Prosody and Prediction in Neural Speech Processing
Research output: Thesis › Doctoral Thesis (compilation)
The present thesis investigated how listeners use prosody to rapidly predict upcoming lexical and syntactic structures. In the first three studies, it was shown that listeners take advantage of Swedish word-level tones to pre- activate upcoming word endings. Every Swedish word has a tone on the word stem – known as a ‘word accent’ – which is either low or high, and the tone is assigned to the stem depending on which suffix follows the stem. Results indicate that listeners use the association between tones and word endings to anticipate the upcoming ending. The predictive mechanism appears to be tied to a left-lateralised event-related potential (ERP) referred to as the 'pre-activation negativity' (PrAN). In the second study, it was shown that when there are fewer possible endings following a word stem, PrAN increases in amplitude, suggesting that it reflects some type of measure of predictive certainty. In the third study, PrAN was found to be underpinned by left temporal, inferior parietal and prefrontal areas of the brain, and it is suggested that less predictive word stems lead to increased activity in prefrontal areas, reflecting the fact that a greater number of possible word stem continuations need to be suppressed, while more predictive word stems – with fewer possible continuations – increase activity in inferior parietal areas associated with rapid lexical access. Results also revealed that predictive word stems allow listeners to restore the meaning of word endings even when they have been replaced by a cough. In the fourth and last study, the PrAN paradigm was extended to sentence-level prosody, and it was found that clause-initial tones function as cues to upcoming word order structures. Sentence-level tones which were more predictive with regard to upcoming sentence structure gave rise to a PrAN which correlated with activity in areas previously known to be related to syntactic and predictive processing, left Brodmann area 44 (Broca's area) and left anterior insula.
|Research areas and keywords||
Subject classification (UKÄ) – MANDATORY
|Award date||2017 Sep 15|
|Publication status||Published - 2017|
Defence details Date: 2017-09-15 Time: 10:15 Place: B152, LUX, Helgonavägen 3, Lund External reviewer(s) Name: de Diego Balaguer, Ruth Title: professor Affiliation: Universitat de Barcelona