Participants
Participants were recruited from a larger, ongoing study of cognitive control development in early childhood at [details omitted for double-anonymized peer review]. Participants were originally recruited using research registries, community events and advocacy groups, clinics, early intervention programs, and word of mouth. Exclusionary criteria included medical disorders or medications impacting the central nervous system, a history of seizures or seizure medication, inability to complete parent questionnaires or testing in English, prolonged prenatal substance exposure, and significant sensory or motor impairments or major physical abnormalities which limited ability to complete the testing battery.
Participants included 19 verbal autistic children (16 male) aged 3.9 to 6.8 years (Mage = 5.6, SD = 0.82 years) at their initial visit. Sixteen children returned for the follow-up visit aged 4.0 to 6.9 years (Mage = 5.6 SD = 0.89). All participants used flexible phrase speech and had an age equivalent of at least 18 months as assessed via the Visual Reception domain of the Mullen Scales of Early Learning (MSEL; Mullen, 1995) as part of their participation in the larger study within the previous two years. Diagnosis of an autism spectrum disorder was determined using the ADOS-2 (Lord, Luyster, et al., 2012, Lord, Rutter et al., 2012) and the ADI-R (Rutter et al., 2003; Kim & Lord, 2012) and DSM-5 criteria (American Psychiatric Association, 2013) based on expert judgment of a licensed clinical psychologist11During the COVID-19 pandemic, the CARS-2 was added to the protocol to further confirm that children met standardized criteria for an autism spectrum disorder.. Sample characteristics are reported in Table 1.