Research Projects
in speech perception and auditory cognition
Non-acoustic information in speech perception
Have you ever wondered why it's so hard to spell over the phone? "That's 'B'... no, 'B' as in 'boy'..." One reason is that the person you're talking to can't see your face. In face-to-face conversation, the shapes made by speakers' mouths as they talk help us understand what they're saying. Another reason is that we gain extra information about speech sounds from the words they're in (that's why the military uses "call signs" for letters like Alpha, Bravo, etc.). Research in our lab focuses on how the brain combines auditory information with these other kinds of information with in speech perception.
Relevant publications:
- Kim, D., Stephens, J.D.W., & Pitt, M.A. (2012). How does context play a part in splitting words apart? Production and perception of word boundaries in casual speech. Journal of Memory and Language, in press.
- Stephens, J.D.W., & Holt, L.L. (2010). Learning to use an artificial visual cue in speech identification. Journal of the Acoustical Society of America, 128, 2138-2149.
Phonetic context effects
The way that you interpret the sounds of spoken language also depends on neighboring sounds. For example, if you hear a syllable that is somewhere in between "da" and "ga," you are more likely to think it is "da" if the previous sound was "ar" and more likely think it is "ga" if the previous sound is "al." This influence is often referred to as compensation for coarticulation. Another line of research in our lab is concerned with understanding precisely how compensation for coarticulation occurs in the perceptual system. This research is currently funded by an R15 grant from the National Institute on Deafness and Other Communication Disorders (PI: Dr. Navin Viswanathan).
Relevant publications:
- Stephens, J.D.W., & Holt, L.L. (2011). A standard set of American-English voiced stop-consonant stimuli from morphed natural speech. Speech Communication, 53, 877-888.
- Holt, L.L., Stephens, J.D.W., & Lotto, A.J. (2005). A critical evaluation of visually moderated phonetic context effects. Perception & Psychophysics, 67, 1102-1112.
- Stephens, J.D.W., & Holt, L.L. (2003). Preceding phonetic context affects perception of nonspeech. Journal of the Acoustical Society of America, 114, 3036-3039.
Other research interests
In addition to speech perception research, Dr. Stephens also collaborates with students and faculty members at NC A&T and other institutions on a variety of projects related to human cognition.
Relevant publications:
- Stephens, J. D. W., Neal, D. S., & Overman, A. A.(submitted). Closing the empathy gap in college students' judgments of end-of-life tradeoffs.
- Overman, A. A., Wiseman, K. D., Stephens, J. D. W., & Allison, M. (submitted). Age differences in memory for crime information.
- Appino, K., Svec, C., Tankard, B., Overman, A. A., & Stephens, J. D. W. (2010). Odor and the effect of schema activation on recognition memory. American Journal of Undergraduate Research, 9(2-3), 7-12.
- Malmberg, K. J., Steyvers, M., Stephens, J. D., & Shiffrin, R. M. (2002). Feature frequency effects in recognition memory. Memory & Cognition, 30, 607-613.