Effects of modality, administration and stimulus on picture descriptions in adults

Background: Picture descriptions are a commonly used tool in the diagnostic process of aphasias, including vascular as well as neurodegenerative disorders affecting language production. However, this widespread clinical use contrasts with the relative scarcity of empirical data exploring the role of different variables which can influence the results, particularly in cases in which the original procedure has been modified. This thesis addresses three areas in which such modifications need a much stronger empirical basis. Firstly, (1) the traditional default approach has been an oral picture description. However, a substantial group of patients, particularly those with neurodegenerative disorders affecting motor functions, cannot produce oral language. In such cases, an assessment of written language could offer a valuable alternative. Such a procedure would require, however, a systematic comparison between linguistic material collected in the spoken and written description. Another little-explored field is (2) the difference between traditional in-person versus remote testing. While remote testing has been possible for several decades, in the recent pandemic it became often the only available option. Research has been conducted on remote testing, but only for video-call testing settings. Automated online testing has not yet been assessed. Finally, in (3) the increasingly globalised world diagnostic material is used in different countries with diverse cultures and routines. Linguistic stimuli are translated (although not always adapted) but this is rarely the case for picture material. Therefore, the picture stimulus itself might be victim to misinterpretation if the patient is not culturally familiar with the depicted scene. However, the influence of the cultural familiarity of the picture material has not been addressed in research yet. AIM: The present thesis addressed the current gaps in research focussing on these three aspects: (1) the influence of production modality (spoken vs. written [handwritten vs. typed], (2) testing modality (in-person vs. video-call vs. automated online) and (3) picture stimulus (North American [traditional] vs. Indian) on the picture description task using a mix of literature reviews and empirical data. Method: A total of 100 healthy participants were tested (1) in two different production modalities, (2) in three different testing modalities and (3) with two different picture stimuli. The picture description was complemented by seven additional tests assessing naming, grammar, possible underlying dyslexia, concept formation, visual-spatial abilities and intelligence. The collected data were interpreted using an extended list of linguistic symptoms, statistical comparisons and linear models. Results: (1) Spoken picture descriptions were significantly longer, containing more words and sentences, whereas written descriptions were more concise, syntactically complex and lexically diverse. Unlike aphasic patients, healthy participants very rarely produced phonetic, syntactic or semantic errors. Isolated language functions and other cognitive abilities did not have a major influence on the picture description task. (2) The testing modality influenced the linguistic performance of the participants. Differences were more pronounced in the written task and could be traced back to differences between handwriting and typing. (3) The non- familiar scene produced a higher lexical diversity, but also a less complex syntax. Discussion: For clinical purposes but also research, (1) written picture descriptions should be considered for diagnosis as it is a more cost-effective method that can lead to conclusions of comparable relevance. Performance on tests of isolated linguistic domains and cognitive abilities do not have a significant influence on picture description tasks in healthy individuals. Therefore, picture descriptions cannot be used as a substitute for the assessment of isolated linguistic functions and cognitive abilities, or vice versa. (2) Equally, picture descriptions cannot be easily replaced by other tests, as they contain other types of information of considerable relevance. Remote testing is a useful tool that can be used in the diagnostic process, however, there are caveats that need to be considered before testing and interpretation. (3) A culturally non-familiar picture stimulus can lead to misinterpretation of the presented scene which might lead to false diagnoses. Therefore, the cultural origin of the stimulus needs to be taken into account when interpreting the results. Conclusion: Overall, all three examined modifications can be clinically feasible and useful. However, they cannot and should not be understood as identical to traditional methods, as they might have different limitations, but also offer different opportunities.