Correlation between Psychological and Physiological Responses

during Fear

Relationship to Perceived Intensity of Fear

Eun-Hye Jang

, Byoung-Jun Park

, Sang-Hyeob Kim

, Myung-Ae Chung

and Jin-Hun Sohn

Biohealth IT Convergence Technology Research Department, Electronics and Telecommunications Research Institute,

Gajeong-ro, Yuseong-gu, Daejeon, Republic of Korea

Future Technology Research Department, Electronics and Telecommunications Research Institute,

Gajeongno, Yuseong-gu, Daejeon, Republic of Korea

Department of Psychology, Brain Research Institute, Chungnam National University,

Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea

Keywords: Fear, Psychological Response, EDA, ECG, Facial EMG.

Abstract: The purpose of this study is to examine the physiological responses to predict the psychological level of

perceived fear. Thirty male and female college students (15 male and 15 female, mean age: 22.6±1.24)

participated in the experiment. EDA (electrodermal activity), ECG (electrocardiogram), and facial EMG

(electromyogram) as physiological signals were measured on the subjects’ hands and face for 60sec before

presentation of emotional stimulus and for 120sec during presentation of stimulus. Experimental conditions

consisted of emotional condition where fear was induced by a threatening film clip and neutral condition

where no emotion was provoked by a neutral film clip. After presentation of the stimulus, subjects rated

their experienced emotion on the emotion assessment scale. Analysis of psychological responses was

performed to examine appropriateness (label of the subjects’ experienced emotion) and effectiveness

(intensity of their experienced emotion). In the analysis of physiological responses, the selected features

were skin conductance level (SCL), skin conductance response (SCR), number of skin conductance

response (NSCR), R-R interval (R-R), heart rate (HR), respiration (RESP), activation in the bilateral

corrugators (COR), and bilateral orbicularis oris’ (ORB). The results showed that the psychological

responses to stimulus were appropriate and effective. Physiological responses showed significant increases

in all features except R-R and ORB during fear condition compared to baseline condition. Also, the

perceived level of fear was positively correlated with SCL, SCR, and ORB. Our result offer that the users’

perceived emotion i.e., individual differences of psychological responses must be considered to recognize

human emotions by physiological signals in HCI.

1 INTRODUCTION

Fear emotion plays a crucial role in adaptation (e.g.,

Darwin, 1872; Ekman, 1999). It’s a negative

withdrawal-related emotion (Coan and Allen, 2003)

and has high arousal valence (Christie, 2002;

Davidson, 2000; Russel and Feldman-Barrett, 1999;

Nyklicek, Thayer and Van Dooornen, 1997). Izard

and Buechler (1980) described fear as a particular

toxic negative emotion that is experienced as

apprehension, uncertainty and a sense of threat or

danger. We might consider fear emotion as a

subject’s perceived feeling to stimulus. For example,

a ‘knife’ is not object of avoidance as only physical

stimuli (knife), but someone feels ‘perceived danger

(e.g., fear of being attacked)’, or even physical pain

as the result of attack. Regardless of what a knife is

made of, it can be perceived as a threat depending on

how the subject perceives it. In other words, what

constitutes ‘fearful responses depend on the

subject’s perception (or interpretation). Therefore, it

is considered that not only the specific motor and

physiological responses but also subjective reaction

are induced by fear if anything or situation is

perceived as threatening or dangerous and it then

triggers coping action, i.e., the harm-avoidance

function of fear (Birbaumer and Schmidt, 1999).

Researchers empathize three major domains of

104

Jang E., Park B., Kim S., Chung M. and Sohn J..

Correlation between Psychological and Physiological Responses during Fear - Relationship to Perceived Intensity of Fear.

DOI: 10.5220/0004728101040109

In Proceedings of the International Conference on Bio-inspired Systems and Signal Processing (BIOSIGNALS-2014), pages 104-109

ISBN: 978-989-758-011-6

 2014 SCITEPRESS (Science and Technology Publications, Lda.)

variables to measure - physiological variables (e.g.,

neurological, autonomic, and endocrine changes),

behavioural variables (e.g., expressive behaviour,

primarily facial expression, tone of voice, gesture,

posture, and movement), and cognitive variables

(e.g., cognitive appraisal processes, prior experience

and introspective perception of feelings, or cognition

of emotional experience (Lang, 1983; Ney and Gale,

1988; Leventhal and Mosbach, 1983; Scherer,

Summerfield and Wallbott, 1983). The cognitive

variables, e.g., perception or appraisal to a situation,

influence the physiological responses in emotion

(Marwitz and Stemmler, 1998).

Despite no consistency of experimental settings to

induce fear, previous results showed common fear-

specific autonomic responses, e.g., increased heart

rate, respiration and skin conductance, and decreased

skin temperature. Additionally, the prototypical facial

expression of fear is that eyebrows raised and pulled

together, upper eyelids raised, and lower lids tensed

combining with an open mouth (e.g., Ekman and

Friesen, 1978). However, there are a few studies

suggesting the relationship between psychological

and physiological responses during fear emotion.

In this study, we have identified physiological

responses such as EDA, ECG and facial EMG

activities and psychological responses induced by

fearful stimulus and found relationships between

physiological and psychological responses (i.e., the

perceived level of fear).

2 EXPERIMENTAL METHODS

30 male and female subjects (15 males, mean age:

22.6±1.24) participated in the experiment. None of

them reported any history of medical illness or

psychotropic medication. They reported no use of any

medication that would affect the cardiovascular,

respiratory, or central nervous system. They were

administered a hearing test, which all of them fell

within the normal hearing range. A written consent

was obtained at the beginning of the study when they

were introduced to the experiment protocols, and they

were also paid $20 USD to compensate for their

participation.

2.1 Emotion-provoking Stimuli

To induce fear and neutral emotions, audio-visual

film clips were used in this experiment (see Figure

1). Audio-visual film clip is known to effectively

portray dynamic information to induce the integrated

and sustained emotional responses than those of still

pictures (Palomba, Sarlo, Angrilli, Mini and

Stegagno, 2000). Parts of a Korean horror movie, ‘A

Tale of Two Sisters (2003)’ were selected as stimuli.

The stimulus consists of two parts, one part with 60

second-long neutral condition and the other 60

second-long fear condition as shown in the Fig 1. It

has been revealed that it has effectiveness of 5.5 on

7-point Likert scale (1 being least effective and 7

being most effective) and appropriateness of 100%

by preliminary experiment.

Figure 1: The example of the experimental stimulus.

(above: neutral, below: fear)

2.2 Experimental Settings

The laboratory was 5mx2.5m big sound-proof

(lower than 35dB) of the noise level where any

outside artifacts are completely blocked. A couch for

a subject was located on the center of the room and

38’ TV was placed 2 meters ahead from the couch to

present the stimuli designed to induce emotions, fear

and neutral. On the right side of the couch,

interphone was installed. CCTV right next to TV

was installed to observe subjects behaviors. Outside

the laboratory, a computer connected to the TV

inside for the presentation of the film clips to the

subjects, VCR and another TV to monitor and record

behaviors of the subjects, a device (MP100) to

measure autonomic and facial EMG, and another

computer to receive all the signals from the

measuring equipment were all installed.

Figure 2: The attachment of electrodes for measure of

physiological signals. (above: ECG and EDA, below:

facial EMG)

Biopac Systems Inc. (California, USA) was used to

CorrelationbetweenPsychologicalandPhysiologicalResponsesduringFear-RelationshiptoPerceivedIntensityofFear

105

measure physiological responses. MP100WS and

AcqKnowledge (version 3.7.1) were used to input

acquire the data and analyze them. ECG was measured

on the left wrist where the pulse can be detected. EDA

was measured on the forefinger and middle finger of

the left hand. And facial EMGs were measured in the

corrugators and orbicularis oris (Figure 2).

Prior to experiment, subjects were allowed to take

time to feel comfortable in the laboratory setting.

Then electrodes were put on their forehead, wrist,

finger, and ankle to measure physiological signals.

They had resting period for 60 seconds before the

presentation of stimulus as baseline and then they

were exposed the stimuli for 2 minutes while their

physiological responses were measured. After this

stimulus presentation period, they were given 30

seconds to get rested and then were to evaluate their

psychological responses on emotion assessment scale.

2.3 Data Acquisition and Analysis

Data for 30 seconds from the baseline and each 30

seconds from two emotional conditions, i.e., neutral

and fear were also used in the analysis. Skin

conductance level (SCL), skin conductance response

(SCR), and number of skin conductance response

(NSCR) were analysed as EDA indicators, which

were used to measure sweat secretion responses of

peripheral nervous system. ECG parameters

measuring heart activity were R-R interval (RRI),

heart rate (HR) and respiration (RESP). To quantify

facial EMG response of bilateral corrugators (CORs)

and orbicularis oris’ (ORBs), EMG signals were

filtered at 20-450Hz, sampled at 1000 Hz, and

maximal EMG was calculated as the average signal

during each condition. A paired t-test for statistical

analysis was done to compare the neutral to fear

state. And correlation coefficient analysis was

performed to identify relation between psychological

and physiological responses induced by fear.

3 RESTULTS

3.1 Result of Psychological Responses

The psychological responses to fear stimulus were

analyzed to examine the appropriateness and

effectiveness based on the subject’s rating.

Appropriateness means the consistency between the

target emotion and emotion experienced by the

subjects. Effectiveness is the experienced emotional

intensity. The results showed that appropriateness is

96.7% and effectiveness 5.00±0.86. In other words,

29 of all subjects reported they experienced fear when

exposed to emotional stimulus and mean intensity of

the experienced emotion was 5.00±0.86.

3.2 Result of Physiological Responses

To compare physiological responses induced by fear

and neutral emotion, paired t-test was done for the

two conditions (i.e., neutral and fear conditions) and

normality check for the data was done using SPSS

ver. 15.0 (see Table 1). In the results, there were

increases in SCL, SCR, NSCR, HR, RESP and

activation in the bilateral COR and decrease in RRI

during the fear condition compared to the neutral

condition (see Figure 3).

Figure 3: Difference of physiological responses between

neutral and fear (A. skin conductance level, B. skin

conductance response, C. number of skin conductance

response, D. R-R interval, E. heart rate, F. respiration rate,

G. Rt. corrugator, H. Lt. corrugator, I. Rt. orbicularis oris,

J. Lt. orbicularis oris).

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Table 1: Differences of physiological responses between

neutral and fear emotions.

feature

neutral fear

M SD M SD

SCL (㎲)

6.84 2.92 8.63 3.52 3.80**

SCR (㎲)

0.08 0.21 1.26 1.08 5.89***

NSCR (N) 0.3 0.60 2.8 2.07 6.86***

R-R

(interval)

796.89 135.94 755.29 163.36 2.48*

HR (BPM) 78.43 16.64 84.40 20.11 2.68*

RESP

(N/min)

15.87 3.52 21.00 5.11 4.76***

COR

(mV)

Lt. 0.0039 0.0048 0.0045 0.0057 2.37*

Rt. 0.0062 0.0063 0.0072 0.0073 2.80**

ORB

(mV)

Lt. 0.0048 0.0120 0.0048 0.0121 0.71

Rt. 0.0062 0.0136 0.0060 0.0136 1.08

* p < .05, ** p < .01, *** p < .001 (N=30)

3.3 Correlation between the Perceived

Intensity and Physiological

Responses of Fear

For correlation coefficient analysis, Spearman rank

correlation coefficient which is appropriate for both

continuous and discrete variables, including ordinal

variables was analysed to examine correlation

between psychological, i.e., perceived fear and

physiological responses induced by fear. The result

is shown in the Table 2. The perceived fear showed

a positive correlation with physiological responses,

i.e., SCL, SCR, as well as activation in the CORs.

Table 2: Correlation between the subjects’ perceived fear

and physiological responses.

features SCL SCR NSCR R-R HR RESP

fear

level

0.54** 0.49** 0.29 0.07 -0.12 -0.20

* p < .05, ** p < .01

features Rt. COR Lt. COR Rt. ORB Lt. ORB

fear level 0.37* 0.25 0.21 0.32

* p < .05, ** p < .01

4 DISCUSSIONS

This study investigated fear-specific physiological

responses and physiological features related to the

subjects’ perceived fear. The used stimulus turned

out to have 96% of appropriateness and more than

5.0 points of effectiveness, which indicates the used

stimulus proved to be effective in producing fear.

Our film clip when compared to the pre-existing one

is a more effective tool to induce stable emotion

with less individual difference as shown in the

subjects’ emotion assessment (Alto et al., 2002;

Iwase et al., 2002) and it helps subjects experience

vivid emotion (Gross and Levenson, 1995).

The results of physiological responses showed

statistically significant increases in SCL, SCR,

NSCR, HR, RESP and activation in the CORs

except RRI. This supports previous results (Main,

Shelton-Rayner, Harkin and Williams, 2003;

Lundgren, Berggren and Carlsson, 2004), reflecting

activation of sympathetic responses indicating fear-

specific responses, e.g., increased HR and

respiration, sweat secretion, and visceral arousal

(James, 1884).

EDA, unlike other physiological signals, was not

affected by parasympathetic response but by

sympathetic (Dawson, Schell and Filion, 1990). An

increase in EDA in fear means activation of sweat

glands, and directly indicates an increased

sympathetic arousal (Boucsein, 1992). On the other

hand, HR and RESP are affected by both

sympathetic and parasympathetic. Sympathetic

activity is responsive to arousal or excitement, while

parasympathetic is responsive to relaxed or resting

states. An increase of HR and RESP can be caused

by either sympathetic activation or parasympathetic

inhibition. In particular, the increased HR indicates

an increased sympathetic activation but decreased

parasympathetic (Hugdahl, 1995), and previous

studies supported an increase in HR (RRI

deceleration), lower amplitude and shorter wave of

RESP (Rainville et al., 2006; Blosh et al., 1991;

Rainville et al., 2006) during fear. Increases of

activation in the bilateral corrugators support reports

by previous studies (Hu & Wan, 2003; Magnee,

Stekelenburg, Kemner & deGelder, 2006; Thomkins,

1963; Vrana, 1993). Activation in the COR is fear-

specific as supported by Ekman and Freisen’s study

(1978). However, no activation in ORB (the muscle

arrowed lips) is reported.

Psychological response by fear showed a positive

correlation with physiological responses, i.e., SCL,

SCR, as well as activation in the COR. The reported

intensity of fear goes higher, SCL, SCR and CORs

CorrelationbetweenPsychologicalandPhysiologicalResponsesduringFear-RelationshiptoPerceivedIntensityofFear

107

activity tend to increase but HR decreased and these

are consistent with previously results (Palmer, 2008;

Gilissen et al., 2006; Castaneda and Segerstrom,

2004).

According to Bradley et al. (1993) and Detenber

et al. (1998), arousal and valence have association

with SCR, HR, activation in the ORB (zygomatic

major) and CORs activity. Dimberg (1986)’s results

indicate that facial muscle activity is closely related

to emotional response and especially facial EMG

reflects emotional characteristics. Particularly, SCR

showed positive relations with arousal, HR and

valence, but a negative relation with activation in the

CORs. This suggests the followings; more changes

in the SCR have something to do with higher level

of arousal; higher HR has a relation with positive

emotions; lower HR has a relation with negative

emotions; and an increased activation in the CORs

has a negative relation with valence.

In sum, our results are that as the perceived fear

level goes higher, SCR and CORs activity increases,

and yet HR decreases, all of which suggest a relation

with negative valence (Dimberg, 1986). Also, this

study showed that more intense fear caused more

sympathetic arousal as well as increased activation

in the right CORs. CORs of facial muscle has a

negative relation with valence and its activation

increases when experience the negative emotion

such as fear (Bradley et al., 1993; Detenber et al.,

1998; Dimberg, 1986). Although HR is known to be

related to valence, no significant change in the HR

by the level of fear was detected.

Figure 4: Correlation between psychological responses by

the subjects’ rating and physiological responses during

fear. The arrows show relations among measures.

5 CONCLUSIONS

We have identified a positive relation between the

intensity of subjects’ perceived fear and SCR, and

CORs activity. Our results support that there is

correlation between psychological and physiological

responses induced by fear. They have also provided

that the intensity of perceived fear effects on

physiological responses significantly. Although our

results are limited to fear emotion, they offer that the

users’ perceived emotion i.e., individual differences

of psychological responses must be considered to

recognize human emotions by physiological signals

in HCI. The analysis of emotional responses induced

by other basic emotions such as happiness, sadness,

anger, etc. are in progress and in further study, we

will develop more detailed algorithms for emotion

classification based on our results.

ACKNOWLEDGEMENTS

This research was supported by the Converging

Research Center Program through the Ministry of

Science, ICT and Future Planning, Korea (2013K00

0329 and 2013K000332).

REFERENCES

Moore, R., Lopes, J., 1999. Paper templates. In

TEMPLATE’06, 1st International Conference on

Template Production. SCITEPRESS.

Smith, J., 1998. The book, The publishing company.

London, 2

edition.

Darwin, C. R., 1872. The origin of species by means of

natural selection, or the preservation of favoured

races in the struggle for life, London: Adamant Media

Corporation.

Ekman, P., 1999. Handbook of cognition and emotion,

Sussex, United Kingdom: John Wiley & Sons, Ltd.

Coan, J. A., Allen, J. J. B., 2002. Frontal EEG asymmetry

and the behavioral activation and inhibition systems,

Psychophysiology, vol. 40, pp. 106-114.

Christie, I. C., 2002. Multivariate discrimination of

emotion-specific autonomic nervous system activity,

MSc Thesis, Virginia Polytechnic Institute and State

University.

Davidson, R. J., 2000. Affective style, psychopathology,

and resilience: Brain mechanisms and plasticity, The

American Psychologist, vol. 55, pp. 1196-1214.

Russel, J. A., Feldman-Barrett, L., 1999. Core affect,

prototypical emotional eposides, and other things

called emotion: Dissecting the elephant, Journal of

Personality and Social Psychology, vol. 76, no. 5, pp.

805-819.

Nyklicek, I., Thayer, J. F., Van Doornen, L. J. P., 1997.

Cardiorespiratory differenciation of musically-induced

emotions, Journal of Psychophysiology, vol. 11, pp.

304-321.

Izard, C. E., Buechler, S., 1980. Aspects of consciousness

and personality in terms of differential emotions

theory, In Plutchik, R. & Kellerman, H. (Eds.),

Emotion: Theory, research, and experience, vol. I (pp.

165–188). New York: Academic Press.

Birbaumer, N., Schmidt, R., 1999. Biologische

Psychologie, Springer Verlag 4. Auflage.

Lang, P. J., Levin, D. N., Miller, G. A., Kozak, M. J.,

BIOSIGNALS2014-InternationalConferenceonBio-inspiredSystemsandSignalProcessing

108

1983. Fear behaviour, fear imagery, and the

psychophysiology of emotion: the problem of

affective response integration, Journal of Abnormal

Psychology, vol. 92, no. 3, pp. 276-306.

Ney, T., Gale, A., 1988. A critique of laboratory studies of

emotion with particular reference to psycho-

physiological aspects, In Wagner, H. L. (Ed.), Social

psychophysiology and emotion: Theory and clinical

applications (pp. 65–83). Chichester: Wiley.

Leventhal, H., Mosbach, P. A., 1983. The perceptual-

motor theory of emotion, In Cacioppo, J. T. and Petty,

R. E. (Eds.), Social psychophysiology (pp. 353–388).

New York: Guilford Press.

Scherer, K. R., Summerfield, A. B., Wallbott, H. G., 1983.

Cross-national research on antecedents and

components of emotion: A progress report, Social

Science Information, vol. 22, no. 3, pp. 355–385.

Marwitz, M., Stemmler, G., 1998. On the status of

individual response specificity, Psychophysiology, vol.

35, pp. 1–15.

Ekman, P., Freisen, W. V., 1978. Facial Action Coding

System: A technique for the measurement of facial

moment, Palo Alto: Consulting Psychologists Press.

Palomba, D., Sarlo, M., Angrilli, A., Mini, A., Stegagno,

L., 2000. Cardiac responses associated with affective

processing of unpleasant film stimuli, International

Journal of Psychophysiology, vol. 36, pp. 45-57.

Alto, S., Näätänen, P., Wallius, E., Metsähonkala, L.,

Stenman, H., Niemi, P. M., Karlsson, H., 2002.

Neuroanatomical substrata of amusement and sadness:

a PET activation sstudy using film stimuli,

Neuroreport, vol. 13, no. 1, pp. 67-73.

Iwase, M., Ouchi, Y., Okada, H., Yokoyama, C.,

Nobezawa, S., Yoshikawa, E., Tsukada, H., Shimizu,

A., Watanabe, Y., 2002. Neural substrates of human

facial expression of pleasant emotion induced by

comic films: a PET Study, Neuroimage, vol. 17, pp.

758-768.

Gross, J. J., Levenson, R. W., 1995. Emotion elicitation

using films, Cognition and Emotion, vol. 9, no. 1, pp.

87-108.

James, W., 1884. What is an emotion?, Mind, vol. 9, pp.

188-205.

Main, R., Shelton-Raynor, G., Harkin, B., Williams, P.,

2003. Observing a fictitious stressful event:

Haematological changes, including circulating

leukocyte activation. Stress, vol. 6, no. 1, pp. 41-47.

Lundgren, J., Berggren, U., Carlsson, S., 2004.

Psychophysiological reactions in dental phobic

patients with direct vs. indirect fear acquisition,

Journal of Behavioral Therapy and Experimental

Psychology, vol. 35, pp. 3-12.

Dawson, M. E., Schell, A. M., ilion, D. L., 1990. The

electrodenna system, In I.T. Cacioppo & LO. Tusinary

(Eds.), Principles of psychophysiology: Physical,

social, and influential elements (pp. 295-324).

Cambridge: Cambridge University Press.

Boucsein, W., 1992. Electrodermal Activity, Plenum

Press, New York, 442.

Hugdahl, K., 1995. Psychophysiology: The mind–body

perspective, Cambridge, MA: Harvard University

Press.

Rainville, P., Bechara, A., Naqvi, N., Damasio, A. R.,

2006. Basic emotions are associated with distinct

patterns of cardiorespiratory activity, International

Journal of Psychophysiology, vol. 61, pp. 5–18.

Blosh, S., Lemeignan, M., Aguilera, N., 1991. Specific

respiratory patterns distinguish among human basic

emotions, International Journal of Psychophysiology,

vol. 11, no. 2, pp. 141-154.

Hu, S., Wan, H., 2003. Imagined events with specific

emotional valence produce specific patterns of facial

EMG activity, Perceptual and Motor Skills, vol. 97,

no. 2, pp. 1091-1099.

Magnee, M. J. C. M., Stekelenburg, J. J., Kemner, C.,

deGelder, B., 2006. Similar facial electromyographic

responses to faces, voices, and body expressions,

Neuroreport, vol. 18, no. 4, pp. 369-372.

Tomkins, S. S., 1963. Affect, imagery, consciousness. (Vol

2): the negative affects, New York: Springer.

Vrana, S. R., 1993. The psychophysiology of disgust:

Differentiating negative emotional contexts with facial

EMG, Psychophysiology, vol. 30, no. 3, pp. 279-286.

Palmer, M. A., 2008. Psychophysiology of Fear, Fear: A

Psychophysiological Study of Horror Film Viewing.

Texas State University. USA.

Gilissen, R., Koolstra, C., van Ijzendoorn, M., Bakermans-

Kranenburg, M., van der Veer, R., 2006. Physiological

reactions of preschoolers to fear-inducing film clips:

Effects of temperamental fearfulness and quality of the

parent-child relationship, Developmental

Psychobiology, vol. 10, pp. 187-195.

Castaneda, J., Segerstrom, S., 2004. Effect of stimulus

type and worry on physiological response to fear,

Anxiety Disorders, vol. 18, pp. 809-823.

Dimberg, U., 1986, Facial reactions to fear-relevant and

fear-irrelevant stimuli, Biological Psychology, vol. 23,

pp. 153-161.

Bradley, M. M., Lang, P. J., Cuthbert, B. N., 1993.

Emotion, novelty, and the startle reflex: Habituation in

humans, Behavioral Neuroscience, vol. 107, pp. 970-

980.

Detenber, B. H., Simons, R. F., Bennett, J. G. G., 1998.

Roll'em! : The effects of picture motion on emotional

responses, Journal of Broadcasting & Electronic

Media, vol. 42, pp. 113-127.

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