The mental lexicon is fully specified: Evidence from eye-tracking.

Four visual-world experiments, in which listeners heard spoken words and saw printed words, compared an optimal-perception account with the theory of phonological underspecification. This theory argues that default phonological features are not specified in the mental lexicon, leading to asymmetric lexical matching: Mismatching input (pin) activates lexical entries with underspecified coronal stops (tin), but lexical entries with specified labial stops (pin) are not activated by mismatching input (tin). The eye-tracking data failed to show such a pattern. Although words that were phonologically similar to the spoken target attracted more looks than did unrelated distractors, this effect was symmetric in Experiment 1 with minimal pairs (tin–pin) and in Experiments 2 and 3 with words with an onset overlap (peacock–teacake). Experiment 4 revealed that /t/-initial words were looked at more frequently if the spoken input mismatched only in terms of place than if it mismatched in place and voice, contrary to the assumption that /t/ is unspecified for place and voice. These results show that speech perception uses signal-driven information to the fullest, as was predicted by an optimal perception account. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Computational Semantics in Discourse: Underspecification, Resolution, and Inference

In this paper I introduce a formalism for natural language understandingbased on a computational implementation of Discourse RepresentationTheory. The formalism covers a wide variety of semantic phenomena(including scope and lexical ambiguities, anaphora and presupposition),is computationally attractive, and has a genuine inference component. Itcombines a well-established linguistic formalism (DRT) with advancedtechniques to deal with ambiguity (underspecification), and isinnovative in the use of first-order theorem proving techniques.The architecture of the formalism for natural language understandingthat I advocate consists of three levels of processing:underspecification, resolution, andinference. Each of these levels has a distinct function andtherefore employs a different kind of semantic representation. Themappings between these different representations define the interfacesbetween the levels.I show how underspecified semantic representations can be built in acompositional way (for a fragment of English Grammar) using standardtechniques borrowed from the -calculus, how inferences can becarried out on discourse representations using a translation tofirst-order logic, and how existing research prototypes (discourseprocessing and spoken-dialogue systems) implement the formalism.     

Neurophysiological evidence for underspecified lexical representations: Asymmetries with word initial variations.

How does the mental lexicon cope with phonetic variants in recognition of spoken words? Using a lexical decision task with and without fragment priming, the authors compared the processing of German words and pseudowords that differed only in the place of articulation of the initial consonant (place). Across both experiments, event-related brain potentials indicated that pseudowords with initial noncoronal place (e.g., *Brachen) activate words with initial coronal place (e.g., Drachen [dragon]). In contrast, coronal pseudowords (e.g., *Drenze) do not as effectively activate noncoronal words (e.g., Grenze [border]). Thus, certain word onset variations do not hamper the speech recognition system. The authors interpret this asymmetry as a consequence of underspecified coronal place of articulation in the mental lexicon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Constraint Language for Lambda Structures

This paper presents the Constraint Language for Lambda Structures(CLLS), a first-order language for semantic underspecification thatconservatively extends dominance constraints. It is interpreted overlambda structures, tree-like structures that encode -terms. Based onCLLS, we present an underspecified, uniform analysis of scope,ellipsis, anaphora, and their interactions. CLLS solves a variablecapturing problem that is omnipresent in scope underspecification andcan be processed efficiently.