On the locus of individual differences in perceptual flexibility: ERP evidence for perceptual warping of speech sounds
Listeners vary in how they categorize speech sounds: some are more step-like, while others are more gradient. Recent work suggests that gradient listeners are more flexible in cue integration and recovery from misperceptions (Kapnoula et al., 2017, 2021). We investigated the source of these differences and asked how they cascade to lexical processing. Individual differences in speech categorization were assessed via a visual analogue scaling (VAS) task. Following Toscano et al. (2010), we used the N1 ERP component to track pre-categorical encoding of speech cues. Separate tasks were used to measure inhibitory control and lexical processes. The N1 linearly tracked the continuum, reflecting a fundamentally gradient speechperception; however, for step-like listeners this linearity was disrupted near the boundary. This suggests that, while all listeners are generally gradient, there are individual differences deriving from the idiosyncratic encoding of specific cues, and that cue-level gradiency cascadesthroughout the system.