Auditory evoked potentials reveal early perceptual effects of distal prosody on speech segmentation

Abstract

Prosodic context several syllables prior (i.e., distal) to an ambiguous word boundary influences speech segmentation. To assess whether distal prosody influences early perceptual processing or later lexical competition, EEG was recorded while subjects listened to eight-syllable sequences with ambiguous word boundaries for the last four syllables (e.g., tie murder bee vs. timer derby). Pitch and duration of the first five syllables were manipulated to induce sequence segmentation with either a monosyllabic or disyllabic final word. Behavioural results confirmed a successful manipulation. Moreover, penultimate syllables (e.g., der) elicited a larger anterior positivity 200–500 ms after the onset for prosodic contexts predicted to induce word-initial perception of these syllables. Final syllables (e.g. bee) elicited a similar anterior positivity in the context predicted to induce word-initial perception of these syllables. Additionally, these final syllables elicited a larger positive-to-negative deflection (P1-N1) 60–120 ms after onset, and a larger N400. The finding that prosodic characteristics of speech several syllables prior to ambiguous word boundaries modulate both early and late event-related potentials (ERPs) elicited by subsequent syllable onsets provides evidence that distal prosody influences early perceptual processing and later lexical competition.

Keywords:

• prosody
• speech segmentation
• event-related potentials
• temporal attention

Acknowledgements

This material is based upon work supported by the National Science Foundation [grant number BCS-0847653] awarded to L.C.D. and was partially funded by a National Institutes of Health Institutional Training Grant [grant number MH16745] which provided post-doctoral training for M.B., and a John Merck Fellowship in the Biology of Developmental Disabilities awarded to L.D.S. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation, the NIH, or the John Merck Foundation. We thank Paul Dainton, Ashley Fitzroy, Martin Nolet and Anton Zakashansky for help with stimulus preparation, and Paul Dainton, Brian Keane and Chase Langeraap for help with data collection and analysis.

Notes

1. Data obtained from the English Lexicon Project Web Site (Balota et al., 2007).