Recognizing Biological Motion and Emotions from Point- Light Displays in Autism Spectrum Disorders Evelien Nackaerts 1 , Johan Wagemans 2 , Werner Helsen 1 , Stephan P. Swinnen 1 , Nicole Wenderoth 1,3 , Kaat Alaerts 1 * 1 Department of Biomedical Kinesiology, Group Biomedical Sciences, Research Center for Movement Control and Neuroplasticity, KU Leuven, Heverlee, Belgium, 2 Laboratory of Experimental Psychology, KU Leuven, Leuven, Belgium, 3 Neural Control of Movement Lab, Department Health Sciences and Technology, ETH, Zurich, Switzerland Abstract One of the main characteristics of Autism Spectrum Disorder (ASD) are problems with social interaction and communication. Here, we explored ASD-related alterations in ‘reading’ body language of other humans. Accuracy and reaction times were assessed from two observational tasks involving the recognition of ‘biological motion’ and ‘emotions’ from point-light displays (PLDs). Eye movements were recorded during the completion of the tests. Results indicated that typically developed-participants were more accurate than ASD-subjects in recognizing biological motion or emotions from PLDs. No accuracy differences were revealed on two control-tasks (involving the indication of color-changes in the moving point-lights). Group differences in reaction times existed on all tasks, but effect sizes were higher for the biological and emotion recognition tasks. Biological motion recognition abilities were related to a person’s ability to recognize emotions from PLDs. However, ASD-related atypicalities in emotion recognition could not entirely be attributed to more basic deficits in biological motion recognition, suggesting an additional ASD-specific deficit in recognizing the emotional dimension of the point light displays. Eye movements were assessed during the completion of tasks and results indicated that ASD- participants generally produced more saccades and shorter fixation-durations compared to the control-group. However, especially for emotion recognition, these altered eye movements were associated with reductions in task-performance. Citation: Nackaerts E, Wagemans J, Helsen W, Swinnen SP, Wenderoth N, et al. (2012) Recognizing Biological Motion and Emotions from Point-Light Displays in Autism Spectrum Disorders. PLoS ONE 7(9): e44473. doi:10.1371/journal.pone.0044473 Editor: Christina Schmitz, Centre Hospitalier Le Vinatier (Ba ˆt. 452), France Received May 15, 2012; Accepted August 8, 2012; Published September 6, 2012 Copyright: ß 2012 Nackaerts et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: Support for this study was provided through grants from the Flanders Fund for Scientific Research (FWO projectsG.0758.10). KA is supported by a FWO postdoctoral Research fellowship grant. This work was also supported by Grant P6/29 from the Interuniversity Attraction Poles program of the Belgian federal government. This study has been conducted in collaboration with the Leuven Autism Research Consortium (LAuRes), funded by the Research Council of the University of Leuven (IDO/08/013). JW is supported by the Methusalem program of the Flemish government (METH/08/02). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: Co-author Nicole Wenderoth is currently serving as an editor for PLOS ONE. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. * E-mail: Kaat.Alaerts@faber.kuleuven.be Introduction Autism Spectrum Disorders (ASD) refers to a set of complex, polygenetic neurodevelopmental disorders which are character- ized by social and communication deficits, in addition to repetitive behavior and restricted interests [1]. In the past, psychological research has increasingly focused on the identification of the social deficits associated with ASD. In this context, it has been shown repeatedly that individuals with ASD differ from typically developed (TD) individuals in their visual perception of facial expressions of emotions [2], reflective of a deficit in facial emotion recognition [3]. However, facial expressions are not the only source of input for conveying emotionally relevant information. In every-day situa- tions, other sources - such as the communicator’s body language or ‘‘bodily kinematics’’ - are equally important, especially when facial expressions are inconsistent or unavailable to the observer. In vision research, point-light displays (PLDs), representing biological motion solely by a set of small lights or markers attached to the major joints of an actor’s body, provide a widely adopted paradigm to investigate bodily motion perception [4]. In TD- subjects, PLDs have been shown to provide sufficient information for recognizing the gender of an actor [5], the activity in which he/she is engaged [4] and, even, the emotional state of the actor [6–7]. Yet, to date, only a few research groups explored whether obsevers with an ASD are different from TD-observers in biological motion or bodily emotion perception from PLDs and results are not entirely consistent [8]. Using a similar set of PLD-stimuli, Moore and colleagues assessed the ability to recognize a person’s actions, subjective states, emotions, and objects conveyed by moving PLDs in groups of low-functioning ASD-children [9], high-functioning ASD- children [10] and high-functioning ASD-adults [11]. Compared to controls, ASD-subjects were shown to have a reduced ability in verbally reporting the subjective states and emotions from the displayed point light animations, but no differences were revealed in reporting actions or objects. In study by Atkinson (2009), the ability of ASD-individuals to recognize actions or emotions from PLDs was readdressed using forced-choice paradigms [12]. Overall, results were replicated by showing ASD-related impair- ments in emotion recognition. However, in contrast to the earlier studies, the ASD-group also revealed deficits in labeling the PLOS ONE | www.plosone.org 1 September 2012 | Volume 7 | Issue 9 | e44473