AI and Aphasia in the Digital Age: A Critical Review.

Aphasiology has a long and rich tradition of contributing to understanding how culture, language, and social environment contribute to brain development and function. Recent breakthroughs in AI can transform the role of aphasiology in the digital age by leveraging speech data in all languages to model how damage to specific brain regions impacts linguistic universals such as grammar. These tools, including generative AI (ChatGPT) and natural language processing (NLP) models, could also inform practitioners working with clinical populations in the assessment and treatment of aphasia using AI-based interventions such as personalized therapy and adaptive platforms. Although these possibilities have generated enthusiasm in aphasiology, a rigorous interrogation of their limitations is necessary before AI is integrated into practice. We explain the history and first principles of reciprocity between AI and aphasiology, highlighting how lesioning neural networks opened the black box of cognitive neurolinguistic processing. We then argue that when more data from aphasia across languages become digitized and available online, deep learning will reveal hitherto unreported patterns of language processing of theoretical interest for aphasiologists. We also anticipate some problems using AI, including language biases, cultural, ethical, and scientific limitations, a misrepresentation of marginalized languages, and a lack of rigorous validation of tools. However, as these challenges are met with better governance, AI could have an equitable impact.

Does Language Distance Modulate the Contribution of Bilingualism to Cognitive Reserve in Seniors? A Systematic Review.

We report a systematic review and exploratory meta-regression investigating the hypothesis that the effects of bilingualism on cognitive reserve are modulated by the distance between the pair of languages a bilingual uses. An inclusive multiple database search was performed in order to identify all relevant published research conducted in bilingual seniors. A combination of qualitative and quantitative synthesis methods were used in order to investigate our research questions. Results suggest that healthy bilingual seniors speaking more distant language pairs show improved monitoring performance on cognitive tasks. Evidence regarding a modulatory influence of language distance (LD) on the age of dementia diagnosis was inconclusive due to the small number of published studies meeting our inclusion criteria. We recommend more detailed reporting of individual differences in bilingual experience to assess the impact of LD and other variables on typical cognitive aging and the development of dementia. Linguistic differences in samples should also be considered as a constraint on bilingual advantages in future studies. Preregistration: PROSPERO CRD42021238705; OSF DOI 10.17605/OSF.IO/VPRBU.

Picture naming in bilingual and monolingual Chinese speakers: Capturing similarity and variability.

Picture-naming latency differs across languages in bilingual speakers. We compared the effects of key psycholinguistic variables on picture naming among two groups of Chinese bilingual speakers and Mandarin monolingual speakers. First, we asked bilingual and monolingual speakers to estimate the age of acquisition, familiarity, visual complexity, name agreement, and imageability of a set of object and action pictures in Mandarin and Cantonese. Next, we recruited 60 Cantonese-English speakers, 50 Mandarin-Cantonese bilingual speakers, and 30 monolingual speakers who named the object and action pictures in Cantonese and Mandarin, respectively. We observed variability in the effects of item-level characteristics among groups, suggesting an interaction between item-level and individual-level characteristics as predicted. This variability was higher in bilingual speakers who spoke similar languages (Mandarin-Cantonese) in comparison to those speaking more distant languages (Cantonese-English). Our results suggest that monolingual norms and bilingual norms capture the same amount of variability; however, grammatical class interactions with other variables are explained differentially by the bilingual and monolingual norms. We discuss the implications of our findings in terms of norming studies for timed picture naming and effects of bilingualism on language processing.

Aphasia in Alzheimer's Disease and Other Dementias (ADOD): Evidence From Chinese.

Speech and language impairments (aphasia) are typical of patients with Alzheimer's Disease and other dementias (ADOD) and in some pathologies are diagnostic e.g. Primary Progressive Aphasia (PPA). One question concerns the reliability and validity of symptomatology across typologically different languages. A review of aphasia in ADOD across languages suggests a similar pattern of word comprehension, naming and word finding difficulties but also evidence of language specific features in symptomatology e.g. processing of tone in Chinese languages. Given differences in linguistic impairments across languages, it is recommended that screening for aphasia in community and epidemiological studies use a Short ScreeningTest (SST) that can be delivered across dialects and languages in indigenous languages and also multilingual populations.

Parallel deterioration to language processing in a bilingual speaker.

The convergence hypothesis [Green, D. W. (2003). The neural basis of the lexicon and the grammar in L2 acquisition: The convergence hypothesis. In R. van Hout, A. Hulk, F. Kuiken, & R. Towell (Eds.), The interface between syntax and the lexicon in second language acquisition (pp. 197-218). Amsterdam: John Benjamins] assumes that the neural substrates of language representations are shared between the languages of a bilingual speaker. One prediction of this hypothesis is that neurodegenerative disease should produce parallel deterioration to lexical and grammatical processing in bilingual aphasia. We tested this prediction with a late bilingual Hungarian (first language, L1)-English (second language, L2) speaker J.B. who had nonfluent progressive aphasia (NFPA). J.B. had acquired L2 in adolescence but was premorbidly proficient and used English as his dominant language throughout adult life. Our investigations showed comparable deterioration to lexical and grammatical knowledge in both languages during a one-year period. Parallel deterioration to language processing in a bilingual speaker with NFPA challenges the assumption that L1 and L2 rely on different brain mechanisms as assumed in some theories of bilingual language processing [Ullman, M. T. (2001). The neural basis of lexicon and grammar in first and second language: The declarative/procedural model. Bilingualism: Language and Cognition, 4(1), 105-122].

Acquired dyslexia in a transparent orthography: an analysis of acquired disorders of reading in the Slovak language.

The first reports of phonological, surface and deep dyslexia come from orthographies containing quasi-regular mappings between orthography and phonology including English and French. Slovakian is a language with a relatively transparent orthography and hence a mostly regular script. The aim of this study was to investigate impaired oral reading in Slovakian. A novel diagnostic procedure was devised to determine whether disorders of Slovakian reading resemble characteristics in other languages. Slovakian speaking aphasics showed symptoms similar to phonological dyslexia and deep dyslexia in English and French, but there was no evidence of surface dyslexia. The findings are discussed in terms of the orthographic depth hypothesis.

Use of the BAT with a Cantonese-Putonghua speaker with aphasia.

The aim of this article is to illustrate the use of the Bilingual Aphasia Test (BAT) with a Cantonese-Putonghua speaker. We describe G, who is a relatively young Chinese bilingual speaker with aphasia. G's communication abilities in his L2, Putonghua, were impaired following brain damage. This impairment caused specific difficulties in communication with his wife, a native Putonghua speaker, and was thus a priority for investigation. Given a paucity of standardised tests of aphasia in Putonghua, our goal was to use the BAT to assess G's impairments in his L2. Results showed that G's performance on the BAT subtests measuring word and sentence comprehension and production was impaired. His pattern of performance on the BAT allowed us to generate hypotheses about his higher-level language impairments in Putonghua, which were subsequently found to be impaired. We argue that the BAT is able to capture the primary language impairments in Chinese-speaking patients with aphasia when Putonghua is the second language. We also suggest some modifications to the BAT for testing Chinese-speaking patients with bilingual aphasia.

Independent effects of orthographic and phonological facilitation on spoken word production in Mandarin.

A picture-word interference paradigm with visually presented distractors was used to investigate the independent effects of orthographic and phonological facilitation on Mandarin monosyllabic word production. Both the stimulus-onset asynchrony (SOA) and the picture-word relationship along different lexical dimensions were varied. We observed a pure orthographic facilitation effect and a pure phonological facilitation effect, and found that the patterns of orthographic and phonological facilitation were different. Of most interest, the additive effects of orthographic and phonological facilitation at -150-ms and 0-ms SOAs indicated that the orthographic effect was largely independent of the phonological effect on spoken picture naming. We argue that the present findings are useful for constraining theoretical models of language production and contend that theoretical models of word production need to consider independent effects of orthography and phonology on picture naming, at least in Chinese.

Age-of-acquisition effects on oral reading in Chinese.

The age of acquisition (AoA) of a word has an effect on oral reading. The mapping hypothesis (Zevin & Seidenberg, 2002, 2004) assumes that AoA effects on oral reading are a consequence of arbitrary mappings between input and output in the lexical network. The Chinese writing system is characterized by mappings between orthography and phonology that are mostly arbitrary, although some regular and consistent characters are predictable. Here, we report reduced effects of written AoA on the reading of predictable characters. We argue that written AoA has an effect on oral reading in Chinese because the family resemblance between lexical items is limited, as compared with written words in alphabetic scripts.

Effects of age of acquisition on brain activation during Chinese character recognition.

The age of acquisition of a word (AoA) has a specific effect on brain activation during word identification in English and German. However, the neural locus of AoA effects differs across studies. According to Hernandez and Fiebach [Hernandez, A., & Fiebach, C. (2006). The brain bases of reading late-learned words: Evidence from functional MRI. Visual Cognition, 13(8), 1027-1043], the effects of AoA on brain activation depend on the predictability of the connections between input (orthography) and output (phonology) in a lexical network. We tested this hypothesis by examining AoA effects in a non-alphabetic script with relatively arbitrary mappings between orthography and phonology--Chinese. Our results showed that the effects of AoA in Chinese speakers are located in brain regions that are spatially distinctive including the bilateral middle temporal gyrus and the left inferior parietal cortex. An additional finding was that word frequency had an independent effect on brain activation in the right middle occipital gyrus only. We conclude that spatially distinctive effects of AoA on neural activity depend on the predictability of the mappings between orthography and phonology and reflect a division of labour towards greater lexical-semantic retrieval in non-alphabetic scripts.

Predictors of timed picture naming in Chinese.

We report normative data collected from Mainland Chinese speakers for 232 objects taken from Snodgrass and Vanderwart (1980). These data include adult ratings of concept familiarity, age of acquisition (AoA), printed-word frequency, and word length (in syllables), as well as measures of rated visual complexity, image agreement, and name agreement. We then examined timed picture naming of these objects with native Chinese speakers in Beijing in two experiments using line drawings and colored pictures. In both experiments, the variables name agreement, rated concept familiarity, and AoA made significant independent contributions to naming latency in multiple regression analyses. We observed a correlation of r = .85 between naming latency with line drawings and colored pictures and a reduced effect of image agreement on naming when colored pictures were presented. We discuss the implications of our findings for the study of lexical processing in Chinese. Normative data for 232 Chinese nouns may be downloaded from www.psychonomic.org/archive.

Deep dysgraphia in Turkish.

Deep dysgraphic patients make semantic errors when writing to dictation and they cannot write nonwords. Extant reports of deep dysgraphia come from languages with relatively opaque orthographies. Turkish is a transparent orthography because the bidirectional mappings between phonology and orthography are completely predictable. We report BRB, a biscriptal Turkish-English speaker who has acquired dysgraphia characterised by semantic errors as well as effects of grammatical class and imageability on writing in Turkish. Nonword spelling is abolished. A similar pattern of errors is observed in English. BRB is the first report of acquired dysgraphia in a truly transparent writing system. We argue that deep dysgraphia results from damage to the mappings that are common to both languages between word meanings and orthographic representations.

Acquired dyslexia and dysgraphia in Chinese.

Understanding how the mappings between orthography and phonology in alphabetic languages are learned, represented and processed has been enhanced by the cognitive neuropsychological investigation of patients with acquired reading and writing disorders. During the past decade, this methodology has been extended to understanding reading and writing in Chinese leading to new insights about language processing, dyslexia and dysgraphia. The aim of this paper is to review reports of patients who have acquired dyslexia and acquired dysgraphia in Chinese and describe the functional architecture of the reading and writing system. Our conclusion is that the unique features of Chinese script will determine the symptoms of acquired dyslexia and dysgraphia in Chinese.