- How does sign language experience shape perceptual abilities?
- How do signers “watch” a signed story and how is this different from reading printed text?
- What cues modulate young infants’ attraction to sign language?
My Research Summary
Much research has been done on how eye-gaze behavior during reading text and scene perception is affected by perceptual, linguistic, and experiential factors. My own work focuses on how signers “read” or “watch” sign language, of which little is known. I conducted experiments that uncovered strong correlations in the distribution of gaze points and age of when adults learned ASL. Compared to late and novice signers, early native signers exhibited more focused fixations in their gaze patterns, and gaze patterns were highly correlated with earlier age of acquisition, better comprehension and higher lexical recall. This led us to ask whether these highly focused gaze patterns are indicators of an advanced perceptual skill or whether they are a result of strong language processing abilities. To test this, we examined a group of novice ASL students who were explicitly instructed to fixate on the face and not move their eyes while watching stories, mimicking the skilled gaze behavior seen in early signers. Eyetracking data showed that their gaze patterns changed according to the instructions, and moreover, that this change resulted in better comprehension accuracy. These results suggest that age-related changes in passive eye gaze behavior can provide a highly sensitive index of sign language processing. We hope to use these findings towards promoting perceptual behaviors that support optimal language processing in deaf signing children. Two manuscripts are near completion and almost ready for submission.
In Dr. Bosworth’s laboratory, Stone, Petitto & Bosworth (under review) asked whether human infants are born with a peaked sensitivity to select salient cues unique to natural language, be it spoken or signed, potentially shedding new light on universals of early language learning. To answer this question, we explored infant sensitivity to visual sonority, or perceptual salience of the language signal. Sound-based sonority has been suggested to be such a cue supporting language acquisition—but only for spoken languages. However, sonority is well documented in signed languages too. This existence of sonority in signed language offers a fascinating opportunity to test hypotheses about the mechanisms governing early language acquisition.
We hypothesized that if hearing infants who had never seen signed language before nonetheless demonstrated a perceptual sensitivity to sonority-based constraints in signed language syllables, it would suggest the existence of a biologically-governed sensitivity to structural cues that guides early language learning in any modality. If they were not, then this would suggest that sensitivity to sonority-based constraints in spoken syllables—which has been reported in the literature—is learned during prenatal language exposure, as the human fetus is able to hear spoken language prosody in the extra-uterine environment but is unable to see such patterning in signed language. Moreover, we asked whether such sensitivities, if they exist, were subject to perceptual narrowing. We tested 38 6-month-old and 12-month-old hearing infants (who had never seen sign language before) on a preferential looking paradigm where they viewed two side-by-side videos of lexicalized fingerspelling that differed only in that one was “high sonority” and the other was “low” sonority. The results revealed that 6-month-old infants preferred high sonority signed syllables, demonstrating a sensitivity to a structured and contrastive cue in a language and sensory modality they had never seen before. Older babies did not, suggesting that this sensitivity attenuates in the absence of signed language exposure.
These results support the hypothesis that infants have a biological predisposition to attend to sonority-based, contrastive patterning presented in both signed and spoken languages. The present findings raise the need for clarifying the role of structured cues in language acquisition and the extent to which infants may be predisposed to exploit these cues—be they spoken or signed—for all early language learning. This paper is under review (Stone, Petitto & Bosworth, in prep).
Bosworth, RG, Wright, CE, Bartlett, MS, Corina, DP, & Dobkins, KR (2003). Characterization of the visual properties of signs in ASL. Chapter in AE Baker, B van den Bogaerde & O Crasborn (Eds.), Cross-Linguistic Perspectives in Sign Language Research. Hamburg: Signum Press.
Bosworth, RG, Bartlett, MS, & Dobkins, KR (2006). Image statistics of American Sign Language: comparison with faces and natural scenes. Journal of the Optical Society of America, A 23(9). 2085-2096.
Emmorey, K, Bosworth, RG, & Kraljic, T (2009). Visual feedback and self-monitoring of sign language. Journal of Memory and Language, 61, 398-411.
Bosworth, RG & Emmorey, K (2010). Effects of iconicity and semantic relatedness on lexical access in American Sign Language. Journal of Experimental Psychology, 36(6), 1573-81.
Stone, A, Petitto, L-A, & Bosworth, RG (2017). Visual Sonority Modulates Infants’ Attraction to Sign Language. Language Learning and Development, (under review).
Bosworth, RG (2016, Jan). How the eyes “read” sign language: An eyetracking investigation of children and adults during sign language processing. Paper to be presented at the 12th meeting of Theoretical Issues in Sign Language Research, Melbourne, Australia.
Stone, A, Bosworth, R, & Petitto, LA. (2017, Jan). Sonority in lexicalized fingerspelling: Perception studies with infants and adults. Paper presented at the Linguistic Society of America, Austin, Texas.
Williams, J, Stone, A, Bosworth, R & Newman, S. (2017, Jan). Neural correlates of sonority: An investigation of fingerspelling. Paper presented at the Linguistic Society of America, Austin, Texas.
Bosworth, RG (2017, April). How do signers watch sign narratives? An eye-tracking investigation of gaze patterns in native signing children and adults. Paper to be presented at the Society for Research in Child Development meeting, Austin, Texas.