Neurolinguistic Studies on the Linguistic Expression of Time Reference in Thai

Abstract

The concept of time is crucial in everyday communication. Temporal expressions help us to understand when things happen, relative to when we are speaking. For instance, the sentence Last night, Jimmy talked to his grandmother shows that the event took place in the past. If Last night was to be replaced by Tomorrow, the sentence becomes ungrammatical, because the new phrase does not match the time frame specified by the verb talk. Time reference has been shown to be affected in individuals with acquired language impairment, such as agrammatic aphasia (e.g., Bastiaanse et al., 2011;Bastiaanse, 2013). Critically, there are many different ways to refer to time; for instance, by morphological markers such as the -ed in English and other Indo-European languages, by the use of tone such as in Akan (Tsiwah et al., 2020), and by aspectual markers (the use of free-standing morphemes to indicate different time frames) such as in Thai, the focus of the current dissertation. INTRODUCTIONAphasia, in Greek 'ἄφατος (áphatos)' from 'ἀ-(a-, not)' and 'φάσις (phásis, speech)' meaning 'no speech', is an acquired language disorder that affects linguistic abilities: the ability to produce and to comprehend (also to read and to write). It is usually caused by left-lateralized brain damage commonly from strokes, brain tumors, head injuries or dementia. Language severity varies individually: to exemplify, for some individuals, it may affect the ability to retrieve words, while for others, it may affect the ability to construct grammatical sentences, or to understand certain types of sentence (e.g., passive sentences and object clefts). Whether the production or comprehension modalities are affected depends on the size and the lesion site of the brain damage (Grodzinsky, 1990).Aphasia is broadly distinguished based on the characteristics of verbal expressions into non-fluent and fluent types (e.g., Davis, 2007;Goodglass & Kaplan, 1972). The focus of this dissertation is on non-fluent aphasia; specifically, agrammatic aphasia. Agrammatic speech is traditionally characterized by non-fluent speech output, with relatively intact comprehension of single words. Menn and Obler (1990) noted that, cross-linguistically, speech rate and utterance length are means of measurement used to define agrammatism.Compared to non-brain damaged (NBD) speakers, individuals with agrammatic aphasia produce slower speech with more simplified grammatical structures. Their connected speech is reported to consist mainly of content words (i.e., nouns, verbs, adjectives), while function words and grammatical morphemes are often omitted and substituted (e.g., Goodglass & Kaplan, 1972). 'Sunee goes to the beach today.' 2. Sunee kub Suma pai talay wannee Sunee and Suma go beach today 'Sunee and Suma go to the beach today.' 3. Sunee kub Suma pai talay peekorn Sunee and Suma go beach year-last 'Sunee and Suma went to the beach last year.' 4. Sunee koei dern pai talay peekorn Sunee PERF walk go beach year-last 'Sunee used to go to the beach (by walking) last year.'To exempli...