Morphological encoding beyond slots and fillers: An ERP study of comparative formation in English.

One important organizational property of morphology is competition. Different means of expression are in conflict with each other for encoding the same grammatical function. In the current study, we examined the nature of this control mechanism by testing the formation of comparative adjectives in English during language production. Event-related brain potentials (ERPs) were recorded during cued silent production, the first study of this kind for comparative adjective formation. We specifically examined the ERP correlates of producing synthetic relative to analytic comparatives, e.g. angrier vs. more angry. A frontal, bilaterally distributed, enhanced negative-going waveform for analytic comparatives (vis-a-vis synthetic ones) emerged approximately 300ms after the (silent) production cue. We argue that this ERP effect reflects a control mechanism that constrains grammatically-based computational processes (viz. more comparative formation). We also address the possibility that this particular ERP effect may belong to a family of previously observed negativities reflecting cognitive control monitoring, rather than morphological encoding processes per se.

Did I say dog or cat? A study of semantic error detection and correction in children.

Although naturalistic studies of spontaneous speech suggest that young children can monitor their speech, the mechanisms for detection and correction of speech errors in children are not well understood. In particular, there is little research on monitoring semantic errors in this population. This study provides a systematic investigation of detection and correction of semantic errors in children between the ages of 5 and 8years as they produced sentences to describe simple visual events involving nine highly familiar animals (the moving animals task). Results showed that older children made fewer errors and corrected a larger proportion of the errors that they made than younger children. We then tested the prediction of a production-based account of error monitoring that the strength of the language production system, and specifically its semantic-lexical component, should be correlated with the ability to detect and repair semantic errors. Strength of semantic-lexical mapping, as well as lexical-phonological mapping, was estimated individually for children by fitting their error patterns, obtained from an independent picture-naming task, to a computational model of language production. Children's picture-naming performance was predictive of their ability to monitor their semantic errors above and beyond age. This relationship was specific to the strength of the semantic-lexical part of the system, as predicted by the production-based monitor.

Producing morphologically complex words: an ERP study with children and adults.

A widely studied morphological phenomenon in psycholinguistic research is the plurals-inside-compounds effect in English, which is the avoidance of regular plural modifiers within compounds (e.g., *rats hunter). The current study employs event-related brain potentials (ERPs) to investigate the production of plurals-inside-compounds in children and adults. We specifically examined the ERP correlates of producing morphologically complex words in 8-year-olds, 12-year-olds and adults, by recording ERPs during the silent production of compounds with plural or singular modifiers. Results for both children and adults revealed a negativity in response to compounds produced from regular plural forms when compared to compounds formed from irregular plurals, indicating a highly specific brain response to a subtle linguistic contrast. Although children performed behaviourally with an adult-like pattern in the task, we found a broader distribution and a considerably later latency in children's brain potentials than in adults', indicating that even in late childhood the brain networks involved in language processing are subject to subtle developmental changes.

Brain potentials during language production in children and adults: an ERP study of the English past tense.

The current study examines the neural correlates of 8-to-12-year-old children and adults producing inflected word forms, specifically regular vs. irregular past-tense forms in English, using a silent production paradigm. ERPs were time-locked to a visual cue for silent production of either a regular or irregular past-tense form or a 3rd person singular present tense form of a given verb (e.g., walked/sang vs. walks/sings). Subsequently, another visual stimulus cued participants for an overt vocalization of their response. ERP results for the adult group revealed a negativity 300-450ms after the silent-production cue for regular compared to irregular past-tense forms. There was no difference in the present form condition. Children's brain potentials revealed developmental changes, with the older children demonstrating more adult-like ERP responses than the younger ones. We interpret the observed ERP responses as reflecting combinatorial processing involved in regular (but not irregular) past-tense formation.

Evidence for a non-lexical influence on children's auditory repetition of familiar words.

This paper examines evidence for a nonlexical influence on children's repetition of real words. We investigate the extent to which two computational models of auditory repetition can simulate the performance of 68 children aged between 5 and 11 years-old when they are attempting to repeat familiar words. Both computational accounts were derived from Foygel and Dell's (J Mem Lang 43:182-216, 2000) semantic-phonological model of picture-naming. Results showed that a dual-route model in which a lexical and a nonlexical route work together to repeat familiar words (Hanley et al. in Cogn Neuropsychol 21:147-158, 2004) provided an accurate simulation of children's repetition, whereas Foygel and Dell (J Mem Lang 43:182-216, 2000) single lexical-route model under-predicted performance. The only exception was the repetition performance of 5 year-old children, which was over-predicted by the dual-route model. It is argued that at 5 years of age, some children have available both a lexical and a nonlexical repetition route but the output of the two routes does not summate when real words are being repeated. Some young children may lack the attentional skills that would enable them to co-ordinate the activity of the lexical and nonlexical repetition routes.