Abstractness of human speech sound representations.

We argue, based on a study of brain responses to speech sound differences in Japanese, that memory encoding of functional speech sounds-phonemes-are highly abstract. As an example, we provide evidence for a theory where the consonants/p t k b d g/ are not only made up of symbolic features but are underspecified with respect to voicing or laryngeal features, and that languages differ with respect to which feature value is underspecified. In a previous study we showed that voiced stops are underspecified in English [Hestvik, A., & Durvasula, K. (2016). Neurobiological evidence for voicing underspecification in English. Brain and Language], as shown by asymmetries in Mismatch Negativity responses to /t/ and /d/. In the current study, we test the prediction that the opposite asymmetry should be observed in Japanese, if voiceless stops are underspecified in that language. Our results confirm this prediction. This matches a linguistic architecture where phonemes are highly abstract and do not encode actual physical characteristics of the corresponding speech sounds, but rather different subsets of abstract distinctive features.

Neurobiological evidence for voicing underspecification in English.

In long-term memory, the phoneme units that make up words are coded for the distinctive features and feature values that are necessary to distinguish between words in the mental lexicon. Underspecification theory says that the phonemes that have unmarked feature values are even more abstract in that the feature is omitted from the representation altogether. This makes phoneme representations in words more sparse than the fully specified phonetic representations of the same words. Eulitz and Lahiri (2004) demonstrated that this theory predicts certain asymmetries in the Mismatch Negativity (MMN) response to phoneme contrasts. We expand on this research by demonstrating underspecification-driven asymmetry in the brain response to laryngeal feature contrasts in English (i.e. what makes /d/ and /t/ different). We add a new test by showing that the asymmetry disappears if the MMN paradigm is modified to encourage the formation of phonetic memory traces instead of phonemic memory traces. This result adds further neurobiological evidence that long-term phonological representations are more sparsely represented than phonetic representations.

Portions and sorts in Icelandic: an ERP study.

An ERP study investigated the processing of mass nouns used to convey 'portions' vs. 'sorts' interpretations in Icelandic. The sorts interpretation requires semantic Coercion to a count noun; the portions interpretation entails extra syntactic processing. Compared to a Neutral condition, Coercion escaped the expected penalty (N400), but the Extra Syntax condition incurred the anticipated costs (anterior negativity followed by P600). Furthermore, we examined the effects of having to revise an initial commitment to head-noun status. When another noun follows the mass noun (creating a compound), the second noun becomes the head-noun. We hypothesized, for Icelandic, there would be no effect for Extra Syntax because the compound should have been built before the second noun was encountered; by contrast, for the Coercion and Neutral conditions, processing costs would be incurred to detect and reconfigure the second noun as the head. These predictions were largely borne out (early and sustained anterior negativities).