 27
of the ASD group; the remaining two participants were
recruited interstate and funds were not available to travel to
assess them. The total ADOS-2 score ranged from 4 to 19
for this sample (M = 11.59, SD = 4.23). Six participants
(21 %) did not meet the criteria for ASD according to the
recently revised ADOS-2 algorithm (Lord et al. 2012),
which is similar to the rate reported by Bastiaansen et al.
(2011). However, when removing participants who did not
meet ADOS-2 criteria for ASD from the analyses, the
pattern of results did not change (with the exception of
internal consistency of RMB in the ASD group falling
below .70). Therefore, as these participants had a
confirmed clinical diagnosis of ASD they remained in the
analysis to preserve statistical power.
Twenty-three (79 %) of the ASD participants and 34
(92 %) of the NT participants completed the Wechsler
Abbreviated Scale of Intelligence (WASI-II; Wechsler
2008) to gain estimates of VIQ, PIQ and FSIQ. Four of the
ASD participants had recently completed the Wechsler
Adult Intelligence Scale (WAIS-III) as part of their
diagnostic assessment and IQ scores were obtained from
their diagnostic reports. Participants who were not assessed
lived interstate (2 ASD, 3 NT). No participants scored
below 89 on any of the IQ measures. Participants who did
not complete an IQ assessment held, or were in the process
of completing, a diploma or Bachelor’s degree and thus
were considered high-functioning. The means, SDs and
ranges for all three IQ scores for both groups are shown in
Data Screening and Statistical Analyses
As in Study 1, non-parametric tests were used for data that
were not normally distributed. The ASD group was
significantly older than the NT group [t(1, 60.26) = 5.08.
p = .03].1 Therefore any group differences may be
confounded by age. However, age was not significantly
correlated with participants’ mean total score on the RBQ-2A
in either the NT (rs = .08, p = .65) or ASD group
(r = -.02, p = .94). Welch’s t-tests, which correct for
unequal sample sizes, showed no significant differences
between the two groups in terms of VIQ [t(1, 42.8) = 1.94,
p = .17], PIQ [t(1, 41.64) = .05, p = .82) or FSIQ (t(1,
45.39) = 1.02, p = .32]. Furthermore, mean total score on
the RBQ-2A was not significantly correlated with VIQ,
PIQ or FSIQ in either of the participant groups (see
The means, SDs, medians and IQRs for RBQ-2A across the
two groups are shown in Table 4. Mean RBQ-2A total
scores ranged from 1 to 1.8 in the NT group and from 1.05
to 2.75 in the ASD group. Participants in the ASD group
scored significantly higher on the RBQ-2A than
participants in the NT group (Z = -5.43, p \ .001, r = -.67),
indicating a large effect size. No significant sex differences
were found in mean RBQ-2A in either the NT or ASD
group (p [ .05). There were significant positive
correlations between mean total RBQ-2A score and mean total
1 The age of the NT group was positively skewed, so square root
transformation was applied to both samples for this test.
AQ score in both ASD participants (rs = .56, p = .002)
and NT participants (rs = .42, p = .01). Finally, the
internal consistency of the RBQ-2A was good in the NT
group (a = .73) and excellent in the ASD group (a = .91).
Mean scores on the two subscales identified in Study 1,
RMB and IS, were calculated for all participants. The
means, SDs, medians and IQRs of the mean scores on each
component for the two groups are shown in Table 4. The
ASD group scored significantly higher than the NT group
on both RMB (Z = -3.32, p = .001, r = -.41) and IS
(Z = -5.51, p \ .001, r = -.68), indicating medium and
large effect sizes respectively. There were no significant
differences between scores on RMB and IS for the NT
group (Z = -.90, p = .37). However, in the ASD group
participants scored significantly lower on the RMB
subscale compared to the IS subscale [t (28) = -5.62,
p \ .001]. There were also no significant sex differences in
either of the subscales in both groups (p [.05). In the ASD
group, the internal consistency was good for both RMB
(a = .75) and IS (a = .87). For the NT group internal
consistency was acceptable for RMB (a = .65) but poor
for IS (a = .55). In addition, RMB and IS were
significantly correlated in the ASD group (r = .64, p \ .001) but
not in the NT group (rs = .15, p = .37).
The subscales of the RBQ-2A as identified from Study 1
exclude sensory items (items 7, 8, 9 and 10). As sensory
atypicalities are a behavioural feature of ASD, an RSMB
variable was created, comprising the RMB and sensory
items (items 1–10, see Table 1). The mean RSMB score of
the NT group was 1.20 (SD = .24; a = .76) and the mean
RSMB score for the ASD group was 1.64 (SD = .47;
a = .85). The medians and IQRs are displayed in Table 4.
The ASD group scored higher than the NT group in terms
of RSMB (Z = -4.20, p \ .001, r = -.52), with a large
effect size. There was no significant within-participant
difference between RSMB and IS for the NT group
(Z = -1.68, p = .09) but there was for the ASD group
(t(28) = -5.11, p \ .001). Again there were no significant
sex differences in terms of RSMB in either group
(p [ .05).
The RBQ-2A scores of the Study 1 sample were also
compared to the NT group from Study 2. In order to create
matched groups, only the older participants from each
group (aged 23 years and older) and those with an AQ
score \26 were selected. This resulted in two NT groups:
one from Study 1 (N = 20) and one from Study 2
(N = 34), which did not significantly differ in terms of age
(Z = -1.68, p = .09) or AQ score [t(1, 36.77) = 3.54,
p = .07]. The mean age, RBQ-2A and AQ scores are
displayed in Table 5. Group comparison of RBQ-2A total
scores showed that the Study 1 NT group scored
significantly higher on the RBQ-2A2 than the Study 2 NT group
[t(1, 27.83) = 12.04, p = .002]. The Cronbach’s alpha of
the older participants from Study 1 was good (a = .87),
lending further support to the internal consistency of the
RBQ-2A in older adults. In addition, when this Study 1 NT
subgroup was compared with the ASD participants aged
23 years and older [N = 26; mean age = 35.64
(SD = 5.03); mean RBQ-2A score = 1.83 (SD = .44)],
the ASD participants still scored significantly more highly
than the Study 1 subgroup [t(1, 44) = 8.02, p = .007].
Study 2 explored the difference in RBQ-2A scores between
NT and adult ASD participants. In line with the hypothesis,
participants with ASD scored significantly higher on the
RBQ-2A than IQ-matched NT participants, in terms of
both total score and scores on the subscales identified in
Study 1. This supports the utility of the RBQ-2A as a
measure of RRBs in adults with ASD as it is able to detect
differences in RRBs between autistic and NT groups.
Additionally, the internal consistency of the RBQ-2A was
supported in this study, with the exception of the IS
subscale in the NT group.
These results indicate that the RBQ-2A is able to
distinguish between NT and ASD participants at a group level,
as NT participants rate themselves lower on RRBs.
However, this finding would be strengthened by assessing the
accuracy of self-report, by testing the correlation between
the RBQ-2A and another type of measure such as
parentreport or observation. Some argue that individuals with
ASD find introspection and reporting their symptoms
difficult (e.g., Williams 2010). Nevertheless, expected group
differences were detected, and the internal consistency of
RBQ-2A and its sub-scales ranged from good to excellent
in the ASD group, indicating that adults with ASD are able
to self-report RMB and IS behaviours with accuracy.
Interestingly, while there is no significant difference
between the subscales of RMB and IS in the NT sample,
participants with ASD rate themselves significantly more
highly on IS compared to RMB. This suggests that among
older adults with ASD, reported IS behaviours are
particularly high compared to RMB. This pattern was repeated
when including sensory items in the RMB factor to create
RSMB. In addition, the NT group scored themselves
significantly lower compared to the ASD group on all three
subscales. For both groups, addition of sensory items
increased the internal consistency compared to RMB. For
2 RBQ-2A scores were positively skewed in the Study 2 sample, so
the RBQ-2A scores of both were transformed using natural logarithm
for this analysis.
Table 4 Study 2: means,
standard deviations (SD),
medians and interquartile ranges
(IQR) for the mean total
RBQ2A score and the components
RMB and IS
Table 5 Study 2: means,
standard deviations (SD),
medians and interquartile ranges
(IQR) for the mean total
RBQ2A and components scores for
the two NT groups
Study 1 NT group
Study 2 NT group
the NT group, addition of sensory items slightly reduced
the mean (from 1.26 to 1.20) whereas for the ASD group,
addition of sensory items increased the mean (from 1.59 to
1.64), increasing the difference between the two groups
established on the RMB subscale. This reflects previous
research that found autistic individuals show higher levels
of sensory symptoms than NT individuals (e.g., Kern et al.
2006). Given these results, it is important to retain the
sensory items in the RBQ-2A when it is administered to an
These results indicate that when matching the two NT
groups in terms of age and total AQ score, the Study 1
university students scored more highly on the RBQ-2A than the
Study 2 sample. Therefore it seems unlikely that either
differences in age or AQ score account for the differences in
RBQ-2A scores of both two NT groups. Although the two
samples were recruited from different countries, both are
Western countries, making country of origin an unlikely
explanation for the difference in RBQ-2A score. A more
plausible explanation might be that in Study 2, NT
participants with anxiety or mood disorders were excluded, while
this did not occur in Study 1. Furthermore, the participants in
Study 1 were university students and it has been shown that
university students have high levels of anxiety symptoms
compared to the general population (e.g., Andrews and
Wilding 2004; Stallman 2010). Anxiety may be related to
RRB, for example rituals in university students (Markt and
Johnson 1993) and in children and adolescents with ASD
(e.g., Lidstone et al. 2014; Rodgers et al. 2012).
Overall, these results indicate that the RBQ-2A is a useful
new self-report measure for assessing RRBs in adults.
Study 1 found a two-component structure in a NT
university student sample that approximately corresponds
to previous research using other measures of RRBs, with
the exception of sensory items. Study 2, using a more
representative sample of adults, found that participants
with ASD score significantly more highly than IQ-matched
NT participants on the RBQ-2A total and subscale scores,
which would be expected from an accurate measure of
RRBs. The internal consistency of the RBQ-2A and its
subscales was high for adults with ASD, providing further
support to its reliability as a measure of RRBs for adults on
the autism spectrum. Both studies showed that RRBs are
significantly associated with AQ score and support the use
of the RBQ-2A as a measure of RRBs in NT adults.
Subsidiary analyses in Study 2 also indicated that although the
university sample in Study 1 had higher levels of RRB than
the adults in Study 2, this was unlikely to be due to
differences in age. Given the potential relationship between
RRBs and anxiety, it can be speculated that the higher
incidence of anxiety traits in university populations
(Andrews and Wilding 2004; Stallman 2010), alongside the
screening for significant psychopathology in the Study 2
NT sample, may have biased the Study 1 group to
relatively higher scores. Further research is needed to explore
both the association between psychopathology symptoms
and RRBs, and whether the RBQ-2A can accurately
distinguish between ASD and psychological disorders that
involve high levels of RRB, such as OCD and other
specific anxiety disorders.
Another unexpected finding from Study 1 is that most
sensory items from the RBQ-2A did not load onto either
component. Furthermore, adding sensory items to the RMB
subscale for the NT group in Study 2 reduced the mean
score on this subscale. These findings indicate that sensory
symptoms are not common in the NT participants across
both studies, whereas they are highly prevalent within the
autistic population (e.g., Boyd et al. 2010; Kern et al. 2006;
Leekam et al. 2007a). This may be partly explained by the
fact that some of the sensory items contain references to
‘special’ interests and items, which may not be relevant for
NT adults. Alternatively, it may be that the RBQ-2A
simply does not capture a wide enough range of sensory
behaviours, as it includes just six items from the original
set of 25 items in the DISCO (items 7, 8, 9, 10, 18 and 19).
A previous study of the general population found evidence
of a wider range of sensory behaviours with a more
detailed questionnaire, the Glasgow Sensory Profile
(Robertson and Simmons 2013). This questionnaire covers
seven modalities, including auditory, vestibular and
proprioceptive, which are not included in the RBQ-2A.
Nevertheless, the RBQ-2A was able to discriminate between
the ASD and NT groups both with and without the sensory
There are also some important limitations to consider for
the studies reported here. Although the samples across both
studies include a fairly wide range of ages from 18 to
50 years old, these findings cannot be generalised to adults
of an older age. Furthermore, as the RBQ-2A was adapted
from a measure for children, it may be missing certain
items that are applicable only to adults. As discussed in the
Introduction, the RBQ-2A as a self-report measure is
currently suitable only for more able adults. Therefore the
RBQ-2A, and any associated findings, are only
generalizable to this population. In both studies, there was
significant positive correlation between the AQ and the RBQ-2A.
However this correlation might be partly explained by the
fact both are self-report measures. As mentioned, it is
therefore important to compare the RBQ-2A with other
measures of autistic traits such as interviews or
informantreport questionnaires. The purpose of the RBQ-2A is to
describe a profile of RRBs; it does not measure social
communicative behaviours and therefore is not suitable as
a stand-alone diagnostic tool for ASD, which includes both
domains as necessary and essential conditions for a
Nevertheless, the studies presented here represent an
important new contribution with the development of an
adult self-report measure of RRBs, which can be used with
both ASD and NT populations. The need for such a
measure is indicated by the findings of both studies, which
indicate that self-reported RRBs in adulthood may present
slightly differently than carer-reported RRBs in childhood.
Specifically, although the subtypes of RRBs remain the
same, the specific behaviours that are endorsed differ. The
potential clinical applications of the RBQ-2A include its
use as a signposting questionnaire or as a supplement to
diagnostic interviews such as the DISCO. Its utility may be
especially helpful given that the AQ does not give an
adequate or reliable assessment of RRBs across typical
populations (e.g., Kloosterman et al. 2011; Lau et al. 2013).
It may also be useful for other clinical conditions that show
RRBs, such as obsessive-compulsive disorder, Gilles de la
Tourette syndrome and Parkinson’s disease (Langen et al.
2011). From a research perspective, the RBQ-2A allows for
the opportunity to accurately and reliably explore RRBs
directly in adults both with and without ASD. Overall,
these results show that the RBQ-2A is a promising
selfreport measure of RRBs in adults. However, further
research should involve older and more diverse NT
participants that include representation of a range of ethnic
and SES groups, as well as a larger sample of adults with
ASD. Although the RBQ-2A is a descriptive questionnaire
that can only identify a profile of behaviours as perceived
by self-informants, further research comparing self- and
other-informant RBQ-2A questionnaires and its use with
clinical interviews may help to assess how well the
RBQ2A complements and streamlines the diagnostic process in
Acknowledgment Sarah Barrett was supported by a joint Ph.D.
studentship from the School of Psychology, Cardiff University, and
the Economic and Social Research Council. In addition, Study 2 was
partially funded by an APEX Trust for Autism Ph.D. grant. The
authors would like to thank Danielle Soliman for assistance with
recruitment and data collection in Study 2. The authors would also
like to thank all of the participants across both studies.
Compliance with Ethical Standards
Ethical standard All procedures performed in studies involving
human participants were in accordance with the ethical standards of
the institutional research committees and with the British
Psychological Society ethical standards.
Informed consent Informed consent was obtained from all
individual participants included in the study.
Open Access This article is distributed under the terms of the
Creative Commons Attribution 4.0 International License
(http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided you give
appropriate credit to the original author(s) and the source, provide a
link to the Creative Commons license, and indicate if changes were
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