Development of Applications for a Wearable Electrode Embedded in Inner Shirt

2.1 First hitoe Cup Heartbeat Shogi Tournament

Heartbeat Shogi is a name we coined for this event. It is a shogi (Japanese chess) TV program in which the heart rates of the players wearing hitoe shirts were measured and displayed to visitors on monitors and to an online audience over the Internet. We were looking for a new form of entertainment in which viewers could not only enjoy the battles taking place on the game boards and the body language of the players but could also understand the physiological changes the players were experiencing that we usually have no means of knowing about from their outside appearance. We set up a tournament and invited three professional players to take part in it (Fig. 2). The players wore hitoe inner-shirts during the matches.

Fig. 2. Heartbeat Shogi.

The heart rates of the players during the final game are shown in Fig. 2(b). The heart rate is plotted along the vertical axis and the shogi move number along the horizontal axis. The heart rate of Shingo Ito, 5-dan (on the right in Fig. 2(a)), was within the 70- to 80-bpm level throughout the entire game. The heart rate of Naohiro Ishida, 4-dan (on the left in Fig. 2(a)), on the other hand, tended to rise from the middle game and even reached the 160-bpm level in the endgame. Such information was delivered to the audience in real time by integrating the wearable technology with an Internet image relay.

If we focus on more subtle heartbeat variations, we see that the heart rate of Ishida peaked at 7-2 rook in the middle game (Fig. 2(b)). This occurred at a game position where he took Ito’s bishop. Ishida’s heart rate continued to rise even in the endgame until Ito resigned. We think that this gives a glimpse into the correspondence between heartbeat variations and game position and can become a method of conveying a further sense of excitement to the audience.

Naohiro Ishida won the tournament and was given the title of First hitoe Heartbeat Shogi Meijin by Hiroo Unoura, President & CEO (Chief Executive Officer) of NTT. A better understanding of the relationship between heartbeat variations and emotional state was gained from the post-game discussion. Ishida, 4-dan, thought back and said that “The endgame was so tense, I could feel my own heartbeat. Even though I was playing aggressively and was in the lead, one false move and I would have lost the game.” We can infer from this that the anticipation of making the most of his chances in the game caused him inner tension. Ito, 5-dan, said that “By the endgame, I thought I had already lost, so I was completely relaxed.” This perspective might be one reason why his heartbeat variations were stable through the game. With shogi, decisive moments and relative superiority according to the game position can be seen on the board. However, the players’ own evaluations of the board positions and their level of tension can usually only be determined by their expressions or actions. We expect that the display of heart rates as an element that mirrors changes in the tension and emotional state of the players during games such as shogi will add new interest for viewers.

2.2 Analog game workshop at Heartbeat University

Heartbeat University is an educational program led by instructors with interests in particular areas. The first instructor we invited to be part of this program was Jun Kusaba, the originator of Game Market, Japan’s largest analog game experience and sales event and also the executive of the Gaming History Society. He gave a lecture and led workshops in an analog game. During the workshops, participants who were acting as students played an analog game under the coaching of Mr. Kusaba. The students wore hitoe shirts, and their heart rates were measured (Fig. 3(a)). We used the card game called Divinare in the workshop sessions (Fig. 3(b)). There are cards in four colors (red, blue, yellow, and green), and the game involves correctly predicting how many cards of each color were dealt. In this game, the luck and hunches of the players feature highly, in contrast to shogi, and even a beginner has a chance of winning. It was therefore expected that the heartbeat variations would be different from those of the shogi players. Each student was given three points if the predicted number of cards matched the correct number of cards, one point if the number differed by one, and minus one point otherwise.

They played four rounds and competed for the total number of points. An example of a student’s heartbeat variations is shown in Fig. 3(c). A rise in heart rate can be seen near the end of each round. This was assumed to be related to the way that the difference in his predicted number of cards and the correct number of cards was revealed at the end of each round; the previously unknown correct number of cards is gradually revealed as the game progresses. One student replied in a questionnaire given after the game was finished, that after the second round, “I was in fine form so I thought I might win if I carried on” and after the fourth round, “I thought that I would definitely hold on to my lead and receive a prize.” This shows that it is possible for such anticipation and agitation to be reflected in the heart rate.

Fig. 3. Heartbeat University.

However, variations in heart rate such as those of this student were not the only interesting example. There was another student whose heart rate remained about 30 bpm higher than usual from beginning to end, irrespective of developments during the game. To integrate biosignal measurements effectively into entertainment, it is important that repeatability between large numbers of people is confirmed and also that variations in the biosignals are presented in correspondence with the event in a way that the audience can understand. It is essential to explore the concept of creating events based on an understanding of the mechanisms of the body, then to search for methods of applying biological information from various viewpoints.