Proceedings of 2nd International Symposium for Color Science and Art 2020-2021

Physiological and Psychological Effects of Light-Emitting Chair
in Synchronization with Heartbeat Rhythm
Takenori Obo
Tokyo Polytechnic Univ., 1583 Iiyama, Atsugi, Kanagawa 243-0297, JapanABSTRACT
In this study, we aim to develop a light-emitting chairin synchronization with heartbeat rhythm. The design ofenvironment through a variety of means such as lighting
and colors can stimulate perceptual and emotional
responses. Interoception is the ability to sense the internal
state of the body and includes the perception of physicalsensations related to internal organ function such as heartbeat. The increase of interoceptive sensitivity can lead toemotion inductions. We therefore propose and discuss anovel approach to bring a feeling of relaxation by using alight-emitting chair.
1. INTRODUCTION
In color psychology, colors in surroundings can affecthuman emotional states and behavioral responses. It has
been broadly discussed that colors can cause certain
psychological, physical, biological and metabolic reactions
within humans. The design of an environment through avariety of means such as lighting and colors can stimulateperceptual and emotional responses [1].
Interoception is the ability to sense the internal state of
the body and includes the perception of physicalsensations related to internal organ function such as heartbeat, respiration, as well as the autonomic nervous system(ANS) activity related to emotions. In the previous works[2,3], it can be assumed that the awareness of individual'sbodily change is linked to the awareness of one's
emotional state and the cognitive processes. However,this differs from the general association of physicalchanges and their perception as the basis of emotional
experience. It is hypothesized that the sensitivity for one's
bodily internal state promotes the ability of self-regulation
to detect bodily changes more accurately and manage
one's emotions. This concept can be related to theembodiment theory.
This paper presents a chair with an internal light sourcethat emits light in synchronization with heartbeat rhythm.
The pneumatic pressure sensor inserted into a cushion on
the chair is used for detecting the ballistocardiograph(BCG) signal caused by human body movement cyclicallyarising from the ejection of blood into the great vessels
with each heartbeat. Without any wearable device, themeasurement system gathers the time-series data of theinvoluntary movement and the ANS activity. Moreover, wepropose a fuzzy spiking neural network to extract
heartbeat signal from the measured data. We furthermore
investigated the effects of the developed light-emitting
chair on physiological and psychological states.

Fig. 1 System Architecture

Fig. 2 Light-Emitting Chair
2. Light-Emitting Chair
2.1 System Architecture
Figure 1 depicts the system architecture. The
light-emitting chair is composed of two parts: heartbeat
detection and light emitting control. In the heartbeat
detection, a pneumatic pressure sensor is used. The
measured data is transferred to a microcontroller board.
The light-emitting is controlled by the microcontroller insynchronization with heartbeat signal. Figure 2 shows anexample of the light emission. In this study, we use thisdeveloped system to encourage interoception awarenessthat can be characterized as the ability to perceive one’s
heartbeats accurately.
2.2 Heartbeat Detection
In this study, the measurement system with apneumatic pressure sensor developed by NEW SENSOR
Inc. is utilized for heart rate variability analysis. The
pneumatic pressure sensor is embedded in a cushion on
the chair as shown in Fig.1. The measurement system isbased on the ballistocardiography (BCG) principle.
Ballistocardiography is a non-invasive methodology forrecording body movement occurring due to thecontractions of the heart to pump the blood. The system
consists of a pneumatic pressure sensor and rubber tube
covered with polypropylene sheets. The inner pressure

5Proceedings of 2nd International Symposium for Color Science and Art 2020-2021
varying with the compression and expansion of the tube
caused by the heart's recoil is detected by the pressuresensor. The sampling interval for the measurement is 2 ms.
The sensor output is converted to a digital output, the data
range of which is 0-1023, by using Arduino board.
Furthermore, we proposed a method of heartbeat
detection with spiking neural network (SNN) that iscomposed of five neurons with the pulse neuron model for
simulating heartbeat signal [4]. The neural network has arecurrent architecture consisting of input layer and output
layer. The values of the weight parameters in each layer
are empirically optimized by using a genetic algorithm.
The SNN can produce the spike outputs corresponding toactual heartbeats. With the small computational
complexity of the optimized neural network, we can realize
the heart detection embedded in the measurement
system.

Fig. 3 Comparative Result between Red andBlue-Colored Light

3. EXPERIMENTAL RESULTIn this experiment, we investigated the physiologicaland psychological effects of the proposed system,comparing the developed chair between in and out ofsynchronization with heartbeat rhythm. Here thecomparison emits light at even time intervals (1 [Hz]),
regardless of detected heartbeat signals. The subjects
consist of 8 male university students. We split them into
two groups. Each subject was required to sit on the chairfor 180 [s] and answer a questionnaire. We used asemantic differential scale to evaluate the effect on theiremotional states. Furthermore, we investigated the color
effect on individual’s emotion and feeling, comparing
between red and blue light emitting.
First, Fig.3 shows a comparative result between redand blue-colored light. From the results, the blue lightpromoted a feeling of relaxation and comfort more
effectively than the red light. This means that the colored
lights can affect the emotional valence depending on thecontexts represented by the color change. Next, Fig.4
shows a result of comparing the systems between in andout of synchronization with heartbeat rhythm. In the figure,the subjects that faced the visual feedback synchronizedwith their heartbeats have more strong emotional
reactions. We therefore assume that the feedback canincrease individual's interoceptive sensitivity andemphasize the feelings.

Fig. 4 Result of Comparing Systems between in andout of Synchronization with Heartbeat Rhythm
As future works, we intend to conduct some additional
experiments to discuss a method of light emitting andcolors to bring and encourage a feeling of relaxation.
Moreover, we will develop a multi light-emitting chairsystem to work on a study of emotional contagion.
REFERENCES[1] A.A Ayash R. T. Kane D. Smith P.G Armytage, “Theinfluence of color on student emotion, heart rate, andperformance in learning environments,” Color
Research and Application, Vol. 41, Issue 2,
pp.196-205, (2015)[2] A. Craig, “How do you feel? Interoception: the sense ofthe physiological condition of the body,” Nat Rev
Neurosci, Vol.3, No.8, pp.655–666 (2002)[3] J. Füstös, K. Gramann, B. M. Herbert and O. Pollatos,“On the embodiment of emotion regulation:interoceptive awareness facilitates reappraisal,”
Soc Cogn Affect Neurosci, Vol.8, No.8, pp.911–917(2013)[4] T. Obo, D. Takaguchi, D. Katagami, J. Sone,
T. Tomoto, Y. Ogai and Y. Udagawa, “HeartbeatDetection Based on Pulse Neuron Model for Heart
Rate Variability Analysis,” In Proceedings of the 2019
International Joint Conference on Neural Networks(2019)

4. SUMMARY
This paper presented a study to investigate thephysiological and psychological effects of light-emitting
chair. In this study, we developed a light-emitting chair thatcan emit light in synchronization with heartbeat rhythm,
using pneumatic pressure sensor for heartbeat detection.
To detect the heartbeat, we applied a fuzzy spiking neuralnetwork as a pulse oscillator to generate the simulatedheartbeat signal. Furthermore, we conducted somecomparative experiments to discuss the applicability of the
proposed approach.

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