title: The nonlinear dynamics of speech categorization.
abstract: Little is known about the processes underlying the nonlinear relationship between acoustics and speech perception. In Experiment 1, we explored the effects of systematic variation of a single acoustic parameter (silent gap duration between a natural utterance of s and a synthetic vowel ay) on judgements of speech category. The resulting shifts in category boundary between say and stay showed rich dynamics, including hysteresis, contrast, and critical boundary effects. We propose a dynamical model to account for the observed patterns. Experiment 2 evaluated one prediction of the model, that changing the relative stability of the two percepts allows categorical switching. In agreement with the model; an increase in the number of stimulus repetitions maximized the frequency of judgments of category change near the boundary. Thus, a dynamical approach affords the rudiments for a theory of the effects of temporal context on speech categorization.
authors.affiliation: Center for Complex Systems, Florida Atlantic University, Boca Raton 33431-0091.
authors.forename: B
authors.initials: B
authors.lastname: Tuller
authors.forename: P
authors.initials: P
authors.lastname: Case
authors.forename: M
authors.initials: M
authors.lastname: Ding
authors.forename: J A
authors.initials: JA
authors.lastname: Kelso
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D013061:Speech Acoustics; D013067:Speech Perception