Degree of ASD symptoms were assessed in all participants by way of an observational measure (the Childhood Autism Rating Scale, CARS, Schopler et al., 1988) and a parental questionnaire (the Social Communication Questionnaire, SCQ – lifetime version Berument et al., 1999). The CARS requires the experimenter to rate the participant from a scale of 1–4 on 15 item behavioral rating scale, for example “emotional response” and “fear and nervousness.” Scores range from 15 to 60 and the cut-off for ASD is 30. The SCQ consists of 40 “Yes/No” questions asking parents if their child currently displays specific autism-related behaviors or whether those behaviors were present between the ages of 4–5 years. Scores range from 0 to 40 and the cut-off score for ASD is 15. Intellectual ability was measured using the Wechsler Abbreviated Scale of Intelligence (WASI, Wechsler, 1999). This is comprised of four standardized sub-tests that assess expressive language, perceptual organization, abstract verbal reasoning, and non-verbal fluid reasoning abilities. The four sub-tests when considered together yield a “full scale IQ” that provides a composite measure of the participant's general intelligence. All participants had normal, or corrected-to-normal, visual acuity.
