Building blocks of suspense: subjective and physiological effects of narrative content and film music

Suspense is a critical element in audience engagement with dramatic narratives, yet its creation and underlying psychological mechanisms remain poorly understood. While plot information is crucial, formal elements like sound, cinematography, and particularly non-diegetic music significantly contribute to suspense. Lehne and Koelsch (2015) define tension and suspense as affective states linked to conflict, dissonance, and uncertainty, creating a yearning for resolution. Both narrative content and formal features can evoke these anticipatory emotions. Suspense is a dynamic process involving bodily responses like chills and arousal; understanding these physiological processes is essential. Audiences generally agree on what constitutes suspense, but judgments are influenced by prior media exposure and genre knowledge. Therefore, this study independently assessed subjective self-reports and physiological responses to identify convergent and divergent patterns, determine the best physiological parameters for capturing responses to narrative content versus music, and relate these to audience judgments.

Previous research explored physiological audience responses to suspenseful film stimuli, using measures like heart rate, electrodermal activity (skin conductance level, SCL), and pulse volume amplitude (PVA). Studies have shown that ambiguous narratives and uncertainty resolution elicit SCL changes. Heart rate often rises during suspense and drops upon resolution, sometimes accompanied by skin temperature increases (vasodilation). However, findings are mixed, with heart rate potentially reflecting attention and cognitive effort as well as arousal. Research on music perception also reveals mixed physiological responses to tension and suspense; parameters like finger temperature, PVA, and SCL show varying correlations with perceived tension. Few studies directly compared the effects of music and narrative content on suspense. Existing research highlights the need for a more comprehensive understanding of how these factors interact to create suspenseful experiences.

The study used the suspenseful short film "Love Field" (5:30 min). Three stimulus versions were created: audio-visual (AV), video-only, and audio-only. Each was followed by a 2-minute, 4-second relaxation video for baseline measurement. 4 coders annotated the film frame-by-frame, identifying objects, people, sounds, and defining four plot phases: (1) diffuse tension, (2) story framing, (3) anticipatory suspense, and (4) resolution/relief. Continuous response measurement (CRM) assessed participants' felt suspense on a 9-point scale (-4 to +4). Physiological data (IBI, PVA, SCL) were recorded using a Lightstone iom1 device at 30 Hz. Participants (N=100) were randomly assigned to one of the three conditions. Data preprocessing involved peak detection in the PPG signal using HeartPy. Analyses included repeated measures ANOVAs and frame-by-frame comparisons. Event-related analyses of IBI responses used a two-step approach: stimulus-based (comparing pre- and post-event IBI for five critical events) and response-based (examining significant IBI differences between conditions).

Self-reported suspense (CRM) showed significant effects of plot segment and condition, with an interaction effect. In the diffuse tension phase, the AV and audio-only conditions showed similar responses, rising with the onset of music, while the video-only condition showed a drop. SCL showed significant differences between conditions and plot phases, with the audio-only and video-only versions showing the most pronounced differences. PVA showed a main effect for condition, with the video-only condition showing lower arousal. IBI revealed a significant interaction effect, with short-term heart rate deceleration responses to salient narrative clues suggesting attention and cognitive resource allocation. Stimulus-based analysis of IBI showed significant pre-post differences for specific events in the AV and audio-only conditions, indicating heart rate acceleration. Response-based analysis revealed heart rate deceleration in response to local events, particularly in the anticipatory suspense phase. PVA and SCL were negatively correlated; increased SCL was associated with higher arousal.

The findings indicate that suspense is multi-faceted, involving various stimulus features, time scales, and subjective and physiological responses. Non-diegetic music strongly affects both physiological responses and self-reported suspense. The dissociation between physiological measures and subjective reports suggests different processing pathways. Music appears to increase overall arousal, while narrative content elicits specific short-term responses like heart rate deceleration related to attention. The observed differences between PVA and SCL might reflect different suspense mechanisms: PVA related to local uncertainty resolution, and SCL to emotionally negative outcomes. Heart rate deceleration is interpreted as cognitive resource allocation. Modality effects might explain lower arousal in the video-only condition.

The study demonstrates the complex interplay of narrative content and non-diegetic music in creating suspense. Physiological and subjective responses reveal distinct processing pathways. Future research could explore the interaction of bottom-up and top-down processes, examine different types of suspense (revelatory vs. completion-based), and refine the terminology surrounding suspense and tension. Investigating the role of mental imagery evoked by auditory stimuli also warrants further study.

The study used a single short film, limiting generalizability. The specific narrative structure might influence findings; narratives with multiple tension points might yield different results. The subjective nature of suspense and the diverse physiological responses complicate interpretation and necessitate further research to clarify the relationship between physiological measures and subjective experiences.