Putting underspecification in context: ERP evidence for sparse representations in morphophonological alternations

N400 Evidence That the Early Stages of Lexical Access Ignore Knowledge About Phonological Alternations

Hearing a word that was already expected often facilitates comprehension, attenuating the amplitude of the N400 event-related brain potential component. On the other hand, hearing a word that was not expected elicits a larger N400. In the present study, we examined whether the N400 would be attenuated when a person hears something that is not exactly what they expected but is a viable alternative pronunciation of the morpheme they expected. This was done using Mandarin syllables, some of which can be pronounced with different lexical tones depending on the context. In two large-sample experiments (total n = 160) testing syllables in isolation and in phonologically viable contexts, we found little evidence that hearing an alternative pronunciation of the expected word attenuates the N400. These results suggest that comprehenders do not take advantage of their knowledge about systematic phonological alternations during the early stages of prediction or discrimination.

Asymmetries in Accessing Vowel Representations Are Driven by Phonological and Acoustic Properties: Neural and Behavioral Evidence From Natural German Minimal Pairs

In vowel discrimination, commonly found discrimination patterns are directional asymmetries where discrimination is faster (or easier) if differing vowels are presented in a certain sequence compared to the reversed sequence. Different models of speech sound processing try to account for these asymmetries based on either phonetic or phonological properties. In this study, we tested and compared two of those often-discussed models, namely the Featurally Underspecified Lexicon (FUL) model (Lahiri and Reetz, 2002) and the Natural Referent Vowel (NRV) framework (Polka and Bohn, 2011). While most studies presented isolated vowels, we investigated a large stimulus set of German vowels in a more naturalistic setting within minimal pairs. We conducted an mismatch negativity (MMN) study in a passive and a reaction time study in an active oddball paradigm. In both data sets, we found directional asymmetries that can be explained by either phonological or phonetic theories. While behaviorally, the vowel discrimination was based on phonological properties, both tested models failed to explain the found neural patterns comprehensively. Therefore, we additionally examined the influence of a variety of articulatory, acoustical, and lexical factors (e.g., formant structure, intensity, duration, and frequency of occurrence) but also the influence of factors beyond the well-known (perceived loudness of vowels, degree of openness) in depth via multiple regression analyses. The analyses revealed that the perceptual factor of perceived loudness has a greater impact than considered in the literature and should be taken stronger into consideration when analyzing preattentive natural vowel processing.

Putting underspecification in context: ERP evidence for sparse representations in morphophonological alternations

Numerous studies have shown evidence for a sparse lexicon in speech perception, often in the guise of underspecification, where certain information is omitted in the specification of phonological forms. While previous work has made a good case for underspecifying certain features of single speech sounds, the role of phonological context in underspecification has been overlooked. Contextually-mediated underspecification is particularly relevant to conceptualizations of the lexicon, as it is couched in item-specific (as opposed to phoneme-specific) patterning. In this study, we present behavioral and ERP evidence that surrounding phonological context may trigger underspecified lexical forms, using regular morphophonological alternations in English.