This collection contains the EEG and behavioural data relating to the article by Manning et al. published in the journal, 'Behavioural and neural indices of perceptual decision-making in autistic children during visual motion tasks'. Many studies report atypical responses to sensory information in autistic individuals, yet it is not clear which stages of processing are affected, with little consideration given to decision-making processes. We combined diffusion modelling with high-density EEG to identify which processing stages differ between 50 autistic and 50 typically developing children aged 6-14 years during two visual motion tasks. Our pre-registered hypotheses were that autistic children would show task-dependent differences in sensory evidence accumulation, alongside a more cautious decision-making style and longer non-decision time across tasks. We tested these hypotheses using hierarchical Bayesian diffusion models with a rigorous blind modelling approach, finding no conclusive evidence for our hypotheses. Using a data-driven method, we identified a response-locked centro-parietal component previously linked to the decision-making process. The build-up in this component did not consistently relate to evidence accumulation in autistic children. This suggests that the relationship between the EEG measure and diffusion-modelling is not straightforward in autistic children. Compared to a related study of children with dyslexia, motion processing differences appear less pronounced in autistic children. Exploratory analyses also suggest weak evidence that ADHD symptoms moderate perceptual decision-making in autistic children.Autism affects social functioning and encompasses sensory symptoms such as aversion to sounds or fluorescent lights. It is not known why sensory symptoms occur. Previous research has overlooked the dynamic process leading to sensory responses, so we do not know the point at which differences arise. For example, whether a heightened sensory response in autism is due to taking in sensory information too quickly or if it is an aversive response triggered at a lower level of sensory stimulation. I will investigate the nature and source of sensory symptoms in autism by studying which stages of sensory processing are different, how differences relate to brain activity and how sensory processing affects movements in people with autism. I will also investigate how processing differences relate to sensory symptoms and whether additional difficulties, such as motor problems or attention difficulties, affect sensory processing in people with autism. I will measure electrical activity at the scalp while children with and without autism respond to sensory information. I will combine behavioural and brain activity measures using mathematical models. Parents will complete questionnaires about their child‘s sensory processing and other difficulties. The findings from this study will help to design future interventions and support for people with autism who experience sensory symptoms.

The sample included 50 autistic children and 50 typically developing children, aged 6 to 14 years. Participants were recruited from local schools, community contacts and invitations to families who participated in previous studies. Two experimental tasks were presented on a computer using MATLAB: a direction integration task and a motion coherence task. In both tasks, children were asked to judge the direction of motion as quickly and accurately as possible. EEG data were collected with a 128-electrode Hydrocel Geodesic Sensor Net connected to Net Amps 300 (Electrical Geodesics Inc., OR, USA), using NetStation 4.5 software. A photodiode attached to the monitor independently checked the timing of stimulus presentation. Children made their responses using a Cedrus RB-540 response box (Cedrus, CA, USA). For further details, please see the published manuscript.