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Imageability is a psycholinguistic variable that indicates how well a word gives rise to a mental image or sensory experience. Imageability ratings are used extensively in psycholinguistic, neuropsychological, and aphasiological studies. However, little formal knowledge exists about whether and how these ratings are associated between and within languages. Fifteen imageability databases were cross-correlated using nonparametric statistics. Some of these corresponded to unpublished data collected within a European research network-the Collaboration of Aphasia Trialists (COST IS1208). All but four of the correlations were significant. The average strength of the correlations (rho = .68) and the variance explained (R (2) = 46%) were moderate. This implies that factors other than imageability may explain 54% of the results. Imageability ratings often correlate across languages. Different possibly interacting factors may explain the moderate strength and variance explained in the correlations: (1) linguistic and cultural factors; (2) intrinsic differences between the databases; (3) range effects; (4) small numbers of words in each database, equivalent words, and participants; and (5) mean age of the participants. The results suggest that imageability ratings may be used cross-linguistically. However, further understanding of the factors explaining the variance in the correlations will be needed before research and practical recommendations can be made.
Time reference, which has been found to be selectively impaired in agrammatic aphasia, is often interwoven with grammatical aspect. A recent study on Russian aphasia found that time reference and aspect interact: Past reference was less impaired when tested within a perfective aspect context (compared to when tested within an imperfective aspect context), and reference to the non-past was less impaired when tested within an imperfective aspect context (compared to when tested within a perfective aspect context). To explain this pattern, the authors argued that there are prototypical associations between time frames and aspectual values. The present study explores the relationship between time reference and aspect focusing on Greek aphasia and healthy ageing and using a sentence completion task that crosses time reference and aspect. The findings do not support prototypical matches between different time frames and aspectual values. Building on relevant studies, we propose that patterns of performance of healthy or language-impaired speakers on constrained tasks tapping different combinations of time frames with aspectual values should reflect the relative frequency of these combinations in a given language. The analysis of the results at the individual level revealed a double dissociation, which indicates that a given time frame-aspectual value combination may be relatively easy to process for some persons with aphasia but demanding for some others.
Comparative research on aphasia and aphasia rehabilitation is challenged by the lack of comparable assessment tools across different languages. In English, a large array of tools is available, while in most other languages, the selection is more limited. Importantly, assessment tools are often simple translations and do not take into consideration specific linguistic and psycholinguistic parameters of the target languages. As a first step in meeting the needs for comparable assessment tools, the Comprehensive Aphasia Test is currently being adapted into a number of languages spoken in Europe. In this article, some key challenges encountered in the adaptation process and the solutions to ensure that the resulting assessment tools are linguistically and culturally equivalent, are proposed. Specifically, we focus on challenges and solutions related to the use of imageability, frequency, word length, spelling-to-sound regularity and sentence length and complexity as underlying properties in the selection of the testing material.
Background: In probable Alzheimer’s disease (AD), different memory systems, executive functioning, visuospatial recognition, and language are impaired. Regarding the latter, only a few studies have investigated morphosyntactic production thus far.
Aims: This study, which is a follow-up on Fyndanis, V., Manouilidou, C., Koufou, E., Karampekios, S., and Tsapakis, E. M. (2013). Agrammatic patterns in Alzheimer's disease: Evidence from tense, agreement, and aspect. Aphasiology, 27, 178–200. doi:10.1080/02687038.2012.705814, investigates whether verb-related morphosyntactic production is (selectively) impaired in AD focusing on two highly inflected languages, Greek and Italian. The morphosyntactic phenomena explored are subject–verb Agreement, Tense/Time Reference, and Mood. Focusing on these phenomena allows us to investigate if recent hypotheses, originally developed in aphasia research, can also capture results related to AD. We tested the hypotheses discussed in Fyndanis, V., Manouilidou, C., Koufou, E., Karampekios, S., and Tsapakis, E. M. (2013). Agrammatic patterns in Alzheimer's disease: Evidence from tense, agreement, and aspect. Aphasiology, 27, 178–200. doi:10.1080/02687038.2012.705814, that is, the Interpretable Features’ Impairment Hypothesis (IFIH) (e.g., Fyndanis, V., Varlokosta, S., & Tsapkini, K. 2012. Agrammatic production: Interpretable features and selective impairment in verb inflection. Lingua, 122, 1134–1147. doi:10.1016/j.lingua.2012.05.004) and 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. Journal of Neurolinguistics, 24, 652–673. doi:10.1016/j.jneuroling.2011.07.001).
Methods & Procedures: Two sentence completion tasks testing the production of subject-verb Agreement, Tense/Time Reference, and Mood were administered to 16 Greek-speaking and 10 Italian-speaking individuals with mild-to-moderate AD, as well as to 16 Greek-speaking and 11 Italian-speaking neurologically intact individuals who were matched with the participants with AD on age and education. Mixed-effects models were fitted to the data.
Outcomes & Results: At the group level, both the Greek and Italian participants with AD performed worse than the controls. Both AD groups revealed selective patterns of morphosyntactic production (Greek: Agreement/Mood > Time Reference; Italian: Agreement > Time Reference > Mood). Past Reference and Future Reference did not dissociate in either of the two AD groups. Nevertheless, in all four participants with AD who showed dissociations, Past Reference was more impaired than Future Reference.
Conclusions: The results indicate that the production of verb-related morphosyntactic categories can be impaired in mild-to-moderate AD. The different patterns observed in the two languages are partly attributable to the different way these languages encode Mood. The group results (of both the Greek-and Italian-speaking participants with AD) do not lend support to the PADILIH, whereas only the results of the Italian AD group are fully consistent with the IFIH. However, the individual data are consistent with the PADILIH, and the IFIH is informed by the present data and modified accordingly so that it can capture cross-linguistic patterns of morphosyntactic impairment.
Method: A sentence completion task testing production of subject-verb agreement, tense/time reference, and aspect in local and nonlocal conditions and two verbal WM tasks were administered to 8 Greek-speaking persons with agrammatic aphasia (PWA) and 103 healthy participants. Results: The 3 morphosyntactic categories dissociated in both groups (agreement > tense > aspect). A significant interaction emerged in both groups between the 3 morphosyntactic categories and WM. There was no main effect of locality in either of the 2 groups. At the individual level, all 8 PWA exhibited dissociations between agreement, tense, and aspect, and effects of locality were contradictory.
Recent studies by Bastiaanse and colleagues found that time reference is selectively impaired in people with nonfluent agrammatic aphasia, with reference to the past being more difficult to process than reference to the present or to the future. To account for this dissociation, they formulated the PAst DIscourse LInking Hypothesis (PADILIH), which posits that past reference is more demanding than present/future reference because it involves discourse linking. There is some evidence that this hypothesis can be applied to people with fluent aphasia as well. However, the existing evidence for the PADILIH is contradictory, and most of it has been provided by employing a test that predominantly taps retrieval processes, leaving largely unexplored the underlying ability to encode time reference-related prephonological features. Within a cross-linguistic approach, this study tests the PADILIH by means of a sentence completion task that 'equally' taps encoding and retrieval abilities. This study also investigates if the PADILIH’s scope can be extended to fluent aphasia. Greek- and Italian-speaking individuals with aphasia participated in the study. The Greek group consisted of both individuals with nonfluent agrammatic aphasia and individuals with fluent aphasia, who also presented signs of agrammatism. The Italian group consisted of individuals with agrammatic nonfluent aphasia only. The two Greek subgroups performed similarly. Neither language group of participants with aphasia exhibited a pattern of performance consistent with the predictions of the PADILIH. However, a double dissociation observed within the Greek group suggests a hypothesis that may reconcile the present results with the PADILIH.