External speakers: Hyoju Kim. Same Input, Different Response: Unraveling Individual Differences in Speech Categorization Consistency

What: Same Input, Different Response: Unraveling Individual Differences in Speech Categorization Consistency

Where: Auditorium zoom room, online talk (If you would like to attend to this meeting reserve at info@bcbl.eu)

Who: Hyoju Kim, Ph.D., Department of Psychological & Brain Sciences, University of Iowa, US. 

When:  Thursday, November 12th at 2pm

Speech perception requires listeners to map continuously varying acoustic signals onto stable linguistic representations. While extensive work has examined how gradiently or categorically listeners map acoustic variation onto phonological categories, much less is known about how consistently they do so. Listeners differ substantially in the stability of their perceptual decisions across repeated encounters with the same speech input, yet the significance of this variability remains poorly understood. In this talk, I will present a series of studies examining categorization consistency—the stability of perceptual decisions across repeated encounters with the same input—and its importance for understanding individual differences in broader outcomes, such as language and reading abilities.
Across studies with adults and children, categorization consistency varies substantially across individuals and is robustly associated with broader language abilities. Listeners who categorize speech more consistently tend to demonstrate stronger oral language abilities, better reading performance in children, and more successful speech perception under some challenging listening conditions. These relationships have been observed across multiple phonological contrasts and languages, pointing to a broader role for categorization consistency in individual differences in speech and language processing.
These associations with distal language and listening outcomes raise a critical mechanistic question: Why are some listeners more perceptually consistent than others? I will examine two potential sources of categorization consistency. First, I will consider bottom-up factors related to the fidelity of auditory encoding. Second, I will examine how top-down linguistic information shapes the stability of perceptual decisions. Together, my recent studies position trial-by-trial stability—an aspect of speech perception that has received relatively little attention—as an important dimension for understanding individual differences in speech perception. I will conclude by discussing ongoing and future work aimed at understanding the mechanisms that give rise to categorization
consistency and how it may be shaped by experience and intervention.