Time reference in French-speaking people with fluent and non-fluent aphasia (part I): tense dissociations, task effects and cognitive predictors

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Background People with fluent and non-fluent aphasia frequently have time reference deficits, which could be more pronounced for the past than for the present and future tenses. However, this performance pattern (past < non-past) is not consensual and might depend on the type of task used. Furthermore, the influence of cognitive processes on time reference deficits remains little explored, as does the origin of these difficulties (e.g. pre-phonological, morpho-phonological).Aims The primary aims of the study were (1) to identify time reference deficits and (2) dissociations between tenses in French speakers with fluent and non-fluent aphasia and (3) to specify the effect of tasks on performance and tense dissociations. Secondly, our study also aimed to determine whether time reference deficits were (4) influenced by cognitive functions and (5) explained by pre-phonological or morpho-phonological deficits.Methods & procedures Twenty-one French-speaking participants with fluent and non-fluent aphasia and 21 matched control subjects performed three tasks assessing time reference (verb inflection production, verb inflection selection, and adverb selection) and five neuropsychological tests (verbal and non-verbal working memory, inhibition, flexibility, and temporality). Quantitative and qualitative analyses were conducted.Outcomes & results Participants with fluent and non-fluent aphasia had worse performances than controls on the three time-reference tasks. The performance of the participants with fluent and non-fluent aphasia was quantitatively similar but qualitatively different on the verb inflection production task (i.e. different error types). A main task effect was also found: the verb inflection production task was the only one to show worse performances in the past than in the present and future. Regarding cognitive predictors, verbal working memory and temporality were linked to the three tasks assessing time reference. In contrast, non-verbal working memory was associated only with the two selection tasks, possibly related to the mental timeline. Finally, task analysis suggested a pre-phonological (encoding of diacritic features deficit) rather than a morpho-phonological origin.Conclusions Our study is the first to replicate time reference deficit in French speakers with aphasia. It suggests that the type of task might influence the performance profiles observed and help to shed light on the origin of the difficulties. Cognitive functions that have rarely been investigated before may also influence performance. These results have important clinical implications by questioning the tasks used to assess time reference. They also underline the importance of identifying the origin of difficulties in proposing targeted treatment.