Interpersonal synchronization as an objective measure of listening engagement
Listening engagement has received increasing attention for its role in effective communication and knowledge transfer. It encompasses a state of deep listening in which a person not only pays attention to a stimulus but is fully absorbed in it. Behavioral measures have been used to assess listening engagement; however, they have limitations and do not fully capture this multidimensional state. Measuring listening engagement objectively using brain and body signals is a compelling alternative. In particular, interpersonal synchronization-observed through synchronized physiological responses among listeners-offers a promising objective measure of this phenomenon. We measured brain, heart rate, and electrodermal activity synchronization between people who listened to engaging and non-engaging stories. As a ground truth, we also measured subjective listening engagement through a questionnaire. Results showed higher synchronization when participants listened to an engaging stimulus compared to a non-engaging one across different modalities of objective response. Furthermore, we found a significant correlation between synchronization measures and subjective engagement ratings. These results confirm that synchronization may serve as a reliable measure of listening engagement.