OBJECTIVE. To determine whether the Evaluation of Social Interaction (ESI) is sensitive enough to differentiate between people without identified diagnoses and those with neurologic or psychiatric disorders in terms of their observed quality of social interaction.
METHOD. Participants were age 16–69 and were without identified diagnoses (n = 304) or had neurologic (n = 77) or psychiatric (n = 104) disorders. They were evaluated using the ESI.
RESULTS. Nonparametric Kruskal–Wallis tests and post hoc Mann–Whitney U tests revealed that the group without identified diagnoses had significantly better quality of social interaction than did either group with disabilities (Us = 3,172 and 3,189, respectively; p ≤ .001).
CONCLUSION. The ESI is sensitive with regard to detecting differences in quality of social interaction among groups expected to differ, suggesting that it is valid for use when the desired purpose is to identify people with diminished quality of social interaction.