
K. Yoshino et al. / Natural Science 3 (2011) 255-258
Copyright © 2011 SciRes. OPEN ACCESS
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subjects while they watched a Japanese professional
baseball game at a stadium. We analyzed how their heart
rate responses to events during games correlated with
their subjective psychological states.
2. METHODS
Ten subjects (five females and five males between the
ages of 21 and 53 years) participated in the on-site
physiological data collection sessions, after providing
their informed written consent approved by the ethical
committee at AIST. All subjects were fans of the Hok-
kaido Nippon-Ham Fighters, a Japanese professional
baseball team, and had been to the Sapporo Dome to
watch Fighters’ games 28 to 250 times.
Subjects watched Fighters’ games at the Sapporo
Dome. We collected physiological data while they
watched the games. Eight subjects watched three games
(one in July, one in August, and one in September of
2008); one subject watched one game in September of
2008; and one watched two games in July and August of
2008. We collected a total of 27 cases. All subjects were
seated in the infield zone. We recorded their RR-inter-
vals with a wearable electrocardiogram device (Active-
Tracer, AC-301, GMS, Japan), from about 5 min before
the start of the game until 10 min after the end of the
game. Typically, the length of a baseball game is 180 min.
We also recorded video images of each subject’s be-
havior. Subjects watched their video images on a sepa-
rate day and recalled their subjective psychological
states at specific events as they watched the games. The
specific events were the Fighters’ and opponents’ scoring
and four fan service events. The four fan service events
were two types of dancing exhibitions, the Fighters’
cheering song, and a show by the Fighters’ mascot. The
subjects registered the intensity of their psychological
states on a 100 mm-long visual analogue scale (VAS)
questionnaire, for which the end points were labeled
“lowest” and “highest”. The questionnaire quantified the
intensity of eight psychological states: happiness, ten-
sion, fatigue, boredom, depression, anger, vigor, and
excitement. Tension, fatigue, depression, anger, and vigor
are scales on the well-known Profile of Mood States
(POMS) questionnaire [10]. In addition to these scales,
we adopted the scales happiness, boredom, and excite-
ment since these intensities vary greatly in an entertain-
ment environment. To reduce inter-individual variability,
we normalized the measured values of psychological
state intensity by transforming the data to a z-score for
each subject.
Figure 1 presents an example of the time course of a
subject’s heart rate from the beginning to the end of a
game. Clearly, heart rate increased when the Fighters
scored.
Figure 1. Example of the time course of a subject’s heart rate
from the beginning to the end of a game. Heart rate increased
when the Fighters scored.
We fitted a linear regression line to the time course of
heart rate measured from the beginning to the end of a
game and then calculated the heart rate response to spe-
cific events. The heart rate response was defined as the
mean deviation of heart rate variability from a linear
regression line from 5 sec before to 25 sec after an event
during a game. The heart rate responses to Fighters’ and
opponents’ scoring and to four fan service events (two
types of dancing exhibitions, the Fighters’ cheering song
and a show by the Fighters’ mascot) were calculated.
The correlation coefficients of the heart rate responses to
the specific events and z-scored psychological state
scores were calculated. The grand mean value of heart
rate response to scoring events in July of 2008 was then
compared with those in August and September of 2008.
We also analyzed how fan career, measured by the total
number of past visits to Sapporo Dome to watch Fight-
ers’ games affected the subject’s heart rate responses to
scoring events.
3. RESULTS
Table 1 summarizes the correlation coefficients be-
tween heart rate responses to scoring and fan service
events and z-scored subjective psychological state inten-
sities. Figure 2 shows the scatter plots from comparing
heart rate response to scoring and fan service events with
the corresponding subjectively evaluated normalized
intensity of happiness. Heart rate responses indicated
significant positive correlations with the subjective
evaluation of happiness (r = 0.56, p < 0.0001) (Figure 2).
Moreover, it indicated significant positive correlations
with vigor (r = 0.55, p < 0.0001) and excitement (r =
0.49, p < 0.0001).
The grand mean heart rate response to Fighters’ scor-
ing in July of 2008 (12.95 bpm) was twice as high as