Schedule of Events | Symposia

Neural evidence supports the attention-invariant effects of phonetic categorical boundary adaptation

Poster Session A - Saturday, March 29, 2025, 3:00 – 5:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Evan Hare^1,2 (evan.hare@duke.edu), Mary Kate Merenich¹, Jamie Kurzer¹, Tobias Overath^1,2,3; ¹Department of Psychology and Neuroscience, Duke University, ²Center for Cognitive Neuroscience, Duke University, ³Duke Institute for Brain Sciences, Duke University

The auditory system addresses the problem of invariance by implementing approximate categorical boundaries around spectrotemporal features, such as the average ratio of prominent frequency bands within vowels. These boundaries can also quickly adapt to new information when contextually labeled as part of an existing category. However, the role of attention in this process remains unclear. While previous research indicates that basic features at the phonemic level can be processed pre-attentively, it is uncertain whether shifting categorical boundaries in response to contextual information requires focused attention on the speech signal. We conducted an experiment with three groups of Native English speakers. Participants performed a phoneme identification task both before and after a 1-back audio-visual attention task in which they either attended to an auditory stream of words containing ambiguous phonemes meant to induce a lexically cued category shift (Attend Auditory Ambiguous (AAA)), or to a concurrent visual stream of grid-like patterns (Attend Visual Ambiguous (AVA)). A control group attended to a different auditory stream of words containing unambiguous vowels to prevent category shifts (Attend Auditory Prototypical (AAP)). While no differences were found between the AAA and AVA groups at the second identification task, they showed robust response differences when compared against the AAP group. Further, early ERP responses to previously ambiguous phonemes showed no difference between the AAA and AVA groups, but their responses were significantly different from the unshifting AAP group. These findings suggest that pre-attentive perception of phonemic information influences phonetic categorical boundaries in response to changing speech properties.

Topic Area: ATTENTION: Auditory