Distinguishing selective mutism and social anxiety in children: a multi-method study

Selective mutism (SM) is an anxiety disorder in which a child fails to speak in some situations (e.g., school) despite the ability to speak in other situations (e.g., home). Some work has conceptualized SM as a variant of social anxiety disorder (SAD) characterized by higher levels of social anxiety. Here, we empirically tested this hypothesis to see whether there were differences in social anxiety (SA) between SM and SAD across behavioral, psychophysiological, self-, parent-, and teacher-report measures. Participants included 158 children (M_age = 8.76 years, SD = 3.23) who were classified into three groups: children with SM and who were also highly socially anxious (SM + HSA; n = 48), highly socially anxious children without SM (HSA; n = 48), and control children (n = 62). Children participated in a videotaped self-presentation task, following which observed SA behaviors were coded, and salivary cortisol reactivity was measured. We also collected child, parent, and teacher reports of children's trait SA symptoms. The SM + HSA and HSA groups had similar observed non-verbal SA behavior, cortisol reactivity, and trait SA symptom levels according to parent and child reports, but SM + HSA children had significantly higher SA according to teacher report and observer-rated verbal SA behavior relative to the HSA group. As expected, control children had lower cortisol reactivity and SA across all measures relative to the other groups. Although SM and SAD in children share many similarities, SM may be characterized by greater SA in certain social contexts (e.g., school) and is distinguishable from SAD on behavioral measures of verbal SA.