Perceptual learning for speech: Is there a return to normal?

Abstract

Recent work on perceptual learning shows that listenersÕ phonemic representations dynamically adjust to reflect the speech they hear (Norris, McQueen, & Cutler, 2003). We investigate how the perceptual system makes such adjustments, and what (if anything) causes the representations to return to their pre-perceptual learning settings. Listeners are exposed to a speaker whose pronunciation of a particular sound (either /s/ or /S/) is ambiguous (e.g., halfway between /s/ and /S/). After exposure, participants are tested for perceptual learning on two continua that range from /s/ to /S/, one in the Same voice they heard during exposure, and one in a Different voice. To assess how representations revert to their prior settings, half of Experiment 1Õs participants were tested immediately after exposure; the other half performed a 25-min silent intervening task. The perceptual learning effect was actually larger after such a delay, indicating that simply allowing time to pass does not cause learning to fade. The remaining experiments investigate different ways that the system might unlearn a personÕs pronunciations: listeners hear the Same or a Different speaker for 25 min with either: no relevant (i.e., ÔgoodÕ) /s/ or /S/ input (Experiment 2), one of the relevant inputs (Experiment 3), or both relevant inputs (Experiment 4). The results support a view of phonemic representations as dynamic and flexible, and suggest that they interact with both higher-(e.g., lexical) and lower-level (e.g., acoustic) information in important ways.

Are there interactive processes in speech perception?

“…In fact, just such a role for lexical context was explicitly suggested by McClelland and Elman [2]. And indeed, in accordance with this, several recent experiments [30][31][32][33][34][35] have demonstrated that lexical influences can also guide tuning of speech perception. When listeners heard a perceptually ambiguous /s/-/f/ sound at the end of an utterance that would be a word if completed with /s/, they identified the sound as /s/.…”

“…Here the same lexical feedback that influences identification of ambiguous speech sounds provides the guidance for tuning the mapping between acoustic and speech sound representations. The TRACE model also accounts for the pattern of generalization seen in several other studies [33], based on the idea that generalization of the tuning effect will be determined by the acoustic similarity between the learned sounds and novel sounds [37].…”

Sensorimotor adaptation affects perceptual compensation for coarticulation

“…The apparent contradiction between the lexically-guided retuning results and the results of exp. 2 may be due to the specificity of the adaptation; Kraljic and Samuel (2005) found that perceptually guided lexical retuning for fricatives along an [s]-[S] continuum transferred from a female training voice to a male test voice, but not in the opposite direction. The authors attribute this asymmetry to the fact that the female training stimuli were close to the frequency of the male test items, while the male training stimuli were far from the female test stimuli, suggesting that transfer may depend on acoustic similarity.…”

“…It is interesting that the remapping during production generalized to the CFC processes during perception, given that perceptual retuning is notoriously specific (Kraljic and Samuel, 2005;Reinisch et al, 2014). This is somewhat true as well for adaptation to altered feedback.…”

Perceptual adaptation to segmental and syllabic reductions in continuous spoken Dutch

“…Moreover, this perceptual learning effect proved to be talker-specific and stable over time (Eisner & McQueen, 2005. Investigating whether there is "a return to normal", Kraljic and Samuel (2005) found that only canonical pronunciation of both phonemes (/s/ and /ʃ/ in this case) appeared to be able to reset the phonemic categories to pre-learning parameters. Importantly, these unambiguous instances had to be uttered by the same speaker listeners had been trained on.…”