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Pupil responses to pitch deviants reflect predictability of melodic sequences
Roberta Bianco1, Lena Esther Ptasczynski2, Diana Omigie2
1Ear Institute, University College London, 332 Grays Inn Road, WC1X 8EE London, United Kingdom.
Brain and Cognition
|December 22, 2019
Summary
The pupil dilation response (PDR) to unexpected music notes is influenced by contextual uncertainty. Higher arousal, indicated by PDR, occurs in less predictable musical contexts, showing sensitivity to long-term environmental patterns.
Area of Science:
- Cognitive Neuroscience
- Auditory Perception
- Computational Auditory Neuroscience
Background:
- Humans possess an automatic system for detecting unexpected events, signaling prediction errors and guiding behavioral adjustments.
- The pupil dilation response (PDR) is linked to subcortical arousal and prediction resetting mechanisms following event violations.
- The influence of contextual factors on the magnitude of the PDR to deviant stimuli remains incompletely understood.
Purpose of the Study:
- To investigate how contextual uncertainty affects the pupil dilation response (PDR) to auditory deviance in music.
- To explore the relationship between musical unexpectedness, contextual entropy, and arousal as measured by PDR.
- To examine the role of music expertise in modulating the PDR to musical prediction errors.
Main Methods:
- Utilized ecologically valid musical stimuli characterized computationally using entropy as a measure of contextual uncertainty.
- Measured pupil dilation response (PDR) in participants listening to musical stimuli containing pitch deviants.
- Analyzed the correlation between PDR magnitude, contextual entropy, and note unexpectedness, while considering music expertise.
Main Results:
- The PDR to pitch deviants was significantly larger in low-entropy (more predictable) musical contexts compared to high-entropy (less predictable) contexts.
- A positive correlation was observed between the PDR and the unexpectedness of individual musical notes.
- No significant effects of music expertise were detected, possibly due to widespread enculturation effects.
Conclusions:
- The pupil dilation response (PDR) is sensitive to the long-term context in which an unexpected event occurs, not just the event's deviation.
- Arousal levels, as reflected by PDR, can vary even for the same environmental change based on preceding contextual factors.
- These findings highlight the adaptive nature of predictive processing, where context modulates the neural response to prediction errors.
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