Now You Hear Me, Later You Don’t: The Immediacy of Linguistic Computation and the Representation of Speech

Abstract

What happens to an acoustic signal after it enters the mind of a listener? Previous work has demonstrated that listeners maintain intermediate representations over time. However, the internal structure of such representations—be they the acoustic-phonetic signal or more general information about the probability of possible categories—remains underspecified. We present two experiments using a novel speaker-adaptation paradigm aimed at uncovering the format of speech representations. We exposed adult listeners ( N = 297) to a speaker whose utterances contained acoustically ambiguous information concerning phones (and thus words), and we manipulated the temporal availability of disambiguating cues via visually presented text (presented before or after each utterance). Results from a traditional phoneme-categorization task showed that listeners adapted to a modified acoustic distribution when disambiguating text was provided before but not after the audio. These results support the position that speech representations consist of activation over categories and are inconsistent with direct maintenance of the acoustic-phonetic signal.

The acquisition of speech categories: beyond perceptual narrowing, beyond unsupervised learning and beyond infancy

“…Second, a wealth of work has documented rapid, robust and powerful forms of perceptual learning for speech in adults, usually in the context of adaptation and retuning to novel speech (e.g., Bradlow & Bent, 2008;Caplan et al, 2021;Davis et al, 2005;Norris et al, 2003). Indeed, a handful of studies have compared children and adults in controlled laboratory learning studies and report similar or even better learning of speech categories by adults than children (Fuhrmeister et al, 2020;Heeren & Schouten, 2010;Wang & Kuhl, 2003).…”

Maintenance of subcategorical information during speech perception: revisiting misunderstood limitations

“…One important direction for future research is thus to integrate and, if necessary, reconcile findings from research on subcategorical information processing during processing and findings from long-term storage of subcategorical information (for relevant discussion and evidence, see Burchill et al, 2018;Falandays et al, 2020;Gwilliams et al, 2018). Recent studies have begun to test, for example, whether phonetic or richer information is available for sufficiently long time periods to facilitate adaptation to talker-specific pronunciations, with partially conflicting results (Burchill et al, 2018;Caplan, Hafri, & Trueswell, 2021; for a potential reconciliation of these findings, see Burchill & Jaeger, 2024).…”

“…A classic study by Connine, Blasko and Hall (1991), for example, is widely cited as evidence that maintenance is (1) restricted to highly ambiguous segments close to a category boundary, and (2) only possible for a few syllables beyond the word boundary. Connine et al (Experiment 1) examined subcategorical information maintenance for VOT continua for stop consonants between 'dent' phonetic or even perceptual representations (for relevant discussion, see Caplan, and 'tent' by manipulating the lag at which disambiguating information was presented in the right-context (3 syllables [near] or 6-8 [far] downstream; see Figure 1a).…”

The acquisition of speech categories: Beyond perceptual narrowing, beyond unsupervised learning and beyond infancy.

“…These generally finding similar or even better learning of speech categories by adults than children (Fuhrmeister et al, 2020;Heeren & Schouten, 2010;Wang & Kuhl, 2003). Moreover, the broader claim of reduced plasticity in adulthood is undercut by an explosion of work demonstrating rapid, robust and powerful forms of perceptual learning for speech in adults, usually in the context of adaptation and retuning to novel speech (e.g., Bradlow & Bent, 2008;Caplan et al, 2021;Davis et al, 2005;Norris et al, 2003). Thus, the evidence for enhanced plasticity in children may be weak, though it is important to note that it is not currently possible to examine infants with such learning techniques in a way that is comparable to adults.…”