Monitoring selectively directed auditory attention in groups can be helpful in a range of contexts, such as in education. In real-world settings, selectively directed attention cannot be monitored by relating physiological signals to known event markers. Determining the similarity of physiological responses across individuals in a group (i.e., physiological synchrony - PS) may provide a solution to this problem, as it has been shown reflective of shared attentional engagement toward audiovisual stimuli. This study was aimed at examining whether PS in autonomic and neural measures are suitable markers to recover selectively directed attentional focus and moments of emotional or task-related relevance in a composite auditory stimulus.
Electroencephalography (EEG), electrodermal activity (EDA) and cardiac inter-beat interval (IBI) were monitored from participants who heard a composite auditory stimulus, consisting of a narrative
audiobook, interspersed with short stimuli. One group of the participants (n = 13) was instructed to attend to the narrative, and the other group (n = 13) was instructed to attend to the short stimuli,
that were tones that attending participants needed to keep track of, emotional sounds and a stress test attending participants needed to perform.
EEG and EDA signals of participants were more strongly synchronized with those of participants in the same attentional condition than with those of participants in the other attentional condition. No such effect was found in IBI. For a single individual, PS in EEG allowed attribution to the correct attentional group in 85% of the cases, for EDA this was 81% and for IBI accuracy was below chance level. Further analyzing EEG, PS was higher during relevant stimulus presentation than over the entire audiobook. PS across stimulus-attending participants was higher than across book-attending participants during these short stimuli.
It is concluded that PS in both autonomic and neural measures can be suitable to recover selectively directed attention, as indicated by the high classification accuracy for EEG and EDA. The results of
this study also indicate that PS may be suited for the detection of moments of emotional or task-related relevance, as PS in EEG was higher during relevant stimulus presentation than over the entire experiment. Future research should investigate whether PS in autonomic measures could also be suited for detection of relevant events.