Physiological synchrony in brain and body as a measure of attentional engagement

Attentional engagement – the emotional, cognitive and behavioral connection with information to which the attention is focused – is important in all settings where humans process information. Measures of attentional engagement could be helpful to, for instance, support teachers in online classrooms, or individuals working together in teams. This thesis aims to use physiological synchrony, the similarity in neurophysiological responses across individuals, as an implicit measure of attentional engagement. The research is divided into two parts: the first investigates how different attentional modulations affect physiological synchrony in brains and bodies, the second explores the feasibility of using physiological synchrony as a tool to monitor attention in real-life settings.
In Part I, the effect of different manipulations of attention on physiological synchrony in brain and body is explored. We find that physiological synchrony does not only reflect attentional engagement when measured in the electroencephalogram (EEG), but also when measured in electrodermal activity (EDA) or heart rate. Moreover, we find that physiological synchrony can reflect both sensory and top-down variations in attention, where top-down focus of attention is best reflected by synchrony in EEG, and where emotionally salient events attracting attention are best reflected by EDA and heart rate.
Part II transitions into the practical applications of physiological synchrony in real-life contexts. Wearables are employed to measure physiological synchrony in EDA and heart rate, demonstrating comparable accuracy to high-end lab-grade equipment. The research also incorporates machine learning techniques, showing that physiological synchrony can be combined with novel unsupervised learning algorithms. Finally, measurements in classrooms reveal that physiological synchrony can be successfully monitored in real-life settings.
While the findings are promising, the thesis acknowledges limitations in terms of sufficient data that are required for robust monitoring of attentional engagement and in terms of limited variance in attention explained by physiological synchrony. To advance the field, future work should focus on the applied, methodological and ethical questions that remain unanswered.