Impaired configural body processing in anorexia nervosa: Evidence

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British Journal of Psychology (2014), 105, 486–508 © 2013 The British Psychological Society www.wileyonlinelibrary.com

Impaired configural body processing in anorexia nervosa: Evidence from the body inversion effect Cosimo Urgesi1,2*, Livia Fornasari3, Francesca Canalaz3, Laura Perini3, Silvana Cremaschi4, Laura Faleschini4, Erica Zappoli Thyrion5, Martina Zuliani5, Matteo Balestrieri3, Franco Fabbro1,2 and Paolo Brambilla2,3* 1

Department of Human Sciences, University of Udine, Italy IRCCS Scientific Institute “E. Medea”, Pordenone, Italy 3 Department of Experimental and Clinical Medical Sciences, Inter-University Centre for Behavioural Neurosciences (ICBN), University of Udine, Italy 4 Child Neuropsychiatric Service, Udine, Italy 5 Department of Mental Health, Eating Disorder Service, Udine, Italy 2

Patients with anorexia nervosa (AN) suffer from severe disturbances of body perception. It is unclear, however, whether such disturbances are linked to specific alterations in the processing of body configurations with respect to the local processing of body part details. Here, we compared a consecutive sample of 12 AN patients with a group of 12 age-, gender- and education-matched controls using an inversion effect paradigm requiring the visual discrimination of upright and inverted pictures of whole bodies, faces and objects. The AN patients presented selective deficits in the discrimination of upright body stimuli, which requires configural processing. Conversely, patients and controls showed comparable abilities in the discrimination of inverted bodies, which involves only detail-based processing, and in the discrimination of both upright and inverted faces and objects. Importantly, the body inversion effect negatively correlated with the persistence scores at the Temperament and Character Inventory, which evaluates increased tendency to convert a signal of punishment into a signal of reinforcement. These results suggest that the deficits of configural processing in AN patients may be associated with their obsessive worries about body appearance and to the excessive attention to details that characterizes their general perceptual style.

Previous studies have documented an inaccuracy in the estimation of one’s own body parts in patients with anorexia nervosa (AN; Cash & Deagle, 1997; Gardner, 1996), suggesting that disorders in body perception may be a central aspect of AN. However, the neuropsychological bases of such alterations are still unclear. In particular, it needs to be clarified to what extent the perceptual deficits of AN patients are limited to the overestimation of their own and others’ body weight and shape or also affect more basic aspects of body perception.

*Correspondence should be addressed to Cosimo Urgesi, Department of Human Sciences, University of Udine, Via Margreth, 3, I-33100 Udine, Italy (email: [email protected]) or Paolo Brambilla, Department of Experimental and Clinical Medical Sciences, Piazzale Kolbe 3, I-33100, Udine, Italy (email: [email protected]). DOI:10.1111/bjop.12057

Configural body processing in anorexia nervosa

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In a recent study (Urgesi et al., 2012), patients with AN were administered a delayed matching-to-sample task in which they were required to discriminate the actions or the morphological details of other individuals’ body parts. Patients showed better visual discrimination performance than controls in the processing of body morphology but not of body actions. Importantly, such perceptual advantage of AN patients positively correlated with their increased tendency to convert a signal of punishment into a signal of reinforcement as measured with the Persistence scale of the Temperament and Character Inventory (TCI; Cloninger, Przybeck, Svrakic, & Wetzel, 1994). This scale is a measure of the extent to which a person is overachieving versus underachieving and high Persistence levels are observed in obsessive personalities (Cloninger et al., 1994; Kim, Kang, & Kim, 2009). The paradoxical advantage in processing body parts observed in the AN patients may thus stem from the AN patients’ tendency to routinely explore body part details as a consequence of their obsessive worries about body appearance and would point to an imbalance between configural and detail-based processing systems in the AN patients’ brain (Suchan et al., 2013) which may favour a more detail-based processing of the human body. In keeping with the visual processing of faces (Maurer, Grand, & Mondloch, 2002) but not of other objects, the visual processing of the human body seems to require configural processing, that involves the analysis of the relations among the different body parts in the context of the whole body space (Reed, Stone, Grubb, & McGoldrick, 2006). Configural processing of the body is typically probed using the body inversion paradigm, which refers to the remarkable disruption in processing whole bodies when displayed upside down (inverted) as compared with their canonical position (upright). This effect is found for faces (Maurer et al., 2002) and bodies (Reed, Stone, Bozova, & Tanaka, 2003) and is an indicator of configural processing. Indeed, the inversion of face and body stimuli is thought to prevent their configural processing, because configurations of faces and bodies may be coded only when the stimuli are presented in their canonical (and overlearned) upright orientation (Maurer et al., 2002; Reed et al., 2006). Thus, inversion of stimuli leaves the perceptual stimuli with only the detail-based processing of the single parts and details of faces and bodies. Detail-based processing is typically used, when presented in either an upright or inverted orientation, for other objects that have different structural properties and are less familiar to the observer. Upright faces and bodies can be processed also on the basis of their single features, as it is with less familiar objects, but configural processing is much more efficient and explains the surprisingly heightened ability of humans in detecting, discriminating and recognizing upright faces and bodies as compared with other objects. Since the inversion of stimuli prevents configural processing, the more the processing of an (upright) stimulus category relies on configural processing, the more severe is the drop of performance after inversion (i.e., greater inversion effect). Patients with brain lesions may present specific deficits in the visual recognition of faces with spared or less impaired processing of other categories, presenting a neuropsychological disorder known as prosopagnosia (Barton, 2003). Notably, patients with prosopagnosia may present strong deficits also in the processing of human bodies (Moro, Pernigo, Avesani, & Bulgarelli, 2012). A similar pattern of recognition deficits also occurs in a developmental disorder, referred to as congenital prosopagnosia (Avidan, Hasson, Malach, & Behrmann, 2005), in which individuals do not develop typical face processing abilities and have severe and selective deficits of face recognition. Prosopagnosia, either acquired or congenital, is thought to reflect a deficit of configural processing which affects mostly those stimulus categories whose processing relies more heavily on it, that is faces and bodies. Indeed, both acquired (Busigny &

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Rossion, 2010) and congenital prosopagnosia (Avidan, Tanzer, & Behrmann, 2011; Behrmann, Avidan, Marotta, & Kimchi, 2005; Righart & de Gelder, 2007) patients show impaired upright face and body discrimination performance as compared to healthy controls and absent inversion effect, whereas the performance for processing inverted faces and bodies is comparable to that of control participants. In a similar vein, although evidence is more mixed on this issue (Weigelt, Koldewyn, & Kanwisher, 2012), patients with autism spectrum disorder may present reduced face (Dawson, Webb, & McPartland, 2005) and body (Reed et al., 2007) inversion effects, reflecting deficits in processing upright stimuli and normal processing of inverted stimuli. Thus, comparing the inversion effects for bodies, faces and objects in AN patients and controls is a viable way to measure to what extent the AN patients’ alterations in processing the human body is associated with impaired and/or unbalanced configural versus detail-based processing systems. Configural processing and detail-based processing of human faces and bodies seem to be underpinned by the activity of different neural structures (Haxby, Hoffman, & Gobbini, 2000; Peelen & Downing, 2007). In particular, while configural face processing involves the activity of the fusiform face area (FFA) in the ventro-medial infero-temporal cortex (Kanwisher, McDermott, & Chun, 1997), detail-based face processing relies on the occipital face area (OFA) in the lateral occipito-temporal cortex (Gauthier et al., 2000). On the other hand, configural body processing may be related to the activity of the fusiform body area (FBA), in the medial occipito-temporal cortex (Peelen & Downing, 2005; Schwarzlose, Baker, & Kanwisher, 2005), whereas detail-based body processing is related to the activity of the extrastriate body area (EBA; Costantini, Urgesi, Galati, Romani, & Aglioti, 2011; Downing, Jiang, Shuman, & Kanwisher, 2001; Peelen & Downing, 2007; Urgesi, Berlucchi, & Aglioti, 2004; Urgesi, Calvo-Merino, Haggard, & Aglioti, 2007; Urgesi, Candidi, Ionta, & Aglioti, 2007). Both FBA and EBA are activated by viewing movies, photographs or sketchy drawings of human bodies and body parts but not faces and objects, thus showing body selectivity (Downing et al., 2001; Peelen & Downing, 2005, 2007). However, FBA responds more to whole bodies, whereas EBA responds to both partial and whole bodies (Taylor, Wiggett, & Downing, 2007). Furthermore, interfering with the activity of EBA using transcranial magnetic stimulation disrupts the discrimination performance of healthy individuals for inverted, but not for upright body stimuli (Urgesi, Calvo-Merino, et al., 2007). All in all, these findings suggest that FFA and FBA may be involved in the configural processing of faces and bodies, respectively, while OFA and EBA are involved in the detail-based processing of, respectively, faces and bodies (Haxby et al., 2000; Minnebusch & Daum, 2009; Peelen & Downing, 2007; Urgesi et al., 2007). Compelling evidence for the role of the fusiform gyrus, where body and face-selective regions strongly overlap (Peelen & Downing, 2005; Schwarzlose et al., 2005), in the configural processing of social stimuli (i.e., faces and bodies) comes from neuroimaging studies showing that its activity is modulated by the inversion of faces and bodies, with greater activation for upright than inverted stimuli (Brandman & Yovel, 2010; Yovel & Kanwisher, 2005). Accordingly, lesions or neurodevelopmental alterations of these face- and body-selective neural structures cause selective deficits in face (Avidan et al., 2005; Rossion et al., 2003) and body (Moro et al., 2008, 2012) processing. Considering the specificity of the neural networks involved in face and body processing, it can be expected that altered body processing in AN might be related to the dysfunction of the neural systems involved in the configural versus local processing of the bodies. In keeping with this expectation, previous neuroimaging studies (Suchan et al., 2010, 2013; Uher, Murphy, & Friederich, 2005; Vocks et al., 2010) have documented the


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existence of functional and structural alterations in the lateral occipito-temporal cortex of AN patients. These neurofunctional alterations have been put in relation to the disturbances of body image observed in AN, but their functional implications in the perceptual processing of other individuals’ body by AN patients are, however, unclear. In the absence of behavioural evidence documenting the specificity of AN patients’ deficits in the perceptual processing of bodies with respect to faces and other objects and testing the extent to which such alterations affect configural versus detail-based body processing, it is difficult to put in relation the documented brain alterations with the establishment and maintenance of the clinical pattern of body image disorders observed in ED. Thus, behavioural studies using paradigms adapted from cognitive neuroscience and probing the cognitive architecture of body processing are needed to bridge the gap between brain alteration findings and clinical manifestations in AN. Here, we used the body inversion effect paradigm to investigate the functionality of configural versus detail-based body processing in adolescent and adult patients with AN as compared to gender-, age- and education-matched controls. According to the above mentioned suggestions, we expected to find a deficit of configural processing in the AN patients, which should be reflected into a reduced body inversion effect with respect to controls and, in particular, into impaired discrimination of upright bodies and spared discrimination of inverted bodies. We also presented face and object stimuli to test whether the AN patient’s perceptual deficits are selective for body stimuli or also involve faces, that elicit an inversion effect (i.e., they require configural processing), or objects, that do not elicit an inversion effect (i.e., they do not require configural processing).

Material and methods Participants A total sample of 18 patients (all women) with a diagnosis of AN were recruited over a 6-month period at the local Child Neuropsychiatric Service and Clinic for the Treatment of Eating Disorders. All the patients reported with a diagnosis of AN at the two recruitment services were initially screened for inclusion and exclusion criteria based on their available clinical data. The main inclusion criteria were age between 13 and 40 years and diagnosis of AN restrictive (AN-R) or purge-binge (AN-PB) type, according to DSM-IV-TR (American Psychiatric Association, 1994). Patients satisfying all criteria for AN except amenorrhoea and that were diagnosed as Eating Disorder Not Otherwise Specified (EDNOS) were also included in the study to avoid excluding that subgroup of AN patients who menstruate despite being anorexic (Attia & Roberto, 2009). Exclusion criteria for patients included: a history of a different type of ED; any personality or psychotic disorder; a history of traumatic brain injury or any other neurological illness; current major medical illness that may affect brain structures such as diabetes, cerebrovascular disease, etc.; substance or alcohol abuse or dependence during the foregoing year. Patients with mood or anxiety disorders were not excluded to select a more representative sample of AN patients, considering the high comorbidity of ED disorder with mood, anxiety and personality disorders (Godart et al., 2007). The adolescent patients were diagnosed using the Kiddie-Sads-Present and Lifetime Version (K-SADS-PL; Kaufman, Birmaher, Brent, Ryan, & Rao, 2000; Kaufman et al., 1997), a semi-structured diagnostic interview to assess current episodes of psychopathology in children and adolescents according to DSM-III-TR and DSM-IV criteria. The adult patients were diagnosed using the Structured Clinical

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Interview for DSM-IV-TR (SCID; American Psychiatric Association, 1994). The patients and their parents were separately interviewed by a clinical psychologist (L. F., L. P. or M. Z.) specialized in the evaluation of ED. Following the diagnostic evaluation conducted at the time of testing, one adolescent patient and five adult patients were found to satisfy the criteria for Bulimia Nervosa (BN) and were not included in the final sample. The remaining 12 AN patients (8 adolescents and 4 adults) were diagnosed as AN-R (n = 7), AN-PB (for binging behaviour; n = 2), or EDNOS (for the absence of the amenorrhea criterion; n = 3). None of them had a clinical history of a different ED. Two AN-R patients presented Obsessive-Compulsive Disorder, one further AN-R patient had a Generalized Anxiety Disorder, Social Phobia and Somatization Disorder, and one AN-R patient had a current Somatization Disorder with a history of Post-Traumatic Stress Disorder and Social and Specific Phobia. The four adult AN-R patients and one adolescent EDNOS patient received pharmacological medication (selective serotonin reuptake inhibitors and/or benzodiazepine) at the time of testing. The remaining adolescent patients were free of medication. Nine patients received individual and/or group and/or familiar psychotherapy at the time of testing. Twelve control participants (all women) were recruited from the local community by word of mouth and through advertisements. AN patients and healthy volunteers were matched 1:1 for age, gender, race, language, education and IQ as evaluated by means of the Raven Standard Progressive Matrices test. For each matched pair, we allowed a discrepancy of no more than 2 years between the age of the patient and the control. Exclusion criteria for controls included: history of any type of ED, being under medication at the time of testing, presence of any DSM-IV axis I disorder, as determined with the screening section of the K-SADS-PL interview (for adolescent individuals) or by the structured interview modified from the SCID-IV non-patient version (SCID-NP; for adult participants), no history of psychiatric disorders among first-degree relatives, no history of alcohol or substance abuse or dependence and no current major medical illness. The demographic characteristics of the AN patients and controls are reported in Table 1. In keeping with the diagnosis, the AN patients had a lower body mass index (BMI) with respect to the controls, while the two groups did not differ for educational level, IQ and parental education and occupational status as evaluated with the Hollingshead Scale of Socio-Economical Status (SES; Table 1). As face and body perception seems to be associated with right hemisphere dominance (Urgesi, Bricolo, & Aglioti, 2005), we also checked the degree of handedness of the participants in order to exclude that any difference in the perceptual performance of the two groups was due to their handedness and the associated degree of hemispheric dominance for spatial function (Vogel, Bowers, & Vogel, 2003). All the participants but one control were right-handed (Briggs & Nebes, 1975) and no difference was observed between the handedness total score of patients and controls. Thus, we can rule out that any differences between patients and controls were due to demographical and socio-cultural variables. All participants reported normal or corrected-to-normal visual acuity in both eyes. They were native Italian speakers of Caucasian race. Informed consent was obtained from all patients and controls; the adult participants and the parents of adolescent participants provided written informed consent. The procedures were approved by the local Ethics Committee. The participants were na€ıve as to the purposes of the experiment and were debriefed at the end of the experimental session. The study was carried out in accordance with the guidelines of the Declaration of Helsinki.


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Table 1. Demographic and clinical information of patients and age-matched controls

Sample size DSM-IV diagnosis

Comorbidity

Age (years) Education (years) IQ (percentile rank) BMI (kg/m2) Handedness index§ Age at onset (years) Duration of illness (months) SES Education SES Occupation SES Total EDI-3 Drive for thinness Bulimia Body dissatisfaction Eating disorder risk Personal alienation Low self esteem Interpersonal distrust Interpersonal alienation Interoceptive awareness deficits Emotional dysregulation Perfectionism Asceticism Maturity fears Ineffectiveness Interpersonal problems Affective problems Overcontrol General psychological maladjustment BSQ (max 204) BUT Global severity index Weight phobia Body image concerns Avoidance§ Compulsive self monitoring Depersonalization Positive symptom total Positive symptom distress index

AN patients Mean (SD)

Controls Mean (SD)

Patients versus controls

12 women 7 AN-R 2 AN-PB 3 EDNOS 2 OCD 1 GAD, SF, SD 1 SD 20.8 (7.7) 12.1 (2) 91.5 (9.8) 17 (1.8) 19.6 (3.1) 16.1 (5.6) 23.4 (15) 11.3 (3.4) 22.7 (12.5) 33.8 (15.1)

12 women –

– –

–

–

17.4 (7.8) 5.3 (7.1) 19.2 (8.8) 40.8 (19.2) 11.6 (4.9) 9.6 (4.8) 8.8 (4.8) 9.3 (4.9) 13.7 (6.8) 9.2 (6.4) 8.8 (4.2) 9.6 (6.1) 16.1 (7.2) 21.2 (9.1) 18.4 (8.9) 22.8 (11.3) 18.3 (9.2) 96.8 (32.7) 99 (36) 1.9 (1.3) 2.7 (1.4) 2.1 (1.5) 1 (1.1) 1.7 (1.4) 1.4 (1.3) 16.8 (10) 2.4 (0.8)

19.83 (7.64) 11.8 (2.5) 87.4 (14.3) 20.4 (1.9) 16.5 (13.3) – – 13.8 (4.6) 32.3 (10) 46.2 (14.3)

t22 = t22 = t22 = t22 = Z= t20 = t20 = t20 = = = = = = = = = = = = = = = = = = =

0.08, p = .937 0.37, p = .717 0.82, p = .423 4.4, p < .001* 0.43, p = .665 – – 1.51, p = .147 1.97, p = .063 1.97, p = .062 4.09, p < .001* 0.22, p = .824 3.05, p = .006* 2.75, p = .012* 3.76, p = .001* 2.5, p = .021* 1.19, p = .248 0.64, p = .528 2.14, p = .044 1.82, p = .083 3.04, p = .006* 2.56, p = .018* 3.98, p < .001* 3.27, p = .004* 1.06, p = .3 2.2, p = .039* 3.17, p = .005* 3.82, p < .001*

5.4 (6.2) 4.7 (5.7) 8.8 (7.3) 19.7 (17.5) 4.7 (3.7) 4.5 (4.9) 6 (6.3) 7.9 (5.7) 6.5 (9.1) 4.3 (6.5) 4.1 (3) 3.6 (4.9) 6.5 (3.6) 9.3 (8.3) 13.8 (11.7) 10.8 (14.8) 7.7 (6.5) 43.6 (34)

t21 t21 t21 t21 t21 t21 t21 t21 t21 t21 t21 t21 t21 t21 t21 t21 t21 t21

60.2 (16.7)

t22 = 3.39, p = .003*

0.5 (0.3) 1 (0.5) 0.7 (0.5) 0 (0.1) 0.4 (0.4) 0.2 (0.4) 6.8 (4.3) 1.3 (1)

t22 t22 t22 Z t22 t22 t22 t22

= = = = = = = =

3.61, p 3.86, p 3.15, p 2.94, p 3.13, p 3.22, p 3.15, p 2.91, p

= < = = = = = =

.002* .001* .005* .003* .005* .004* .005* .008*

Continued

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Table 1. (Continued)

Chapman scales PAS (max 35)§ MIS (max 30) HPS (max 48) TCI (% max score) NS HA RD P SD C ST

AN patients Mean (SD)

Controls Mean (SD)

Patients versus controls

4.4 (6.3) 4.8 (3.5) 11.7 (5.4)

2.8 (4.6) 5.5 (4) 14.8 (7.2)

Z = 0.173, p = .862 t22 = 0.43, p = .669 t22 = 1.22, p = .237

43.1 (17.1) 70.2 (21.4) 57.4 (22.4) 76.9 (23.3) 52.4 (21.1) 70.2 (16.3) 20.2 (7.3)

57.9 (20.6) 54.8 (10.7) 62.9 (19.5) 54.4 (21.4) 66 (17.7) 84.8 (11.5) 49.1 (26.6)

t22 = t22 = t22 = t22 = t22 = t22 = t22 =

1.91, p 2.23, p 0.64, p 2.46, p 1.71, p 2.52, p 3.63, p

= = = = = = =

.069 .036* .529 .022* .101 .019* .001*

The data of patients and controls were compared by means of independent sample t-test (two-tailed) for normally distributed variables. The Mann–Whitney U-test was used for the variables with a non-normal distribution (marked with §). Significant differences are marked with an asterisk. AN-R = anorexia nervosa restrictive; AN-PB = anorexia nervosa purge-binge; EDNOS = eating disorder not otherwise specified; OCD = obsessive–compulsive disorder; GAD = generalized anxiety disorder; SF = social phobia; SD = somatization disorder; IQ = intelligence quotient; BMI = body mass index; SES = socio-economical status; EDI-3 = Eating Disorder Inventory-3; BSQ = Body Shape Questionnaire; BUT = Body Uneasiness Test; PAS = Perceptual Aberration Scale; MIS = Magical Ideation Scale; HPS = Hypomanic Personality Scale; TCI = Temperament and Character Inventory; NS = novelty seeking; HA = harm avoidance; RD = reward dependency; P = persistence; SD = self-directedness; C = co-operativeness; ST = self-transcendence.

Clinical evaluation Standard clinical scales were administered in order to characterize the patients’ disorder as compared to the controls (Table 1) and to provide a basis for comparing our sample of patients with those reported in previous studies. All participants, except one control, completed the Italian version of the Eating Disorder Inventory-3 (EDI-3; Garner, 2008) to measure disordered eating attitudes and behaviours and personality traits common to individuals with ED. Body representation disturbances were evaluated using the 34-item self-report Body Shape Questionnaire (BSQ; Cooper, Taylor, Cooper, & Fairbum, 1987), that measures shape and weight concerns, and the Body Uneasiness Test (BUT; Cuzzolaro, Vetrone, Marano, & Garfinkel, 2006), that measures subjective body experience and the attitude towards one’s body. The Perceptual Aberration Scale (PAS; Chapman, Chapman, & Raulin, 1978), the Magical Ideation Scale (Eckblad & Chapman, 1983) and the Hypomanic Personality Scale (Eckblad & Chapman, 1986) were used to measure aberrant bodily experiences, erroneous beliefs that are based on magical thinking, and overactive, gregarious personality styles associated with psychosis-proneness. The Italian translation of the TCI was also administered (Cloninger et al., 1994).

Experimental stimuli and tasks The stimuli were colour pictures taken with a digital camera and depicting whole body postures, human faces and objects (Figure 1). Each stimulus was presented upright or


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Figure 1. Example of stimuli and time line of the discrimination task trials. One example trial is provided for each experimental condition of the factorial design category (bodies, faces and objects) and orientation (upright, inverted). Please note that for body and face categories, both male and female stimuli were presented, although only examples of female stimuli trials are shown in the figure.

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upside down. Overall, 64 stimuli for each category were used (32 upright and 32 inverted), for a total of 192 stimuli. Stimuli subtended a 7.6° 9 7.6° square region (300 pixels). Body stimuli depicted eight different whole postures involving displacement of upper and/or lower limbs and acted by 2 male and 2 female models aged 20–28 years. The models’ face was not removed since previous studies have reported absent inversion effects for headless bodies (Minnebusch, Suchan, & Daum, 2009; Yovel, Pelc, & Lubetzky, 2010), but it was scrambled in order to rule out the impact of face identity discrimination in performing the body-related task. Face stimuli consisted of eight pairs of face pictures depicting male and female models aged 20–28 years and taken with a neutral expression and from a frontal perspective. Object stimuli depicted eight pairs of different exemplars of motorcycles viewed from a frontal or sideway perspective. Motorcycle stimuli were used as control because: (i) different exemplars of motorcycles share the same overall structure like different exemplars of bodies and faces do; (ii) similar to bodies, motorcycles have a symmetric and articulated structure in space; (iii) motorcycles are likely to be unfamiliar to most potential participants and are not likely to elicit configural processing; (iv) motorcycles are not typical feminine objects and are less likely to induce emotional reactions in our sample of young women with respect to other more familiar objects, for example, shoes; and (iv) previous studies have used motorcycles as control for body processing in healthy individuals (Urgesi et al., 2004) and brain lesion patients (Moro et al., 2008, 2012). Participants were given a delayed matching-to-sample task adapted from the previous study (Urgesi et al., 2012) that documented differences in the performance of AN patients and controls in the processing of body, face, and object parts. Participants had to decide which one of the two different probe images matched a previously presented sample stimulus. In the discrimination of body stimuli, the matching and non-matching stimuli depicted two different models of the same gender and with the very same body posture. In the discrimination of face stimuli, the matching and non-matching stimuli depicted the faces of two models of the same gender and with the same neutral expression. In the discrimination of object stimuli, the matching and non-matching stimuli depicted two different exemplars of motorcycle viewed from the same perspective. Thus, for all categories participants were required to discriminate the identity of the stimuli to correctly match the correct probe with the sample. In each trial, both sample and probe stimuli were presented upright or inverted.

Procedure Patients and controls were recruited and participated in a first screening session in which the K-SADS-PL or the SCID was administered. After the initial clinical screening, the experimental tasks were administered in a single experimental session lasting approximately 45 min. The administration of the clinical scales was performed in a further session carried out within 1 week of the first session. During the experimental session, participants sat 57 cm away from a 15.6-inch LCD monitor (resolution, 1,024 9 768 pixels; refresh frequency, 60 Hz) where stimuli appeared on a white background. Stimulus-presentation timing and randomization were controlled by using E-prime V1.2 software (Psychology Software Tools Inc., Pittsburgh, PA, USA) running on a PC. The body, face and object categories were presented in three separate 128-trial blocks, with each stimulus presented twice. The order of the three blocks was counterbalanced between participants. Before proceeding with each experimental block, the participants were introduced to the tasks and presented with


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eight practice trials which were not considered in the analyses. In each block, 64 upright and 64 inverted trials were randomly presented. A trial started with the presentation of a central fixation point lasting 500 ms and followed by a sample stimulus presented for 250 ms at the centre of the monitor. The sample duration was in keeping with previous studies testing body inversion in healthy individuals (Minnebusch et al., 2009; Reed et al., 2006; Yovel et al., 2010), thus ensuring the optimal conditions to detect it. The experimenter monitored eye position by checking continuously the participant’s gaze during tachistoscopic presentation. Image persistence was limited by presenting a random-dot mask (7.6° 9 7.6° in size; duration, 500 ms) obtained by scrambling the corresponding sample stimulus by means of custom-made image segmentation software. Immediately after the disappearance of the mask, the two probe stimuli appeared and remained on the screen until a response was made. They were presented one to the left and one to the right of the screen with 1.5° eccentricity. The left or right position of the matching stimulus was randomized. Participants were asked to respond as quickly and accurately as possible by using their index or middle finger to press the left or the right key, respectively, on the computer mouse to indicate whether the matching probe stimulus was to the left or to the right of the screen. Participants always responded with their dominant hand. Reaction times (RTs) and accuracy were automatically recorded and stored for analysis.

Data handling We calculated the proportion of correct responses (accuracy) and the mean RTs for correct responses for each individual, category and orientation (64 trials per cell). Trials with RTs higher than 5,000 ms were identified (0.28% of the total trials in AN participants and 0.30% in control participants) and removed from the computation of both accuracy and RTs values. The Kolmogorov–Smirnov test confirmed the normality assumption for the accuracy and RTs data (all d < 0.22, p > .15) and for all the demographical and clinical variables (all d < .26828, p > .10) with the exception of the handedness score (d = .29, p < .05), the PAS (d = .33, p < .01) and the Avoidance subscale of the BUT (d = .4, p < .01). We followed two strategies of analysis. In the first, we entered accuracy and RTs data into a three-way mixed-model ANOVA with group (AN patients, controls) as between-subjects variable and category (body, face, object) and orientation (upright, inverted) as within-subjects variables. This analysis allowed us to test for the presence of significant inversion effects for the three stimulus categories and in each group and to compare directly the performance of patients and controls in the matching of upright and inverted stimuli. In the second analysis, we directly compared the amount of body inversion effect in patients and controls, also taking into account the gender of the model body. An index of body (BIE), face (FIE) and object inversion effect (OIE) was calculated by subtracting, for each category, the accuracy in discriminating inverted stimuli from that in discriminating upright stimuli. The BIE, FIE and OIE indexes measure the extent to which each participant was better at discriminating upright versus inverted stimuli for bodies, faces and objects, respectively. This allowed us to evaluate the configural processing ability in each participant, independently of her general visual perception performance. The BIE indexes for male and female body stimuli were entered into a 2 9 2, Group 9 Gender mixed-model ANOVA. This analysis allowed us to directly compare the amount of BIE in patients and controls and to test whether the lack of BIE in AN patients was selective for only female bodies or extended also to male bodies. Newman–Keuls post-hoc tests were used for pair-wise comparisons. The clinical data of

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patients and controls were compared by means of an independent sample t-test (two-tailed) for normally distributed variables and the Mann–Whitney U-test for non-normally distributed variables. Significance threshold was set at p < .05 in all statistical tests. All data are reported as mean and standard deviation (SD). Since a previous study (Urgesi et al., 2012) found a positive correlation between visual body discrimination abilities and obsessive personality traits, as measured with the TCI Persistence scale, we tested the correlation between the degree of body, face and object inversion effects and the scores at the Persistence scale of the TCI, that evaluates the tendency to convert a signal of punishment into a signal of reinforcement, and at the Perfectionism scale of the EDI-3, that evaluates that the extent and desire of the need to excel and be the best and not being satisfied with anything less than perfect. These scales measure related but distinct personality traits and both present higher values in AN patients than in controls (Fassino & Abbate-daga, 2002; Halmi et al., 2000). Pearson correlation analyses were used to correlate the amount of inversion effect in each individual as measured by the BIE, FIE and OIE and the individual Persistence and Perfectionism scale scores. As we expected that variations in Persistence and Perfectionism scores should correlate with the amount of inversion effect in both AN patients and control participants, the data of the two groups were entered together into the analysis to increase power. The correlation p-values were adjusted with a Bonferroni correction procedure to control for multiple testing (6).

Results Clinical scales The clinical data of patients and controls are reported in Table 1. The analysis of the EDI-3 data revealed that patients had higher scores with respect to controls on the Drive for thinness, Body dissatisfaction, Eating disorder risk, Personal alienation, Low self-esteem, Interoceptive awareness deficits, Perfectionism, Asceticism, Maturity fears, Affective problems, Overcontrol and General psychological maladjustment. Patients and controls did not differ on the Bulimia, Interpersonal distrust, Interpersonal alienation, Emotional dysregulation and Interpersonal problems scales. Furthermore, patients had higher scores than controls on the BSQ and all BUT scales. No difference was observed between patients and controls on the Chapman scales, while the TCI revealed higher Harm avoidance and Persistence scores and lower Cooperativeness and Self transcendence scores in patients with respect to controls.

Accuracy The analysis on the AN patients’ and controls’ accuracy (Figure 2A) in the discrimination of upright and inverted body, face and object stimuli revealed a non significant main effect of group (F1,22 = 1.39, p = .252, gp2 = .06), but significant main effects of category (F2,44 = 105.94, p < .001, gp2 = .8286) and orientation (F1,22 = 60.09, p < .001, gp2 = .732). These main effects were further qualified by the significant two-way interactions between group and orientation (F1,22 = 6.53, p = .018, gp2 = .23) and between category and orientation (F2,44 = 5.2, p = .009, gp2 = .19) and by the significant three-way Group 9 Category 9 Orientation interaction (F2,44 = 4.49, p = .017, gp2 = .17). Post-hoc analysis showed that controls presented a significant inversion effect (Accuracy upright > Accuracy inverted) for bodies (85.25 8.64% vs.


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Figure 2. Performance of patients with anorexia nervosa (AN) and controls at the experimental tasks. Mean accuracy (A) and reaction times (RTs; B) of AN patients and controls are reported. Error bars indicate SD. Asterisks indicate significant pair-wise comparisons.

74.42 7.59%, p = .001) and faces (96 2.76% vs. 90.33 3.52%, p = .006), but not for objects (96.33 2.31% vs. 92.67 4.64%, p = .149). Conversely, AN patients showed a significant inversion effect for faces (97.17 2.59% vs. 90.33 7.24%, p = .002), but not for bodies (75.67 8.32% vs. 73 10.8%, p = .213) and objects (93.75 4.99% vs. 93.08 3.87%, p = .671). For both orientation conditions, body stimuli were more difficult to discriminate than faces and objects in both AN patients and controls (all ps < .001), while no difference was present between objects and faces in both groups (all ps > .14). Importantly, comparing the performance of patients and controls revealed non significant effects in any conditions (p > .6) with the notable exception of the discrimination of upright bodies, in which patients presented a significantly impaired performance with respect to controls (p = .001). Thus, the performance of AN patients was comparable to that of controls not only in the discrimination of upright and inverted faces and objects, but also in the discrimination of inverted bodies. They presented a selective deficit in the configural processing of upright bodies, which were discriminated with the same accuracy level than inverted bodies. The Cohen’s d for the upright body discrimination was 1.18 (very large effect; Cohen, 1992), indicating that the AN patients performed more than 1 SD below the age-matched controls, while only a Cohen’s d of .16 was estimated for the inverted body discrimination task. The Cohen’s d relative to the between-group difference for the other categories ranged from .1 to .69, indicating negligible to medium effects.

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Since we used both male and female body and face stimuli, we also tested whether the lack of BIE in AN patients was selective for only female bodies or extended also to male bodies. Therefore, we entered the BIE index for male and female body stimuli into a 2 9 2, Group 9 Gender mixed-model ANOVA. This analysis revealed only a main effect of group (F1,22 = 8.99, p = .007, gp2 = .29), but nonsignificant gender main effect (F1,22 = 2.89, p = .103, gp2 = .116) and interaction (F1,22 = 1.3, p = .267, gp2 = .05). This shows that AN patients had a lower BIE than controls for both male (2.08 3.1% vs. 9.68 2.79%) and female stimuli (3.58 2.56% vs. 14.67 2.15%).

Speed of response The ANOVA on RTs (Figure 2B) revealed significant main effects of group (F1,22 = 7.57, p = .012, gp2 = .256) and category (F1,22 = 80.85, p < .001, gp2 = .786) and of their interaction (F2,44 = 8.32, p < .001, gp2 = .274). Post-hoc test showed that patients were overall slower than controls in discriminating body stimuli (p < .001), while no difference was found for faces (p = .301) and objects (p = .252), independently of their orientation. Body stimuli were more difficult to discriminate than faces and objects in both the AN patients and controls (all ps < .003), while no difference was present between objects and faces in both groups (all ps > .45). The ANOVA on RTs yielded also the main effect of orientation (F1,22 = 25.87, p < .001, gp2 = .54) and of the interaction Category 9 Orientation (F2,44 = 4.67, p = .014, gp2 = .175). Post-hoc test showed a significant inversion effect (RTs upright < RTs inverted) for bodies (p < .001) and faces (p < .001) but not for objects (p = .159). The three-way interaction Group 9 Category 9 Orientation, however, was not significant (F2,44 < 1, gp2 = .015), suggesting that patients were slower than controls in discriminating both upright and inverted bodies. This rules out that the specific between-group differences in the accuracy for upright body discrimination were due to speed accuracy trade-off.

Correlation analysis The correlation analysis showed that only the negative correlation between the individual BIE and the TCI Persistence scores was significant (r = .627, adjusted p = .006; Figure 3), while the correlation between the BIE and the EDI-3 Perfectionism scale did not survive the Bonferroni correction procedure (r = .473, adjusted p = .138). No significant correlation was obtained for the FIE and OIE indexes (all .45 < rs < .14).

Discussion In this study, we investigated the perceptual ability of patients suffering from AN in the configural and detail-based processing of the human body. Several previous studies have reported body representation disorders in the AN patients (Cash & Deagle, 1997; Hrabosky et al., 2009; Stice & Shaw, 2002). Here, we tested whether altered body representation in AN is specifically linked to deficits of the configural versus detail-based processing of human bodies. Visual processing of the human body in the healthy is thought to involve both the representation of the spatial relation among body parts in the context of the whole body space (configural processing; Reed et al., 2006) and the analysis of the details of single body parts (detail-based processing). While the latter processing is used for all objects,


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(a)

(b)

Figure 3. Pearson correlation between body inversion effect and the clinical scale of persistence and perfectionism. The graph shows the correlation between the accuracy of the participants’ body inversion effect (BIE) and their individual scores at the Persistence scale of the TCI and at the Perfectionism scale of the EDI-3. Only the correlation between the BIE and the Persistence scale scores survived the Bonferroni-corrected significance threshold of p < .008.

configural processing is more used for specific object categories, especially face and body stimuli (Maurer et al., 2002). We tested configural versus detail-based processing of others’ body in AN using the body inversion paradigm, which estimates the drop of performance following inversion of stimuli, a manipulation that is thought to impair configural processing (Reed et al., 2003, 2006). We found that the AN patients were selectively impaired in processing upright, but not inverted, bodies. The inferior perceptual ability of the AN patients with respect to the controls in discriminating upright bodies cannot be ascribed to different IQ and education levels, because the two groups were strictly matched on these variables (see Table 1). The between-group difference was selective for upright body stimuli and was not present in the inverted body discrimination task or in both upright and inverted face and object discrimination tasks. Thus, patients did not present general deficits in processing social

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stimuli, but a specific impairment in the configural processing of the body. Crucially, the same stimuli were used in the upright and inverted body discrimination tasks, thus ruling out that any differential performance of patients and controls in the two tasks could be ascribed to low-level visual differences in the stimuli or to non-specific emotional reactions to viewing human figures. Indeed, those non-specific alternative interpretations could not explain the differential ability of the two groups in executing different processing of the same stimuli in the upright and inverted conditions. Furthermore, the BIE reduction was comparable for female and male bodies, suggesting that the deficit affects basic aspects of body perception and is not only limited to the processing of body figures similar to the patients’ body. While the body inversion effects were absent for AN patients’ accuracy data, they were significant in both patients and controls when the speed of response was considered. This suggests that also the AN patients’ processing of upright bodies was speeded up with respect to inverted bodies, although this was not associated with an improved discrimination accuracy. This might reflect that both patients and controls attempted to use different processing strategies for upright and inverted bodies, but only controls succeeded in processing the overall configuration of upright bodies. Thus, the strong reduction of BIE in AN patients points to a deficit of configural body processing in AN patients. Several previous neuropsychological studies have documented that attention to details (weak central coherence) is a specific trait of AN patients (Lopez, Tchanturia, Stahl, & Treasure, 2008; Lopez, Tchanturia, Stahl, & Treasure, 2009; Lopez, Tchanturia, Stahl, Booth, et al., 2008; Southgate, Tchanturia, & Treasure, 2008) even in those that have recovered their weight (Harrison, Tchanturia, & Treasure, 2011; Lopez et al., 2009; Tenconi et al., 2010). These studies have used different visuospatial neuropsychological tests involving local information processing, for example the embedded figure test that requires locating and tracing several simple shapes embedded in complex designs (Lopez et al., 2008), or configural information processing, for example the matching familiar figures task that requires participants to identify the exact replica of a familiar object among an array of very similar alternatives (Southgate et al., 2008). AN patients consistently present superior performance for those tests that require local processing when compared with tests requiring configural processing. This keeps with previous finding that AN patients present an advantage in discriminating the morphological details of body parts that differentiate different individuals (Urgesi et al., 2012). Such pattern of performance points to a detail-based information processing style that seems to reflect weak central coherence, a general cognitive style that does not allow integration of the information and leave them fragmented (Lopez et al., 2008). Thus, the deficits of configural body processing observed in this study may reflect the general attention to details observed in AN patients. Crucially however, the fact that AN patients had preserved face configural processing, at least as measured with the inversion paradigm, suggests that weak central coherence affects the perceptual abilities of AN patients especially for non-facial body parts. Although both face and body stimuli may rely on configural processing, it is possible that the specific type of configural processing that is used for the two categories may differ (Reed et al., 2006). Indeed, previous studies have shown that both face and body inversion effects do not occur for: (i) single parts, suggesting that they reflect processing of the whole stimulus configuration; (ii) scrambled stimuli, suggesting that destroying the first order relations among the parts of faces and bodies prevents configural processing; and (iii) for upper-lower halves, suggesting that disrupting the structural hierarchy within each symmetric part of a face (i.e., the presence of the eye over the nose and the nose over


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the mouth, etc.) or body (i.e., the presence of the head and arm and leg attached to the torso, etc.) impairs configural processing (Reed et al., 2006). In a similar vein, significant body and face inversion effects were found for left-right halves, suggesting that destroying the symmetry between the two vertical parts of the stimuli preserves configural processing (Reed et al., 2006). On the other hand, evidence for more extreme types of configural processing has been reported for faces using, for example, the face composite effect, that is the drop of performance in recognizing a top half face presented in a composite with a different half face when the composite is upright and aligned than when the composite is inverted or misaligned (Maurer et al., 2002). The face composite effect suggests that faces can be processed using an extreme type of configural processing (often labelled as holistic) that is based on a template, in which the second-order relations (i.e., metric distance) between the parts are specified (Maurer et al., 2002). Conversely, the composite effects does not apply for bodies (Soria Bauser, Suchan, & Daum, 2011) suggesting that the different body parts are not processed all together as a single gestalt. Thus, while face processing may involve a template-based holistic processing, body processing may be only based on the hierarchical structure of body parts, since their metric distances may greatly vary during movements (Reed et al., 2006). Different patterns of relative deficit and sparing in different components of configural processing may explain the dissociations between face, body and object perception abilities that have been previously observed in prosopagnosic patients (Busigny, Joubert, Felician, Ceccaldi, & Rossion, 2010; Duchaine, Yovel, & Nakayama, 2007), in individuals with autism (Reed et al., 2007) and schizophrenia (Soria Bauser et al., 2012) and, finally, in our AN patients. The finding of a preserved face inversion effect and impaired body inversion effect in AN might suggest that AN patients have difficulties in processing the hierarchical structure of the body, while more extreme forms of holistic processing which allow the direct matching of the exemplar to a template might be spared. Further studies using different measure of configural processing (e.g., the composite effect) are needed, however, to better investigate perceptual body processing in AN. Both patients and controls were better at discriminating faces (and objects) with respect to bodies, indicating that the three categories are not matched for discrimination difficulty. This, however, is unlikely to explain the different inversion effect for bodies and faces in AN patients, since control participants presented comparable body and face inversion effects in spite of different baseline discrimination performance. Furthermore, when the correlations between the individual inversion effect for bodies and faces and the clinical scales of persistence and perfectionism were tested, only the BIE but not the FIE significantly correlated with the Persistence score of the TCI, with higher Persistence scores associated with lower BIE. Thus, the participants’ configural body processing ability was predicted by their increased tendency to convert a signal of punishment into a signal of eventual reinforcement, persisting in a given activity despite intermittent reward (higher Persistence scores). No correlation was, instead, found between BIE and the Perfectionism subscale of the EDI-3 (Garner, 2008), despite patients had higher scores than controls on both the Persistence and Perfectionism scales. The EDI-3 Perfectionism scale evaluates the extent and desire of the need to excel and be the best and not being satisfied with anything less than perfect. On the other hand, the TCI Persistence scale is composed of eight items evaluating individual differences in drive for effort in response to an anticipated reward, work-hardening and overachieving after intermittent punishment or non-reward, and perfectionistic perseveration in response to intermittent reward (Cloninger et al., 1994). As high Persistence levels are observed in obsessive personalities (Cloninger et al., 1994; Kim et al., 2009),

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the increased Persistence scores observed in the AN patients may be, thus, associated with their tendency to routinely explore body parts as a consequence of their obsessive worries about body appearance. Interestingly, a bias towards a more detail-based processing of human faces has been reported (Feusner, Townsend, Bystritsky, & Bookheimer, 2007; Feusner et al., 2010) in patients with body dysmorphic disorders, a different mental disorder characterized by a distressing or impairing preoccupation with an imagined or slight defect in one’s physical appearance, especially with those of face (American Psychiatric Association, 1994). Although the body dysmorphic disorder and the AN patients present different clinical features, studies have highlighted commonalities of body image disturbances both at the emotional and perceptual levels (Hrabosky et al., 2009; Kollei, Brunhoeber, Rauh, de Zwaan, & Martin, 2012). The dissociation between face and body configural processing (and speculatively their different alterations in body dysmorphic disorder and AN patients) is consistent with the segregation of the medial and lateral occipito-temporal areas involved in the configural versus detail-based processing of facial and non-facial body parts (Downing et al., 2001; Haxby et al., 2000; Kanwisher et al., 1997; Peelen & Downing, 2005). Indeed, viewing faces and bodies activates category selective areas in the occipito-temporal cortex that discriminate not only between person-related and object stimuli but also between facial and non-facial body parts. Furthermore, while face- and body-selective areas in the ventro-medial inferior temporal cortex (FFA and FBA) are involved in the configural processing of social stimuli, the areas in the lateral occipito-temporal cortex (OFA and EBA) are involved in processing their single part details (Haxby et al., 2000; Yovel & Kanwisher, 2005). Although face- and body-selective areas, especially in the fusiform cortex, are largely overlapping, they can be dissociated at the anatomical and functional levels (Peelen, Wiggett, & Downing, 2006; Schwarzlose et al., 2005). It is, thus, possible to speculate that selective alterations of the fusiform representation of faces and/or of bodies may underlie the deficits of face and/or body configural processing in body dysmorphic and AN patients. It is worth noting that a recent study (Brandman & Yovel, 2010) has reported that the body inversion effect, like the face inversion effect (Yovel & Kanwisher, 2005), is mediated by the activity of face-, not body-specific areas in the fusiform cortex. Indeed, while the activity of face-selective areas (OFA and FFA) was modulated by the presence of the head in body stimuli and adapted more for repeated presentations of upright than inverted bodies (and faces), the response of face-selective areas (EBA and FBA) to body stimuli was independent from the presence of the head and adapted to a similar extent to upright and inverted postures. Paired with the notion that the body inversion effect is reduced for headless bodies and depends on the presence of the head (Minnebusch et al., 2009; Yovel et al., 2010), this finding suggests a strong link between the cognitive processes and neural bases of the configural processing for faces and bodies. However, as body- and face-selective voxels strongly overlap in the fusiform cortex, it may be difficult to distinguish their activity with standard neuroimaging methods (Peelen et al., 2006). Furthermore, although body and face inversion effects may be mediated by overlapping areas in the fusiform cortex, it is possible that the pattern of connectivity with other areas involved at lower or higher levels of the visual information flow may be different for the two categories. The neurofunctional alterations of configural body processing in AN may stem from an intrinsic dysfunction of the occipito-temporal cortices, by the altered connections between the occipito-temporal cortices involved in configural and detail-based


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processing, or by the top-down modulation of visual areas by medial or lateral prefrontal cortices. Previous neuroimaging studies (Suchan et al., 2010; Uher et al., 2005) in patients with AN have documented the existence of functional and structural alterations in the occipito-temporal cortex including EBA, which have been related to the impaired perceptual processing of self body image in ED. Notably, a recent study (Suchan et al., 2013) documented reduced connectivity between EBA and FBA in AN patients, thus suggesting that the imbalance between configural and detail-based processing may be related to altered flow of information processing in the body perception network. The finding of altered connectivity in the body-related network is particularly interesting for the present study because it might explain the dissociation between deficits of body inversion effect and normal face inversion effects in AN patients. Indeed, altered connectivity between FBA and EBA with relative sparing of the connectivity between FFA and OFA may underlie the pattern of impaired configural processing of bodies but not of faces, although the brain areas involved in configural processing for bodies (FBA) and faces (FFA) overlap in the fusiform gyrus (Brandman & Yovel, 2010). Finally, it is also possible that high-order prefrontal areas may exert top-down modulation of the activity of extrastriate visual cortex inducing differences between patients and controls in the activity of the occipito-temporal body network and in the configural processing of body stimuli. Although the present behavioural study cannot inform on the possible neural underpinnings of altered body perception in AN, the finding that patients present selective deficits in the body inversion effects would point to an imbalance between configural and detail-based processing systems in the AN patients’ brain. One possible limitation of our study is the comparatively low number of patients tested and further studies in larger sample populations are needed to evaluate the clinical significance of the findings. Furthermore, although the selective impairment of AN patients for upright bodies rules out that the effects might be ascribed solely to low-level visual abilities, we collected only self-report measures of visual acuity and thus cannot exclude any unreported or unnoticed visual loss. It is also worth noting that the mean BMI of our AN patient group was relatively high (17 kg/m2), thus urging caution in generalizing the results to the overall population. While a relatively high BMI may attenuate the impact of possible spurious effects of emaciation on cognitive functions, it cannot be excluded that the different body fatness of AN patients and controls may have contributed to their performance in body perception (Babiloni et al., 2009; Legenbauer et al., 2011). In conclusion, this study documented altered body inversion effects but normal face inversion effects in AN patients. In keeping with the advantage in the processing of body morphology reported in a previous study (Urgesi et al., 2012), this finding suggests that AN patients have a deficit of configural processing of human bodies that is associated with their persistence temperament trait. This unbalanced body processing may favour a more detail-based processing of the human body and may be associated, at least partly, with the complex pattern of perceptual and emotional body image disturbances in AN patients. Crucially, the configural processing deficits of AN patients seem to be specific for body stimuli and do not affect the configural processing of face stimuli. Future studies are needed to better understand why the detail-based perceptual style of AN patients affects mainly body processing and spares face processing. Moreover, combined neuropsychological and neuroimaging investigations should be conducted to deepen our knowledge of the neurocognitive alterations of body representation underlying AN.

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Acknowledgements CU was supported by the Italian Ministry of Health (Progetto Giovani Ricercatori, grant number GR-2008-1137139) and IRCCS “E. Medea” (Ricerca Corrente 2012, Italian Ministry of Health). PB was partly supported by the Italian Ministry of Health (Progetto Giovani Ricercatori, grant number GR-2010-2316745) and IRCCS “E. Medea” (Ricerca Corrente, Italian Ministry of Health). We thank Maria Maddalena Savonitto for helping in recruiting control participants and all participants who took part in this study. All authors reported no financial interests or potential conflicts of interest.

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