Differences in Physiological Responses to Exposure of Disturbing Auditory Versus Audiovisual Stimuli

Abstract

Fear plays a significant role in the lives of many people, from crippling fear that prevents people from performing everyday activities, to that which is intentionally experienced from video game or horror movies. The physiological responses to fear-inducing stimuli may vary between individuals, but some common reactions include increased heart rate, respiration rate and muscle tension, collectively referred to in this study as the “fear response”. These common reactions are a result of the sympathetic nervous system reacting when presented with a threat, a.k.a: a scary scene in a horror movie. The hypothalamic-pituitary adrenal axis regulates the body’s behavior, including the autonomic responses that are being measured in this experiment. The purpose of this study is to analyze the fear response to either audio or audiovisual stimuli, and compare the severity of the physiological changes induced by both stimuli against each other. The 29 participants were randomly assigned to one of two groups: 15 Audio (Group A) and 14 Audiovisual (Group AV). Group A was instructed to listen only to the audio track of a stimulating horror movie trailer broken up into 4 segments, and Group AV was subjected to the same trailer but also experienced the visual aspects of the stimulus. It was hypothesized that the fear response to an auditory stimulus would be larger than the response to the audiovisual stimulus. Of the two groups, those who received the audiovisual stimulus elicited a stronger physiological response than the audio group in heart rate and respiration frequency, but there were no statistically significant difference between the two groups when measuring muscle tension and respiration frequency. However, the audio stimulus induced a biological response of greater magnitude in muscle tension compared to the audiovisual stimulus. The reason for heart rates showing the only significant difference in physiological measurements between Group A and Group AV may be because heart rate is an involuntary physiological response. In contrast, the measurements for EMG and respiration could be voluntarily altered by participants during the experiment. Overall, although our results did not all show statistical significance, differences between the two treatments groups were observed for each variable and therefore show a degree of biological significance.