Narrative predicts cardiac synchrony in audiences

Abstract

Audio-visual media possesses a remarkable ability to synchronise audiences' neural, behavioural, and physiological responses. This synchronisation is considered to reflect some dimension of collective attention or engagement with the stimulus. But what is it about these stimuli that drives such strong engagement? There are several properties of media stimuli which may lead to synchronous audience response: from low-level audio-visual features, to the story itself. Here, we present a study which separates low-level features from narrative by presenting participants with the same content but in separate modalities. In this way, the presentations shared no low-level features, but participants experienced the same narrative. We show that synchrony in participants' heart rate can be driven by the narrative information alone. We computed both visual and auditory perceptual saliency for the content and found that narrative was approximately 10 times as predictive of heart rate as low-level saliency, but that low-level audio-visual saliency has a small additive effect towards heart rate. Further, heart rate synchrony was related to a separate cohorts' continuous ratings of immersion, and that synchrony is likely to be higher at moments of increased narrative importance. Our findings demonstrate that high-level narrative dominates in the alignment of physiology across viewers.

Keywords: Audiences; Immersion; Narrative; Physiological synchrony; Story.

Fig. 1

Heart rate intersubject correlations for audio-only, visual-only, and the between-group narrative comparison. Boxplots show medians and interquartile range, and the horizontal dashed line represented zero correlation. Each point shows the average intersubject correlation for one participant. For the audio-only and visual-only conditions, ISCs were calculated for each participant with each other participant in the same group. For the between-group narrative comparison, ISCs were calculated for each participant with participants in the other condition. The grey lines denote the same participant in each condition (within a group, or between-groups). Filled circles denote significance for each participant at p < .05, using a circular shuffle technique with 10,000 iterations and a false discovery rate of q = 0.05. To calculate significance for each participant, heart rate was shifted circularly by a random value, and ISCs with other participants were recomputed. The proportion of significant ISCs below the true ISC value was used to determine significance.

Fig. 2

Correlation between heart rate ISC and continuous ratings of immersion. Left: Heart rate ISC and immersion ratings over time, averaged across all participants. Filled area represents 95% CI. Right: Correlation between heart rate ISC and immersion ratings. Each point represents the average rating and ISC at one time point. Filled area represents 95% CI.

Fig. 3

Heart rate ISC across time. Lighted grey area denotes 95% CIs. Dashed line indicates 3 SDs above the mean. Labels depict events, described below. Exploratory investigation of these events, shown by the labels and descriptions, may suggest these points relate to moments of narrative importance or emotional saliency. A. The man is placed in an MRI scanner, struggling to recall aspects of his life. He asks for a song to be played, but then cannot recall it, as it becomes clear that he has amnesia from the car crash. B. The man and Luci, a waitress, walk out of the restaurant. The restaurant explodes behind them. C. The man and Luci speculate that someone may be trying to kill him. D. The man arrives at a bed and breakfast, with insufficient money to pay for a room. The sympathetic owner lets him stay anyway. E. The man and Helen, a policewoman, are talking on the phone. Helen reveals the police found a camera in the wreckage of his car, which may provide information on his identity. They also share a joke which came up earlier. F. The cowboy arrives at the hospital, and asks to see the man. G. The cowboy leaves the hospital, putting on his hat and whistling a tune heard as he earlier attempted to kill the man. It becomes clear he is the truck driver who originally attempted to kill the man. H. Luci, the waitress, is at home scrolling through her phone. She is deleting photos or her and the man together, revealing that she previously knew him. In the background, the song which the man asked to be played in the MRI scanner is playing. I. The man is in a viscerally described, and visually disgusting bathroom.