Martina Penke

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.

The Acquisition of Agreement Morphology and its Syntactic Consequences: New Evidence on German Child Language from the Simone-Corpus

The general background for our study is the hypothesis of Lexical Learning, i.e., the question in what ways the emergence of syntactic structure in child language is determined through the acquisition of properties of lexical (and morphological) items. In the Universal Grammar (UG) framework it has recently been argued that parameters of UG should only refer to categories of lexical items or to properties of lexical items, for example canonical government. Rizzi (1989) proposed, for example, that only heads (=X°) or properties of heads may enter into a UG parameter. Chomsky (1989), based on previous work by Borer (1984), explored the possibility of allowing only functional categories to be parameterized. These attempts to constrain the class of UG parameters have lead to the hypothesis that in child language development the syntax of a particular language could be determined by the acquisition of lexical and/or functional categories (X°).

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 Brocas 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.

Word Order in Sentence Processing: An Experimental Study of Verb Placement in German

We examine the question of whether the human comprehension device exhibits word-order preferences during on-line sentence comprehension. The focus is on the positioning of finite verbs and auxiliaries relative to subjects and objects in German. Results from three experiments (using self-paced reading and event-related brain potentials) show that native speakers of German prefer to process finite verbs in second position (i.e., immediately after the subject and before the object). We will account for this order preference in terms of the relative processing costs associated with SVfO and SOVf. Our finding that word-order preferences play an important role in the on-line comprehension of German sentences is compatible with results from previous studies on English and other languages.

Broca's area and inflectional morphology: evidence from broca's aphasia and computer modeling.

In a series of articles Ullman (2001, 2004; Ullman et al., 1997) has proposed that regular inflection is critically subserved by Brocas area. This suggestion is motivated by the finding that English speaking Brocas aphasics show selective deficits with regular inflection. Here we argue that this proposal does not hold cross-linguistically but is based on a confound between inflectional suffix and regularity that is specific to the English language. We present data from two experimental studies of participle inflection with 13 German and 12 Dutch Brocas aphasics. None of these aphasic speakers are selectively impaired for regular inflection but instead most of them show selective deficits with irregular inflection. These data suggest that a selective regular deficit is not a characteristic of Brocas aphasia across languages, and that Brocas area is not critically involved in regular inflection. To investigate the nature and localization of the processes underlying inflection we present a connectionist neural network model that accounts for the deficits of the German aphasic speakers. The model implements the view that the inflection of all verb types is based on a single mechanism with multiple representations that emerge from experience-dependent brain development. We show that global damage to this model results in a selective deficit for irregular inflection that is comparable to that of the German aphasic speakers. This finding suggests that a selective impairment of irregular participles as observed by German and Dutch aphasic speakers does not presuppose two distinctly localized mechanisms or processes that can be selectively affected by brain damage.

Production and comprehension of wh-questions in German Broca's aphasia

Current proposals suggest that agrammatic speakers have severe deficits in producing and understanding wh-questions. Whereas the CP layer is assumed to be pruned such that wh-questions can no longer be produced, for comprehension it has been suggested that the agrammatic deficit leads to a deletion of movement traces in syntactically derived sentences. We present data from three experiments testing the production and comprehension of wh-questions in nine German agrammatic Brocas aphasics. In an elicitation and a repetition task we find that complete and grammatical wh-questions can be produced by German agrammatic aphasics, thus indicating that the CP layer can still be projected. The results of a picture-pointing task show, however, that deficits in the comprehension of wh-questions (who and which N questions) are common. A closer analysis reveals a variety of error patterns in our subjects. The additive effects that non-canonical word order and the discourse-linking of a referential NP (which N) exert on the comprehension performance of our subjects cannot be captured by current syntactic deficit accounts on agrammatism.

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 Brocas 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 Brocas 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.

How are inflectional affixes organized in the mental lexicon?: evidence from the investigation of agreement errors in agrammatic aphasics.

Recent psycholinguistic studies have provided evidence that regularly inflected words are decomposed into stems and affixes, both of which have their own representations in the mental lexicon. Specific models of the lexical organization of inflectional affixes have, however, only rarely been investigated in psycho- or neurolinguistic work. We test two recently proposed theoretical models: a representation of affixes (i) in default inheritance trees (Corbett and Fraser, 1993) and (ii) in underspecified paradigms (Wunderlich, 1996). Based on an analysis of agreement errors in elicited speech-production data of German agrammatic aphasics, we argue that affixes are organized with respect to the morphosyntactic features they encode. Specifically, our data indicate that inflectional affixes are best captured within an underspecified paradigm.

Psycholinguistic Evidence for the Underspecification of Morphosyntactic Features.

This paper investigates the paradigmatic relations between inflected word forms (or their affixes) and the feature specifications of these elements. In two sentence-matching experiments German speakers had to decide whether sentence pairs involving inflected adjectives or determiners were identical or not. In both experiments, there was a delay when an inflected form contained positive feature specifications for grammatical features that did not match the feature specifications of the grammatical context in which it appeared. No delay, however, occurred when an incorrectly inflected form had mismatching negative specifications, whereas its positively specified features matched the respective positive features of the context. This result provides evidence for a different status of positively and negatively specified morphosyntactic features. It supports the idea of radical underspecification according to which only positive feature specifications are part of the representations of morphologically complex forms or affixes, whereas negative feature specifications are assigned on the basis of paradigmatic contrasts.