William Badecker

On considerations of method and theory governing the use of clinical categories in neurolinguistics and cognitive neuropsychology: The case against agrammatism

Abstract The pervasive use of clinical categories of aphasia in neurolinguistic and cognitive neuropsychological research reflects the assumption that these patient groupings represent disruptions of the normal language processing system along theoretically significant lines. This premise is examined here with particular reference to the status of ‘agrammatism’. It is argued that there are compelling reasons to question the coherence of agrammatism as a psychological entity. To overcome these objections, the clinical intuitions on which this aphasic category is based must be replaced by objective criteria for selecting a theoretically significant patient grouping. To reach this goal, it is especially important that a theoretically motivated distinction be made between within-and across-category variation. It is argued that in the case of categories like agrammatism, there are serious methodological obstacles which make such goals unreachable. It is argued, therefore, that our theories should not take categories like agrammatism as psychological givens, especially if the purpose of our research is to reach an understanding of the mechanisms of language processing or of individual aphasic deficits themselves. Furthermore, it is argued that the single case methodology for the study of aphasia can address these goals by taking patterns of performance on particular linguistic tasks as basic units of analysis, and that this approach avoids the methodological pitfalls faced by studies which take clinical categories as starting points.

THE TWO-STAGE MODEL OF LEXICAL RETRIEVAL : EVIDENCE FROM A CASE OF ANOMIA WITH SELECTIVE PRESERVATION OF GRAMMATICAL GENDER

The two-stage theory of lexical production distinguishes the retrieval of lemmas from the subsequent retrieval of the forms of words. The information made available by lemma retrieval includes semantic and grammatical details that are specific to a particular word, but not the direct specification of its phonological or orthographic form. This theory makes very strong predictions regarding the dissociability of these information types. In this report, we present the case of an Italian anomic patient whose performance bears on these predictions. In various naming tasks this patients intact ability to identify the grammatical gender of words that he cannot produce stands in stark contrast with his inability to provide any information regarding particular lexical forms. We document the reliability of this performance pattern, and we discuss the significance of this pattern both in terms of the support it provides for the two-stage theory of lexical retrieval and in terms of the evidence it furnishes regarding the mental specification of grammatical information.

The Processing Role of Structural Constraints on the Interpretation of Pronouns and Anaphors

The authors report 6 self-paced word-by-word reading studies of how morphosyntactic agreement, focus status, and the structural constraints of binding theory apply and interact during the online interpretation of pronouns (e.g., him, her) and anaphors (e.g., himself, each other). Previous studies held that structural conditions on coreference work as interpretive filters that impose exceptionless limits on which antecedent candidates can be evaluated by subsequent, content-based processes. These experiments instead support an interactive-parallel-constraint model, in which multiple weighted constraints (including constraints on binding) simultaneously influence the net activation of a candidate during preselection stages of antecedent evaluation. Accordingly, structurally inaccessible candidates can interfere with antecedent selection if they are both prominent in focus structure and gender-number compatible with the pronoun or anaphor.

Priming homographic stems

Three lexical decision experiments were carried out to address the issue of the morphological organization of lexical representations in the orthographic (input) lexicon. Lexical decisions were more difficult for simultaneously or sequentially presented words with homographic stems than for control words that did not have homographic stems. Stem homographs are stems that are orthographically identical but semantically and/or grammatically different. Lexical decisions for stimulus pairs such as portare (to carry)/porte (doors), which share the stem port-, were difficult relative to nonhomographic stem pairs such as collo (neck)/colpo (blow), which have the stems coll- and colp-. It was also found that morphologically related forms of the same ambiguous stem (e.g., porta (door)/porte (doors)) are easiest to process. The pattern of results provides strong support for the hypothesis that lexical representations are stored in morphologically decomposed form.

Morphological analysis in sentence processing: An ERP study

We examined the effects of syntactic (tense) violations occurring on regularly versus irregularly inflected verbs using event-related brain potentials (ERPs). Participants read sentences in which the main verb varied in terms of regularity (regular vs. irregular), frequency (high vs. low), and grammaticality (tense violation vs. no tense violation). For regular verbs, we found a reliable N400 effect for verb frequency and a reliable P600 effect for grammaticality, with no interaction between lexical frequency and grammaticality. For irregular verbs, we found interactions between lexical frequency and grammaticality, with tense violations on high-frequency forms (*will stood) eliciting a much earlier P600 response than tense violations on low-frequency forms (*will knelt). We discuss the implications of these results with respect to morphological parsing, the time course of syntactic feature analysis, and their consequent effects on temporal properties of ERP components.

Processing inflectional and derivational morphology

Abstract Three lexical decision experiments were carried out to investigate the nature of morphological decomposition in the lexical system. The first of these experiments compares the priming effect of inflectionally and derivationally related forms on a simple inflected word. Italian derived words like mutevole (changcable) were as effective as non-derived inflected words like mutarono (they changed) in priming the related form mutare (to change). The design of the remaining experiments is based on the stem homograph paradigm (Laudanna, Badecker, & Caramazza, 1989, Journal of Memory and Language , 28 , 531–546) . When an unambiguous word like mute (mute) is primed by a stem homograph like mutarono (they changed)—a morphologically unrelated word with a homographic stem—there is a robust inhibitory effect when compared with unrelated prime conditions. Experiments two and three compared the effect on forms like mute of priming by an inflected stem homograph ( mutarono ) and priming by a derived “root homograph” like mutevole —a morphologically unrelated derived word with a homographic root ( mut- ). While there was a consistent inhibitory effect with the inflected primes, there was no such effect with the derived primes. These results indicate that there is a level of lexical representation in the input lexicon at which inflected and derived words are analyzed in terms of their inflectional stems and affixes, but not also in terms of their derivational roots and affixes. It is argued that the inhibitory effects found in experiments two and three and the facilitation effects found in experiment one and elsewhere support the notion that there are multiple representational levels at which morphological structure is represented.

The structure of graphemic representations in spelling: Evidence from a case of acquired dysgraphia

Abstract A single-case study of an acquired dysgraphic patient is presented. On the basis of the patients pattern of spelling errors, and especially his errors on words with geminate letters (e.g. “cross” spelled croos), it is argued that stored spelling representations are not simple linear sequences of letter tokens (e.g. C-R-O-S-S). Rather, it is proposed that the graphemic representations processed by the cognitive spelling mechanisms are multidimensional structures that encode separately letter position, letter identity, letter doubling, and consonant/vowel status.

Lexical morphology and its role in the writing process: Evidence from a case of acquired dysgraphia

A case of acquired dysgraphia is presented in which the deficit is attributed to an impairment at the level of the Graphemic Output Buffer. It is argued that this patients performance can be used to identify the representational character of the processing units that are stored in the Orthographic Output Lexicon. In particular, it is argued that the distribution of spelling errors and the types of lexical items which affect error rates indicate that the lexical representations passed from the lexical output system to the Graphemic Output Buffer correspond to the productive morphemes of the language.

Morphological Composition in the Lexical Output System

Abstract This paper presents a case of acquired lexical impairment which results in the production of morphological and other paraphasias. It is argued that these errors result from an output impairment, and that the paraphrastic morphological forms are the result of compositional errors, and not whole-word lexical substitutions.

The Analysis of Morphological Errors in a Case of Acquired Dyslexia

An issue that is persistently raised in studies of subjects who produce morphological errors in reading and other tasks is whether these errors are the consequence of a morphological processing deficit, or whether they in any way reflect morphological principles of organization in the lexicon. We discuss the performance of one such subject on a number of tasks and evaluate standard arguments for attributing aspects of his performance to a morphological processing deficit. Although there are several features of his performance that are suggestive in this regard; we argue that, when these issues are addressed in the context of a sufficiently elaborated theory of lexical processing, a morphological processing deficit cannot be demonstrated. We also survey a number of recent reports that purport to provide evidence for a morphological processing deficit and argue that, in most cases, they fail to support such claims for similar reasons. An important moral to be drawn from a critique of these studies is that in order to make valid inferences concerning the role of morphology in organizing the lexicon, we must consider these errors in the context of theories of the lexicon that take seriously the effects of converging lexical factors in processing.