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Role of somatosensory inputs and the linguistic background in the perception of Japanese vowel quantity contrast
Poster Session E, Friday, October 2, 11:00 am - 1:00 pm, Wangari Maathai
Inès Vallois1, Takayuki Ito1; 1Univ. Grenoble Alpes, CNRS, Grenoble INP, GIPSA-lab
Somatosensory function can play an important role in speech perception and in linking speech perception and production. While this has been frequently investigated in relation to the somatosensory influence on the perception of phonemic identity, it remains unclear whether language processing or linguistic background is involved in this somatosensory perceptual interaction. To address this question, we focused on the perception of the phonological contrast of quantity, which is utilized in some languages, such as Japanese, but not in others, such as French. In the current study, we applied a perception test of Japanese quantity contrast to French speakers with no prior experience of Japanese and examined whether, and how, somatosensory inputs influence this perception despite their lack of experience and familiarity with these phonemic distinctions. We tested 19 native French speakers with no prior experience of Japanese, and 20 native Japanese speakers as a control. We carried out an identification task using Japanese words /od͡ʑisan/ (“uncle” in English) and /od͡ʑiːsan/ (“grandfather” in English), contrasting mainly in the vowel /i/ duration. A 10-step auditory continuum was generated by changing the duration of /i:/ in equal steps. The participants were asked to identify the presented words as /od͡ʑisan/ or /od͡ʑiːsan/ under control and somatosensory conditions. In the somatosensory condition, the orofacial skin lateral to the oral angle was stretched backward in the period corresponding to the production of the vowel /i:/ from /od͡ʑi:san/. A total of 800 pseudo-randomized trials were conducted, with the control and somatosensory conditions alternating every 10 trials. The first 160 trials were excluded from the analysis to allow for task familiarization. To examine perception differences between groups, the slope of the psychometric function in the control condition was compared between groups. For the somatosensory effect, the average proportion of /od͡ʑi:san/ responses across stimuli was computed and compared between conditions. An identification pattern related to vowel length similar to that commonly observed in the identification test of phonemic contrast was seen in both French and Japanese groups. However, the slope in the control condition was significantly lower in French group (t(33.825) = 3.509, p < .01), indicating an effect of language background on the perception of the phonological contrast of quantity. The proportion of /od͡ʑi:san/ responses significantly increased under the somatosensory condition (F(1,37) = 7.068, p = .011), indicating that participants perceived the duration of /i/ as longer when hearing the stimuli sounds with somatosensory inputs. Post-hoc tests revealed a significant increase in Japanese group (t(19) = -2.78, p = .023), but not in French group (t(18) = 1.26, p = .22). The results suggest that the effect of somatosensory input on the perception of vowel-quantity can vary depending on the group’s language background. This between-group difference can be due to a sensorimotor tuning specific to the native language. Japanese speakers could have learned somatosensory-auditory associations specific to vowel quantity. Overall, these findings suggest that the sensorimotor representations shaped by the linguistic background may underlie clear somatosensory effect on the perception of the phonological quantity contrast.
Topic Areas: Multisensory or Sensorimotor Integration, Speech Perception