Japanese Journal of Applied Psychology
2020, Vol. 46 (Special edition), 19-28

ArticleEffects of the angle between objects of gaze and a visual target whendriving a train1）
Kazushige WADA＊ and Makiko HATAOKA＊
Train drivers must look ahead and react to many kinds of signals or signs when driving a train. We investigatedwhether they could perceive a visual signal when driving a train in actual setting while paying attention to the ordinary
signal. In this experiment, train drivers (N = 41) were asked to blow a whistle as quickly as possible, when they see atarget light about 610-720 meters ahead. The target light was set to be seen at 0, 1.8, 3.3 degrees away from an ordinary signal on the rail track. Each driver responded for just one target. There were no missed target errors. However,RTs (Reaction times) analysis indicated that RTs for targets separated by 1.8 and 3.3 from the central vision was significantly longer than those at 0. We concluded that when driving a train, it is hard for drivers to respond to a target
that was separated from a focused object and discussed applicability of this result to driving environment and driver’s
education.
key words: train driving, visual attention, view field, eccentricity, actual setting of driving train

INTRODUCTION
Train drivers are required to look forward whendriving trains. A train runs on railway tracks and various objects, such as signals, signs, and stations, appear in the direction of travel. Safe driving isachieved by giving full attention to each of these objects and recognizing them correctly and taking appropriate actions. However, sometimes an unexpected
incident might occur while driving, such as an obstacle that appears suddenly, or a flashing signal indicating a problem at a railway crossing. Drivers are required to respond appropriately to these sudden incidents by accurately perceive them to maintain safe
driving. In other words, train drivers need to immediately identify sudden incidents while attending to theusual signals and signs. Therefore, visual information
processing is considered to play an essential role intrain operations.
Field of vision while driving
People observe objects using their central vision,
such that they perceive the object with high accuracy
using the central area of the retina. The field of cen1）

tral vision ranges by a visual angle of 2 degrees. Object recognition beyond this range is conducted by using the peripheral vision, in which the accuracy decreases as it gets farther from the central visual field.
Therefore, it is predicted that the response would deteriorate when a visual target appears away from thepoint of gaze (e.g., Carrasco, Evert, Chang, & Katz,
1995; Carrasco, & Frieder, 1996; Carrasco, & Yeshurun, 1998).
Many studies have been conducted on the visual
field of car. Crundall, Underwood, and Chapman(1999) conducted an experiment in which they
showed a video clip of the driver’s visual scene whendriving a car to the participants, place holders were
presented in the four corners with individual eccentricities from the center of the screen. When the eccentricity exceeded 7°, the hit rate decreased, and thereaction time was delayed. In this experiment, theprocessing demand was also manipulated based on
the level of hazard that could be perceived from thevideo. When the processing demand was higher, thereaction time was delayed. Miura (2002) used a realcar, pasted miniature light bulbs on the windshield

We would like to thank Kenichi Takehara, Katsuya Yamada, Shuji Fujimoto, Hiroko Takeuchi, and Yuji Morimoto for great assistance and cooperation in conducting of this experience and pilot study. We also thank to anonymous reviewers for helpfuladvice on this article.
＊
Safety Research Institute, West Japan Railway Company, 1-2-12 Matsuzaki-cho, Abeno-ku, Osaka, 545-0053, Japane-mail: kazushige-wada02@westjr.co.jp

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Japanese Journal of Applied Psychology, Vol. 46

with certain eccentricities, and responses to the miniature light bulbs that were flashed randomly were examined. The results indicated that when the degree oftraffic congestion increased, the eccentricity to which
participants could respond decreased. The above results suggest correlations between processing demand
and the field of vision. Williams (1982; 1985) also indicated a tunnel vision, such that when the processing
demand increases, the visual field becomes narrower.
Although visual attention is also important whendriving trains, only a few experimental studies havebeen conducted on the visual field of train drivers. In
train driving, the route has been determined in advance, which is different from driving a car, and adriver cannot arbitrarily change the route or choose
where to turn. Therefore, train drivers can allocate
more attention to the forward direction than car drivers. Therefore, when visual targets that disturb train
drivers, such as emergency signals or flying objects,
appear in front of trains, the driver’s response might
not be delayed even when the visual targets are far
from the gaze point to some extent.
On the other hand, close attention is paid to objects
that appear while driving a train even during regular
operations. Especially, signals notify the safetyconditions of the train tracks, and it is indispensablefor drivers to obey signals to maintain safety because
train drivers are responsible for their passengers, andsafe driving is their first priority. As a result, train
drivers tend to pay much attention to objects and instruments related to safety, such as signals, and when
they are looking at safety-related instruments or objects, their visual fields might become excessively
narrow.
As described above, the detection of visual targets
while driving trains has different characteristics fromcar driving. Therefore, empirical research is required
for train driving. In this experiment, we examined theeffects of eccentricities from the gaze point on the detection of visual targets in operation of an actual inservice train.
METHODS
PurposeOur purpose was to examine the effects of eccentricities from the gaze point on the detection of visualtargets that appear while watching a different object
when driving the train during an actual train operation setting (in service). Through this experiment, we
expected to examine attention condition to the gazepoint under a workload and the pressure of transporting passengers.
Participants
In-service train drivers (N = 41, 39 male and 2 females, mean age = 34.5, SD = 5.5) participated in theexperiment. The experimental conditions consistingof three types of target eccentricities were developed;
0°, 1.8°, and 3.3°. Participants were randomly allocated to each condition ( between-subjects design ) .
Twelve participants were assigned to 0°, 13 to the
1.8°, and 16 participants to the 3.3° conditions.
Dates and location
In this study, the section where the target might appear was set as approximately 20 km that included
five stations so that the appearance of the target might
be similar to a sudden incident, and drivers would not
be able to predict the point at which the target would
appear. The experiment was conducted on Aug 4-6,
2015, from 10:00 to 17:00, on a part of the JR Sanyomain line in Okayama and Hiroshima prefecture infine weather.
Gaze point and visual target
The experiment was conducted in an actual train
operation setting. It was necessary that the gaze point
was a real object, and the targets were objects thatwould be easily identified without a sense of incongruity when they appeared on train tracks. Therefore,
signals were regarded as the object of visual attention. Drivers carefully attend to signals, which engage
their visual attention most effectively, among otherobjects of attention for safety.
Firstly, in this experiment, a block signal that appeared while driving the train was the gaze point.
Block signals are placed in each block. The block is asection made by dividing the route between stations
into parts, such that only one train might occupy a
block at any given time. Block signals indicate
whether there is another train in the next block, i.e.,
whether the train can enter the block. By following
the signal, trains are able to maintain a distinct separation and assure their safety. To ensure safety, train
drivers must not miss block signals, and therefore, theK. WADA and M. HATAOKA: Effects of the angle between objects of gaze and a visual target when driving a train

The gaze

3.3 1.8 0 point

4

The signal
conĮrmaƟŽn sign

The lighƟng point:
68m from the conĮrmaƟon sign
Figure 1 Layout of target signals and the gaze point fromthe driver’s cab.

drivers’ visual attention is strongly focused on watching these signals.
Secondly, a light was used as the visual target.
However, if the same light as the block signal wasused as the target, the drivers might regard the target
as the real signal. On the other hand, placing an object that is not normally found on the railway tracks
might attract the drivers’ attention excessively andalso prevent the driver from responding, which would
also influence the safe operation of the train. Moreover, a red signal which is used to notify danger, or astop, would hinder the experiment and train operation.
Therefore, in this experiment, a device imitating an
obstruction warning indicator by using a green light
was developed. An obstruction warning indicator is asignal that usually emits a red light when problems
occur at railway crossings, and has a different shapefrom a blocking signal that is currently used. As a result, there was only a limited possibility of mistaking
these two signals and causing misunderstandings.
Moreover, by using a green light instead of a red
light, drivers were able to recognize that it is not arisk or a stop sign. The obstruction warning indicators
is one of major signs that notifies sudden incidents.
By confirming responses to a target that is similar tothe obstruction warning indicator, responses similar
to the responses to sudden incidents that might occur
in actual driving settings would be made. Based on
the above reasoning, the green light was consideredappropriate as the experimental stimulus.
The visibility distance was set to be identical to（ 21 ）

real obstruction warning indicators (over 800 m). If
the target light is too bright compared to obstruction
warning indicators, drivers might perceive it to be abnormal. Therefore, the visibility of the signal was
made as similar as possible to the real signal to examine responses to sudden incidents in actual settings.
The degree of luminescence was decided based on
the evaluations by participants with driving experience to ensure an identical degree of visibility.
Setting of visual targets
Three types of visual target eccentricities were prepared ; within the central vision, within the useful
field of view but outside the central and broader vision. The target within the central vision can be detected when drivers are looking ahead. The useful
field of view is close to the central vision, although it
is included in the peripheral visual field. The useful
field of view is the range of the visual field that contributes to perception, which has a visual angle of 4°20° (Miura, 2007). Considering that participants were
driving a train, the angle was set as under 4° ( theminimum angle, one side 2°). Moreover, a more extensive eccentricity condition was prepared because
the detectable range of the target might be wider.
These three conditions were set up using a curve. As
a result, the following three types of eccentricities
were prepared; 0°, 1.8°, and 3.3°, all on the left sideof the gaze point (Figure 1, 2). The targets were set
up using telegraph poles. Therefore, the three angles
were defined in accordance with the positions of thetelegraph poles. The target was not seen when the angle exceeded 3.3° , because of obstructions. Therefore, 3.3° was set as the maximum angle.
There were no height differences in this section. It
was confirmed that there were no obstructions between the target and the point where the target started
to flash. When the target started flashing, the distance
between the train and the target was approximately
610-720 m (Figure 2, Table 1).
Participants were instructed that the experiment
would be conducted in the 20 km-long section that
included the five stations (A, B, C, D, and E). The
targets were always presented between B and C,
whereas there were four sections in the experimental
section.
The signal confirmation sign was used as the refer-（ 22 ）

Japanese Journal of Applied Psychology, Vol. 46

The blocksignalT

Target light 3
Target light 2

Target light 1

The lighting point
Point of the signal
confirmation sign

Figure 2

Layout of target signals and the point of starting to emit light.

Table 1 Angle and distances of each condition
Target light Visual angle (θ)
1
2
3

0°
1.8°
3.3°

Distance (D)
610 m
671 m
718 m

ence point for deciding the point at which the targets
started to flash. The signal confirmation sign is a signfor instructing drivers to confirm the signal (go, becautious, or stop). This sign is almost put up to a telegraph pole, drivers usually confirm an index of signal
by calling or pointing when the train pass the sign.
When they found the signal (usually about 100 m before the signal confirmation sign), they continue tomonitor it until they reached the confirmation sign.
During this period, drivers kept watching the signal.
Therefore, the point at which the targets started to
flash was set within 100 m before the sign so that thetarget would start to flash when drivers were watching the gaze point. In this experiment, trains were observed, stimuli were presented, and responses were
measured from the side of the train track. Therefore,
landmarks were necessary to confirm the passing
train from the side of the track. A telegraph polestood 68 m before the signal confirmation sign, which
was useful for checking the passing train. When thefront part of the train passed the pole, a cue for emitting light was sent by the staff. That is, this pole wasregarded as the lighting point (Figure 3). The eccentricities of the targets were the angles when looking at
the gaze point from the point of flashing.
Apparatus and materials
Figure 4 shows the size and shape of the target

light. The width of the light-emitting part was 80 mm,
and the height was 400 mm. The light was set on apole with a height of 2300 mm rom rail track levels.
Flashing rate was 8.3 Hz.
The vehicles used in the experiment were 115, 117,
and 213 series trains. Participants used the whistle toindicate making a reaction, and experimenters judgedthat the response was made by the whistle. Participants could blow a whistle by stepping the foot pedal.
The experiment was conducted on a train with passengers. Devices, including foot pedal (for whistle),
power handles, and brakes, among others, were inspected in advance, and no abnormalities were confirmed. Measurements were made using two video
cameras (SONY HDR-CX680). The recording mode
was MP4 (resolution 1280 × 720), with a frame rate
was 30p. A transceiver (ICOM IC-DPR6) was used
for transmitting signs, among others.
Tasks
Participants were instructed to immediately blow awhistle when they found the target of green light
flashing at a specified spot when driving the train.
The target light started flashing at the moment when
the train reached the lighting point. Participants werealso instructed that the target would be placed atsome point along the railroad track between A Stationand E Station ( distance = 19.3 km, driving time =about 20 minutes). However, the exact place where
the target would be encountered was not specified inadvance.
Procedures
Figure 4 shows the experimental procedures. All
the participants were instructed about the experimental procedures 1-6 days before the experiment. The

K. WADA and M. HATAOKA: Effects of the angle between objects of gaze and a visual target when driving a train

1-6 days ago

Pre-instruction

Experimental day

Practice
trial

Instruction

Start ofdrivingStart ofpractice

Figure 3

Figure 4（ 23 ）

Experimental trial

A sta. (EndEnd
of practice)

Final interview

B sta.
a. C sta.
E sta.

Experimental procedures

The green target
light used in theexperiment

instructions stated that a green light would appear
when they would be driving the train between A station and E station. When they noticed the light, they
have to blow a whistle immediately. A picture of thegreen light was shown to them and they were requested not to tell the place where they observed thetarget to other participants after the experiment. After
instruction, the participants informed consent to takepart in the experiment was obtained.
On the day of the experiment, we arranged experimental staffs at the starting station of train driving(staff A), the practice section (staff B), the lighting
point (staff C), the video recording point (staff D), thesetting point of the target (staff E), and the end stationof train driving (staff F), as shown in Figure 5. Participants were again explained the procedure by staff
A before they started to drive. When the train entered
the practice trial area, the target started flashing on
the left side of the railroad track. The practice trial
was conducted in a straight section of the railway-linewith good visibility. After confirming the response to
the target in the practice trial (staff B), the train entered the experimental section of the trial.
When the train reached the lighting point, the staff
C gave the other staff a cue using a transceiver, andthe staff D immediately turned on the target light.
Participants blow the whistle as soon as watching the
flashing light. The target kept flashing until the driver
blew the whistle or passed the target (all the drivers
responded before passing the target). After the trainreached the final station and halted, the drivers wereasked about immediacy of response by staff F, “Didyou blow the whistle immediately when you noticed
the green light?” The drivers responded using a fivepoint scale ranging between 1 (Responded at once) to
5 (Considerably delayed).
The experiment was conducted for three days. The
conditions were changed between the morning andthe afternoon. As shown in Table 2, the experimental
conditions were designed such that the number of trials in each condition was equal as much as possible.
This experiment was conducted using in-service
car in actual settings. All experimental staff played
their roles out of trains.

（ 24 ）

Japanese Journal of Applied Psychology, Vol. 46

Staff E
Staff A

Starting
station ofdriving train

Staff B

Whistle!

The lighting
point

Practicetrial section

Staff F

Staff C

FinishingstationStaff D
Camera A
Camera B

D0
D2

D1
P1

PR

P0

Point of actuallylighting the target

Point of reactingof whistle

Point of settingof camera A, B

Figure 5 Layout of experimental staffs, apparatus and each point of measurement

Table 2 Assignment of each condition (number ofsample)Days

Morning
Afternoon

1st

2nd

3rd

3.3° (6)1.8° (9)0° (5)
3.3° (10)1.8° (4)0° (7)

Measurements
Two video cameras were used for making themeasurements (Figure 5). These two cameras wereset at almost the same point (P 0 ) so that the two videos can be synchronized. Camera A with a microphone recorded the flashing target as well the whistle.
Camera B also recorded the whistle to be synchronized with Camera A and the scene of a train passing
the specific landmark in front of the camera for calculating the speed of the train. The railroad track was
gently curved from where the target was flashing (P1)to the point where the target was set up. Therefore, it
was a coasting section without acceleration, and it
was considered that the speed at the point where thetarget started flashing was kept maintained to thepoint where the driver made a response.
The reaction time and reaction point were calculated based on the videos taken from Cameras A andB using the following procedure. First, the time fromthe target starting to flash to the whistle blow wasanalyzed using Camera A, which was regarded as theassumed reaction time ( RT 0 ) . Moreover, the timefrom the front of the train passing the landmark to theend of the train passing the landmark was measured
using Camera B, and the speed of the train was calculated (V m/s). The length of the train was 20 m a car.
Time was calculated using the frame rate (30p) of thecamera.
Next, two videos were synchronized using thewhistle recorded by the two cameras and the timefrom the target starting to flash to the train passing
the landmark was measured (T1). By using T 1 and V,
the distance (D 0 ) from P 1 to P 0 was calculated using
the formula below (Although the point where the target started flashing was theoretically defined, in reality, the flashing was started manually by a cue from astaff member, which might have caused some errors.
Therefore, the accurate position was calculated
through the analysis).
D0 = V × T1 (1)D0 = D1 + D2 (2)D1 = distance from P1 to PR (reaction point)
D2 = distance from PR to P0
RT 0 includes the traveling time from P 1 to PR andthe sound propagation from PR to the camera. RT 0 is
expressed as follows by regarding the speed of soundas 350 m/s,
RT0 = D1/V + D2/350 (3)（ 25 ）

K. WADA and M. HATAOKA: Effects of the angle between objects of gaze and a visual target when driving a train

E station

A station
Block signal
‫ۑ‬

0 deg

‫ڹ‬

1.8 deg‫ڧ‬

3.3 deg

616m from thelighting point

3.3 deg
Camera setting point

The lighting point

View pointof staff C

1.8 deg
0 deg

Signal confirmation sign

Figure 6 Bird’s-eye view of the reaction distribution and stimulus points

Based on (2) and (3), the accurate reaction time
(RT 1 ) from the start of flashing to the reaction point(PR) was calculated.
RT1 = D1/V (4)(D1/V = RT0−D2/350)
The reaction point was plotted on the map after it
was identified. By measuring the distance on themap, the angle between the gaze point when the response was made, and the target was calculated bymeasuring each direct distance between the reaction
point and the gaze point, between the reaction point
and the target, and between the gaze point and the target by using the second cosine theorem. The calculated reaction times and angles were used for analysis. Both Cameras A and B were fixed at the same
point for three days.
RESULTS
Reaction points from a bird view
The calculated points where the whistle was blown
were plotted on a map of the experimental site (Figure 6 ) , which indicated that the range of reaction
points extended as the angle increased. The numberof participants that made a response before the signal
confirmation sign, at which point they were expectedto pay the most attention to the gaze point, was 8(75%) at 0°, 2 (15.4%) at 1.8°, and 1 (6.3%) at 3.3°.
A chi-square test was conducted on these ratios,
which indicated a significant difference ( χ 2 ( 2 ) =14.02, p < .001). Multiple comparisons using Ryan’s

method were conducted, which indicated that the
number of reactions made at 0° was significantly
larger than to 1.8° and 3.3° (0° vs. 1.8°, p = .015; 0°
vs. 3.3°, p = .002). There was no significant difference between 1.8° and 3.3° (p = .57).
Reaction performance
Error rate There were no participants that did
not respond between the target starting to flash andreaching the target, indicating that the error rate was0%.
Reaction time The time from the target starting
flashing to a driver blowing the whistle was regarded
as RT, and the values were logarithmically converted
and compared among the conditions (Figure 7). A
one-way analysis of variance ( ANOVA ) was conducted, which indicated a significant main effect offactor (F(2, 38) = 6.07, p = .005, ηp 2 = .24). Bonferroni’s multiple comparisons indicated a significant
delay in RT at 3.3°, compared to 0° (p = .004) and afurther delay in RT at 1.8°, compared to 0° (p = .06).
No significant differences were shown between 1.8°
and 3.3° (p = 1.00).
Moreover, the speed of the train, age, and experience of the driver was compared among the conditions as indices affecting the RT. Each one-way
ANOVA indicated no significant main effect of thefactor (Table 3, speed; F(2, 38) = 0.28, p = .76, ηp2 =.01; experience; F(2, 38) = 0.75, p = .48, ηp 2 = .04;
age; F(2, 38) = 1.52, p = .23, ηp 2 = .07). The experiment was conducted outdoors. Therefore, the effect（ 26 ）

Japanese Journal of Applied Psychology, Vol. 46

of sunlight was analyzed before and after lunchtime(13:00-14:00) (Table 4). A two-way ANOVA; eccentricity (0°, 1.8°, 3.3°) × before/afternoon indicated asignificant main effect of the eccentricity (F(2, 35) =5.12, p = .01, ηp 2 = .23). On the other hand, there
were no significant main effect of before/afternoon (F(1, 35) = 2.72, p = .11, ηp2 = .07) and interactions (F(2, 35) = 0.28, p = .76, ηp2 = .22).
Degree of eccentricity at the reaction point
The visual angle between the gaze point at the reaction point and the target was calculated, and a oneway ANOVA was conducted (Table 3), which indicated a significant main effect of the factor (F(2, 38)= 1037.09, p < .001, ηp 2 = .98). Bonferroni multiple
comparisons indicated that there were significant differences between all three conditions (0° vs. 1.8°, 0°
vs. 3.3°, 1.8° vs. 3.3°; ps < .001).
Immediacy of response The percentage of participants that answered 4 or 5 was 0% , suggesting
there was no delay in responding to the target. Moreover, the rating score was reversed and analyzed by aone-way ANOVA (4.67 vs. 4.77 vs. 4.88). There wasno significant main effect of the factor (F(2, 38) =0.65, p = .53, ηp2 = .03)

8.0

6.1
5.1

RT (s)

6.0

DISUCUSSION
We experimentally investigated whether a driver
could correctly perceive a target if a visual target appears while watching an object while driving a train
and whether the perception was affected by the position of the target were examined in an actual train operation setting. The results indicated that the drivers
did not miss the target, although they were not informed of the position of the target in advance. However, RT was affected by the eccentricity of the target
from the object of the gaze. When the eccentricity increased, RT increased. There was neither differencein RT based on the speed or the drivers’ age or experience nor interaction between eccentricity and sunlight. Therefore, the above results were considered tohave resulted from eccentricity.
It has been indicated that when a visual target appeared while driving a car, the driver might be able torespond to it when the angle between the object of thegaze and the target is smaller than 3.3°, suggesting
eccentricity might not affect the accuracy of perception. However, the RT differed. RT at 1.8° and 3.3°
were delayed compared to 0° , suggesting that although participants could cope with an eccentricity
exceeding the central vision when the target started
flashing, they could cope with larger eccentricities
with time. This issue is discussed below.

2.7

4.0

Table 42.0

Means and SD of RT in each condition
Eccentricity

0.0
0 deg
Figure 7

1.8 deg
Eccentricity

3.3 deg

Morning
Afternoon

Reaction time under each condition (error bars
represent standard errors)

Table 3

M
SD
M
SD

0°

1.8°

3.3°

2.79
2.61
2.72
1.57

3.41
1.40
5.83
2.80

4.70
2.56
6.92
3.22

Means and SD of Speed, age, driver experience, and eccentricities of reaction points in each condition
0° (n = 12)

Speed (km/h)
Age (years)
Driver experience (years)
Eccentricities of reaction points (°)

1.8° (n = 13)

3.3° (n= 16)

M

SD

M

SD

M

SD

90.3
33.7
8.6
0.0

4.0
9.9
10.7
0.0

89.5
42.0
13.6
2.3

3.9
13.5
11.4
0.2

90.5
36.3
9.4
3.9

3.1
11.8
9.8
0.3

K. WADA and M. HATAOKA: Effects of the angle between objects of gaze and a visual target when driving a train

The eccentricity changed depending on the position. Participants might find and react after eccentricities of 1.8° and 3.3° conditions were within central
visual field, 1°. However, when analyzing the eccentricity at the reaction point, eccentricities of 1.8° and
3.3° were larger than 0°, suggesting that participants
did not make a response after the eccentricity was included in the central vision. The reaction was rather
made in the larger eccentricity than 1.8° or 3.3°. It is
possible that responses made just after the flashing
started and responses at places further away from thepoint where flashing started were made using different strategies.
This idea was supported by the significant difference indicated by the analysis of the reaction ratioaround the signal confirmation sign. Compared to 0°,
participants made a response more often after passing
the confirmation sign at 1.8° and 3.3°. In other words,
perception for dealing with larger eccentricities thatexceed the central vision might be conducted after
passing the confirmation sign. The confirmation of
signals is an important task for train drivers, which isindispensable for driving safety. Therefore, drivers’
attention to signals increases, and perception in thecentral vision is prioritized at the point where they are
required to check a signal. On the other hand, drivers’
attention to other objects might increase, and theymight try to explore a range of fields after passing theconfirmation point, and drivers are released from theneed to attend to the signal strongly. As a result, theiruseful field of view might expand at least to around4°, or the central vision might shift in the curve direction.
The above findings indicated that when driving a
train, it is difficult to respond to a target appearing
outside of the central vision while closely attending
to an object. On the other hand, it becomes possible
to perceive things outside of the central vision after
being released from focusing on the object. Therefore, participants did not miss the target of perception.
Possible application of experimental results
The results of this experiment suggest that the visual field narrows while watching the gaze point. The
present study was conducted in the actual in-service
situation, using the target setting that the appearance（ 27 ）

position was unexpected. Therefore, the following
applications of the results of this study are suggested
for sudden incidents. Firstly, critical signals or signs
that appear out of the central vision might be missed
in sections where drivers must focus attention on theblock signal. Therefore, especially, signals that need
to be detected when they are emitted, even though
they usually not emitted, such as obstruction warning
indicators, should be placed in an area where they canbe easily detected.
Secondly, regarding drivers’ education, there is apossibility that drivers might miss things that appear
out of the central vision, although usually things thatappear in the direction of travel are easily perceived
when driving a train. In the present experiment, on
average, 2.1-3.5 second delays were observed. Whena train is running at 90 km/h, which is identical to the
speed in this experiment, a 3-second delay will increase the stopping position by 75 m. Although the
distance of visibility of signals is over 600-800 m, it
includes the braking distance, whereas the distancerequired for identifying an object is not considered
carefully. The risk of collision is increased by overrunning the stopping position by 75 m. Based on thedata obtained from this experiment, drivers are able
to recognize the risk. Moreover, such phenomena
tend to occur when watching important items, such as
signals. Therefore, places that need careful attention
are easily identified, and necessary measures can betaken in advance, such as trying to expand the visual
field by accurately confirming essential factors.
It was indicated that target detection decreases
when watching an object while driving a train. This
result might be applied to improving the driving environment and drivers’ education. There are only a few
studies on visual attention when driving a train (e.g.,Dunn, & Williamson, 2012 ; Luke, Brook-Cater,
Parkes, Grimes, & Mills, 2006). It is suggested thatstudies that are applicable to actual train operation
settings should be conducted in the future.
References
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eccentricity effect: Target eccentricity affects performanceon conjunction searches. Perception and Psychophysics,
57, 1241-1261.

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Japanese Journal of Applied Psychology, Vol. 46

Carrasco, M. , & Frieder, K. S. 1997 Cortical magnification
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(Received: 2019.8.2; Accepted: 2020.2.19)