Distinct Influences of Timing Predictions on Content Processing in Music and Speech: An EEG and Behavioural Investigation

Prediction is a fundamental cognitive process that allows us to anticipate the content (“what”) and timing (“when”) of upcoming events. However, it is unclear how these predictions are integrated within the brain, and whether their interaction occurs similarly across domains such as music and speech. The current EEG study employed independent manipulations of content and timing within melodies and sentences to investigate how the predictability of timing influences content processing on a behavioural (i.e., completion ratings) and neural (i.e., evoked responses) level. Musician (n=24) and non-musician (n=24) participants were recruited to assess the influence of musical expertise. Results highlighted distinct influences of timing predictability manipulations on music and speech content processing, as well as different patterns of results for musicians and non-musicians, in both brain and behaviour. For melodies, the manipulation of timing impacted completion judgements and neural responses to the last note across all participants, irrespectively of content predictability. For sentences, the effect of timing was only observed in the completion ratings of the musicians when content was unpredictable. Musicians also displayed enhanced sensitivity to melodies, characterised by larger differences in behavioural and neural responses between predictable and unpredictable content. In speech, non-musicians showed a larger difference in completion ratings between predictable and unpredictable content, while musicians displayed neural patterns indicative of enhanced processing for predictable content. Overall, these results highlight how the interplay between content and timing predictions is shaped by domain and musical training. The current findings have implications for understanding the neural processes that support prediction across different contexts.