Language and Brain Interest Group

PI Dr. Matt Masapollo recently gave a lecture at UF’s Language and Brain Interest Group, entitled, “Universal biases in infant and adult perception of vowel elements in speech.”

Abstract: Most research on cross-language speech perception has focused on investigating how the perception of consonant and vowel elements change with linguistic experience over the course of development. This emphasis on exploring what is language-specific as opposed to what is universal in the speech perception process derived in part from the much-studied “perceptual magnet effect,” which emphasized the relative difficulty experienced by listeners in discriminating stimuli near the best exemplars of phonetic categories compared with the ease in discriminating stimuli near category boundaries. It has become increasingly clear, however, that there are also universal perceptual biases in place early in development that guide and constrain how listeners from diverse linguistic backgrounds decode the input acoustic signal. In the domain of vowel perception, it is now known that listeners (both infant and adult) are universally biased toward articulatorily and acoustically extreme vowels, and that this bias operates independently of language-specific prototype categorization. This generic vowel bias is often demonstrated in discrimination tasks as a directional asymmetry: listeners perform better when discriminating changes from a relatively less to more peripheral vowel compared to the reverse. In this talk, I will discuss evidence suggesting that the processes underlying these directional effects operate on amodal articulatory information, rather than on acoustic information per se. I will begin with findings from cross-language experiments with adults and infants indicating that asymmetries occur with vowels presented in either the auditory or the visual modality, regardless of native language. I will then present findings indicating that analogous asymmetries emerge using schematic non-speech visual analogs of vocalic gestures, but only if the visual displays depict both the shape and movement of a talking mouth producing vowels. Collectively, these findings suggest that the perceptual processes underlying asymmetries in vowel discrimination are sensitive to speech-specific motion and configural properties, and raise foundational questions concerning the role of specialized and general processes in speech perception.