Impaired Perception of Facial Motion in Autism Spectrum Disorder

Citation: O'Brien J, Spencer J, Girges C, Johnston A, Hill H ( Impaired Perception of Facial Motion in Autism Spectrum Disorder Justin O'Brien 0 Janine Spencer 0 Christine Girges 0 Alan Johnston 0 Harold Hill 0 Galit Yovel, Tel Aviv University, Israel 0 1 Centre for Research in Infant Behaviour, Department of Psychology, Brunel University , Uxbridge , United Kingdom , 2 Cognitive , Perceptual and Brain Sciences, Psychology and Language Sciences, University College London , London , United Kingdom , 3 School of Psychology, University of Wollongong , Wollongong, New South Wales , Australia Facial motion is a special type of biological motion that transmits cues for socio-emotional communication and enables the discrimination of properties such as gender and identity. We used animated average faces to examine the ability of adults with autism spectrum disorders (ASD) to perceive facial motion. Participants completed increasingly difficult tasks involving the discrimination of (1) sequences of facial motion, (2) the identity of individuals based on their facial motion and (3) the gender of individuals. Stimuli were presented in both upright and upside-down orientations to test for the difference in inversion effects often found when comparing ASD with controls in face perception. The ASD group's performance was impaired relative to the control group in all three tasks and unlike the control group, the individuals with ASD failed to show an inversion effect. These results point to a deficit in facial biological motion processing in people with autism, which we suggest is linked to deficits in lower level motion processing we have previously reported. - The human body conveys an abundance of information necessary for mediating socio-emotional communication [1]. Bodily movements, facial expressions and eye gaze shifts allow us to extract information from others. We can then use this to understand their thoughts, intentions and moods [2]. Without the ability to perceive this information, social interaction would be difficult. Autism spectrum disorder (ASD) is a heterogeneous developmental disorder, characterised by a severe impairment in social communication and interaction. One factor may be due to abnormalities in the mechanisms responsible for biological motion (BM) perception. BM has been widely studied in ASD, yet the current data is equivocal. The first discrepancy concerns what aspect of this perception is actually impaired in ASD. A number of studies report that the deficit only exists when perceiving emotional BM [3 6]. For example, one study found that high-functioning children with ASD only experienced difficulty perceiving point-light emotions. Performance was relatively normal on tasks involving body actions or inanimate movement [7]. Similarly, impairment has been observed when those with autism identify point-light bodily expressions of anger, happiness and disgust [8]. By contrast, there is evidence of the impairment extending to non-emotional stimuli too [911]. Blake et al., asked children with autism to state whether a brief point-light animation represented a body or not. Such task was relatively unemotional, and should have evoked a normal performance. This was not the case however; those with autism still made many more errors compared to the control group [12]. These findings were later replicated by Annaz et al., [13] and Nackaerts et al., [14], further suggesting that all elements of BM perception is weakened in ASD. The second discrepancy regards data which conversely report intact BM mechanisms in ASD. One study presented participants with point-light displays (walking figures, translating triangles, or translating unfamiliar shapes) embedded in noise and asked them to determine the direction of movement. Those with ASD performed similarly to controls across all three tasks [15]. Murphy and colleagues also showed that ASD participants could successfully identify the direction in which a point-light walker (embedded in noise) was moving in. The authors suggest that ASD participants were able to integrate local motion cues to produce a coherent perception of BM [16]. Such findings may reflect an experimental bias caused by testing different age groups. Studies conducted with ASD children consistently report a deficit in BM perception [7,12,17], whereas the adult data is less conclusive. Perhaps such perception improves with chronological age [4,13]. It is possible that older ASD subjects acquire compensatory mechanisms, and thus perform similarly to typically developing subjects on BM tasks. For example, the absence of global processing may force ASD adults to acquire superior processing with local cues [18]. Alternatively, factors such as symptom severity [12] or general intelligence [19] could affect the ability of ASD participants to perceive BM. Indeed, Rutherford and Troje [20] showed that only those ASD individuals with a low IQ had a poor perception of BM. While the existi (...truncated)