On-line processing of tense and temporality in agrammatic aphasia

It Costs To Exist: Acceptability Judgments of the Temporal Concord of the Auxiliary Verbs You and Hui in Taiwan Mandarin

The mechanisms underlying the processing of the temporal reference of a sentence are still unexplored. Most of the previous psycholinguistic studies used the temporal concord violation between deictic time adverbs and tense marking on the verb to investigate this issue. They found that processing past tense marking is more difficult than non-past tense, indicated by lower accuracy rates and/or longer reaction time. However, it is not clear whether this complexity is due to tense marking or the temporal reference it denotes. This paper examines this issue with a judgment acceptability experiment in Taiwan Mandarin, which is analyzed as a tenseless language. The two modal auxiliary verbs you and hui were placed after deictic past time adverbs (grammatical with you but not with hui) and deictic future time adverbs (grammatical with hui but not with you). The temporal concord violation of the auxiliary verb you led to higher acceptability rates but longer reaction time than hui, reflecting higher processing difficulties. This paper argues that these complexities are due to the existential-assertive meaning of you, which interplays with the meaning of the event described by the verb rendering the situation more or less likely to occur in the future. The computation of the temporal concord of hui, displaying a future sense meaning, is more straightforward and therefore easier to process. This suggests that the mechanisms responsible for temporal reference processing are of different nature depending on the semantics of the temporal marker in the sentence.

Time reference in aphasia: are there differences between tenses and aphasia fluency type? A systematic review and individual participant data meta-analysis

Time reference is used to build the temporal framework of discourse and is essential in ensuring efficient communication. Several studies have reported time reference deficits in fluent and non-fluent aphasia and have shown that tenses (past, present, future) are not all impaired to the same extent. However, there is little consensus on the dissociations between tenses, and the question of the influence of the type of aphasia (fluent vs. non-fluent) on time reference remains open. Therefore, a systematic review and an individual participant data meta-analysis (or mega-analysis) were conducted to determine (1) whether one tense is more impaired than another in fluent and non-fluent aphasia and, if so, (2) which task and speaker-related factors moderate tense effects. The systematic review resulted in 35 studies reporting the performance in time reference of 392 participants. The mega-analysis was then performed on 23 studies for a total of 232 participants and showed an alteration of past tense compared to present and future tenses in both types of aphasia. The analysis also showed a task and an age effect on time reference but no gender effect, independently of tenses. These results add to our knowledge of time reference in aphasia and have implications for future therapies.

A reconceptualization of sentence production in post-stroke agrammatic aphasia: the synergistic processing bottleneck model

The language production deficit in post-stroke agrammatic aphasia (PSA-G) tends to result from lesions to the left inferior frontal gyrus (LIFG) and is characterized by a triad of symptoms: fragmented sentences, errors in functional morphology, and a dearth of verbs. Despite decades of research, the mechanisms underlying production patterns in PSA-G have been difficult to characterize. Two major impediments to progress may have been the view that it is a purely morphosyntactic disorder and the (sometimes overzealous) application of linguistic theory without interceding psycholinguistic evidence. In this paper, empirical evidence is examined to present an integrated portrait of language production in PSA-G and to evaluate the assumption of a syntax-specific syndrome. In light of extant evidence, it is proposed that agrammatic language production results from a combination of morphosyntactic, phonomotor, and processing capacity limitations that cause a cumulative processing bottleneck at the point of articulatory planning. This proposed Synergistic Processing Bottleneck model of PSA-G presents a testable framework for future research. The paper ends with recommendations for future research on PSA-G.

Online Processing of Temporal Agreement in a Grammatical Tone Language: An ERP Study

Previous electrophysiological studies that have examined temporal agreement violations in (Indo-European) languages that use grammatical affixes to mark time reference, have found a Left Anterior Negativity (LAN) and/or P600 ERP components, reflecting morpho-syntactic and syntactic processing, respectively. The current study investigates the electrophysiological processing of temporal relations in an African language (Akan) that uses grammatical tone, rather than morphological inflection, for time reference. Twenty-four native speakers of Akan listened to sentences with time reference violations. Our results demonstrate that a violation of a present context by a past verb yields a P600 time-locked to the verb. There was no such effect when a past context was violated by a present verb. In conclusion, while there are similarities in both Akan and Indo-European languages, as far as the modulation of the P600 effect is concerned, the nature of this effect seems to be different for these languages.

Preserved processing of musical structure in a person with agrammatic aphasia

Evidence for shared processing of structure (or syntax) in language and in music conflicts with neuropsychological dissociations between the two. However, while harmonic structural processing can be impaired in patients with spared linguistic syntactic abilities (Peretz, I. (1993). Auditory atonalia for melodies. Cognitive Neuropsychology, 10, 21-56. doi:10.1080/02643299308253455), evidence for the opposite dissociation-preserved harmonic processing despite agrammatism-is largely lacking. Here, we report one such case: HV, a former musician with Broca's aphasia and agrammatic speech, was impaired in making linguistic, but not musical, acceptability judgments. Similarly, she showed no sensitivity to linguistic structure, but normal sensitivity to musical structure, in implicit priming tasks. To our knowledge, this is the first non-anecdotal report of a patient with agrammatic aphasia demonstrating preserved harmonic processing abilities, supporting claims that aspects of musical and linguistic structure rely on distinct neural mechanisms.

Production of Verb Tense in Agrammatic Aphasia: A Meta-Analysis and Further Data

In a majority of languages, the time of an event is expressed by marking tense on the verb. There is substantial evidence that the production of verb tense in sentences is more severely impaired than other functional categories in persons with agrammatic aphasia. The underlying source of this verb tense impairment is less clear, particularly in terms of the relative contribution of conceptual-semantic and processing demands. This study aimed to provide a more precise characterization of verb tense impairment by examining if there is dissociation within tenses (due to conceptual-semantic differences) and an effect of experimental task (mediated by processing limitations). Two sources of data were used: a meta-analysis of published research (which yielded 143 datasets) and new data from 16 persons with agrammatic aphasia. Tensed verbs were significantly more impaired than neutral (nonfinite) verbs, but there were no consistent differences between past, present, and future tenses. Overall, tense accuracy was mediated by task, such that picture description task was the most challenging, relative to sentence completion, sentence production priming, and grammaticality judgment. An interaction between task and tense revealed a past tense disadvantage for a sentence production priming task. These findings indicate that verb tense impairment is exacerbated by processing demands of the elicitation task and the conceptual-semantic differences between tenses are too subtle to show differential performance in agrammatism.

Losing track of time? Processing of time reference inflection in agrammatic and healthy speakers of German

BACKGROUND

Individuals with agrammatic aphasia (IWAs) have problems with grammatical decoding of tense inflection. However, these difficulties depend on the time frame that the tense refers to. Verb morphology with reference to the past is more difficult than with reference to the non-past, because a link needs to be made to the past event in discourse, as captured in the PAst DIscourse LInking Hypothesis (PADILIH; Bastiaanse, R., Bamyaci, E., Hsu, C., Lee, J., Yarbay Duman, T., Thompson, C. K., 2011. Time reference in agrammatic aphasia: A cross-linguistic study. J. Neurolinguist. 24, 652-673). With respect to reference to the (non-discourse-linked) future, data so far indicate that IWAs experience less difficulties as compared to past time reference (Bastiaanse, R., Bamyaci, E., Hsu, C., Lee, J., Yarbay Duman, T., Thompson, C. K., 2011. Time reference in agrammatic aphasia: A cross-linguistic study. J. Neurolinguist. 24, 652-673), supporting the assumptions of the PADILIH. Previous online studies of time reference in aphasia used methods such as reaction times analysis (e.g., Faroqi-Shah, Y., Dickey, M. W., 2009. On-line processing of tense and temporality in agrammatic aphasia. Brain Lang. 108, 97-111). So far, no such study used eye-tracking, even though this technique can bring additional insights (Burchert, F., Hanne, S., Vasishth, S., 2013. Sentence comprehension disorders in aphasia: the concept of chance performance revisited. Aphasiology 27, 112-125, doi:10.1080/02687038.2012.730603).

AIMS

This study investigated (1) whether processing of future and past time reference inflection differs between non-brain-damaged individuals (NBDs) and IWAs, and (2) underlying mechanisms of time reference comprehension failure by IWAs.

METHODS AND PROCEDURES

A visual-world experiment combining sentence-picture matching and eye-tracking was administered to 12 NBDs and 6 IWAs, all native speakers of German. Participants heard German sentences with periphrastic future ('will+V') or periphrastic past ('has+V-d') verb forms while they were presented with corresponding pictures on a computer screen.

RESULTS AND DISCUSSION

NBDs scored at ceiling and significantly higher than the IWAs. IWAs had below-ceiling performance on the future condition, and both participant groups were faster to respond to the past than to the future condition. These differences are attributed to a pre-existing preference to look at a past picture, which has to be overcome. Eye movement patterns suggest that both groups interpret future time reference similarly, while IWAs show a delay relative to NBDs in interpreting past time reference inflection. The eye tracking results support the PADILIH, because processing reference to the past in discourse syntax requires additional resources and thus, is problematic and delayed for people with aphasia.

Understanding discourse-linked elements in aphasia: a threefold study in Russian

BACKGROUND

Agrammatic speakers have problems with grammatical encoding and decoding. However, not all syntactic processes are equally problematic: present time reference, who questions, and reflexives can be processed by narrow syntax alone and are relatively spared compared to past time reference, which questions, and personal pronouns, respectively. The latter need additional access to discourse and information structures to link to their referent outside the clause (Avrutin, 2006). Linguistic processing that requires discourse-linking is difficult for agrammatic individuals: verb morphology with reference to the past is more difficult than with reference to the present (Bastiaanse et al., 2011). The same holds for which questions compared to who questions and for pronouns compared to reflexives (Avrutin, 2006). These results have been reported independently for different populations in different languages. The current study, for the first time, tested all conditions within the same population.

AIMS

We had two aims with the current study. First, we wanted to investigate whether discourse-linking is the common denominator of the deficits in time reference, wh questions, and object pronouns. Second, we aimed to compare the comprehension of discourse-linked elements in people with agrammatic and fluent aphasia.

METHODS AND PROCEDURES

Three sentence-picture-matching tasks were administered to 10 agrammatic, 10 fluent aphasic, and 10 non-brain-damaged Russian speakers (NBDs): (1) the Test for Assessing Reference of Time (TART) for present imperfective (reference to present) and past perfective (reference to past), (2) the Wh Extraction Assessment Tool (WHEAT) for which and who subject questions, and (3) the Reflexive-Pronoun Test (RePro) for reflexive and pronominal reference.

OUTCOMES AND RESULTS

NBDs scored at ceiling and significantly higher than the aphasic participants. We found an overall effect of discourse-linking in the TART and WHEAT for the agrammatic speakers, and in all three tests for the fluent speakers. Scores on the RePro were at ceiling.

CONCLUSIONS

The results are in line with the prediction that problems that individuals with agrammatic and fluent aphasia experience when comprehending sentences that contain verbs with past time reference, which question words and pronouns are caused by the fact that these elements involve discourse linking. The effect is not specific to agrammatism, although it may result from different underlying disorders in agrammatic and fluent aphasia.

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.

Production and Comprehension of Time Reference in Korean Nonfluent Aphasia

Objectives

Individuals with nonfluent agrammatic aphasia show impaired production and comprehension of time reference via verbal morphology. However, cross-linguistic findings to date suggest inconsistent evidence as to whether tense processing in general is impaired or time reference to the past is selectively difficult in this population. This study examined production and comprehension of time reference via verb morphology in Korean-speaking individuals with nonfluent aphasia.

Methods

A group of 9 healthy controls and 8 individuals with nonfluent aphasia (5 for the production task) participated in the study. Sentence priming production and auditory sentence to picture matching tasks were used, parallel with the previous cross-linguistic experiments in English, Chinese, Turkish, and others.

Results

The participants with nonfluent aphasia showed different patterns of impairment in production and comprehension. In production, they were impaired in all time references with errors being dominated by substitution of incorrect time references and other morpho-phonologically well-formed errors, indicating a largely intact morphological affixation process. In comprehension, they showed selective impairment of the past, consistent with the cross-linguistic evidence from English, Chinese, Turkish, and others.

Conclusion

The findings suggest that interpretation of past time reference poses particular difficulty in nonfluent aphasia irrespective of typological characteristics of languages; however, in production, language-specific morpho-semantic functions of verbal morphology may play a significant role in selective breakdowns of time reference.

Why reference to the past is difficult for agrammatic speakers

Many studies have shown that verb inflections are difficult to produce for agrammatic aphasic speakers: they are frequently omitted and substituted. The present article gives an overview of our search to understanding why this is the case. The hypothesis is that grammatical morphology referring to the past is selectively impaired in agrammatic aphasia. That is, verb inflections for past tense and perfect aspect are hard to produce. Furthermore, verb clusters that refer to the past will be affected as well, even if the auxiliary is in present tense, as in he has been writing a letter. It will be argued that all these verb forms referring to the past require discourse linking [Zagona, K. (2003). Tense and anaphora: Is there a tense-specific theory of coreference. In A. Barrs (Ed.), Anaphora: A reference guide (pp. 140-171). Oxford: Blackwell Publishing] and discourse linking is affected in agrammatic aphasia [Avrutin, S. (2006). Weak syntax. In K. Amunts, & Y. Grodzinsky (Eds.), Broca's region (pp. 49-62). New York: Oxford Press]. This hypothesis has been coined the PAst DIscourse LInking Hypothesis (PADILIH) [Bastiaanse, R., Bamyaci, E., Hsu, C.-J., Lee, J., Yarbay Duman, T., & Thompson, C.K. (2011). Time reference in agrammatic aphasia: A cross-linguistic study. Journal of Neurolinguistics, 24, 652-673]. The PADILIH has been tested in several languages and populations that have hardly been studied before in aphasiology: languages such as Turkish, Swahili and Indonesian were included, as well as monolingual and bilingual populations. In all these populations, the same test has been used: the Test for Assessing Reference of Time [Bastiaanse, R., Jonkers, R., & Thompson, C.K. (2008). Test for assessing reference of time (TART). Groningen: University of Groningen] to enable reliable comparisons between the languages. The results show that the PADILIH predicts the performance of agrammatic speakers very well: discourse-linked grammatical morphemes expressing time reference to the past are hard to produce for agrammatic speakers, whereas non-discourse-linked verb inflections (for present and future) are relatively spared. In languages that use aspectual adverbs (free-standing and optional time reference markers), such as Chinese and Indonesian, time reference to all time frames is impaired, since all aspectual adverbs, regardless of the time frame they refer to, require discourse linking. Remarkably, the problems are not restricted to grammatical morphemes: the production of temporal lexical adverbs is impaired as well.

Agrammatism in Jordanian-Arabic speakers

The studies of agrammatism show that not all morpho-syntactic elements are impaired to the same degree and that some of this variation may be due to language-specific differences. This study investigated the production of morpho-syntactic elements in 15 Jordanian-Arabic (JA) speaking individuals with agrammatism and 15 age-matched neurologically healthy individuals. Two experiments were conducted to examine the production of complementizer, tense, agreement and negation morphology in JA. The results indicated that the speakers of JA with agrammatism had marked dissociations in producing specific morpho-syntactic elements. The observed impairment patterns overlapped, in many respects, with those observed in other linguistic groups. The findings are discussed with respect to current theories of agrammatism, including both morpho-syntactic and computational accounts.

Time reference in agrammatic aphasia: A cross-linguistic study

It has been shown across several languages that verb inflection is difficult for agrammatic aphasic speakers. In particular, Tense inflection is vulnerable. Several theoretical accounts for this have been posed, for example, a pure syntactic one suggesting that the Tense node is unavailable due to its position in the syntactic tree (Friedmann & Grodzinsky, 1997); one suggesting that the interpretable features of the Tense node are underspecified (Burchert, Swoboda-Moll, & De Bleser, 2005; Wenzlaff & Clahsen, 2004, 2005); and a morphosemantic one, arguing that the diacritic Tense features are affected in agrammatism (Faroqi-Shah & Dickey, 2009; Lee, Milman, & Thompson, 2008). However recent findings (Bastiaanse, 2008) and a reanalysis of some oral production studies (e.g. Lee et al., 2008; Nanousi, Masterson, Druks, & Atkinson, 2006) suggest that both Tense and Aspect are impaired and, most importantly, reference to the past is selectively impaired, both through simple verb forms (such as simple past in English) and through periphrastic verb forms (such as the present perfect, 'has V-ed', in English). It will be argued that reference to the past is discourse linked and reference to the present and future is not (Zagona, 2003, in press). In-line with Avrutin's (2000) theory that suggests discourse linking is impaired in Broca's aphasia, the PAst DIscourse LInking Hypothesis (PADILIH) has been formulated. Three predictions were tested: (1) patients with agrammatic aphasia are selectively impaired in use of grammatical morphology associated with reference to the past, whereas, inflected forms which refer to the present and future are relatively spared; (2) this impairment is language-independent; and (3) this impairment will occur in both production and comprehension. Agrammatic Chinese, English and Turkish speakers were tested with the Test for Assessing Reference of Time (TART; Bastiaanse, Jonkers, & Thompson, unpublished). Results showed that both the English and Turkish agrammatic speakers performed as hypothesized, showing a selective deficit for production of inflected forms referring to the past, despite the typological difference between the languages. The Chinese agrammatic speakers were poor in reference to the past as well, but reference to the present and future also was severely impaired. For comprehension, the results were strikingly similar for the three languages: reference to the past was impaired for all. These results confirmed our hypothesis that reference to the past is discourse linked and, therefore, grammatical morphology used for reference to the past is impaired in agrammatic aphasia, whether this is done through Tense and/or Aspect markers.