Helsingin yliopisto, Helsinki 2006
Tarkkaavaisuuden vaikutus puheen merkityssisällön käsittelyyn: Aivojen herätevastetutkimus
Pro gradu, huhtikuu 2006.
Semantic processing can be studied with semantic priming. Target words that are preceded by semantically related prime words are recognized faster and more accurately than targets preceded by unrelated prime words. Semantic priming also affects the magnitude of the N400 event-related potential. The response is smaller to a target word when it is preceded by a related than an unrelated prime word. The effect is called the N400 effect. It is not yet clear, however, how attention modulates semantic priming and the N400 effect.
This study investigated how the direction of attention affects the semantic processing of speech. The N400 effect was studied in experimental conditions in which the subjects' attention was directed 1) away from the speech stimuli, 2) to phonological features of the speech stimuli, and 3) to semantic features of the speech stimuli. The first aim of the study was to investigate whether the N400 effect for spoken words is dependent on attention to the auditory information. The second aim was to study the differences in the N400 effect when attention is directed to the semantic or other features of speech stimuli.
The results showed an N400 effect even when attention was directed away from the speech stimuli. The N400 effect was, however, stronger in conditions during which the speech stimuli were attended. The magnitude of the behavioral semantic priming and the N400 effect did not differ between the conditions during which attention was directed to the semantic or phonological features of the words. The findings indicate that the semantic processing of spoken words is not dependent on attention to auditory information. Furthermore, the results suggest that whether or not semantic processing is relevant for the task performance does not affect the semantic processing of attended spoken words.
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© Helsingin yliopisto 2006
Viimeksi päivitetty 02.05.2006