Aphasic Speech Research Articles

Semantic, lexical, and phonological influences on the production of verb inflections in agrammatic aphasia

Verb inflection errors, often seen in agrammatic aphasic speech, have been attributed to either impaired encoding of diacritical features that specify tense and aspect, or to impaired affixation during phonological encoding. In this study we examined the effect of semantic markedness, word form frequency and affix frequency, as well as accuracy and error patterns, in an attempt to evaluate whether diacritical or affixation operations are impaired. Verb inflections ( V+ ing, V+ ed, V+ s, and V stem in present progressive, past, present 3rd person singular, and future tense contexts, respectively) were elicited in eight mild-moderate agrammatic aphasic individuals in a sentence context using a picture description task. Results revealed that the majority of verbs produced were affixed (75%) although accuracy was low (36%). Word form frequency was found to be a significant predictor of the accuracy with which verb inflections were produced; while affix frequency and semantic markedness were not found to influence accuracy. These results suggest that a diacritical deficit is more likely to undermine the production of verb inflections than a affixation deficit, and indicate that when diacritical processes are compromised, word form frequency is likely to influence production of verb inflections in agrammatic aphasia.

The relationships between morphological and phonological errors in aphasic speech: data from a word repetition task

Current theories of single-word processing predict that in some cases brain damage should selectively impair morphological processes, resulting in the selective occurrence of morphological errors. However, such a selective pattern of errors has never been documented, and the available case studies report the systematic association of morphological and phonological (segmental) errors in the same subject. The number of relevant case reports is very small, however. To better understand the relationship between morphological and phonological processes, we analyzed the repetition performance of 26 subjects who produced morphological errors in a screening battery for aphasia. Although the results confirm that subjects who make morphological errors also invariably make phonological errors, the probabilities of the two types of errors are not (quantitatively) correlated. Furthermore, the relationship between morphological and phonological errors was asymmetrical: although all subjects who produced morphological errors also produced phonological errors, some aphasics who produced phonological errors did not also produce morphological errors. The one-way relationship between morphological and phonological errors could result either from the anatomical proximity of the structures involved in morphological and phonological processes, or from the functional inseparability of the two processes. The fact that phonological errors can occur either in isolation or in association with morphological errors could be attributed to the functional heterogeneity of phonological errors, and to the separability of the neural substrates involved in processing various aspects of phonological information.

Structural constraints in aphasic speech errors

Structural constraints in aphasic speech errors

Structural properties of syntactically reduced speech: A comparison of normal speakers and Broca’s aphasics

We carried out a study in which we elicited spatial expressions from agrammatic and normal speakers by means of a picture description test. The purpose of our study was to investigate structural properties of Dutch agrammatic speech. We focussed on syntactic simplification phenomena that show up in addition to finiteness omission. We therefore invited the normal speakers to use sentences no longer than three or two words each and compared the picture descriptions of aphasic and normal speakers. In the picture descriptions two types of structures emerged that are relatively infrequent in free conversation: verbless predicative constructions with an adjectival head and intransitive prepositions as predicates. We have been able to show that the use of these construction types is directly related to syntactic reduction in both agrammatic and normal speech: it is present primarily in the speech of Broca’s aphasics who produce one- and two-word utterances and of control speakers with a word limitation by instruction in the same range. The choice of reduced construction types is determined by the syntactic complexity of the phrases involved. A compensation strategy was observed both in control and aphasic speech: if utterances are shorter, the number of utterances increases.

A Cantonese linguistic communication measure

Although there has been a longstanding interest in English aphasic speech, studies of Cantonese aphasic narratives have only emerged recently. This paper presents a Cantonese linguistic communication measure (henceforth, CLCM), which is a convenient measure for analysing Cantonese aphasic narratives. Taking into consideration the characteristics of the Cantonese grammar, the lexical diversity, communication efficiency, grammaticality and elaborateness of Cantonese aphasic speech are quantified. Sixteen Cantonese-speaking aphasic patients and 16 control subjects were recruited to carry out a picture description task. The findings indicated that most indices could distinguish between normal and aphasic speakers. Moreover, two indices indicating the length of the narrative and the rate of information conveyed could further discriminilte fluent from non-fluent aphasics. Given the simplicity of index computation, the CLCM may render speech therapists in general clinical settings an objective, quick and convenient means to quantify patients' expressive language abilities.

Null subject pronouns in Broca's speech production

Background: Pronouns are known to be often missing from the spontaneous speech production of Broca's aphasic patients. Null subject pronouns are found in nonfinite utterances. These structures may result from the underspecification of the Tense head and the unavailability of Nominative case for a subject. It is not clear, though, whether null subject pronouns are restricted only to nonfinite structures.Aims: The paper investigates the occurrence of null subject pronouns in finite sentences of Broca's patients. A detailed study into the syntactic and distributional properties of finite null subjects will reveal their nature and origin in aphasic speech production.Methods & Procedures: The spontaneous speech of 13 Dutch patients was investigated. The following variables were included: finiteness (finite versus nonfinite utterances), sentence position (initial versus non‐initial position), and type of pronoun (personal versus demonstrative pronoun). The speech production of the patients was contrasted to normal spoken Dutch.Outcomes & Results: The results demonstrate that finite null subject pronouns in Broca's speech production can be interpreted as instances of normal omission phenomena found in Germanic languages (Topic Drop and I‐Drop).Conclusion: A unified account is proposed for nonfiniteness and finite null subjects in terms of underspecification of functional heads in the syntactic structure. Underspecification is not due to a linguistic impairment, but rather a means to reduce the processing load of the utterance. It is concluded that nonfiniteness is a core phenomenon in Broca's speech production, while finite null subjects reflect an additional omission phenomenon.

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.

Phonological neighborhood effects in aphasic speech errors: spontaneous and structured contexts

The current study investigates the influence of phonological neighborhoods on the accuracy of speech production in aphasia by examining errors produced in both spontaneous and structured speech tasks. Characteristics of the phonological neighborhoods of spontaneously produced aphasic errors are compared to the neighborhood characteristics of correctly produced targets in a picture description task. Accuracy of picture naming is also examined with reference to the phonological neighborhood characteristics of the stimuli. Results show that frequency of occurrence and neighborhood density play a facilitative role in speech production, replicating findings from recent studies with normal subjects. It is argued that the results are most parsimoniously explained within an interactive activation framework of lexical access.

‘Little words’—not really: function and content words in normal and aphasic speech

Production and comprehension of content and function words was compared in aphasic patients who showed an apparent dissociation between these categories of vocabulary in spontaneous speech. These comprised four patients who had suffered CVA (three non-fluent and one fluent) and one fluent patient with semantic dementia (SD) or progressive aphasia. Where discrepancies in performance between, for example nouns and function words, were shown in reading, these effects disappeared when imageability was controlled. This suggests that the abstractness of function words might be responsible for poor performance in some aphasic patients, in the same way that imageability has been shown to be associated with poor verb production and comprehension in aphasia. A triads method was used to assess the semantic (and/or syntactic) information which could be accessed from the written word. An association was demonstrated between control subjects’ RT data and accuracy in patients. It was apparent that there was no simple dissociation between content and function words for any of these patients, and accuracy for all but the SD patient correlated with imageability. This patient performed at chance on all manipulations in both content and function words except that of gender, suggesting the preservation of this aspect of semantic knowledge.

Clinical evaluation of conversational speech fluency in the acute phase of acquired childhood aphasia: does a fluency/nonfluency dichotomy exist?

Traditional neurologic tenets claim that the clinical picture of acquired childhood aphasia is nonfluent irrespective of lesion location. In the past 20 years, however, several case studies have shown that fluent aphasic patterns can be observed in children with acquired childhood aphasia. But the question remains open as to whether the pattern of their speech characteristics is similar to the one described in adult aphasics as studies addressing spontaneous speech fluency characteristics in larger series of children with acquired childhood aphasia are scarce. The objective of this study was to investigate whether an analysis of spontaneous speech fluency as has previously been performed in adult aphasics by other investigators would also yield two distinct groups of aphasic children and, if so, whether the distribution of the different speech characteristics in both groups would reflect the rank order found in adults, that is, whether nonfluent verbal output characteristics would predominate in one group and fluent features in the other. Audiotaped and videotaped recordings of 24 cooperative children with acute acquired childhood aphasia unselected for age, gender, etiology, and aphasia severity ratings were analyzed according to 10 different speech characteristics. A cluster analysis (two-means clustering) was performed to seek the existence of two distinct groups of aphasic children. Results were confirmed, and exact P values were computed with Mann-Whitney U-tests. A two-means clustering created two distinct classes. Mann-Whitney U-tests ranked the speech characteristics according to their discriminating power between clusters. Comparing this rank order with the one previously found in adults revealed a high correlation (Spearman's rank correlation: r = .915, P << .005), thus indicating that the clusters we found were highly similar to the adult clusters. Thus, the use of the speech variables proposed to evaluate adult aphasic spontaneous speech enabled us to demonstrate a fluent/nonfluent dichotomy in a childhood aphasic population as well. This study shows that the traditional views on the uniformity of the clinical picture of acquired childhood aphasia are obsolete. Our findings corroborate data issued from several case reports of fluent acquired childhood aphasia and from the few studies focusing on speech fluency in acquired childhood aphasia, which all point to the existence of an adultlike heterogeneity of childhood aphasic syndromes. Current clinical evidence no longer supports the hypotheses of equipotentiality and progressive lateralization but favors the notion that the anatomic substrate for language representation in the child is similar to that in adults, even in young subjects.

Grammatical structuring in Broca's and Wernicke's aphasia in Finnish

The purpose of this paper is to examine the linguistic problems of aphasic speakers of Finnish. The focus is on Broca's and Wernicke's aphasia. First, we present an overview of the special characteristics of the grammar of Finnish. Secondly, there is a discussion of previous studies on aphasic speakers of Finnish. Thirdly, we present an analysis of our data from conversation and picture description task by speakers with Broca's and Wernicke's aphasia. The analysis focuses on case marking, subject-verb agreement, word order and the expression of tense in the speech of Finnish aphasics. As a whole, many linguistic features are preserved both in Broca's and Wernicke's aphasia. Even the neologistic words in Wernicke's aphasia are appropriately inflected. However, our findings suggest that aphasic errors are not always systematic and furthermore, they may be context-dependent. For example, Broca's aphasics produced case marking and agreement patterns in some contexts correctly, whereas in some other contexts they were produced erroneously. The word order patterns were similar to those found in conversational discourse in general. However, it is sometimes impossible to give a definitive analysis of the word order or structure of a given grammatical construction. This is due to the fact that sentence structure is sometimes badly distorted both in Broca's and Wernicke's aphasic cases because of difficulty in finding lexical content words. We conclude with a comparison of our findings with previous studies of Finnish aphasics, proposing some methodological implications for further studies.

On manifestations of aphasia in Catalan: a case study of Broca's aphasia

This paper discusses a case of Broca's aphasia in light of the impact of the structure of the patient's mother tongue, Catalan, on the types of errors he makes. What seems to be most affected in the present case, in terms of Kolk's (1995) theory of “structural simplification” —proposed originally for sentence production and comprehension—are those linguistic levels that are most complex in Catalan: closed class word morphology and verb morphology as well as production and comprehension of sentences with non-canonical word order. The types of errors presented always occur in structurally obligatory contexts where the semantic or propositional content of the omitted or misused elements is rather small. Another important fact to bear in mind when studying Catalan aphasics is that, due to the bilingualism of all speakers, some of the signs and symptoms of aphasic speech have to be interpreted in light of the rival language, Spanish.

Aphasia manifestations in Basque

This paper presents a description of the main symptoms of agrammatism found in a corpus of spontaneous speech production of 59 Basque-speaking aphasic patients. The main symptoms relate to deficits in the production of inflectional morphology. From the standpoint of grammatical structure, the deficits involve the production of the syntactic category Infl, that heads the sentence (IP). Basque has a morphologically complex Inflection, containing up to three agreement markers, plus tense and modality specifications. The most outstanding symptom of agrammatism is the absence of inflected verbs, or its extremely low frequency, correlated with a high frequency of uninflected participial forms. The study of the inflected forms produced in aphasic speech reveals a significant number of errors in the selection of appropriate morphemes, particularly number and dative agreement markers, and a considerable number of newly coined impossible forms, resulting form the combination of morphemes from conflicting paradigms. However, the relative order of the morphemes in the auxiliary is correct, which could indicate that the basic structure of Inflection is not affected, at least in the case of patients that produce inflected forms. Errors in case-marking also appear, mostly involving ergative and absolutive markers.

Voice recognition and aphasia: can computers understand aphasic speech?

Purpose : This preliminary investigation of the use of voice recognition software by people with aphasia presents a new method of training the software, which allows the aphasic user to by-pass the linguistically demanding standard training. It examines how accurately voice recognition software performed with aphasic speech and language as compared to that of control subjects. Method : Five non-impaired controls and six participants with aphasia used a vocabulary of 50 words and 24 phrases to train the software over a maximum of five sessions. For the people with aphasia baseline assessments provided a profile of speech and language impairment. Measures of software accuracy were taken for all subjects at baseline and after four subsequent training sessions, for both single word and phrase level dictation. Results : Word level production resulted in similar accuracy levels for both groups. Phrase level production showed greater accuracy levels than single word level production for both aphasics and controls, but participants with greater speech difficulties had lower software accuracy scores. Conclusions : Training the software on a specific vocabulary allows people to access it whose speech and language difficulties would otherwise have prevented them. Findings are discussed in relation to use of the software as a dictation tool and as an input device to therapy software.

Non-Fluent Aphasia in a Multilingual World

“Non-fluent Aphasia in a Multilingual World” is an up-to-date introduction to the language of patients with non-fluent aphasia. Recent research in languages other than English has challenged our old descriptions of aphasia syndromes: while their patterns can be recognized across languages, the structure of each language has a profound effect on the symptoms of aphasic speech. However, the basic linguistic concepts needed to understand these effects in languages other than English have rarely been part of the training of the clinician. “Non-fluent Aphasia in a Multilingual World” introduces these concepts plainly and concretely, in the context of dozens of examples from the narratives and conversations of patients speaking most of the major languages of Europe, North America and Asia. Linguistic and clinical terms are carefully defined and kept as theory neutral as possible. “Non-Fluent Aphasia in a Multilingual World” is especially useful for speech-language pathologists whose patients are immigrants and guestworkers, and for the clinician who must deal creatively with the challenges of providing aphasia diagnosis and therapy in a multicultural, multidialectical setting.

The Interaction of Preserved Pragmatics and Impaired Syntax in Japanese and English Aphasic Speech

Elicited narrative studies have shown that the underlying pragmatic factor of empathy is relatively preserved in aphasic speakers of Japanese and English (7 Japanese and 14 English-speaking aphasics of varied diagnostic types). Occasional “reversal errors” can be explained in terms of a conflict between the normal encoding of the empathic characteristics of an event and the syntactic limitations imposed by impaired production processes. To account for these findings, we propose a production model following Levelt (1989) for making pragmatic choices among syntactic forms. We also suggest that preferential access to “canonical form” might be a matter of surface morphosyntax, rather than involving semantics or more abstract levels of syntax.

A Parallel Licensing Model of Normal Slips and Phonemic Paraphasias

A model of phonological processing in speech production based on prosodic licensing can capture general patterns of errors found in both normal and aphasic speech. All segments must be licensed by some prosodic category (syllable, nucleus, or rime) in order to be produced. Constraints on licensing, including both phonotactic and binding constraints, ensure that only correct licensing associations are retained. A computer simulation of our model produces utterances in qualitative agreement with human speech error data. Phonemic paraphasias are claimed to arise from the same mechanisms as normal speech errors; the difference being only a matter of disturbance of the lexical retrieval and licensing processes. The fact that these errors, which can involve gross disruption of the segmental sequence, still produce phonotactically well-formed strings is a direct consequence of the syllabic licensing that forms the core of our theory of speech production.

Can the Right Hemisphere Speak?

While a capacity for the right hemisphere in language and language related functions is established, a role for the right hemisphere in speech production is controversial. The question of the nature of a possible right hemisphere speech production capability has centered mainly on the Jacksonian notion of nonpropositional speech. In this paper I examine whether the right hemisphere does have a particular role in nonpropositional speech through an exploration of the neurophysiological evidence, research in aphasic speech automatisms, and degree of propositionality in the retained speech of adult left hemispherectomy patients.

Where do lexical speech automatisms come from?

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.

Cinderella revisited: A comparison of fluent and non-fluent aphasic speech

The speech of two fluent and three non-fluent aphasic patients was analysed using the quantitative method devised by Saffran, Berndt and Schwartz et al. ( Brain and Language 37, 440–479, 1989) [6]. The differences between agrammatic and non-agrammatic aphasic speech were broadly replicated, in that the non-agrammatic non-fluent patients were impaired only on measures of syntactic complexity and well-formedness. The fluent patients' sentence production was indistinguishable from that of the non-fluent non-agrammatics, except with respect to fluency itself. All five patients were retested 1–2 years after the first sample. The two patients who had improved in the quantitative analysis showed a similar improvement in picture naming. For one patient at least, an increased availability of low-frequency nouns appeared to be underlying this improvement.