Fig. 8.

Schematic summary of results and proposed common mechanism. A video stimulus is processed cognitively by the brain, similarly in different subjects (dashed arrows—indicate cognitive processing encompassing perception and cognition; obviously signals enter the brain through eyes and ears). This cognitive processing causes similar fluctuations in signals of the body that exhibit robust brain–body coupling (solid arrows). Therefore, brain, physiological, and behavioral signals correlate between subjects (bold arrows). Subjects' attention variably engages with the stimulus, such that cognitive processing as a mediator of common fluctuations varies, across subjects and time. This variation results in a co-modulation of ISC in different signals. Links indicated in blue have been measured in this study as correlation. Narrow arrows are hypothesized causal effects (note that brain–body links may be bidirectional, which is obvious for the eyes and is discussed below for the heart as well).