Aphasic Speakers Research Articles

Grammatical Encoding and Learning in Agrammatic Aphasia: Evidence from Structural Priming.

The present study addressed open questions about the nature of sentence production deficits in agrammatic aphasia. In two structural priming experiments, 13 aphasic and 13 age-matched control speakers repeated visually- and auditorily-presented prime sentences, and then used visually-presented word arrays to produce dative sentences. Experiment 1 examined whether agrammatic speakers form structural and thematic representations during sentence production, whereas Experiment 2 tested the lasting effects of structural priming in lags of two and four sentences. Results of Experiment 1 showed that, like unimpaired speakers, the aphasic speakers evinced intact structural priming effects, suggesting that they are able to generate such representations. Unimpaired speakers also evinced reliable thematic priming effects, whereas agrammatic speakers did so in some experimental conditions, suggesting that access to thematic representations may be intact. Results of Experiment 2 showed structural priming effects of comparable magnitude for aphasic and unimpaired speakers. In addition, both groups showed lasting structural priming effects in both lag conditions, consistent with implicit learning accounts. In both experiments, aphasic speakers with more severe language impairments exhibited larger priming effects, consistent with the "inverse preference" prediction of implicit learning accounts. The findings indicate that agrammatic speakers are sensitive to structural priming across levels of representation and that such effects are lasting, suggesting that structural priming may be beneficial for the treatment of sentence production deficits in agrammatism.

Semantic context effects on picture naming in aphasia

Semantic context effects on picture naming in aphasia

The role of frequency in the retrieval of nouns and verbs in aphasia

ABSTRACTBackground: Word retrieval in aphasia involves different levels of processing—lemma retrieval, grammatical encoding, lexeme retrieval, and phonological encoding—before articulation can be programmed and executed. Several grammatical, semantic, lexical, and phonological characteristics, such as word class, age of acquisition, imageability, and word frequency influence the degree of success in word retrieval. It is, however, not yet clear how these factors interact. The current study focuses on the retrieval of nouns and verbs in isolation and in sentence context and evaluates the impact of the mentioned factors on the performance of a group of 54 aphasic speakers.Aims: The main aim is to measure the effect of word frequency on the retrieval of nouns and verb by disentangling the influence of word class, age of acquisition, imageability, and lemma and lexeme frequencies on word retrieval in aphasia.Methods & Procedures: Four tests for retrieval of nouns, verbs in isolation, and infinitives and finite verbs were administered to 54 aphasic speakers. The influence of lemma and lexeme frequency, Age of Acquisition on the word retrieval abilities was analysed.Outcomes and Results: Word class, age of acquisition, and imageability play a significant role in the retrieval of nouns and verbs: nouns are easier than verbs; the earlier a word has been learned and the more concrete it is, the easier it is to retrieve. When performance is controlled for these factors, lemma frequency turns out to play a minor role: only in object naming does it affect word retrieval: the higher the lemma frequency of a noun, the easier it is to access. Such an effect does not exist for verbs, neither on an action-naming test, nor when verbs have to be retrieved in sentence context. Lexeme frequency was not found to be a better predictor than lemma frequency in predicting word retrieval in aphasia.Conclusions: Word retrieval in aphasia is influenced by grammatical, semantic, and lexical factors. Word frequency only plays a minor role: it affects the retrieval of nouns, but not of verbs.

Paraphasies phonémiques et/ou phonétiques ? Des raisons et des difficultés de cette distinction

Resume L’origine phonologique ou phonetique de transformations observees dans la production de patients aphasiques est souvent source de debat aussi bien chez les cliniciens que chez les chercheurs. Dans cette revue de la litterature nous proposerons un survol des modeles theoriques expliquant la production d’erreurs phonologiques et phonetiques et leur dynamique temporelle durant la planification de la parole et revisiterons les arguments en faveur de la separation phonologique-phonetique. Nous illustrerons en particulier les raisons sous-tendant les difficultes d’identification de l’origine phonologique ou phonetique des paraphasies phonemiques ainsi que les debats theoriques sur la distinction entre processus phonologiques et phonetiques.

Production of plural nouns in German: evidence from non-fluent aphasia

This paper investigates the production of German plural nouns by two aphasic participants with non-fluent speech production. Experimental tasks included two production tasks: (1) picture naming of single and multiple objects, and (2) an elicitation task of singular and plural nouns. Materials were controlled for regularity and predictability of plural form, and for dominance of number, referring to the relative difference in word form frequency between a singular and its corresponding plural form. Both regularity and number dominance have been shown to affect plural noun production in both unimpaired and aphasic speakers, but the underlying functional origin of these effects is still a matter of debate. The results point to differences in the lexical representation and processing of regular and irregular German plural nouns. Thus, the data are in line with the dual mechanism account.

The Taiwanese Mandarin Linguistic Communication Measure (TM-LCM): An adaptation study for quantifying discourse produced by healthy individuals and speakers with aphasia in Taiwan

The Taiwanese Mandarin Linguistic Communication Measure (TM-LCM): An adaptation study for quantifying discourse produced by healthy individuals and speakers with aphasia in Taiwan

Spontaneous speech: Quantifying daily communication in Spanish-speaking individuals with aphasia.

Spontaneous speech: Quantifying daily communication in Spanish-speaking individuals with aphasia.

Producing and inflecting verbs with different argument structure: Evidence from Greek aphasic speakers

Background: Verb argument structure affects language production in aphasia. Unaccusative verbs have been found to be more difficult than transitive or unergative verbs across languages. Transitivity is also a factor with variable influence across aphasia types. Verb inflection production, and in particular tense and aspect, has been found to be vulnerable in aphasia, too. These domains have been studied independently of each other, and their potential interaction has been scarcely addressed.Aims: The present study explores the effects of argument structure and past tense on verb production in Greek aphasia. Additionally, we address the question of the interrelation between inflection and verb and argument structure production.Methods & Procedures: Two tasks were administered to 10 aphasic participants (six anomic, two Wernicke’s and two agrammatic Broca’s). The first task (sentence elicitation) consisted of video presentation and description of the video. The second task (tensed sentence elicitation) consisted of presentation of a video preceded by an adverbial prompting for a specific inflection marking. Participants had to produce a sentence with a verb in a specific past form. In both tasks, three verb classes were tested (unergative, unaccusative and transitive verbs with one object) with six items each.Outcomes & Results: The sentence elicitation task showed that unaccusative verbs are the most difficult class for the aphasic participants whose predominant error was the production of +agentive verbs instead of unaccusatives. The tensed sentence elicitation task showed that while for most patients there was no effect of inflection on verb and verb argument production, a decremental effect was noticed for an agrammatic participant.Conclusions: We suggest that +/− agentivity ranks above transitivity concerning verb production. To account for the unaccusativity effect, we provide a novel account based on the distinction between thematic and aspectual dimension and argue that unaccusative verbs are more difficult to produce, because they involve a mismatch between the two dimensions of argument structure (thematic and aspectual dimension). Concerning the effect of past tense on verb production we show that such pattern is possible but it does not emerge at the group level. Finally, our group data do not suggest any interrelation between inflection, on the one hand, and verb and argument structure production, on the other hand.

A Multidimensional Review of Bilingual Aphasia as a Language Disorder

Aphasia as a multifaceted language disorder associated with the complicated links between language and brain has been and is of interest and significance to the stream of research in different disciplines including neurolinguistics, psycholinguistics, cognitive studies and language acquisition. Along with explorations into the manifestations of aphasia in monolingual speakers, bilingual aphasia has similarly become the most current form of this language disorder due to the rising number of bilingual speakers in recent decades all over the world and the probability of facing bilinguals suffering from this language deficit. To paint a picture of this multidimensional linguistic impairment and to get out of the labyrinth of aphasia and in particular bilingual aphasia, the present review study aims to provide a summary of aphasia-related studies in different contexts worldwide and run through the variables affecting the manifestations and language recovery patterns in bilingual aphasic speakers.

Perceived liveliness and speech comprehensibility in aphasia: the effects of direct speech in auditory narratives

Previous studies have shown that in semi-spontaneous speech, individuals with Broca's and anomic aphasia produce relatively many direct speech constructions. It has been claimed that in 'healthy' communication direct speech constructions contribute to the liveliness, and indirectly to the comprehensibility, of speech. To examine the effects of the occurrence of direct speech constructions on the perceived liveliness and speech comprehensibility of narratives produced by individuals with and without aphasia. Thirty-seven naive listeners rated 30 speech fragments with and without direct speech from ten speakers with and ten speakers without aphasia. The fragments originated from semi-structured interviews. The raters scored the perceived liveliness and the perceived comprehensibility of these fragments. For both groups of speakers, fragments containing direct speech constructions received higher scores for liveliness than fragments without direct speech constructions. However, no effect of direct speech was found on perceived comprehensibility. This is the first research to demonstrate that communication is perceived as more lively when it contains direct speech than when it does not, but yet is not more comprehensible. Individuals with Broca's and anomic aphasia are known to produce regularly direct speech constructions in elicited narratives. Given that liveliness is known to increase listeners' involvement and to help listeners stay focused, we suggest that this relative increase in direct speech by aphasic speakers may reflect a strategy to increase not only the liveliness of their discourse, but also listener focus and involvement.

Time reference decoupled from tense in agrammatic and fluent aphasia

Background: Reference to an event’s time frame can be accomplished through verb inflection. In agrammatic aphasia, a deficit in past time reference has been identified by Bastiaanse and colleagues (2011). In fluent aphasia, specific problems with this time frame (expressed by the past tense) have been found as well (Dragoy & Bastiaanse, 2013; Jonkers & de Bruin, 2009). However, time reference does not always coincide with tense; in languages such as Dutch and English, reference to the past can be established by using past tense (e.g., “he wrote a letter”) or a present tense auxiliary in combination with a participle, i.e., the present perfect (e.g., “he has written a letter”).Aims: The goal of this study is twofold. First, it aims to untangle tense problems from problems with past time reference through verb morphology in people with aphasia. Second, this study aims to compare the production of time reference inflection by people with agrammatic and fluent aphasia.Methods & Procedures: A sentence completion task was used to elicit reference to the non-past and past in Dutch. Reference to the past was tested through (1) a simple verb in past tense and (2) a verb complex with an auxiliary in present tense + participle (the present perfect). Reference to the non-past was tested through a simple verb in present tense. Fourteen agrammatic aphasic speakers, sixteen fluent aphasic speakers, and twenty non-brain-damaged speakers (NBDs) took part in this study. Data were analysed quantitatively and qualitatively.Outcomes & Results: NBDs scored at ceiling and significantly higher than the aphasic participants. Agrammatic speakers performed worse than fluent speakers, but the pattern of performance in both aphasic groups was similar. Reference to the past through past tense and [present tense auxiliary + participle] was more impaired than reference to the non-past. An error analysis revealed differences between the two groups.Conclusions: People with agrammatic and fluent aphasia experience problems with expressing reference to the past through verb inflection. This past time reference deficit is irrespective of the tense employed. The error patterns between the two groups reveal different underlying problems.

Collaborative participation in aphasic word searching: comparison between significant others and speech and language therapists

Background: Searching for words is a common phenomenon in conversations of people with aphasia. When searching for a word the speaker interrupts the emerging conversational turn with a pause, vocalisation (e.g., uh), and/or a question (e.g., what is it). Previous studies suggest that gazing and pointing can be used to invite conversational partners to join the search.Aims: This study compares the collaborative actions of different conversational partners of people with aphasia (significant others vs. speech and language therapists) during aphasic word searching. The aphasic speakers’ actions inviting assistance from the partners in the search are also examined.Methods & Procedures: The data for the study comprised 20 conversations, half videotaped at the participants’ homes and half in aphasia therapy sessions. The conversations were transcribed and analysed sequentially with a special emphasis on taking non-verbal actions into account. In the analysis, word search sequences were identified and the collaborative participation of the significant others, as well as the speech and language therapists, compared.Outcomes & Results: The analysis showed that institutional and non-institutional conversational partners collaborate in different ways during word searching. When invited to join the search, often non-verbally, the significant others quickly offer words for the aphasic speakers to complete the search. When successful, these immediate completions solve the search and the core conversation can continue. On the other hand, even if invited non-verbally, speech and language therapists do not join in searching by offering words. Instead, they ask questions or offer their candidate understandings that are more elaborate than one word. Furthermore, they regularly shift the speaking turn back to the aphasic speaker encouraging the aphasic speaker to continue the search by him or herself.Conclusions: The institutional and everyday practices of sequential resolutions of word searching differ to a great extent. Everyday conversational practices of collaborative completion appear more effective in solving the search and allow the aphasic speaker to experience smoothly flowing conversational interaction. Everyday practices could also be systematically used within aphasia therapy. Furthermore, if necessary, speech and language therapists should promote the use of these practices within daily interactions of the aphasic clients and their significant others.

Processing of nominal compounds and gender-marked determiners in aphasia: Evidence from German

The present study tests theories about the representation of compound nouns and grammatical gender in the mental lexicon. Comprehension and production of determiner–compound-noun phrases were examined in three aphasic native speakers of German, a language that marks grammatical gender on definite determiners of nouns.In picture naming, participants were more impaired in retrieving compounds than matched simple nouns and showed different error patterns. However, retrieving the correct determiner was equally impaired for compounds and simple nouns. Clear dissociations between impaired determiner retrieval in production and relatively preserved processing of determiner–noun phrases in comprehension were observed for existing compounds and simple nouns. In contrast, processing of novel compounds was more impaired in both modalities, and gender-mismatch effects were especially observed for novel compounds. The results support the account of decomposed word forms and holistic lemma representations of compound nouns in the mental lexicon.

Verb use in aphasic and non-aphasic personal discourse: What is normal?

Sentence and discourse analysis research provides evidence of both impaired and intact ability in verb production in aphasia, based on comparisons made within aphasic subtypes, and between aphasic and control speakers. Comparisons are complicated due to variation in elicitation tasks and genre, participant sample size, and aphasia subtype, as well as methodological differences in determining fluency. In this study, we examined the impact of aphasia on speakers' capacity to talk about their quality of life, applying three analytical methods to 58 speakers' discourse (29 predominantly fluent aphasic speakers; 29 non-aphasic speakers). Both speaker groups produced similar quantity, weight, and type of verbs, with substantial overlap in verb tokens. Relational, material and mental verbs were prevalent. Aphasic speakers had significantly lower predicate argument structure scores, and produced significantly more 0 argument structures, more [Aux + 0] constructions, fewer 1 argument structures in general and fewer 1 argument structures with clausal embedding, compared to non-aphasic speakers. This study provides evidence for intact (semantic weight and type) and impaired (PAS) verb production in aphasia. The heterogeneity within both participant samples challenges assumptions of normality and typicality.

Effects of Phonological Neighborhood Density on Accuracy of Picture Naming in Aphasia

Effects of Phonological Neighborhood Density on Accuracy of Picture Naming in Aphasia

The neural correlates of reference to the past

Background Recently, Bastiaanse et al. (2011) identified past time-reference morphology as a particular source of the prominent verb inflection problems in agrammatism. Using a verb form with past time-reference requires additional processing, because a link has to be made to the event in discourse—this in contrast to non-past time-reference. Discourse-related electrophysiological processing differences were demonstrated in non-brain-damaged speakers earlier (Bos et al., 2013).

Parallel functional category deficits in clauses and nominal phrases: The case of English agrammatism.

Individuals with agrammatic aphasia exhibit restricted patterns of impairment of functional morphemes, however, syntactic characterization of the impairment is controversial. Previous studies have focused on functional morphology in clauses only. This study extends the empirical domain by testing functional morphemes in English nominal phrases in aphasia and comparing patients' impairment to their impairment of functional morphemes in English clauses. In the linguistics literature, it is assumed that clauses and nominal phrases are structurally parallel but exhibit inflectional differences. The results of the present study indicated that aphasic speakers evinced similar impairment patterns in clauses and nominal phrases. These findings are consistent with the Distributed Morphology Hypothesis (DMH), suggesting that the source of functional morphology deficits among agrammatics relates to difficulty implementing rules that convert inflectional features into morphemes. Our findings, however, are inconsistent with the Tree Pruning Hypothesis (TPH), which suggests that patients have difficulty building complex hierarchical structures.

Voxel-based lesion-parameter mapping: Identifying the neural correlates of a computational model of word production

The dual-route interactive two-step model explains the variation in the error patterns of aphasic speakers in picture naming, and word and nonword repetition tasks. The model has three parameters that can vary across individuals: the efficiency of the connections between semantic and lexical representations (s-weight), between lexical and phonological representations (p-weight), and between representations of auditory input and phonological representations (nl-weight). We determined these parameter values in 103 participants with chronic aphasia from left hemisphere stroke whose lesion locations had been determined. Then, using voxel-based lesion-parameter mapping, we mapped the parameters onto the brain, thus determining the neural correlates of the model’s mechanisms. The maps and the behavioral findings supported the model’s central claim that word repetition is affected by both the p and nl parameters. We propose that these two parameters constitute the model’s analogue of the “dorsal stream” component of neurocognitive models of language processing.

Functionally relevant items in the treatment of aphasia (part II): Further perspectives and specific tools

Background: This paper is the second in a two part series. In part I, we reviewed the concept of “functionally relevant” and the strategies underlying identification of such vocabulary items for aphasia treatment. Based on the review, we concluded that there is a lack of definitions, strategies and specific tools to assist with identification of functionally relevant items for aphasia therapy. We suggested that frequency-based vocabulary lists could and should be used to increase the number of potentially relevant items in aphasia therapy and that therapy should be directed to words other than the most concrete nouns and verbs. Aims: This article reviews the existing strategies and materials from adjacent fields relating to functionally relevant stimuli with the aim of establishing resources for identifying potentially relevant therapy items at the level of both vocabulary items and topics of conversation. Main contribution: By reviewing the core concepts and research from other fields, this article brings together knowledge and materials that can improve current practice regarding identification of functionally relevant items in aphasia therapy. The focus of the review is on studies that have been published in the field of augmentative and alternative communication (AAC) and research that has provided information on unimpaired and impaired adult speakers’ everyday conversations. By reanalysing data sets from these studies and using a large psycholinguistic database, we present four resources. Two of the data sets provide evidence regarding the most frequent topics of conversation; one is based on unimpaired speakers conversations and the other extends this by including information from both unimpaired and aphasic speakers’ topics of conversation. In addition, to provide evidence of the most frequent vocabulary in adult conversations, we present a list of words compiled from three separate data sets. Finally, a vocabulary list of the 1000 most frequent words retrieved from an objective frequency count (SUBTLEX-US) is presented. Together these resources provide a means for clinicians to select objectively frequent topics and vocabulary as stimuli for functionally relevant therapy. Conclusions: The agenda for future research is to identify specific vocabulary within the most common topics of conversation. The resources provided as part of this article serve as a first step towards the ultimate goal of enabling clinicians to select stimuli for therapy in a more systematic, transparent and objective way.

Direct speech constructions in aphasic Dutch narratives

Background: Previous studies have shown that individuals with aphasia are usually able to produce direct reported speech constructions. So far these studies have mainly been conducted in English. The results show that direct speech is beneficial for aphasic speakers for various reasons. In Dutch the construction goes along with a grammatical characteristic that makes it attractive for aphasic speakers. This study examines the diffuse phenomenon of direct speech in narratives of Dutch individuals with and without aphasia. Aims: The purpose of this study is to assess the use of direct speech in the semi-spontaneous speech of Dutch individuals with aphasia. The question is whether this construction, which is highly communicative, is used by aphasic speakers and in which forms it becomes manifest. In addition the effect of the nature of the underlying disorder, (i.e., grammatical versus lexical), is assessed. Methods & Procedures: A total of 61 transcripts of individuals with aphasia (n = 31) and 146 transcripts of non-brain-damaged speakers (n = 88) were analysed. The question of how the forms and relative frequencies of direct speech constructions differ across tasks and subgroups is addressed. For this purpose the relative frequencies of direct speech are determined and compared within and between tasks and subgroups. In addition different forms of the phenomenon are distinguished and categorised based on the patterns found in the data. Outcomes & Results: Individuals with aphasia use direct speech significantly more often than non-brain-damaged speakers. Individuals with Broca's aphasia exhibit a preference for direct speech constructions without a reporting verb, whereas individuals with anomic aphasia predominantly produce instances of direct speech that do include a reporting verb. Even though all subgroups produce direct speech constructions, the frequencies and forms vary across tasks and subgroups. Conclusions: Both groups make use of various forms of direct speech but the frequencies and distributions over categories are different. A possible explanation for the greater production of direct speech by aphasic speakers is its strategic utilisation to get around grammatical problems and word-finding difficulties. There is a quantitative difference between the individuals with anomic aphasia and the control speakers, whereas the difference between the individuals with Broca's aphasia and the control group is qualitative in nature. An explanation for the dissimilarities between the aphasic subgroups is the difference in grammatical complexity between subtypes of direct speech constructions.