Gerhard Blanken

Spontaneous speech in senile dementia and aphasia: Implications for a neurolinguistic model of language production

Abstract We analyzed spontaneous speech production in semi-standardized interviews conducted with 10 patients suffering from moderate senile dementia of the Alzheimer type (SDAT), 5 Wernickes aphasics, and 5 elderly controls without brain damage. Data analysis revealed in both patient groups a reduction of sentence length but absence of systematic paragrammatic symptoms on the part of the demented patients. A relatively selectively diminished use of nouns was striking in the production of both patient groups, whereas word finding ability was surprisingly well preserved in the SDAT patients. Both patient groups exhibited marked deficits but different patterns of pathological behaviour on the discourse level of responding to the interviewers questions. Results are interpreted within a proposed neurolinguistic language production model. It is argued that the formulation process may be preserved in demented patients but is disturbed in aphasia. Language-related disturbances in senile dementia are assumed to result from pre-linguistic disorders in the formation of the conceptual structure of the intended speech act.

Formal paraphasias: a single case study.

A case study is reported of an aphasic patient, RB, who showed frequent form-related whole-word substitutions in oral naming, writing to dictation, and reading aloud. In both written language tasks, the abstractness of the targets influenced the number of formal errors. In oral naming, a high proportion of formal paraphasias was related to the intended words in both form and meaning. A comparison between targets and formal paraphasias indicated a high agreement both in word class, number of syllables, stress pattern, and in basic (stressed) vowels. The agreement in consonants (including word-initial consonants), however, was low. It is argued that RBs formal substitutions are not caused solely by errors of lexical selection but that semantic, lexical, and segmental factors contribute to the error outcome.

LEXICALISATION IN SPEECH PRODUCTION: EVIDENCE FROM FORM RELATED WORD SUBSTITUTIONS IN APHASIA

One of the major empirical sources of theories of speech production are speech errors in normal speakers. Speech errors occurring during lexicalisation of a concept to be expressed can result in whole-word substitutions that are target related in form and/ or meaning or can appear as nonword productions (neologism). Similar error phenomena have been reported for aphasic patients. The present study describes the aphasic, HZ, who produced mainly form-related word substitutions and neologisms in several single-word processing tasks (picture naming, repetition, and reading aloud). In picture naming, meaning-related substitutions also occurred as well as substitutions that were related both in meaning and form (mixed errors). Three hypotheses of the origin of formal errors were tested: the full interactive activation hypothesis postulating meaning-form interactions, the lexical (form) retrieval hypothesis, and the post-lexical phonological encoding hypothesis. HZs performance on repetition and reading aloud (tests showed no mixed errors and no effects of imageability and of target frequency on formal errors) failed to support the predictions of the first two hypotheses. However, the phonological encoding hypotheses (enriched by a comprehensionbased editor) could also not account for the data (e.g. for some task-specific asymmetries in the error pattern). Instead, an attempt is made to account for formal and mixed errors by construing word form encoding as an interactively organised component within a two-stage model of lexicalisation. Formal errors are traced back to interactions between lexical forms and sublexical phonological information during the second stage of lexicalisation. Mixed errors occur when lexical forms of the targets semantic competitors are involved in word form encoding.

The functional basis of speech automatisms (recurring utterances)

Abstract Speech automatisms (or recurring utterances) are stereotyped and repetitive productions especially seen in more severely handicapped aphasic patients. First this paper summarizes important observations on the occurrence and phenomenology of that symptom. It then addresses the issue of syndrome categorization of these patients. The main part of this review deals with attempts to account for this sterotyped output pattern. Theories assuming a non-propositional mode of automatism production can elucidate the very first occurrence of some lexical automatisms. However, this approach cannot explain their repetitive and stereotyped character. Other accounts are founded on detailed single case studies within the framework of language processing models. Based on these studies it is argued that speech automatisms are triggered by modality-specific and subphonemic mechanisms. It is proposed that a subphonemic buffer system is involved in automatism generation. This system can be dysfunctional by direct impa...

The representation of homophones: Evidence from remediation

Background: This single case study examines the linguistic phenomenon of ambiguous spoken words: homophones. In the psycholinguistic research literature the lexicalisation of homophones is the subject of extensive debate. A common assumption is that these words share one word form but have two grammatical representations (lemmas). An opposing view postulates two separate word form entries for homophones - without assuming a lemma level. Aims: The single case study presented here searches for empirical evidence for the representation of homophones using aphasic speech production. Can aphasic speech production give us some evidence regarding how many processing levels have to be completed prior to articulation? Methods & Procedures: A treatment study with MW, a man with global aphasia and severe anomia, is presented. Treatment comprised an intensive picture-naming training with exclusively phonological cues. Naming was facilitated using the following cueing hierarchy: (i) giving the initial phoneme, (ii) tapping the syllable number, and (iii) giving the target word for repetition. How this pure phonological training would affect naming performance of homophones, semantically and phonologically related words, and unrelated words was investigated. Outcomes & Results: The results showed significant short-term, item-specific effects for treated words and generalisation to untreated homophone words alone. The outcome is discussed with reference to the debate regarding homophone production in psycholinguistics and the debate regarding the facilitatory effects of phonological techniques. Conclusions: The results support the two stage model, with only one word form and two lemma entries for homophones. In addition, the outcome of this phonological treatment supports the common assumption that pure word form training rarely results in long-term improvement or generalisation.

Producing speech automatisms (recurring utterances): Looking for what is left

Abstract Nine expressively severely impaired aphasics with a predominant production of syllabic speech automatisms (e.g. do-do-do) were investigated. Firstly, the group respected differential length types in relation to three types of questions (yes/no, wh-questions and narrative requests) in a standardized interview. Secondly, preserved articulatory and phonological capacities in series and syntagmatic cueing conditions were found in a subgroup. Finally, observations in written language suggest that automatisms are restricted to oral speech. Results are discussed within the framework of a language production model.

Where do lexical speech automatisms come from

Abstract Aphasic speech automatisms (or recurring utterances) are stereotypical and repetitive utterances, which can be produced either as lexical forms or as neologisms. The present study investigates the two-source hypothesis which states that lexical speech automatisms are generated by right-hemisphere (and limbic) structures (non-propositional speech), while non-lexical automatisms are accounted for by disturbed left-hemisphere phonological processes (propositional speech). A classification of the lexical automatisms of 30 aphasics yielded a high proportion of non-propositional utterances (e.g., emotional expressions, interjections, proper names, holistically organized multiple-word utterances). However, there were also utterances that could not be classified as non-propositional speech. A subgroup of the aphasics produced non-lexical forms along with lexical forms. It is argued that lexical and non-lexical speech automatisms are generated by similar pathological mechanisms and that the high proportion of non-propositional utterances allows conclusions about the initial availability of these forms but not about their repetitive-stereotypical usage.

Implications of preserved written language abilities for the functional basis of speech automatisms (recurring utterances): A single case study

Abstract A patient is described whose oral speech consists exclusively of repetitively used stereotypical utterances (speech automatisms) but whose written performance is far better preserved. Written language investigation revealed that his phonological route for writing was not totally blocked. In writing to dictation, word length and syllabic structure were largely respected, even for nonwords. Picture-matching tasks which manipulated phonological similarity demonstrated relatively preserved access to lexical phonology. A nonlexical and sub-phonemic hypothesis of automatism-generation is proposed.

Is there an anatomical basis for the production of speech automatisms

Abstract The CT scans of fifty-nine right-handed patients who had suffered a single left middle cerebral artery infarction including more than 2% of forebrain volume were analysed for correlations between lesion configuration and the presence of speech automatisms. No remarkable effects were found concerning lesion size and configuration of the cortical lesion. All eighteen patients with speech automatisms shared a common lesion in the deep fronto-parietal white matter. This finding was assumed to indicate that the pathology underlying the production of speech automatisms involves structures in the depth of the area of supply of the middle cerebral artery. However, the pathogenesis of speech automatisms seems to be multifactorial. Parameters of lesion anatomy could account for only a fraction of the variance included in automatism production. Age at infarction was demonstrated to have a significant effect upon the production of speech automatisms.

Serial processing in graphemic encoding: evidence from letter exchange errors in a multilingual patient

Abstract We report on the spelling performance of a multilingual patient who developed symptoms of pure dysgraphia after concussion. In all languages studied (German, English, Finnish) her main error type consisted of adjacent letter exchanges (e.g. and→adn). Closer examinations showed that LMs spelling impairment could be attributed to a relatively selective disorder of the Graphemic Buffer. It is suggested that her exchange errors result from anticipations and complementary perseverations during graphemic selection and can be located between the activation of graphemic strings coded in parallel and serial conversion into subgraphemic units.