Dissociation in cross-feature integration between behavioral and pupil dilation responses in auditory deviant detection

The detection of deviant events in complex soundscapes requires tracking fluctuations across multiple acoustic features such as pitch, timbre, and loudness. While both behavioral measures and pupil dilation responses (PDR) are sensitive to individual feature changes, it remains unclear how these cues are integrated in complex acoustic scenes. We examined cross-feature interactions underlying auditory deviance using a deviant-detection task and PDR recordings as participants listened to dynamic soundscapes with deviant events. Using the Dynamic Regularity Extraction (D-REX) model, we quantified feature-specific and integrated surprisal to relate stimulus structure to observed responses. Constrained regression analyses showed that behavioral responses exhibited clear cross-feature integration, whereas PDRs were better explained by feature-specific surprisal with limited evidence of cross-feature interactions. These findings highlight a dissociation between physiological and behavioral responses and provide a framework for comparing how different response modalities relate to the acoustic structure of auditory scenes.