A Study of Sense of Self-Agency Focused on
Noise and Delay in Multiple Input Operation
Toshiki Kataoka∗ , Kenji Funahashi∗ , Koji Tanida† and Katsuya Yashiro‡∗ Department of Computer Science, Nagoya Institute of Technology, Japan† Department of Mechanical Engineering, Kindai University, Japan‡ Automobile R & D Center, Honda R & D Co., Ltd., Japan

Abstract—Sense of self-agency has been proposed in psychology field, and it is the sense that I am the initiator or source of theaction. Human perception should be considered to design a betterinterface, so that sense of agency is spotlighted in ergonomics androbotics interface design field. In previous study we concluded
that sense of agency is affected by both of a noise and a delayin the case of an operation between an action (input signal) andits effect (output signal). In this study we tested the sense in thesituation that required multiple inputs like car driving operation.
We considered that the behavior of sense of agency by each ofa noise and a delay for each of multiple input. The knowledge
may be applicable to an interface required complex operations.
Keywords—Ergonomics; Robotics Interface; Psychology; Senseof self-agency;

I. I NTRODUCTION
The operational feeling is deteriorated by noise and delay ininteractive operation due to the performance of the interface.
Usability is generally evaluated by various factors, and thedegree of operational feeling affects user’s satisfaction for
the interface. Incidentally, sense of self-agency which is thesense that I am the initiator or source of the action has been
proposed in psychology field [1]. Human perception should
be considered to design a better interface, so that sense ofagency is spotlighted in ergonomics and robotics interface
design fields [2]. The researches about the sense of self-agency
have focused on discrete operation like turning indication on
at the pressing of a button [3]. Therefore we have focusedon continuous operation. In previous study we discussed thesense of self-agency to find out the change of the sense for achange of delay and cross-correlation, which is the degree ofnoise between an action as an input signal and its effect as anoutput signal. We concluded that the sense of self-agency isnot dependent on the operation form and the presentation typeof the output and is affected by both of a cross-correlation
and a delay in the case of an operation between input andoutput [4]. However there are interfaces that required multiple
inputs and multiple outputs like car driving operation. In thisstudy we considered the sense of self-agency in the situationof car driving that require two inputs (steering wheel andaccelerator pedal) and two substantial outputs (the amount ofchange in front-back direction and left-right direction, we do
not consider that driver feel to control revolution of engine
and steering angle). Here each of the left-right direction andthe front-back direction is affected by both inputs. A similar
result was obtained for multiple inputs, the knowledge may be
applicable to interfaces requiring complex operations like cardriving. It is expected that this is useful for ergonomics androbotics interface design.

II. E XPERIMENT
We consider sense of agency in car driving operation as oneof the interfaces that require multiple inputs. We also consider
sense of security because it is an important factor to evaluate
interface performance in the case of operation involving risks
such as car driving operation. We performed the following
experiment.
A. ParticipantsParticipants who had been sought from the public and took
part in this experiment of their own free will were 10 men and
10 women, and about 20 years old. They received explanationsof this research contents orally and through documents, andgave informed consent in writing. This experiment is acceptedby the bioethics review of Nagoya Institute of Technology andHonda R & D Co., Ltd.
B. System
Participants used GT Force Pro that was a steering control
device (Fig. 1). They operated steering wheel and accelerator
pedal to control a target car to trace the locus of an examplecar, and to keep the specified distance between the target andthe example. In figure 2, we drew the road width at 2.0.
The smallest black circle (radius is 0.1) is a target that theyoperated. The black line in the front-back direction is the locusof an example car, and the black line in the left-right directionis the line that is the specified distance away from an examplecar. We drew two circles (radii are 0.2 and 0.5) centered on theintersection of the two black lines. Participants substantiallyoperated the target to overlap these circles. The example
car motion was calculated randomly in specified range. Thebehavior of the target was determined by the turning radius R(Fig. 3), that is defined as follows:
R=AV,
θ(1)

Fig. 1. Appearance of experimentFig. 3. The behavior of the target

time is as follows:Vθ
sin ∆t,(5)θAVθ∆x = A (1 − cos ∆t).
(6)
θA
The target moves sequentially according to the equation (5)and (6). Here V and θ were affected by noise and delay, thenit was difficult to follow the example exactly. The degree ofnoise is represented by a coefficient of cross-correlation thatis defined as follows:
PT{X(t)Y (t + τ )}C = max t=0,(7)τkX(t)kkY (t)k∆zFig. 2. Example of screen to present

where V is the velocity of the target in the travel direction,
θ is the angle between the travel direction and the tire, andA is a constant. For simplification we assumed that the targetalways faces forward without considering the direction anddisplayed it as a circle. Moreover V was obtained from theinput value of an accelerator pedal, and θ was obtained fromthe input value of a steering wheel. The moving distance infront-back direction ∆z and left-right direction ∆x in a verysmall time ∆t are obtained from the following equation:∆z= Rsin∆ϕ,(2)∆x= R(1 − cos∆ϕ),(3)where ∆ϕ is the center angle of the turning circle and obtainedfrom the following equation:∆ϕ =V∆t.
R(4)From equations (1) to (4), the moving distance in a very small=A

where X and Y are signals between which cross-correlation isdetermined, and τ is delay between them. In this experiment
X and Y were input signal (the value of an accelerator pedal
or a steering wheel) and output signal (V or θ that was affectedby noise), and τ was different from the delay time we decided.
In past experiment [4], we experimented with combinationof five degree of noise (coefficient of cross-correlation is 1.00,0.98, 0.96, 0.94 and 0.92) and four delay time (0.0, 0.2, 0.4
and 0.6 seconds). However if we applied in the same way inthis experiment, the combination became enormous. Therefore
we limited the combination of noise and delay as follows.
1) We arranged all combinations in descending order of theevaluation value of sense of agency in past experiment.
2) We compared each combination with the combinationof highest sense of agency in descending order.
3) We extracted a combination that had significant difference for the first time.
4) We compared each combination with the combinationthat were extracted in 3), and repeat 3).
We extracted three combinations ((coefficient of crosscorrelation, delay time (second)) = (1.00, 0.0), (0.96, 0.0),(0.92, 0.6)). We further adopted a median value ((1.00, 0.6),(0.98, 0.4)) between them and decided a total of five combinations.

We adopted Perlin Noise as noise [5]. It is a noise obtainedby randomly generating a gradient for each control point atintervals and complementing between points according to thegradient. We set each parameter empirically and made severalstages of noise.
C. Procedure
Participants evaluated sense of agency and sense of security
in five steps subjectively for each combination of crosscorrelation and delay. It should be noted that we instructed
them to answer whether they felt they could operate it bythemselves because we considered that they were not familiar
with the word, sense of self-agency. Before the experimentparticipants experienced the configurations coefficient 1.00 –delay 0.0, and coefficient 0.92 – delay 0.6 for each input. They
operated it for 30 seconds for each trial, total trial number was
5×5×14 = 350. The trials were divided equally and randomly
for 20 participants.

Fig. 4. Evaluation value of sense of self-agency

III. R ESULTThe figure 4 and figure 5 show the result of the evaluation
value of the sense of self-agency and the sense of security forchanges of noise and delay for steering wheel and accelerator
pedal. This is similar to the result of the previous study
for single input experiment. The change of noise and delayfor steering wheel had a significant effect to the sense ofagency (F4,325 = 62.186, p < 0.01) and the sense of security(F4,325 = 61.447, p < 0.01). The change of noise and delay
for accelerator pedal also had a significant effect to the sense ofagency (F4,325 = 71.635, p < 0.01) and the sense of security(F4,325 = 58.803, p < 0.01). The effect of noise and delay tothe sense of agency and the sense of security did not show
significant difference between accelerator pedal and steering
wheel (t(38) = 0.604, p > 0.05), (t(38) = 0.131, p > 0.05).
It was suggested that the effect of noise and delay to thesense of agency did not depend on the operation form of thetarget. We defined P as an operation score that indicates theaccuracy of the operation. We calculated P as follows. First
we calculated Dt that is the value of the average distance
between the target and the example for each trial from thefollowing equation:
PN|Dt |Dt = t=0,(8)N
where Dt is the value of the distance between the target andthe example at time t and N is the total number of frames
for each trial. The trial time is 30 seconds and the frame rate
is 60 fps so that N is 30 × 60 = 1800 in this experiment.
We normalized P according the following equation so thatP = 100 when Dt = 0 and P = 0 when Dt = 0.5.
P = −200 × Dt + 100.

Fig. 5. Evaluation value of sense of security(9)
Fig. 6. Operation score

The figure 6 shows an operation score for changes of noise anddelay for steering wheel and accelerator pedal. As the noiseand delay increase, a operation score is lower. We compared
the sense of agency, the sense of security and operation score.

There was a strong correlation between them (correlation
coefficient is about 0.9 in any combination). Participants

probably evaluated the sense of agency based on the operation
accuracy felt by themselves in this experiment.
IV. C ONCLUSION
In this study we considered sense of agency in the situationof car driving that required multiple input. Our experimentresults validate and suggest as follows. The effect pattern ofnoise and delay to the sense of self-agency for single input
operation is probably applied to multiple input operation. The
strength of the effect does not depend on the operation styleprobably. There was a strong correlation between the senseof agency and the accuracy of the operation. In the future wewould like to consider the situation with an exhaust soundthat might affect sense of self-agency and sense of security,and compare them each other, and with the accuracy of theoperation.
ACKNOWLEDGMENT
We thank our colleagues in Funahashi laboratory in Nagoya
Institute of Technology for useful discussions.
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