Participants

This study was carried out as part of the Autism Center of Excellence (ACE) Program funded by the National Institute of Mental Health (NIMH). Psychometric and neuroimaging data were acquired at four sites: (1) the Center for Translational Developmental Neuroscience, Yale University, New Haven, CT (73 volunteers); (2) the Laboratory of Cognitive Neuroscience, Boston Children's Hospital, Harvard Medical School, Boston, MA (49 volunteers); (3) the Center on Human Development and Disability, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, WA (92 volunteers); (4) the Staglin IMHRO Center for Cognitive Neuroscience, David Geffen School of Medicine, University of California, Los Angeles, CA (73 volunteers). All research was performed in accordance with US federal law (45 C.F.R. 46) and with the approval of the Institutional Review Boards (IRBs) of both the University of Southern California (USC) and the four institutions where the neuroimaging and psychometric data had been acquired. Recruited subjects included N₁ = 110 ASD patients (55 males) and N₂ = 83 TD subjects (43 males), for a total of N = N₁ + N₂ = 193 volunteers. All subjects and their legally authorized representatives provided informed written consent. The Differential Ability Scales (DAS-II)—including the Verbal (V), Non-Verbal (NV), Spatial (S), General Conceptual Ability (GCA), and Spatial Non-Verbal Composite (SNC) scales—were used to assess the cognitive abilities of the participants. SNC scores were unavailable for 9 subjects and one additional subject did not have DAS scores available. Welch's t-test for samples with unequal variances was used to evaluate the significance of differences in age and DAS scores between the two cohorts. To test the statistical significance of the difference in sex composition between the two groups, sex was coded as a binary variable and a χ² test was used.