Differentiating Questions from Statements: The Role of Intonation

The most salient cues to yes/no questions and statements are rising and falling terminal pitch contours. Because young children readily differentiate rising from falling pitch contours, the presumption is that they can discern speakers’ questioning or declarative intentions from intonation alone. This thesis examined developmental changes in the use of intonation to identify questions and statements. In the first of three studies, participants from 5 years of age judged naturally produced utterances and low-pass filtered versions as questions or statements. Children correctly identified utterance type above chance levels and achieved adult accuracy levels at 9 years of age, highlighting younger children’s confusion about the links between intonation contours and pragmatic intentions. In the second study, participants from 8 years of age judged utterances with graded manipulations of terminal contours as questions or statements. Children’s question/statement judgments shifted more gradually than those of adults, reflecting greater uncertainty, but the location of the category shift was comparable across age. Adults' discrimination of utterance pairs was best for the pair that crossed the category shift, implying categorical perception of the intonation contours. In the final study, participants from 7 years of age judged the statement or question status of child- and adult-directed utterances in a gating task with words added incrementally. After limited exposure to the speaker’s voice, adults and children from 9 years of age correctly identified questions and statements from the initial word, demonstrating for the first time that English-speaking adults and children perceive pre-terminal cues to these utterance types. Identification was more accurate for child-directed than for adult-directed utterances, indicating that the former speech register exaggerates the distinctions between question and statements. Collectively, the findings reveal a protracted course of development for the questioning and declarative intentions signalled by intonation patterns and, more generally, for the pragmatic functions of intonation.Ph.D