Academic journal article Psychonomic Bulletin & Review

An Interactive Hebbian Account of Lexically Guided Tuning of Speech Perception

Academic journal article Psychonomic Bulletin & Review

An Interactive Hebbian Account of Lexically Guided Tuning of Speech Perception

Article excerpt

We describe an account of lexically guided tuning of speech perception based on interactive processing and Hebbian learning. Interactive feedback provides lexical information to prelexical levels, and Hebbian learning uses that information to retune the mapping from auditory input to prelexical representations of speech. Simulations of an extension of the TRACE model of speech perception are presented that demonstrate the efficacy of this mechanism. Further simulations show that acoustic similarity can account for the patterns of speaker generalization. This account addresses the role of lexical information in guiding both perception and learning with a single set of principles of information propagation.

(ProQuest-CSA LLC: ... denotes formulae omitted.)

Lexical knowledge can affect listeners' categorization of speech sounds. For example, an ambiguous /g/-/k/ sound-one that is classified about equally often as /g/ or /k/ when it occurs in a lexically neutral context-tends to be classified as /g/ when preceding ift but as /k/ when preceding iss (Ganong, 1980). Our focus here is on recent studies snowing that lexical knowledge can also guide tuning of the mapping from auditory input representations to speech sound representations (Norris, McQueen, & Cutler, 2003; see also Davis, Johnsrude, Hervais-Adelman, Taylor, & McGettigan, 2005; Eisner & McQueen, 2005; Kraljic & Samuel, 2005, 2006; Maye, Aslin, & Tanenhaus, 2003). In the basic paradigm (Norris et al., 2003), when listeners hear a perceptually ambiguous /s/-/f/ sound at the end of an utterance that would be a word if completed with /s/, they both identify the sound as /s/ and retune perception so that ambiguous sounds tend to be identified subsequently as /s/, even in lexically neutral contexts. Further studies employing this paradigm have revealed an interesting and complex pattern of generalization of this effect.

Our goal in this report is to demonstrate that interactive processing, initially proposed to account for lexical effects on perception (McClelland & Elman, 1986), provides the needed information to prelexical levels to support lexically guided tuning effects. The principle of interactive processing has been challenged by proponents of autonomous models (Norris, McQueen, & Cutler, 2000), who attribute most lexical effects to postperceptual decision processes rather than to interactive processing. However, to account for lexically guided tuning of perception, these proponents allow feedback to guide tuning of perceptual mechanisms but not to guide the perceptual mechanisms themselves. We propose instead that feedback is indeed at work in perception and that this feedback has the right properties to successfully guide the retiming process.

There are now several findings supporting the view that lexical factors can affect prelexical processing, as predicted by the interactive approach and in contrast to the claims of autonomous models (for a full review, see McClelland, Mirman, & Holt, 2006). These effects of lexical factors on prelexical processing include lexically guided compensation for coarticulation (Elman & McClelland, 1988; Magnuson, McMurray, Tanenhaus, & Aslin, 2003; Samuel & Pitt, 2003) and lexically guided selective adaptation (Samuel, 1997, 2001). When taken together with these findings, lexically guided tuning of speech perception would simply be another instance of a prelexical consequence of lexical feedback.

More broadly, the principle of interactive processing predicts that context will affect processing at many levels, across many different domains and modalities, and that such effects should in turn contribute to the guidance of tuning. For example, recent studies showing that visual information can guide tuning of mappings from auditory to speech sound representations (Bertelson, Vroomen, & de Gelder, 2003) are completely consistent with the perspective presented here. …

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