Abstract
Attentional engagement is a major determinant of how effectively we gather information through our senses. Alongside the sheer growth in the amount and variety of information content that we are presented with through modern media, there is increased variability in the degree to which we “absorb” that information. Traditional research on attention has illuminated the basic principles of sensory selection to isolated features or locations, but it provides little insight into the neural underpinnings of our attentional engagement with modern naturalistic content. Here, we show in human subjects that the reliability of an individual's neural responses with respect to a larger group provides a highly robust index of the level of attentional engagement with a naturalistic narrative stimulus. Specifically, fast electroencephalographic evoked responses were more strongly correlated across subjects when naturally attending to auditory or audiovisual narratives than when attention was directed inward to a mental arithmetic task during stimulus presentation. This effect was strongest for audiovisual stimuli with a cohesive narrative and greatly reduced for speech stimuli lacking meaning. For compelling audiovisual narratives, the effect is remarkably strong, allowing perfect discrimination between attentional state across individuals. Control experiments rule out possible confounds related to altered eye movement trajectories or order of presentation. We conclude that reliability of evoked activity reproduced across subjects viewing the same movie is highly sensitive to the attentional state of the viewer and listener, which is aided by a cohesive narrative.
SIGNIFICANCE STATEMENT Modern technology has brought about a monumental surge in the availability of information. There is a pressing need for ways to measure and characterize attentional engagement and understand the causes of its waxing and waning in natural settings. The present study demonstrates that the degree of an individual's attentional engagement with naturalistic narrative stimuli is strongly predicted by the degree of similarity of his/her neural responses to a wider group. The effect is so strong that it enables perfect classification of attentional state across individuals for some narrative stimuli. As modern information content continues to diversify, such direct neural metrics will become increasingly important to manage and evaluate its effects on both the healthy and disordered human brain.
This article is freely available online through the J Neurosci Author Open Choice option.
