*3.1. Aim 1: Feasibility and Floor Effects*

Feasibility and floor effect indices for raw scores, percentile ranks, and/or standard scores (as appropriate) of the NEPSY-II Theory of Mind, NEPSY-II Affect Recognition, and SRS-2 are presented in Table 1. Two of the three measures evaluated in this study met the a priori criterion for feasibility: the NEPSY-II Theory of Mind (86.3–87.7%) and the SRS-2 (87.7%). NEPSY-II Affect Recognition fell below acceptable criterion for feasibility (71.2%) and therefore was investigated for Aim 3 as part of the post hoc analysis for low feasibility measures. Reasons for missing the NEPSY-II Affect Recognition subtest included not understanding the task (17.8%), behavioral noncompliance (3.4%), and verbal refusal (0.7%). A small portion of participants only completed the subtest at one time point (6.9%). Additionally, 15.4% of participants who completed the measure were described as exhibiting "acquiescence", defined as selecting responses without considering each response option. Floor effects followed the same pattern for the NEPSY-II raw scores and SRS-2 T-scores, with acceptable levels of floor effects for the NEPSY-II Theory of Mind (15.1–19.2%) and the SRS-2 (12.3%), and unacceptable levels for the NEPSY-II Affect Recognition (28.8%). Floor effects for percentile rank on the NEPSY-II Theory of Mind and standard scores on the NEPSY-II

Affect Recognition were both below a priori criteria. Specifically, of the participants who could complete the measures, 95% had the lowest percentile rank (<2%) on the NEPSY-II Theory of Mind Verbal, 97% had the lowest percentile rank (<2%) on the NEPSY-II Theory of Mind Total, and 39% had the lowest standard score (1) on the NEPSY-II Affect Recognition. Table 1 presents floor effects that include those with the lowest score on each measure and those who were unable to complete the task.


**Table 1.** Social cognition performance and feasibility at Time 1, *n* = 73.

<sup>a</sup> *n* at floor includes children who got the lowest score on the measure and those who could not complete the task; <sup>b</sup> Some descriptive statistics not reported for percentile ranks; <sup>c</sup> NEPSY-II Theory of Mind Total score percentile rank is not normed for 6-year-olds (*n* = 3); ToM = Theory of Mind; AR = Affect Recognition; SRS-2 = Social Responsiveness Scale, Second Edition; RRBI = Restricted, Repetitive Behaviors and Interests.
