Several lines of evidence challenge Black and Uhde's theory that selective mutism is simply a severe manifestation of social anxiety. Key counter-arguments include contradictory empirical findings from Melfson et al. showing lower social anxiety scores in children with selective mutism, discrepancies in the typical age of onset (with selective mutism appearing much earlier than social phobia), and clinical observations that selective mutism is frequently outgrown spontaneously, unlike social phobia.