Controversies about CP: a comparison of language acquisition and language impairments in Broca's aphasia.

In both language acquisition research and the study of language impairments in Broca's aphasia there is an ongoing debate whether or not phrase-structure representations contain the Complementizer Phrase (CP) layer. To shed some light on this debate, I will provide data on German child language and on German agrammatic Broca's aphasia. Analyses of subordinate clauses, wh-questions, and verb placement indicate that early child grammars do not generate the CP layer yet, whereas the ability to project the CP layer is retained in agrammatism.

The representation of inflectional morphology: evidence from Broca's aphasia.

Dualistic models of inflection assume a qualitative distinction between affix-based regular forms and stored irregular forms, predicting that the two distinct mechanisms can be selectively affected in language disorders. We present data on German participle formation from 11 agrammatic Broca's aphasics which show that irregular participles can be selectively affected in agrammatism. Moreover, the distribution of errors reveals a frequency effect for irregular but not for regular participles. Both findings argue for a dualistic representation of inflection. Moreover, we want to propose a modification of dualistic models by suggesting that both regularity and irregularity are better conceived of as scalar.

How the brain processes complex words: an event-related potential study of German verb inflections.

Event-related brain potentials (ERPs) were recorded as German-speaking subjects read verbs in correct and incorrect participle forms. The critical words were presented in three different versions to three different groups of subjects, as part of a simple sentence, in a word list, and embedded in a story; for each version separate ERPs were recorded. Three types of verbs were investigated, regulars, irregulars and nonce verbs. We compared correct regular and irregular participles with incorrect ones; the latter had -(e)n on verbs that actually take -t participles (* getanz-en), or -(e)t on verbs that require -(e)n (* gelad-et). For the nonce verbs, we compared participles with the unexpected -(e)n ending with the expected -t participle forms. The ERP responses were very consistent across the three versions of the experiment: (i) incorrect irregular participles (* gelad-et) elicited a left frontotemporal negativity; (ii) incorrect regulars (* getanz-en) produced no differences to the correct ones; (iii) nonce verbs were associated with an N400 component but did not show a difference between expected and unexpected endings. We will interpret these findings with respect to psycholinguistic models of morphological processing and argue that the brain processes regularly inflected words differently from irregularly inflected ones, the latter by accessing full-form entries stored in memory and the former by a computational process that decomposes complex words into stems and affixes.

Brain potentials indicate differences between regular and irregular German plurals.

Event-related brain potentials were recorded as 18 German-speaking subjects read sentences that contained as critical words German nouns in correct and incorrect plural forms. Two types of plurals were investigated: regular -s plurals (e.g. Karussell-s 'roundabouts') and irregular -(e)n plurals (Muskel-n "muscles'). We compared correct regular and irregular plurals with incorrect ones; the latter had -(e)n on nouns that actually take -s plurals (*Karussell-en), or -s on nouns that require -(e)n (*Muskel-s). ERPs showed different responses to regular and irregular plurals: incorrect irregular plurals (*Muskel-s) elicited a ramp-shaped left frontotemporal negativity, whereas incorrect regulars (*Karussell-en) produced a central phasic negativity with a maximum at 380 ms. This dissociation supports the view that regularly inflected words are processed differently from irregularly inflected ones.