Effects of distributional information on categorization of prosodic contours

Although prosody clearly affects the interpretation of utterances, the mapping between prosodic representations and acoustic features is highly variable. Listeners may in part cope with this variability by adapting to distributions of acoustic features in the input. We examined whether listeners adapt to distributional changes using the construction It looks like an X. When pronounced with an H* pitch accent on the final noun and a low boundary tone, the construction supports an affirmative interpretation (e.g., It looks like a ZEBRA [and I think it is one]). Conversely, when pronounced with a L+H* pitch accent and a rising boundary tone, it suggests a negative interpretation (e.g., It LOOKS like a zebra.... [but it is not]). Experiment 1 elicited pragmatic interpretations of resynthesized 12-step continua with these two contours as the end points. In Experiment 2, one group of listeners heard items sampled from the most ambiguous region along the continua followed by affirmative continuations (e.g., It looks like a zebra because it has stripes all over its body) and items near the contrastive endpoint followed by negative continuations (e.g., It looks like a zebra but it is actually something else). Another group heard the reverse (i.e., ambiguous items with negative continuations and non-contrastive items with affirmative continuations). The two groups of participants subsequently derived diverging interpretations for novel ambiguous items, suggesting that prosodic processing involves flexible mappings between acoustic features and prosodic representations that are meaningful in interpretation of speech.