Effects of moving task condition on improving
operational performance with slight delay
Yakumo Miwa*

Kenji Funahashi†

Koji Tanida

Shinji Mizuno

Nagoya Inst. of Tech., Japan

Nagoya Inst. of Tech., Japan

Kindai University, Japan

Aichi Inst. of Tech., JapanA BSTRACT
We made a hypothesis that appropriate delay in operational system
would improve its operational performance from some reviews andpapers. As an experimental result, performance was improved inslight delay. The sensory evaluation also confirmed that the subject
felt support even though there was no actual force support. Anotherexperiment confirmed that depth movement restriction, and the moveratio of the virtual tool on a screen to the input device affected toimprove performance. We also investigated that difference of task
conditions, i.e. moving task distance and target area size, affect toperformance improvement.

Figure 1: (Left) Screen of experiment 1, (Right) Screen from experiment 2 onward

Index Terms: Human-centered computing—Interaction design—
Empirical studies in interaction design
1

I NTRODUCTION

It is generally believed that latency has a negative impact on tool
operation. However, Japanese car maker “Mazda” said that a slightdelay is a necessary factor apparently —When you start to move theaccelerator pedal, the time until the tension of the neck muscle starts
is constant at 0.2 to 0.3 seconds. It is the first necessary condition
that acceleration is generated in accordance with the “timing of thestance” to realize a reasonable and natural reaction (last part ofsection 2.2 in reference [4]). Based on this opinion and previous
experiments in which delays made subjects feel partial interference
from others that did not exist [2], we made a hypothesis that appropriate delay in operational system would improve its operationalperformance. Our previous experiment [1] was conducted in tasks
that were somewhat more complex than simple button pressing operations [2]. A reach extender was displayed in a screen. Subjects
operated it with a 3D position input device. They moved a ball froma table to another table by a reach extender (Figure 1(left)). Delay
was inserted intentionally between the operation of an input device
and the response of a reach extender. As a result, performance wasimproved (i.e. the average time to move the ball decreased) in slightdelay of about 50 to 100 ms (Figure 2(left)). However, we havenot concluded that slight delay improves performance anytime inany condition. Therefore, we researched which conditions affect theimprovement in operational performance due to slight delay [3]. We
prepared new experimental system which did not show performance
improvement in a same task (Figure 1(right)). Parameters weredecided with trial and error. The experiment confirmed that depth
movement restriction, and the movement ratio of the reach extender
on a screen to the input device affected to improve performance. The
sensory evaluation also confirmed that the subject felt support eventhough there was no actual force support. We also investigated thatdifference of table conditions, i.e. moving task distance and target
table size, affect to performance improvement. However, the main
objective of this study is not to focus on the mechanism by which* e-mail: y.miwa.915@stn.nitech.ac.jp† e-mail: kenji@nitech.ac.jp

Figure 2: (Left) Result of operating time of experiment 1, (Right)
Result of operating time of experiment 2-5

delay improves performance, but rather to identify the conditions
under which performance improvement occurs.
2F IRST EXPERIMENTThe first experiment [1] is referred to as experiment 1. In the experiment 1 (and following sections’ experiments), a PHANTOM(Geomagic Phantom Omni) was used as an input device, and a22-inch LCD display was used as the output device. The subjects
operated the reach extender on the screen using a PHANTOM tomove the ball object on the screen from a table to another table.
Delay was added between the PHANTOM and the reach extender toimplement the delay from the subject’s hand to the extender and themovement of the object. It was necessary to measure the movement
time of the object to obtain the operation scores. It was also needed
to clearly distinguish between steady state and transient state. A“lid” was drawn on the object to visually indicate that it was fixed.
The reach extender on the screen was also restricted to move, andthe PHANTOM was fixed. A 3-second countdown was displayed innumerals to announce the start of the movement operation. After thecountdown, the subject could move the reach extender. If the positional relationship between the tables was always the same, subjects
might become accustomed to the operation, so the position of thetables could be changed. These distances should not differ significantly, because changing the distance between each other would not
maintain fairness among tasks. The delay in this experiment (andfollowings ) was 0 ms to 450 ms, with 10 steps of 50 ms, and eachsubject performed 10 movement tasks in a trial. In experiment 1, 20
subjects were assigned 5 trials and 5 delays per a subject in random
order. Performance was improved in slight delay.

Table 1: Table size and positioning, and ratio of hand to screen
coordinate distance
Hand coord. dist.
71.8/156/156/220
46/67/147/161
46/67/147/161
46/92/201/220
58/67/147/161
58/92/201/220

Screen coord. dist.
56/122/122/173
72/89/222/239
35/52/114/126
35/71/156/171
44/52/115/126
44/71/156/171

Large
Depth

(diameter/vertical dist./horizontal dist./direct dist.)Expt.1
Expt.2 & 3
Expt.4 & 5
Expt.6
Expt.7
Expt.8

Table 4: Combination of conditions and results of all expt.

Ratio0.78
1.48
0.78
0.78
0.78
0.78

Table 2: Combination of conditions and result of expt.2–5

Restrict.

Ratio

Narrow

Wide
Expt.1 [*]§
P=4.34%

Expt.7 [#]P=22.6%
P=27.2% [#]Expt.8 [#]P=36.2%
no imp. [–]

0.78
1.48
0.78

No restrict.

1.07
1.48

Small
Narrow
Wide
Expt.5 [*]P=5.00%Expt.3 [#]P=34.8%
Expt.4 [#]Expt.6 [–]P=36.8%P=54.8% [#]no imp. [–]Expt.2 [–]§ Different window size, depression angle of gaze, color tone and shading[∗] Improvement with 5% significant difference[#] Improvement with no significant difference[–] No improvement

Movement ratio
0.78
1.48
Expt.5 [*]Expt.3 [#]Depth movement
Yes
P=5.00%P=34.8%
restriction
Expt.4 [#]Expt.2 [–]No
P=36.8%[∗] Improvement with 5% significant difference[#] Improvement with no significant difference[–] No improvement

Table 3: Combination of conditions and result of expt.4 & 6–8
Dist. of table
Narrow
Wide
Expt.7 [#]Expt.8 [#]Large
Size of Table
P=22.6%
P=36.2%Expt.4 [#]Expt.6 [–]Small
P=36.8%[#] Improvement with no significant difference[–] No improvement

3E XPERIMENT A BOUT D EPTH R ESTRICTION AND M OVE MENT R ATIO

Experiments 2–5 examined the effects of two elements, depth
movement restriction and the movement ratio of the reach extender
on a screen to the input device, on the improvement of slightdelay [3]. Although procedure of experiments were same as a firstexperiment, the system was renewed in terms of, for example,
window size, color tones, and shading. In experiment 2, 30
subjects were assigned 8 trials and 8 delays. In experiment 3, 24
subjects and in experiment 4 and 5, 10 subjects were assigned 10trials and 10 delays. The conditions, combination and results areshown in Table 1 and Table 2. It was suggested that the restriction
and the ratio of movement affected to improve performance(Figure 2(right)). In experiment 2, the subjects were informed inadvance that it might assist or disturb them with a force display
device even though any force was not provided actually. Sensory
evaluation was conducted after the experiment. The result showedthat the subjects felt that they were assisted at delays of 50 to 150 ms.

4

E XPERIMENT A BOUT TABLE C ONDITIONSExperiments 6–8 examined the effects of two elements, the distance
between tables and the target table size, along with experiment 4.
System and procedure of experiments were also same as previousexperiments. In experiments 6–8, 5 subjects were assigned 10 trials
and 10 delays. The conditions, combination and results are shownin Table 1 and Table 3. The table distances in experiments 6 and 8
were wider than in experiment 4, and the table sizes in experiments 7and 8 were larger than in experiment 4. Other conditions were same
as experiment 4; there was no depth movement restriction and moveratio was 0.78. The results of experiments 6–8 show that the averagetime of the task operation was longer for larger delays in general
as in previous experiment 4 (Figure 3). In experiment 7 and 8, it
was slightly shorter with 50 ms than with 0 ms delay as in previous
experiment 4. Although there were no significant differences, thep-values and the result that the performance was not improved inexperiment 6 would seem to suggest that closer table distance andlarger table size were associated with better performance (Table 3).

Figure 3: Result of operating timeof experiment 4 & 6-8

Figure 4: Appearance of experiments

By the way, four experiments with a ratio of 1.07 had been also
conducted earlier as preliminary experiments (Table 4). Although
there were no significant differences in these as well, it appeared thata similar trend could be observed. However, it is not clear whether
further increasing the table size and decreasing the distance would
lead to better results.
5 C ONCLUSION
We have made a hypothesis that appropriate delay in operational
system would improve its operational performance. In our previous experiment, performance was improved in slight delay. We
researched which conditions affect the improvement in operational
performance due to slight delay. Table size and distance would haveless affect than depth restriction and movement ratio. These findings
will contribute to VR interface design. In the future, we would liketo examine other combinations, and with further changes in movement ratio, table distance, and table size. We would also like to testfor differences in window size, depression angle of the gaze, color
tone, and shading, which have not yet been closely examined. Afterthe conditions for the positive effects of delay are found out, theaddition of slight delay will be considered for an operating devices.
It would surely have a significant influence on the UI and enrich theexperience associated with the operation.
ACKNOWLEDGMENTS
This work is supported in part by JSPS KAKENHI Grant Number
JP20K11918 and JP23K11182.
R EFERENCES[1] R. Akimoto, M. Miyaji, K. Funahashi, K. Tanida, and S. Mizuno. Positive effect of slight delay for operational performance,. In Proc. of theGCCE 2021, pp. 162–166, 2021.
[2] C. Farrer, G. Valentin, and J. M. Hupé. The time windows of the senseof agency. Consciousness and Cognition, 22(4):1431–1441, Dec. 2013.
doi: 10.1016/j.concog.2013.09.010[3] Y. Miwa, K. Funahashi, K. Tanida, and S. Mizuno. Positive effect ofslight delay and task conditions for operational performance. In Proc. ofthe GCCE 2023, pp. 460–464, 2023.
[4] H. Watanabe, K.Tanaka, H.Kuniwake, and T. Yamaguch. Performancefeel for new demio. In MAZDA tech. review (in Japanese), pp. 42–47,Jan. 2015.