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PSYCHIATRY AND PRECLINICAL PSYCHIATRIC STUDIES - ORIGINAL ARTICLE
Impairment in face processing in autism spectrum disorder:a developmental perspective
Ellen Greimel • Martin Schulte-Ruther •
Inge Kamp-Becker • Helmut Remschmidt •
Beate Herpertz-Dahlmann • Kerstin Konrad
Received: 6 December 2013 / Accepted: 25 March 2014
� Springer-Verlag Wien 2014
Abstract Findings on face identity and facial emotion
recognition in autism spectrum disorder (ASD) are incon-
clusive. Moreover, little is known about the developmental
trajectory of face processing skills in ASD. Taking a
developmental perspective, the aim of this study was to
extend previous findings on face processing skills in a
sample of adolescents and adults with ASD. N = 38 ado-
lescents and adults (13–49 years) with high-functioning
ASD and n = 37 typically developing (TD) control sub-
jects matched for age and IQ participated in the study.
Moreover, n = 18 TD children between the ages of 8 and
12 were included to address the question whether face
processing skills in ASD follow a delayed developmental
pattern. Face processing skills were assessed using com-
puterized tasks of face identity recognition (FR) and
identification of facial emotions (IFE). ASD subjects
showed impaired performance on several parameters of the
FR and IFE task compared to TD control adolescents and
adults. Whereas TD adolescents and adults outperformed
TD children in both tasks, performance in ASD adolescents
and adults was similar to the group of TD children. Within
the groups of ASD and control adolescents and adults, no
age-related changes in performance were found. Our find-
ings corroborate and extend previous studies showing that
ASD is characterised by broad impairments in the ability to
process faces. These impairments seem to reflect a devel-
opmentally delayed pattern that remains stable throughout
adolescence and adulthood.
Keywords Autism spectrum disorder � Development �Age � Face recognition � Emotion
Introduction
When interacting with other persons, an individuals face is
an important source of information that gives insight into
personality traits, demographic characteristics and the
emotional state of an individual (Flowe 2012). Individuals
with autism spectrum disorder (ASD), a neurodevelop-
mental disorder characterized by restricted interests,
impaired communication and deficits in social interaction
(American Psychiatric Association 1994), often have
marked difficulties in reading faces. These difficulties
involve problems in recognizing a persons emotional
expression in a face or even the person’s identity (Schultz
2005).
In the past decades, a large number of studies have
examined deficits in face processing in ASD. The majority
of these studies focused on emotional face processing and
employed emotion matching or labelling tasks. These
studies have provided evidence for deficient recognition of
facial expressions in children and adults with ASD (Boelte
E. Greimel � M. Schulte-Ruther � K. Konrad
Child Neuropsychology Section, Department of Child and
Adolescent Psychiatry, Psychosomatics and Psychotherapy,
University Hospital of the RWTH Aachen, Aachen, Germany
E. Greimel � B. Herpertz-Dahlmann
Department of Child and Adolescent Psychiatry, Psychosomatics
and Psychotherapy, University Hospital of the RWTH Aachen,
Aachen, Germany
E. Greimel (&)
Department of Child and Adolescent Psychiatry, Psychosomatics
and Psychotherapy, University Hospital Munich,
Pettenkoferstraße 8a, 80336 Munich, Germany
e-mail: [email protected]
I. Kamp-Becker � H. Remschmidt
Department of Child and Adolescent Psychiatry, University
Hospital Giessen and Marburg, Campus Marburg, Germany
123
J Neural Transm
DOI 10.1007/s00702-014-1206-2
and Poustka 2003; Boraston et al. 2007; Kuusikko et al.
2009), although results remain inconsistent (Adolphs et al.
2001; Gepner et al. 2001). A number of studies have
investigated whether the impairment in emotional face
recognition applies to all basic emotions or is specific to
certain emotion categories. Results of these studies sug-
gests that ASD individuals are predominantly impaired in
recognizing negative emotions (e.g., sadness, anger or
fear), whereas deficits in the recognition of happy faces
seem to be less robust (for a recent review see Harms et al.
2010; but see also Wright et al. 2008; Humphreys et al.
2011).
Facial identity recognition in ASD has also been
extensively studied. Again, results are inconclusive: while
a number of studies have found impairments (Klin et al.
1999; Wolf et al. 2008; Weigelt et al. 2012), others report
intact facial identity recognition skills (Deruelle et al.
2004; Celani et al. 1999). It is of interest that even in
studies reporting intact performance, subtle peculiarities in
face identity processing were often revealed. For example,
a number of these studies found that ASD subjects do not
show a decrement in performance when asked to identify
inverted faces, which can be typically found in controls
(Langdell 1978; Hobson et al. 1988; but see Weigelt et al.
2012).
Inconsistent findings on face processing abilities in ASD
might be due to methodological differences between the
studies. An important factor that might influence results is
the specification of ASD subjects that were included. While
many studies with low-functioning subjects with ASD
reported deficits in face processing (Celani et al. 1999;
Hobson 1986), studies with high-functioning ASD subjects
often found intact face processing skills (Adolphs et al.
2001) or detected only deficits in more demanding condi-
tions, e.g., inferring emotional states from the eye region
(Baron-Cohen et al. 1997). Differential findings for ASD
subtypes are in line with studies that found that face pro-
cessing abilities and autism severity are negatively corre-
lated (Uono et al. 2011; Bal et al. 2010). Importantly, the
vast majority of studies that have found intact abilities in
facial identity and emotion recognition in individuals with
ASD only reported accuracy rates (and not response times).
This approach might not be sensitive enough to detect
abnormalities in face processing in high-functioning ASD
subjects due to ceiling-effects. Finally, inconclusive data
on face processing skills in ASD might also be related to
differences between the age groups investigated. The latter
might be particularly important when assessing ASD, as
there is evidence for deviant developmental trajectories of
face processing in affected subjects. Although data are
scarce, results from a small number of cross-sectional
studies suggest that ASD individuals show no or less age-
dependent improvement in face processing abilities beyond
late childhood compared to typically developing individ-
uals (O‘Hearn et al. 2010; O’Connor et al. 2005; Rump
et al. 2009). Consequently, studies may have found intact
or deficient face recognition abilities in ASD depending on
the age group investigated.
In typically developing (TD) individuals, face process-
ing skills continue to improve after the childhood years
(Herba 2004), although the ability to discriminate faces and
facial emotions emerges early in live (Walker-Andrews
1997; Blass and Camp 2004). The majority of studies on
typical development in face processing have focused on
infancy and early childhood. However, the limited number
of studies examining age-related influences on the ability to
read faces beyond childhood suggests increased accuracy
and faster processing of facial expressions and identity
from childhood to adolescence (Carey et al. 1980;
O’Connor et al. 2005; Batty and Taylor 2006; Thomas
et al. 2007; but see, e.g., Durand et al. 2007). The
improvement in identity and facial emotion recognition in
TD individuals beyond the childhood period is closely
paralleled by age-related structural and functional changes
in brain structures involved in face processing (Aylward
et al. 2005; Wang et al. 2006; Greimel et al. 2010). For
example, is has been shown that the fusiform gyrus grad-
ually increases in size and becomes more face selective
from childhood to adulthood (Peelen et al. 2009). By
contrast, studies in ASD subjects have shown that matu-
ration of temporal brain structures subserving face pro-
cessing is disrupted in affected adolescents and adults
(Wallace et al. 2010; Raznahan et al. 2010; Lee et al.
2007). Taken together with behavioural studies reporting a
lack of age-related improvement of face processing skills
in ASD, these findings underscore the importance of
studies that take a developmental perspective. Comparing
face processing abilities in ASD individuals to the typical
course of development provides important further insights
into the developmental trajectory of these skills in affected
persons. Such approaches might also be helpful to identify
critical time periods when intervention is particularly
important for individuals with ASD.
The aims of the present study were twofold. First, we
aimed to extend previous studies on face processing in
high-functioning ASD subjects in a large and homogenous
sample covering a wide age-range. Second, we aimed to
characterize the developmental course of face processing
abilities in ASD relative to typical development. We
included ASD and control subjects aged 13–49, thereby
extending the age range that has been typically investigated
in studies of face recognition in ASD. Additionally, a
group of younger TD children was included to address the
question whether face processing abilities in ASD follow a
delayed developmental course relative to TD individuals.
To comprehensively assess face processing skills, an
E. Greimel et al.
123
emotional face recognition and an face identity recognition
task were employed.
Based on previous studies in ASD adolescents and
adults (Boraston et al. 2007; Kirchner et al. 2011; Bor-
mann-Kischkel et al. 1995), we hypothesized that subjects
with ASD would show deficits in the ability to process both
facial identity and emotion. Moreover, in line with previ-
ous studies on age-related changes in face processing in
ASD (O’Connor et al. 2005; O‘Hearn et al. 2010), we
expected that these deficits follow a delayed developmental
pattern relative to TD individuals.
Methods
Participants
A total of 93 male subjects participated in the study. The
sample included 38 adolescents and adults with ASD (ASD
group), and 37 TD adolescents and adults (control group).
In addition, 18 TD children between the ages of 8 and 12
were investigated. Only subjects with an IQ C 80 (WISC-
III (Wechsler 1991) or WAIS-III (Wechsler 1997) were
included. Groups did not differ in IQ. Moreover, there were
no significant differences in age between ASD subjects and
controls (see Table 1 for demographic characteristics).
ASD individuals had been diagnosed by experienced cli-
nicians according to ICD-10 (World Health Organization
1993) and DSM-IV (American Psychiatric Association
1994) for Asperger’s syndrome or high-functioning autism.
Diagnoses were confirmed by the Autism Diagnostic
Observation Schedule-Generic (ADOS-G) (Lord et al.
2000; Ruehl et al. 2004), which was conducted by certified
examiners (E. G.; I. K.-B.). In adolescents with ASD,
autism-specific assessment additionally included a semi-
structured parent interview (Autism Diagnostic Interview-
Revised; conducted by E. G.; I. K.-B.) (LeCouteur et al.
1989; Boelte et al. 2006a) and the Social Communication
Questionnaire (Rutter et al. 2003; Boelte and Poustka
2006). Adults with ASD additionally completed the Autism
Spectrum Questionnaire (Baron-Cohen et al. 2001) (see
Table 2 for clinical characteristics).
In ASD subjects aged \18 years, comorbid psychopa-
thology was screened using the Child Behavior Checklist
(CBCL) (Achenbach 1993) and the FBB-HKS (German
parental report on ADHD symptoms) (Doepfner et al.
1994). In ASD subjects aged C18 years, the Brief Symp-
tom Inventory (Derogatis 1993) and the ADHD Behavior
Checklist for Adults (Murphy and Barkley 1995) were
used. Moreover, in all ASD individuals comorbidity was
assessed based on an extensive psychiatric, psychological
and neurological examination. With regard to psychiatric
Table 1 Demographic characteristics (M, SD) of the study sample
TD
children
(n = 18)
Control group
(n = 37)
ASD group
(n = 38)
Group
difference
Age 10.5 (1.3) 20.6 (7.0) 21.1 (9.5) p \ 0.05a
Age
range
8.1–12.4 13.1–46.9 13.0–49.6
IQ 111.7
(15.6)
113.0 (10.2) 107.7 (13.2) n.s.
IQ
range
83–139 89–133 81–139
TD typically developing, ASD autism spectrum disordera Note that there was no significant difference in age between TD and
ASD adolescents or TD adults and ASD adults
Table 2 Clinical characteristics (M, SD) of the study sample
TD
children
Control
group
ASD
group
ADOS-G total n.a. n.a. 11.5
(3.9)
Communication n.a. n.a. 3.9 (1.9)
Social interaction n.a. n.a. 7.6 (2.3)
ADI-Ra
Social interaction n.a. n.a. 17.3
(5.2)
Communication n.a. n.a. 13.4
(4.5)
Restricted behaviors n.a. n.a. 6.3 (3.0)
Onset \36 months n.a. n.a. 2.0 (1.5)
SCQ totala 4.3 (3.2) 2.7 (2.0) 21.0
(7.4)
AQb n.a. 15.6 (4.6) 32.2
(10.3)
FBB-HKSa,c
Inattention 1.2 (1.3) 0.3 (1.3) 5.8 (2.6)
Hyperactivity 0.2 (0.5) 0.1 (0.3) 3.0 (2.6)
Impulsivity 0.2 (0.4) 0.3 (0.7) 2.2 (1.4)
ADHD behavior checklist for adultsb
Inattention n.a. 4.7 (2.9) 8.3 (4.8)
Hyperactivity/Impulsivity n.a. 4.2 (3.0) 6.6 (3.4)
CBCL total T-scorea 52.9
(9.8)
50.4 (13.8) 73.2
(7.8)
BSI positive symptom distress
indexbn.a. 1.3 (0.3) 1.6 (0.8)
n.a. not applicable, TD typically developing, ASD autism spectrum
disorder, ADOS-G Autism Diagnostic Observation Schedule-generic,
ADI-R Autism Diagnostic Interview-Revised, SCQ Social Commu-
nication Questionnaire, AQ Autism Spectrum Questionnaire, FBB-
HKS Fremdbeurteilungsbogen fur hyperkinetische Storungen (Ger-
man parental report on ADHD symptoms), CBCL Child Behavior
Checklist, BSI Brief Symptom Inventorya This instrument was only applied in subjects aged \18 yearsb This instrument was only applied in subjects aged C18 yearsc Number of elevated items
Face processing in autism spectrum disorder
123
comorbidities, n = 4 subjects showed symptoms of ADHD
and n = 1 subject had been diagnosed with chronic tic
disorder, and n = 1 subject with depressive disorder.
Seven participants were medicated at the time of testing
(atomoxetine n = 2; atypical neuroleptics n = 3, typical
neuroleptics n = 1; antidepressant medication n = 1).
Since the inclusion of these participants did not change the
result pattern, findings are reported based on the full
sample. If subjects received stimulants (n = 3), these were
discontinued 48 h before testing.
TD subjects were extensively screened to exclude psy-
chiatric disorders using a semi-structured interview (K-
SADS-PL) (Kaufman et al. 1997) and the Child Behavior
Checklist (Achenbach 1993) for subjects aged \18 years
and the Brief Symptom Inventory (Derogatis 1993) for
subjects aged C18 years. Moreover, in TD subjects, ASD
symptoms were screened using the Social Communication
Questionnaire (Rutter et al. 2003; Boelte and Poustka
2006) for participants aged \18 years and the Autism
Spectrum Questionnaire (Baron-Cohen et al. 2001) for
participants aged C18 years. ADHD symptoms were
screened in TD subjects based on the FBB-HKS (Doepfner
et al. 1994; in subjects\18 years) and the ADHD behavior
checklist for adults (Murphy and Barkley 1995; in subjects
C18 years). Descriptive data from clinical questionnaires
are summarized in Table 2.
The study was approved by the institutional review board
of the University Hospital of the RWTH Aachen and has been
performed in accordance with the Declaration of Helsinki. All
participants were informed in detail about the aims and the
protocol of the study and provided written informed consent
(participants C18) or assent (participants \18). For partici-
pants\18, additional written informed consent was obtained
by the parents/legal custodians, after the parents/legal custo-
dians had been informed about all aspects of the study.
Procedure
A standardized computerized assessment was conducted
based on two tasks from an established neuropsychological
test battery (DeSonneville 2001). The testing procedure
lasted about 15 min. All participants received identical
spoken instructions. To make sure that all participants were
able to perform the tasks, all tasks were preceded by
standardized practice trials.
Measures
Face identity recognition
Face identity recognition skills were assessed using the
face recognition (FR) task from the Amsterdam Neuro-
psychological Task battery (DeSonneville 2001). The face
stimulus set of this task consisted of color photographs of
20 individuals (5 boys, 5 girls, 5 men 5 women) with a
neutral expression. The task involved the continuous
presentation of 40 target faces (target duration 2.5 s), each
followed by a post-target interval of 500 ms and a display
set of four faces. Each individual photograph was pre-
sented twice as a target picture. The age and the gender of
the faces shown in the display set always matched the age
and gender of the target face. Participants were instructed
to push the ‘yes’ button of a mouse with the dominant
hand whenever the target was presented in the display set
(20 target trials) and to press the ‘no‘ button with the non-
dominant hand if the target was absent in the consecutive
display set (20 non-target trials). The display set disap-
peared from the screen when a response was given, i.e.,
the display duration was identical with the reaction time.
The post-response interval was set to 1,000 ms.
Dependent measures of the FR task included mean
reaction times (RT) of hits in target trials and the total
number of errors (false alarms and misses).
Identification of facial emotion
Emotional face recognition skills were assessed using the
Identification of Facial Emotion (IFE) task from the
Amsterdam Neuropsychological Task battery (DeSonne-
ville 2001). In each of four emotion conditions (happy, sad,
angry and fearful), subjects were first shown a face
expressing the target emotion for 2,500 ms. After a post-
target interval of 500 ms, emotional face stimuli were
shown and subjects had to press the ‘yes‘ button with the
dominant hand whenever a face with the target expression
appeared (20 target trials) and to press the ‘no‘ button with
the non-dominant hand if a face with a non-target emo-
tional expression appeared (20 non-target trials). The face
stimulus set of this task consisted of color photographs of
four individuals (2 males, 2 females), each showing the
four emotions. The face expressing the target emotion also
appeared in the following series of emotional faces. The
four individuals presented in IFE task overlapped with four
(of 20) individuals expressing a neutral face in the FR task.
Face stimuli remained on the screen until a response key
was pressed. Thus again, the display duration was variable
and identical with the reaction time. The post-response
interval was 1,000 ms.
Dependent measures of the IFE included mean RTs of hits
in target trials and the total number of errors (false alarms,
misses), both separately for the four emotion conditions.
Statistical analysis
The data were analyzed using SPSS 16 (SPSS Inc. 2008). A
one-way multivariate analysis of variance (MANOVA) with
E. Greimel et al.
123
group (ASD, control group) as between-subject factor was
conducted for the parameters (RT, errors) of the FR task. For
the parameters of the IFE task (RTs, errors for the four
emotion conditions), a two-way repeated measures MA-
NOVA with group (ASD, control group) as between-subject
factor and emotion (happy, sad, angry, fearful) as within-
subject factor was calculated. A multivariate approach was
chosen for the analysis of task performance in the FR and
IFE, respectively, since the parameters within the tasks
correlated substantially (p \ 0.05) across subjects.
MANOVAs were followed by univariate analyses of
variance (ANOVAS). Where appropriate, degrees of free-
dom were adjusted using Greenhouse-Geisser’s procedure.
Effect sizes were calculated using partial eta square (gp2). If
significant emotion or interaction (group by emotion)
effects in the ANOVA were obtained, further post hoc
comparisons were conducted adjusting p values (p0)according to the Holm procedure.
In the case of worse performance of the ASD group in
FR or IFE parameters compared to controls, we examined
whether these group differences can be accounted for by a
developmental delay in the ASD group. For this purpose,
the control and the ASD group were compared to the group
of TD children using independent t tests, again applying
Holm’s adjustment for multiple comparisons for parame-
ters of the FR and IFE task, respectively.
To examine the possibility of linear and quadratic age-
related changes in face processing abilities within the
groups of adolescent and adult ASD and control subjects,
respectively, linear and quadratic regression curve fitting
analyses were conducted for parameters of the FR and IFE
(separately for both groups). To reduce the number of
comparisons, these analyses were restricted to the follow-
ing parameters: RT and errors in the FR task, RT and errors
in the IFE task collapsed across emotion conditions. Again,
Holms procedure was used to adjust for multiple testing.
Results
Group differences between controls and ASD subjects
Face identity recognition
Descriptive data for all FR parameters are summarized in
Figs. 1 and 2. The MANOVA for the two parameters of the
FR (RT, errors) task revealed a significant main effect of
group (F(2, 72) = 17.0, p \ 0.001, gp2 = 0.31). In follow-
up ANOVAs, significant group differences emerged for RT
(F(1, 73) = 9.8, p \ 0.01, gp2 = 0.12) and the number of
errors (F(1, 73) = 25.0, p \ 0.001, gp2 = 0.26), with faster
RTs and less errors in controls compared to ASD
individuals.
Identification of facial emotions
Mean IFE parameters are summarized in Figs. 3 and 4. The
MANOVA for the IFE parameters (RTs, errors) revealed a
significant main effect of group (F(2, 72) = 13.0, p \ 0.001,
gp2 = 0.27) and emotion (F(6, 68) = 54.9, p \ 0.001,
gp2 = 0.83). Moreover, the interaction group by emotion was
found to be significant (F(6, 68) = 3.2, p \ 0.01, gp2 = 0.22).
In the follow-up ANOVA for RT in the IFE, a signifi-
cant main effect of group (F(1, 73) = 8.3, p \ 0.01,
gp2 = 0.10) emerged, with faster RTs in the control com-
pared to the ASD group. Moreover, a significant main
effect of emotion (F(2.6, 188.0) = 54.5, p \ 0.001,
gp2 = 0.43) was revealed. The interaction group by emotion
was found to be significant (F(2.6, 188.0) = 3.4, p \ 0.05,
gp2 = 0.04). Post-hoc comparisons (applying the Holm
adjustment for multiple comparisons) of the four emotions
showed that, irrespective of group, RTs to happy faces
were faster compared to sad, angry and fearful faces (all
p’s \ 0.05). RTs for sad faces were significantly slower
compared to fearful faces (p0\ 0.05). To follow up the
interaction between group and emotion, the ASD and
control group were compared for each of the four emotion
categories using independent t tests (again applying the
Holm adjustment). These analyses revealed that TD control
subjects responded faster to angry and fearful faces (all
p’s \ 0.05) than ASD individuals, whereas performance of
Fig. 1 Reaction times in the face recognition (FR) task. TD typically
developing, ASD autism spectrum disorder
Fig. 2 Errors in the face recognition (FR) task. TD typically
developing, ASD autism spectrum disorder
Face processing in autism spectrum disorder
123
the two groups were comparable for the remaining emotion
categories (p’s [ 0.05) (see Fig. 3).
The univariate test procedure for the number of errors
revealed a significant main effect of group (F(1,
73) = 17.4, p \ 0.001, gp2 = 0.19); ASD subjects com-
mitted more errors compared to controls. Moreover, a
significant main effect of emotion (F(2.5, 182.2) = 51.3,
p \ 0.001, gp2 = 0.41) emerged. Irrespective of group,
subjects were more accurate in the happy emotion condi-
tion compared to the other emotion conditions (all
p’s \ 0.05). Sad faces were recognized worse than angry
and fearful faces (all p’s \ 0.05). Moreover, angry faces
were recognized worse than fearful faces (p0\ 0.05).
The interaction effect group x emotion also proved to be
significant (F(2.5, 182.2) = 4.1, p \ 0.05, gp2 = 0.05). To
further investigate the interaction between group and
emotion, the two groups were compared for each of the
four emotion categories using independent t tests. These
analyses revealed that TD control subjects made less error
in the three negative emotion categories (all p’s \ 0.05),
whereas no group difference emerged for the happy emo-
tion condition (p0[ 0.05) (see Fig. 4).
Comparison of ASD and control subjects with TD
children
Face identity recognition
RTs in the FR task did not differ between TD children and
the ASD group (t(54) = 1.2, p0[ 0.05). By contrast,
comparison of TD children and the TD control group
revealed significantly faster RTs in the older age group
(t(20.7) = 4.3, p0\ 0.05). While the number of errors in
the FR task was comparable between TD children and the
ASD group (t(44.9) = -0.3, p0[ 0.05), significant dif-
ferences emerged between the TD groups, with less errors
in TD adolescents and adults (t(20.2) = 4.5, p0\ 0.05; for
descriptive statistics, see Figs. 1 and 2).
Identification of facial emotions
RT to angry (t(49.7) = -1.1; p0[ 0.05) and fearful faces
(t(54) = 0.7; p0[ 0.05) were comparable between TD
children and the ASD group. By contrast, the TD control
group responded faster to both angry (t(53) = 4.9;
p0\ 0.05) and fearful faces (t(25.9) = 3.7; p0\ 0.05) than
TD children. Similarly, while the number of errors for all
three negative emotion conditions did not differ between
TD children and the ASD group (tsad(54) = 1.0;
tangry(54) = 0.6; tfear(54) = 0.5, all p’s [ 0.05), the older
TD group outperformed the younger TD group in all
three parameters (tsad(53) = 4.1; tangry(22.9) = 3.9;
tfear(53) = 3.8; all p’s \ 0.05; for descriptive statistics, see
Figs. 3 and 4).
Linear and quadratic effects on age on face processing
performance
In the control group, no linear or quadratic relationships
between age and performance in the FR (errors and RT)
and IFE task (errors and RT collapsed across emotions)
were found (all p’s [ 0.05). In the ASD group, a positive
linear relationship between age and RT in the IFE task was
revealed (r = 0.30, p = 0.047; p [ 0.05 for linear or
quadratic effects of age on all remaining parameters)
indicating slowing of RTs with increasing age. However,
after correcting for multiple comparisons, this correlation
was non-significant.
Discussion
The aim of the present study was twofold. First, we sought
to extend previous studies on face processing in ASD.
Second, we aimed to explore whether deficits in face
Fig. 3 Reaction times in the identification of facial emotion (IFE)
task for the four emotion conditions. TD typically developing, ASD
autism spectrum disorder
Fig. 4 Errors in the identification of facial emotion (IFE) task for the
four emotion conditions. TD typically developing, ASD autism
spectrum disorder
E. Greimel et al.
123
processing abilities in ASD individuals might reflect a
developmental delay relative to TD subjects.
In sum, we found evidence for deficits in face identity
recognition abilities and the identification of facial emo-
tions in the ASD compared to the control group. Perfor-
mance in ASD adolescents and adults was similar to a
group of TD children, suggesting that face processing
abilities in ASD follows a delayed developmental
trajectory.
Group differences in face processing between controls
and ASD subjects
Our findings on deficits in face identity recognition and
identification of facial emotions in ASD individuals add to
the growing body of literature on face processing abnor-
malities in ASD. Sample sizes of previous studies were
often small (but see Klin et al. 1999) and restricted to a
narrow age range. Moreover, the interpretation thereof was
further complicated by insensitive methodological
approaches. Our study included a large number of subjects
and extended the age range that has been typically inves-
tigated in studies of face processing in ASD to solidify and
extend previous results.
In the FR task, ASD subjects were slower and commited
more errors compared to TD adolescents and adults. Def-
icits in the ability to process facial identity in ASD have
been previously reported (Boucher and Lewis 1992; Klin
et al. 1999; Kirchner et al. 2011; Weigelt et al. 2012).
Previous studies have demonstrated that these deficits are
domain-specific and cannot be explained by impaired
attentional processes or general cognitive abilities (Bou-
cher and Lewis 1992; Klin et al. 1999). A number of
studies have also reported intact abilities in facial identity
recognition (Celani et al. 1999; Deruelle et al. 2004; Krebs
et al. 2011). However, most of these studies did only report
error parameters or used a face-matching task. Both
approaches might not be sensitive enough to capture
impairments in relatively able subjects with ASD, espe-
cially in studies with small sample sizes.
Various studies have shown that ASD subjects process
faces differently from healthy subjects. Evidence from
behavioural studies and studies using eye-tracking suggest
that ASD individuals tend to focus more on the lower (i.e.,
the mouth) than on the upper part of the face, whereas TD
subjects predominantly focus on the eye region (Dalton
et al. 2007; Langdell 1978; Neumann et al. 2006). As the
eye region provides the most salient information about a
person’s identity, this peculiarity may in part explain
problems of ASD persons in recognizing faces. Moreover,
some studies have shown that, unlike TD persons (Rossion
2002), ASD individuals do no not show a decrease in
performance when asked to recognize faces upside down
(Tantam et al. 1989; Hobson et al. 1988). Because the
recognition of inverted faces relies predominantly on the
extraction of local features, the absence of a ‘‘face inver-
sion effect’’ in ASD has been taken as evidence for a local
and less holistic processing style (but see, e.g., Lahaie et al.
2006 and the review from Weigelt et al. 2012 for con-
flicting results on the face inversion effect), which is pre-
sumed to be less effective when recognizing faces.
In the IFE task, ASD subjects exhibited longer RTs to
fearful and angry faces compared to controls. Moreover,
ASD subjects committed more errors in the negative
emotion conditions of the IFE than TD controls. Our results
are in line with a large body of literature showing impaired
performance in ASD individuals in emotional face recog-
nition (for a review see Harms et al. 2010). It is of interest
that some studies have also found that ASD individuals are
as accurate as TD subjects in recognizing emotional
expressions. As the majority of these studies included
adults with high-functioning ASD (Adolphs et al. 2001;
Neumann et al. 2006), it has been claimed that these
individuals may have developed compensatory mecha-
nisms for processing faces (Harms et al. 2010). Compen-
satory mechanisms in ASD individuals might explain the
longer RTs in the ASD group in the IFE task, as such
compensatory processes may involve explicit verbal or
cognitive strategies to recognize emotional expressions in
contrast to a more intuitive, rapid and automatic processing
style in TD subjects. In support of this claim, a number of
studies have shown that in ASD, general cognitive and
language abilities are more strongly related to performance
in emotional face recognition than in TD individuals (Dyck
et al. 2006). Our finding that ASD subjects committed
more errors in negative emotion conditions but not in the
happy emotion condition might also support the idea that
affected subjects may possess compensatory mechanisms
for processing emotional faces: unlike negative emotional
expressions, a happy face can be identified on a rule-based
strategy to focus on the angle of a mouth. Moreover, the
differential results for the negative and positive emotion
conditions may also pertain to the fact that three negative
emotional expressions were presented in the IFE task along
with only one positive face. This may have resulted in
more difficulties (particularly for ASD subjects) in cor-
rectly recognizing the negative faces, as finer distinctions
had to be made for these emotion categories.
Face processing in typically developing controls
and in ASD subjects: a developmental perspective
TD adults and adolescents outperformed TD children in
parameters of the FR and IFE task. Our findings challenges
the older view that by late childhood, face processing abili-
ties reach adult levels (e.g., Durand et al. 2007) and are in line
Face processing in autism spectrum disorder
123
with other studies showing that face processing abilities
continue to develop well into adolescence (Carey et al. 1980;
O’Connor et al. 2005; Batty and Taylor 2006; Thomas et al.
2007). Several cognitive and neuropsychological explana-
tions have attempted to explain age-related changes in face
identity recognition and decoding of emotional faces during
childhood and adolescence. Among approaches focusing on
cognitive aspects, a prominent explanation is that children
and adolescents rely more strongly on configural compared
to featural processing of faces with increasing age. Among
other lines of evidence, support for this assumption is pro-
vided by studies showing that the face inversion effect
increases with age (Mondloch et al. 2002; Baudouin et al.
2010; but see also Crookes and McKone 2009).
Within the group of TD adults and adolescents, we
found no evidence of further age-related changes in the
ability to identify faces and recognize emotional expres-
sions. Thus, by adolescence, behavioral performance in
face processing seems to reach adult levels. This result is
consistent with previous findings which also show stability
of performance in the identification of faces and the rec-
ognition of prototypical emotional expressions from ado-
lescence into adulthood (Kolb et al. 1992; Greimel et al.
2010). Importantly, however, a number of studies suggest
that developmental changes in more fine-grained face
processing abilities (e.g., decoding of the intensity of an
emotional expression or recognition of mixed emotional
expressions) may also occur beyond the adolescent period
(Thomas et al. 2007; Rump et al. 2009). Moreover, the
absence of age-related differences on the behavioral level
does not exclude the possibility of developmental changes
in the neural substrates underlying face processing in TD
individuals. Indeed, evidence from functional and struc-
tural neuroimaging studies suggest that neural networks
known to be involved in the decoding of (emotional) faces
(e.g., the amygdala, the fusiform gyrus) continue to mature
from adolescence into adulthood (Aylward et al. 1999;
Monk et al. 2003; Guyer et al. 2008).
Comparison of the ASD group with TD children revealed
that both groups performed equally on all face parameters in
which TD controls outperformed ASD individuals. This
finding implies that ASD subjects lag behind typical devel-
opment in the domain of face processing suggesting that face
abnormalities in ASD can be interpreted in terms of a
developmental delay. The notion of a developmental delay in
the ability to process faces in ASD is supported by recent data
from cross-sectional neuroimaging studies which show
atypical maturation of face sensitive brain regions in ado-
lescents affected by the disorder (Raznahan et al. 2010; Lee
et al. 2007; Wallace et al. 2010).
An important question that arises from our results is
whether comparable performance in the FR and IFE task in
young TD subjects and older ASD individuals also reflect
similar face processing mechanisms in both groups. Based
on studies in ASD (Tantam et al. 1989; Hobson et al. 1988)
and on developmental studies in TD individuals (Baudouin
et al. 2010; Mondloch et al. 2002), it seems plausible that the
processing style in both groups might be characterized by a
focus on facial features and to a lesser extent on configural
information in the face. However, this claim remains spec-
ulative and future developmental studies in ASD children
and adults that use tasks like the face inversion paradigm or
the composite face paradigm (Young et al. 1987) are needed
to further shed light on the delayed developmental pattern of
face processing abilities in ASD.
Within the group of ASD adolescents and adults, no
improvement of face processing abilities was evident with
increasing age. Indeed, there was a tendency that older
ASD subjects even exhibited longer RTs compared to
younger ones (not significant after correction for multiple
comparisons). In line with the compensation hypothesis,
one might speculate that subjects with ASD become more
aware of their deficits with increasing age and thus, meta-
cognitive strategies are more commonly applied during
tasks which are known to be difficult resulting in a more
cognitively controlled processing of faces and slower RTs.
Taken together, the results of our study are in accordance
with other studies showing that face processing in ASD does
not improve during the adolescent period (O’Connor et al.
2005; Rump et al. 2009; but see Kuusikko et al. 2009). In this
regard, it is worth stressing that the term ‘‘delay’’ used to
describe the result pattern of face processing in ASD subjects
in the present study does not imply that these individuals
catch up at some point of development, albeit some indi-
viduals may develop cognitive strategies to cope with their
impairments in identifying and reading faces.
It is yet unexplored which environmental factors might
impact on the developmental trajectory of face processing
in ASD. As similarly advocated by O’Hearn et al. (2010),
the apparent lack of improvement with increasing age
reported in a number of cross-sectional studies might in
part reflect that younger subjects with ASD may have
benefited from early intervention, whereas many adults
with ASD had been diagnosed late and had received only
limited support. Future longitudinal studies including
clinical trials are needed to further examine the develop-
mental trajectory of face processing in ASD and to assess
the impact of early intervention programs targeting deficits
in the ability to identify faces and facial emotions.
Limitations
Only ASD subjects with an IQ above 80 were studied to
allow for homogenous groups. By necessity, the general-
izability of our findings to the whole spectrum of autistic
E. Greimel et al.
123
disorders may be limited. Moreover, in future studies, it
would be important to also include children with ASD to
further gain insight into the developmental course of face
processing in ASD.
The FR task used in the present study resembles a 1-back
task and thus draws on working memory processes. Although
several studies have shown that ASD subjects are unimpaired
in n-back tasks (for a review see Kenworthy et al. 2008),
future studies should include a control condition where
objects/no face stimuli are presented to control for unspecific
(cognitive) processes. On a related note, future studies
should include a neutral condition in the emotional face
recognition task to rule out the possibility that the results
obtained might be explained by the mere presence of face
stimuli and not to the emotional expression per se.
Conclusions
Our findings corroborate and extend previous studies
showing that ASD is characterised by broad impairments in
the ability to process faces. These impairments seem to
reflect a developmentally delayed pattern relative to healthy
individuals that remains stable throughout adolescence and
adulthood. Longitudinal studies spanning a wide age range
are needed to further elucidate the developmental trajectory
of face processing and its underlying neural mechanisms in
ASD. In such studies, it would be particularly important to
examine the impact of intervention programs targeting social
impairments and face recognition abilities in individuals
affected by the disorder (Boelte et al. 2006b).
Acknowledgments We are grateful to all participants with their
families who took part in this study.
Conflict of interest B. H.-D. receives industry research funding
from Vifor Pharma. K. K. received speaking fees from Novartis and
Medice. All other authors declare that they have no conflicts of
interest.
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