IEEE GCCE 2022 1570814034

1	  2	  3	  4	  5	  6	  7	  8	  9	  10	  11	  12	  13	  14	  15	  16	  17	  18	  19	  20	  21	  22	  23	  24	  25	  26	  27	  28	  29	  30	  31	  32	  33	  34	  35	  36	  37	  38	  39	  40	  41	  42	  43	  44	  45	  46	  47	  48	  49	  50	  51	  52	  53	  54	  55	  56	  57	  60	  61	  62	  63	  64	  65	  Fear magnified by vibratory stimuli to theupper-body at predictive horror scenes
Tastuki Makioka

Shogo Okamoto

Ibuki Tara

Tokyo Metropolitan UniversityTokyo, JapanTokyo Metropolitan UniversityTokyo, Japan

Nagoya University
Nagoya, Japan

Abstract—We investigated how predictive vibratory interoceptive stimuli along with audio-visual content affected viewers’
emotional experiences. It is known that vibratory stimuli toupper body presented at monster’s appearance scenes of horror
movies magnify fear experiences; however, arousing vibratory
stimuli before such scenes also may be effective to enhanceviewers’ emotions. Vibration was presented at predictive scenesthat suggested an incoming horror scene in videos. The predictive vibratory-interoceptive stimuli significantly increased theviewers’ physiological responses which were measured as skinconductance response at fingers and subjective fear of subsequenthorror scenes.
Index Terms—interoception, horror movie, vibratory stimuli

A. Audio-visual contents (horror movies)

I. I NTRODUCTION
Vibratory stimuli presented in conjunction with emotionallyarousing scenes in audio-visual content influence viewers’
subjective evaluations and physiological responses [1]–[5].
We hypothesized that stimulating the viewer’s interoceptive
sensations before emotionally arousing scenes enhances theemotional experience during such scenes. To date, no study
has investigated this.
Although several studies have demonstrated the emotional
effects of vibratory stimuli [1]–[5], the underlying principles
have not been clarified. We hypothesized that vibratory stimuli
to the upper body enhance emotions by affecting interoceptive
sensations, mainly visceral sensations. Vibration stimuli tothe upper body mechanically stimulate visceral sensations.
Emotions are considered to represent the brain’s representationof changes in interoceptive sensations [6]. Making the viewersof horror movies arousing by using interoceptive vibratory
stimuli may affect their fear experiences at horror scenes.
In this study, we analyzed the viewers’ physiological responses and subjective evaluations of watching horror videos
with and without predictive vibratory stimuli and investigatedthe effects of vibratory stimuli at predictive scenes on theemotional experiences of succeeding emotionally appealing
scenes.
II. M ETHODSThe experimental protocols were approved by the Institutional Review Board of Hino Campus, Tokyo Metropolitan
University (H21-046).

/22/$31.00 ©2022 IEEE

Fig. 1. Vibratory-stimuli vest. One voice-coil actuator each on the abdomen
and back

As audio-visual content, we used horror movies that included a jump-scare scene in which a monster or other horrificobjects appeared suddenly accompanied by a loud sound to
startle the viewer and scenes that suggest a succeeding jumpscare scene. In this study, we refer to the latter type of scenes
as predictive scenes. Two movies perceived as approximately
equally scary were used. Each video was approximately 1–2
min in length and is referred to as movie 1 and movie 2 inthis paper.
B. Data recording equipment
The skin conductance of the hand was measured using
AP-U030m II (Nihon Suntech, Japan) with an amplifier(MaPI720CA, Nihon Suntech, Japan). The outputs from theamplifier were recorded at 100 Hz using a data acquisition
device (NI USB-6211, National Instrument Corp., TX) andcontrolled by the Dara Acquisition Toolbox of MATLAB(MATLAB 2021a, Mathworks, MA).
C. Vibratory stimuli
Two voice coil motors (Vp604, Acouve Lab., Japan) wereused to generate vibration stimuli. As shown in Fig. 1, they
were attached to the vest - one was in contact with the epigastric fossa and the other with T5 of the spine. Additionally,participants wore a corset over the vest to ensure close contact
between the body and voice coil motors.
Vibratory stimuli were continually presented for 17 s during
the predictive scenes. This period consisted of six units ofvibration, each of which lasted 0.7 s. The frequency of thevibration was 70 Hz. The amplitude monotonically increased1583

for 0.4 s from the start of the vibration and then monotonically decreased. The frequency and amplitude profiles weredesigned to match the predictive scenes by those familiar withvibratory stimuli, including the authors. The time between
the last vibratory stimulus and jump-scare scene was approximately 15 s.
D. Measurement of skin conductance response
The skin conductance response of participants was measured as a physiological signal. The skin conductance changes
due to sweating associated with tension and excitement andincreases within 1–2 s after the onset of a stimulus, allowing
the measurement of the arousal response to the instantaneous
fear stimulus in the horror movie [7], [8]. Furthermore, theskin conductance reaches its peak in another 1—2 s. We
calculated the difference between the resting level before theskin conductance started changing and the subsequent local
peak amplitude.
E. Participants
We recruited eight university students (20 years or older,average: 22 years) who were unaware of the purpose of theexperiment after obtaining written informed consent.
F. Tasks
Before the experiment began, the participants experienced
vibratory stimuli thrice to familiarize themselves with thevibration. Participants then experienced audio-visual content
with or without the vibration stimuli. The combination andorder of the two movies and vibration conditions (with orwithout) were randomly determined for each participant. Before watching each movie, participants rested for at least 90 s.
As a subjective evaluation, participants indicated the degree towhich the jump-scare scene in the second movie was scarierthan that in the first movie.
G. Analysis
We investigated the effect of vibration on skin conductanceamplitude and subjective evaluation of fear. Multiple linear
regression models with dummy variables were used to remove
the differences in fear between the two movies. The model
equation was
y = avib xvib + amovie xmovie + constant(1)

where y is the skin conductance amplitude or subjective fearvalue. The skin conductance amplitudes and subjective fearvalues were normalized to have an arithmetic and geometricmean of 1 within individual participants, respectively. xvib
is a binary variable representing the presence (xvib = 1) orabsence (xvib = 0) of vibrations. xmovie is a binary variable
representing the movie type. xmovie is 0 and 1 for movie 1 andmovie 2, respectively. avib is the partial regression coefficient
representing the effect of the vibration stimulus on y. amovie
is the partial regression coefficient for the effect of movie
type. The avib and amovie values were tested to determine
whether they differed from 0. Two of the participants did

Fig. 2. Means and standard errors of avib , that is, the effect of vibratory
stimuli. Left: Effect on skin conductance response Right: Effect on questionnaire

not exhibit a variation in the skin conductance response to
the vibratory stimuli and horror movies; hence, their skinconductance values were not included in the analysis.
III. R ESULTS
The left and right parts of Fig. 2 show the values of avib
for the skin conductance amplitude and subjective reports withstandard errors, respectively. For skin conductance amplitudes,
avib = 0.94 (p = 0.003). For subjective reports, avib = 0.48
(p = 0.009). Therefore, the vibration had a significant effecton the skin conductance amplitudes and subjective reports.
Regarding the effects of the two movies, amovie was −0.67(p = 0.018) and −0.48 (p = 0.011) for skin conductance
amplitude and subjective report, respectively, indicating thatmovie 2 felt more horrific than movie 1 to the participants.
IV. C ONCLUSION
Vibratory stimuli to the upper body in scenes predicting
jump-scare scenes increased viewers’ horrific experiences asevidenced by subjective reports and physiological responses.
Thus, conjunctive use of vibratory stimuli in predictive andjump-scare scenes is expected to further enhance the emotional
experience of movies and horror games. In future, the effects
observed in the present study should be studied in a largecohort.
R EFERENCES[1] P. Lemmens, F. Crompvoets, D. Brokken, J. Van Den Eerenbeemd,and G.-J. de Vries, “A body-conforming tactile jacket to enrich movie
viewing,” in Proceedings of IEEE World Haptics 2009-Third Joint EuroHaptics Conference and Symposium on Haptic Interfaces for Virtual
Environment and Teleoperator Systems. IEEE, 2009, pp. 7–12.
[2] G. Karafotias, A. Teranishi, G. Korres, F. Eyssel, S. Copti, and M. Eid,
“Intensifying emotional reactions via tactile gestures in immersive films,”
ACM Transactions on Multimedia Computing, Communications, andApplications, vol. 13, no. 3, pp. 1–17, 2017.
[3] I. Tara, S. Okamoto, Y. Akiyama, and Y. Yamada, “Heightening fear
response to horror video scenes by applying vibratory stimuli to upper
bodies of viewers,” in Proceedings of IEEE Global Conference on Life
Science and Technologies, 2022, pp. 254–256.
[4] I. Tara, S. Okamoto, Y. Akiyama, and Y.Yamada, “How important isthe timing of vibrotactile stimuli for the excitement feeling of audiovisual contents,” in Proceedings of IEEE Global Conference on Consumer
Electronics, 2021, pp. 183–185.

2584

[5] C. Branje, F. Russo, G. Nespoli, and D. Fels, “The effect of vibrotactile
stimulation on the emotional response to horror films,” Computers inEntertainment, vol. 11, no. 1, p. 5, 2014.
[6] A. Damasio, “Feelings of emotion and the self,” Annals of the New York
Academy of Sciences, vol. 1001, no. 1, pp. 253–261, 2003.
[7] A. D. Craig, “How do you feel? Interoception: the sense of the physiological condition of the bod,” Nature Reviews Neuroscience, vol. 3, no. 8,pp. 655–666, 2002.
[8] T. Makioka, S. Okamoto, and I. Tara, “Difference in skin conductancedynamics to horror and family bond emotional movies,” in Proceedingsof IEEE Global Conference on Consumer Electronics, 2022.

3585