Browsing by Subject "semanttinen prosessointi"

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  • Seppälä, Ina (Helsingin yliopisto, 2019)
    Aims. Most languages in the world use pitch in defining the meaning of words. Pitch is therefore a relevant field of study within semantics. The aim of this study is to examine the effects of pitch on the semantic processing of the Swedish language, and to compare these to the effects of pronunciation. In Swedish, the syllable which, based on its pitch, separates the word semantically from other words is called the lexical pitch accent tone. The Swedish language enables a unique study composition where a dialect with pitch accents (Standard Swedish) can be compared to a dialect with no pitch accents (Finland’s Swedish) within one language. Methods. There were eight subjects in both the Standard Swedish and Finland’s Swedish groups of the study. During the exam, the target words used in the stimulus sentences were minimal pairs: pairs of words which semantically differ from each other based only on either the pronunciation or the pitch accent of a single syllable. On the behavioural level, participants were instructed to use a button to express, whether they thought they heard the sentence was semantically sensible or not. The neural responses were measured with electroencephalography or EEG. The target of examination was in particular the event-related potential N400, the strength of which has been discovered to correlate positively with the magnitude of the challenges related to semantic processing. Results. Pronunciation had a significant effect in both participant groups: the words of the minimal pairs which, based on their pronunciation, did not fit the sentence context, were recognized significantly less often and lead to stronger N400 potentials than the words which did fit. The appropriateness of pitch had no effect on the N400 potential in either participant groups, but the speakers of Standard Swedish considered words with either a wrong or an inappropriate pitch accent as fitting the context slightly less often than the speakers of Finland’s Swedish. Conclusion. Based on the results of the study, pitch accent does not have as significant of an effect on semantic processing as pronunciation and context in either Standard Swedish or Finland’s Swedish. Based on the behavioural results, however, pitch accent did influence the processing of words of those whose mother tongue was Standard Swedish but not of those whose was Finland’s Swedish. It is therefore also possible that the relatively small effects of pitch accent on the N400 potential could not be detected because of the small sample size of the study.
  • Kurkinen, Karoliina (Helsingin yliopisto, 2019)
    Semantics is a study of meaning in language and basis for language comprehension. How these phenomena are processed in the brain is still unclear especially in naturalistic context. In this study, naturalistic language comprehension, and how semantic processing in a narrative context is reflected in brain activity were investigated. Subjects were measured with functional magnetic resonance imaging (fMRI) while listening to a narrative. The semantic content of the narrative was modelled computationally with word2vec and compared to voxel-wise blood-oxygen-level dependent (BOLD) brain signal time courses using ridge regression. This approach provides a novel way to extract more detailed information from the brain data based on semantic content of the stimulus. Inter-subject correlation (ISC) of voxel-wise BOLD signals alone showed both hemispheres taking part in language comprehension. Areas involved in this task overlapped with networks of mentalisation, memory and attention suggesting comprehension requiring other modalities of cognition for its function. Ridge regression suggested cerebellum, superior, middle and medial frontal, inferior and medial parietal and visual cortices bilaterally and temporal cortex on right hemisphere having a role in semantic processing of the narrative. As similar results have been found in previous research on semantics, word2vec appears to model semantics sufficiently and is an applicable tool in brain research. This study suggests contextual language recruiting brain areas in both hemispheres and semantic processing showing as distributed activity on the cortex. This activity is likely dependent on the content of language, but further studies are required to distinguish how strongly brain activity is affected by different semantic contents.
  • Åkerla, Anniina (Helsingin yliopisto, 2021)
    Objective. The effects of attention on language processing have been studied extensively, but there is still no clear understanding of to which extent language processing requires attention and to which extent it is automatic. The aim of this study was to examine how selective attention affects semantic processing of sentences in a situation where linguistic information is presented both visually and auditorily simultaneously. Methods. 17 native speakers of Finnish took part in the study. In the experiment, a written and a spoken sentence were presented simultaneously and attention was directed either to the visual modality or to the auditory modality depending on the experimental condition. The last word of the sentence either fit or did not fit the context of the sentence, and the task was to judge whether the sentence was rational or bizarre. Electroencephalography (EEG) was used to measure brain activity. The N400 component, which previous research has found to be linked with semantic processing, was analysed. Results. The logic of attended sentences had a significant effect on the amplitude of the N400 component: illogical sentences elicited a larger N400 than logical sentences. The logic of unattended sentences, on the other hand, had no significant effect on the amplitude of the N400 component. Conclusions. The results suggest that the meaning of unattended sentences was not automatically processed in the same way as the meaning of attended sentences. This suggests that semantic processing of sentences is not a completely automatic process that is independent of attention.