**4. Discussion**

This study evaluated the psychometric properties of two clinical assessments of social cognition and one social behavior parent questionnaire (summarized in Table 5). Both direct assessments of social cognition and parent-report of social behavior met criteria for a portion of the psychometric indices evaluated. Associations with cognition and language abilities emphasize how these social cognition and behavior measures relate to broader developmental domains. Additionally, the relations among measures show a clear pattern of correlation within NEPSY-II subtests and within SRS-2 subdomains, but no correlations were found across the direct assessments and parent-report measures. The SRS-2 demonstrated the strongest psychometric properties, with high feasibility, moderate to excellent test-retest reliability, and no practice effects, suggesting this measure could be appropriate for use in clinical trials involving youth with DS. The NEPSY-II Theory of Mind subtest raw scores also demonstrated good psychometrics; however, percentile rank floor effects indicate this measure is not suitable for this population. Feasibility for the NEPSY-II Affect Recognition was problematic and this measure may only be appropriate for certain IQ ranges of children and adolescents with DS.


**Table 5.** Summary of social cognition and behavior measures assessed on a priori criteria.

+ indicates study criterion met: <20% floor effects, ≥80% feasibility, ≥0.75 test-retest ICC, small and non-significant practice effects; − indicates study criterion not met: ≥20% floor effects, <80% feasibility, <0.75 test-retest ICC, medium/large and significant practice effects; RRBI = Restricted, Repetitive Behaviors and Interests.
