We are interested in how children and young people with Down syndrome and Prader-Willi syndrome process and understand social information. We are particularly interested in whether social information processing relates to observable social behaviour skills that are central to navigating day-to-day interactions. Our research involves tasks and activities that demonstrate a person’s social skills, verbal, and non-verbal abilities. We also use eye-tracking tasks, which involve looking at social information. Parents/carers will be asked to fill out some questionnaires and complete an interview over the phone. Overall, the whole study takes approximately 2-3 hours to complete and can be conducted over multiple sessions. We are looking for children and young people with Prader-Willi syndrome or Down syndrome aged 4-19-years-old to take part. It is hoped that this research will lead to improved understanding of the social-cognitive strengths and difficulties that are characteristic of these syndromes, and possibly associated with co-occurring autism traits.