Verb Inflection Errors Research Articles

Morphosemantic treatment of inflection of verb tense in Persian-speaking aphasic patients with agrammatism: a single-subject study

ABSTRACT Background The production of verb inflection, especially tense marking, is commonly impaired in persons with agrammatic aphasia. In Persian, verbs are inflected in three tenses the past, present, and future, and play a key role in the sentence.A group of theories attributes verb inflection errors to syntactic or semantic deficits in sentence formulation. Aims The present study intends to investigate the effect of morphosemantic treatment on the inflection of regular and irregular verbs in the past, present, and future tenses in Persian-speaking agrammatic participants. Methods & Procedure A single-subject study with an ABA design was performed to evaluate the effect of morphosemantic treatment on four Persian-speaking agrammatic participants. In the current study, in addition to presenting descriptive statistics and visual analysis, percent of non-overlapping data (PND) was used to determine whether there was an effect of intervention during the treatment phase, and d1 statistics of effect size analysis was used to determine whether there was a maintenance effect during the withdrawal phase. Outcomes & Results All participants demonstrated significant improvement in the trained regular and irregular tenses and generalized to the production of tense morphology on untrained regular and irregular verbs. The effect of therapy was maintained for a three-week follow-up. Also, the morphosemantic intervention was associated with an increase in most narrative measures and language tests scores. Conclusions Therapy for verb inflection in spontaneous speech is clinically important. The current study demonstrated that morphosemantic intervention could be successfully used for tense marker deficits in Persian-speaking participants with aphasia and agrammatism.

Inhibitory control is needed to overcome written verb inflection errors: Evidence from a developmental negative priming study

Systematic written verb inflection errors occur in sentences such as the dog of the neighbors come (instead of comes). In French, similar verb inflection errors are observed in sentences such as I eat them because the plural pronoun is placed between the subject pronoun and the verb and has the same written morphology as the determiner providing the noun inflection. Thus, subjects can erroneously inflect the verb with the plural mark for nouns. We investigated whether these verb inflection errors are related to the ability to inhibit this misleading strategy. We designed a variant of the negative priming (NP) paradigm with children, adolescents and adults. NP effects are observed in all participants. Critically, the magnitude of the NP effects decreased between children and adolescents. These results suggest that learning verb inflections relies not only on the acquisition of declarative grammatical knowledge but also on the ability to inhibit an overlearned strategy.

Subthalamic nucleus stimulation and spontaneous language production in Parkinson’s disease: A double laterality problem

BackgroundAsymmetric degeneration of dopaminergic neurons, are characteristic for Parkinson’s disease (PD). Despite the lateralized representation of language, the correlation of asymmetric degeneration of nigrostriatal networks in PD with language performance has scarcely been examined. Objective/hypothesisThe laterality of dopamine depletion influences language deficits in PD and thus modulates the effects of subthalamic nucleus (STN) stimulation on language production. MethodsThe spontaneous language production of patients with predominant dopamine depletion of the left (PD-left) and right (PD-right) hemisphere was compared in four stimulation conditions. ResultsPD-right made comparatively more verb inflection errors than PD-left. Bilateral STN stimulation improves spontaneous language production only for PD-left. ConclusionsThe laterality of dopamine depletion influences spontaneous language production and the effect of STN stimulation on linguistic functions. However, it is probably only one of the many variables influencing the effect of STN stimulation on language production.

The effects of language impairment on the use of direct object pronouns and verb inflections in heritage Spanish speakers: A look at attrition, incomplete acquisition and maintenance

This study examined object clitic pronouns (OCPs) and verb inflections in twenty-five school-age children with typical development (TD) and twenty children with bilingual language impairment (BLI). MANOVA and ANOVA were used to explore differences according to grade level and language status (TD vs. BLI). Although children with BLI produced higher rates of grammatical errors overall, accuracy on number and gender assignment for OCPs was better for both groups in the higher grades. Although the rate of verb inflection errors did not differ for children with TD and BLI in the lower grades, a significant interaction yielded higher error rates on subject–verb agreement for third person singular and plural inflections in the later grades for children with BLI. Greater accuracy on OCP use in later grades weakens claims that bilingualism exacerbates language impairment. For BLI, whether incomplete acquisition or delayed development is the determining factor for verb inflection errors remains undetermined.

Using Swahili and English to test explanations of agrammatism

Background: This study is on time reference through verbs in two Swahili-English bilingual agrammatic speakers. Recent studies in several languages have shown that time reference through verb inflection, and more specifically through tense, is impaired in agrammatic speakers. Consequently, several theories have been proposed to account for this phenomenon. We explore three kinds of theories of agrammatism that are eligible to account for these data: (1) a deficit in Tense; (2) a deficit in Discourse Linking; (3) a Morphological-System deficit. Aims: The study investigated the patterns and degree of severity of time reference impairments in bilingual agrammatic speakers of Swahili and English. Production of past and future verb forms was examined in both languages to determine which of the explanations for verb inflection errors holds in bilingual agrammatic speakers. Methods & Procedures: A sentence completion test was developed in two languages to elicit sentence constructions that refer to the past and the future. This test was administered to two bilingual agrammatic speakers of Swahili and English and three age- and education-matched control participants. Outcomes & Results: The performance of the control participants on the two tests was perfect in both languages. Similarly, the two agrammatic speakers' performance in Swahili as well as future tense in English was at ceiling. However, both agrammatic speakers had selective deficits in the production of English past tense. Conclusions: The discrepancy between the English and Swahili data cannot be explained by a syntactic or discourse linking theory. Only a morphological deficit in terms of number of possible candidates for a particular inflectional form fits with the data.

Syntax at Age Two: Cross-Linguistic Differences1

The 1990s witnessed a major expansion in research on children's morphosyntactic development, due largely to the availability of computer-searchable corpora of spontaneous speech in the CHILDES database. This led to a rapid emergence of parallel findings in different languages, with much attention devoted to the widely attested difficulties in inflectional morphology in the speech of two-year-olds. First written in 1995, and framed within the terms of contemporary syntactic theories, this article argues that cross-linguistic differences in the distribution of children's morphosyntactic errors provide important clues to the source of the errors, in particular whether they are morphological or syntactic in origin. The article takes as its starting point some striking previous findings that children's verb inflection errors are systematically correlated, on a sentence-by-sentence basis, with errors in the use of overt subjects, and with the use of syntactically complex constructions such as wh-questions. The article shows that these correlations are found in some languages but not in others, and argues that these differences are predictable, based on the verb movement and case licensing properties of individual languages. The article argues that children's errors reflect a combination of grammatical and speech production deficits.

A comparison of two theoretically driven treatments for verb inflection deficits in aphasia

Errors in the production of verb inflections, especially tense inflections, are pervasive in agrammatic Broca's aphasia (*The boy eat). The neurolinguistic underpinnings of these errors are debated. One group of theories attributes verb inflection errors to disruptions in encoding the verb's morphophonological form, resulting from either a general phonological deficit or a morphological affixation impairment. A second group of theories attribute verb inflection errors to disruptions that arise during sentence formulation, either for syntactic reasons or due to impairments in making fine semantic distinctions between inflectional variants of a verb (+PAST→ate, hugged; +FUTURE→will eat, will hug). These morphophonological and morphosemantic accounts were evaluated by comparing the efficacy of two treatment protocols that exclusively targeted either morphophonological operations or morphosemantic distinctions. Using a single participant design, it was found that aphasic individuals who received morphosemantic treatment showed significant improvement in accurate production of trained and untrained verb inflections in sentence contexts. In contrast, individuals who received morphophonological treatment failed to show improvements in accuracy of sentence production, although the number and diversity of inflected verbs increased. The differential outcomes suggest that morphosemantic impairments contribute to verb inflection deficits in agrammatic aphasia to a greater extent than morphophonological impairments, at least in this group of participants.

Functional category production in English agrammatism

Background: Individuals with agrammatism show selective deficits in functional categories. The tree‐pruning hypothesis (TPH; Friedmann & Grodzinsky, 1997) suggests that this results from inability to project certain nodes in the syntactic tree. On this account, higher nodes in the tree are more vulnerable than lower ones. Other theories, however, suggest that functional category impairments can be explained in the context of a morphological deficit (e.g., Arabatzi & Edwards, 2002; Penke, 2003; Thompson, Fix, & Gitelman, 2002). Aims: This study examined production of complementisers, tense, and agreement morphology in four English‐speaking agrammatic participants to test the hierarchical nature of functional category deficits. The consistency of verb inflection errors was also tested under conditions examining a minimal set versus a full array of English inflected forms. Materials & Procedures: In Experiment 1 participants were asked to produce sentences by using a complementiser (i.e., whether, that, and if), a tense (‐ed), or agreement marker (‐s), in structured sentence elicitation tasks. In Experiment 2 the participants' production of both finite and non‐finite verb inflection forms was examined. Outcome & Results: All participants produced complex sentences successfully using a complementiser, indicating intact projection to the Complementiser Phrase (CP). As for tense and agreement—structures within the Inflection Phrase (IP)—the agrammatic speakers were impaired in both categories and they showed higher scores in non‐finite vs finite verb conditions. Further, their errors were dominated by substitutions, rather than omissions, with various non‐target morphemes. Conclusions: Our agrammatic participants' deficits are morphological, rather than syntactic. The participants were able to project to the uppermost structure, CP. They showed the ability to project verb inflection and to implement inflectional rules in their grammar. However, instantiation of grammatical markers sometimes failed to operate, resulting in incorrect inflectional forms. These findings suggest that within the domain of functional categories, IP‐ and CP‐level deficits may result from disruption of differing underlying mechanisms and, therefore, they may require separate treatment strategies.

Factors affecting the production of verb inflections in Greek aphasia

Verb inflection errors are commonly observed in the speech of aphasic individuals, but the errors are selective and not evenly distributed across different functional categories (e.g., Friedman & Grodzinsky, 1997). An investigation of verb inflection errors in seven Greek aphasic individuals showed more errors in aspect and tense than in agreement (Varlokosta et al., 2006). Moreover, the productions revealed a large proportion of repetition and lexical errors in addition to pure inflectional errors. The presence of different types of errors raises the question of the nature of the underlying deficit in the production of the functional categories. An erroneous production of a verb may involve an error in morphological suffixation, preserving the verb stem; an error in lexical selection, preserving the inflection; and a mixed error, involving both the morphological suffixation and the verb stem. Because all verbs in Greek are affixed, a bare stem is not a possibility as it would result in an illegal word. According to Levelt’s (1999) model of word production, morphological suffixation errors indicate a breakdown at the level of diacritical (lexical–semantic) features, whereas lexical and mixed lexical–morphological errors reflect additional difficulty in lexical selection. Repetition errors involve the least amount of computation and thus may indicate a difficulty in affixation during phonological encoding. To address the above question, we re-examined the productions of the Greek speaking aphasic individuals studied by Varlokosta et al. (2006) by re-classifying the errors as morphological, lexical, or mixed. A second aim was to examine the contributions of severity of spoken language impairment, verb familiarity, regularity, and presence of consonant cluster to the performance per functional category.

Verb inflections in agrammatic aphasia: Encoding of tense features

Across most languages, verbs produced by agrammatic aphasic individuals are frequently marked by syntactically and semantically inappropriate inflectional affixes, such as Last night, I walking home. As per language production models, verb inflection errors in English agrammatism could arise from three potential sources: encoding the verbs’ morphology based on temporal information at the conceptual level, accessing syntactic well-formedness constraints of verbal morphology, and encoding morphophonological form. We investigate these aspects of encoding verb inflections in agrammatic aphasia. Using three sentence completion experiments, it was demonstrated that production of verb inflections was impaired whenever temporal reference was involved; while morphological complexity and syntactic constraints were less likely to be the source of verb inflection errors in agrammatism. These findings are discussed in relation to current language production models.

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.