Specifically, cortical tracking of phrase structure was stronger for regular sentences than for control stimuli that were matched in terms of either lexical semantics (word lists) or both prosody and syntactic structure ( jabberwocky sentences), suggesting that this neural response is driven by the compositional meaning of sentence structures. (2020) showed that the neural signal aligns more strongly with periodically occurring linguistic units, such as syntactic phrases, when these contain meaningful information and are therefore relevant for linguistic processing. What it is still elusive, however, is which aspects of content determine cortical speech tracking. These studies indicate that the inferred content of a signal affects the extent to which the brain tracks that signal (see also Keitel et al., 2018 Martin, 2020 ten Oever & Martin, 2021). Our findings suggest that cortical tracking of structure in sentences indexes the internal generation of this structure, a process that is modulated by the properties of its input, but not by the compositional interpretation of its output. While there were no effects of compositional meaning on the degree of phrase-structure tracking, analyses of event-related potentials elicited by sentence-final words did reveal meaning-induced differences between conditions. Overall, these mutual information analyses showed stronger tracking of phrases in regular sentences than in stimuli whose lexical-syntactic content is reduced, but no consistent differences in tracking between sentences and stimuli that contain a combination of syntactic structure and lexical content. Tracking was quantified through mutual information between the EEG data and either the speech envelopes or abstract annotations of syntax, all of which were filtered in the frequency band corresponding to the presentation rate of phrases (1.1–2.1 Hz). To this end, we recorded electroencephalography (EEG) of 38 native speakers who listened to naturally spoken Dutch stimuli in different conditions, which parametrically modulated the degree to which syntactic structure and lexical semantics determine sentence meaning.
We investigated whether cortical tracking of phrase structures is modulated by the extent to which these structures compositionally determine meaning.
Recent research has established that cortical activity “tracks” the presentation rate of syntactic phrases in continuous speech, even though phrases are abstract units that do not have direct correlates in the acoustic signal.
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