Grammar, Prosody, Discourse and the Brain. ERP-studies of Language Processing

The project aims at studying the course of interaction between word order, prosody, and discourse in the brain when sentences are processed. Investigations aiming at arriving at a better understanding of this interaction are carried out using EEG (Electroencephalography) and the ERP (Event-Related Potentials) method which measures neurophysiological changes during language comprehension.

In spoken Swedish, embedded clauses occur with main clause word order after verbs of saying and thinking but not after verbs like HOPE. In order for embedded clauses to sound natural with main clause word order, they must also be introduced by a High tone. We used Event Related Potentials (ERP) to see how brain activity is influenced during sentence processing. We could see that verbs like HOPE decreased listeners' expectation for main clause word order. When participants heard main clause word-order after such verbs, we could observe in the ERP-signal P600 how the unexpected clause structure was reanalysed in the brain. Initial High tones were seen to increase the expectancy for main clause word order. Embedded clauses with main clause word order that lacked a High tone also required reanalysis reflected in a P600. In a later study, we saw that the opposite effect does not hold: reanalysis of embedded clauses with subordinate clause word order was not affected by initial high tones. The High tone seems to increase the expectancy for a main clause without decreasing the expectancy for subordinate clause word order. There are other phenomena in Swedish where word order and prosody interact in language processing. A study of Object Shift, which allows pronouns, but not full NPs to occur both clause finally and before a sentence adverb showed that movement of a full NP before the sentence adverb led to both a word order reanalysis effect (P600) and an early semantic effect.