False but phonologically plausible linguistic priors induce cross-linguistic auditory illusions and attenuate electrophysiological markers of surprise.

According to predictive coding theory, perception arises from the interplay between top-down expectations and bottom-up sensory input. In the auditory domain, this interplay can lead to illusory experiences-for instance, when phonetic similarities between languages cause listeners to mishear foreign lyrics as familiar words in their native language. This study investigated how linguistic priors influence auditory perception during song listening. Participants read sentences in English or Italian before hearing English song excerpts, then rated how well the lyrics matched the text. Crucially, some of the Italian sentences were phonologically similar to the English lyrics, resulting in a cross-linguistic auditory illusion ("Illusory Trials") in which listeners reported the content of the lyrics matched that of the Italian text. EEG analysis showed that two neural markers of surprise-P200 amplitude and gamma-band activity-were heightened while listening to songs that were not perceived to match the preceding text, reflecting the violation of expectations. In contrast, these markers were attenuated in illusory trials, suggesting reduced prediction error despite the lack of semantic match. Time-frequency analysis revealed an early gamma response followed by beta-band dominance in the illusory condition, consistent with initial sensory mismatch followed by top-down assimilation. Together, these findings show that phonologically plausible but false linguistic priors can induce auditory illusions and modulate predictive processing during song perception.