Time reference in agrammatic aphasia: A cross-linguistic study.

Area of Science:

• Linguistics
• Neurolinguistics
• Psycholinguistics

Background:

• Agrammatic aphasia is characterized by difficulties with verb inflection, particularly tense.
• Existing theories propose syntactic, feature-based, or morphosemantic deficits.
• Recent research suggests a broader impairment of both Tense and Aspect, with a specific deficit in past reference.

Purpose of the Study:

• To investigate the selective impairment of past tense and aspect morphology in agrammatic aphasia.
• To test the PAst DIscourse LInking Hypothesis (PADILIH), positing that past reference is discourse-linked and thus impaired.
• To examine if this impairment is language-independent and affects both production and comprehension.

Main Methods:

• Tested agrammatic speakers of Chinese, English, and Turkish using the Test for Assessing Reference of Time (TART).
• Assessed production and comprehension of verb forms referring to past, present, and future events.
• Analyzed performance in relation to the typological differences of the languages studied.

Main Results:

• English and Turkish agrammatic speakers showed a selective deficit in producing past-referring verb forms, supporting the hypothesis.
• Chinese agrammatic speakers exhibited broader impairments, affecting past, present, and future reference.
• Comprehension results were consistent across all three languages, with impaired reference to the past for all participants.

Conclusions:

• The findings support the PADILIH, indicating that reference to the past is selectively impaired in agrammatic aphasia.
• This impairment is linked to the discourse-dependent nature of past reference and affects grammatical morphology for tense and/or aspect.
• The study highlights language-independent aspects of agrammatic aphasia, particularly concerning past temporal reference.