Participants

Participants were drawn from a larger study examining potential biomarkers in ASD at Cincinnati Children’s Hospital Medical Center. The present study included 42 individuals with ASD (83.33% male), 29 age-, gender-, and IQ-matched developmental disability (DD) controls (89.65% male), and 62 age-, gender-matched TD controls (88.79% male) between 3 and 25 years of age (M = 12.33, SD = 5.80). Of the sample, 72% were White, 12% were Black, 10% were Other/Multiracial, 3% were Hispanic/Latino, 2% were Asian, and 1% were Native Hawaiian or Other Pacific Islander. The ASD group had a confirmed diagnosis of ASD through a structured clinical interview using the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) ASD criteria (American Psychiatric Association, 2013), testing with the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2; Lord et al., 2012), and administration of the Social Communication Questionnaire (SCQ; Rutter et al., 2003). Further, the ASD participants did not have any known syndromic or other genetic variant associated with their ASD diagnosis. The TD control participants had no reported or suspected developmental concerns, fell in the normal range (e.g., between 90 and 125) of cognitive functioning on IQ measures administered through the study, and an SCQ total score less than 15. The DD control group was matched with a subgroup of the ASD participants with an IQ less than 90. The DD control group was also administered the ADOS-2 to ensure none of the participants had undiagnosed ASD. All participants or their guardians provided written informed consent and participant assent (if feasible) for study participation, and the study was approved by the local Institutional Review Board.

Participants’ cognitive functioning was measured across all three groups utilizing the Stanford-Binet Intelligence Scales, Fifth Edition (SB-5; Roid, 2003) or the Differential Ability Scales-II (DAS-II; Elliott, 2007) to obtain a Full-Scale IQ score. One DD control participant and eight ASD participants were not able to complete one of the above cognitive measures due to behavioral concerns or functioning level. This resulted in statistically significant differences between the mean Full-Scale IQ score of the ASD group and the DD control group (F_(2,121) = 54.70, p = 0.000); however, adding in the eight lower functioning individuals would assumedly account for these differences and decrease the ASD mean Full-Scale IQ score. These participants were still included in the original sample due to their ability to complete the eye-tracking task despite their low cognitive abilities. Participants’ caregivers or guardians across all groups completed the SCQ. Participants’ caregivers of the ASD group completed the Aberrant Behavior Checklist (ABC; Aman et al., 1985) and the Social Responsiveness Scale (SRS; Constantino and Gruber, 2005). No significant group differences were found based on chronological age (F_(2,120) = 2.29, p = 0.106). As expected, significant group differences emerged across groups on the SCQ consistent with the lack of ASD diagnosis in the DD and TD control groups (F_(2,130) = 90.79, p = 0.000). See Table 1 for participant descriptive statistics along with the caregiver rating scales for the analyzed sample.

Descriptive statistics of ASD, DD, and TD variables.

Note. Table includes data from the analyzed sample of participants; ASD, autism spectrum disorder; DD, developmental delay controls; TD, typically developing controls; SD, standard deviation; ABC, Aberrant Behavior Checklist; SRS, Social Responsiveness Scale. ^aGroup differences found on full scale IQ (TD > ASD>DD). ^bGroup differences found on SCQ (ASD > DD > TD).