“Um…” Thinking out loud: Children infer the social meaning of speech disfluencies

Delays and disfluencies (“um”) are ubiquitous in conversation and signal what's going on inside a speaker's mind. Three studies demonstrate how children (age 4–9) draw mental inferences from disfluencies (N = 305; 48% girls; majority White; collected 2019–2022). When 2 speakers made accurate factual claims, children by 4 inferred that a disfluent speaker was less knowledgeable, but made no such inference when speakers claimed ignorance (Experiment 1). When 2 speakers stated a toy preference, children by 6 inferred that a disfluent speaker had a weaker preference for that toy, but a stronger preference for an alternative (Experiments 2 and 3). Overall, children use disfluencies to reason flexibly about the mental states behind someone's words, imbuing disfluencies with radically different meanings across these conversational contexts.