2017 26th IEEE International Symposium on
Robot and Human Interactive Communication (RO-MAN)
Lisbon, Portugal, Aug 28 - Sept 1, 2017.

Investigating Effects of Light Animations on Perceptions of a
Computer: Preliminary Results
Sichao Song1 and Seiji Yamada2
new methods that can improve a user’s interaction experience
while being simple and low cost to apply.

Abstract— A preliminary experiment is carried out to investigate the effects of LED light animations on a user’s perceptionof a computer. As anthropomorphism has become an importantfactor in interaction design, current research tends to add
human-like expression abilities to interactive devices. Suchmethods, however, have limitations as they are complex andnot applicable to many currently-in-use appearance-constrained
devices such as personal computers. Thus, in this work weinvestigate an alternative method: expressive light. We attacheda programmable RGB LED strip to the front-bottom of amonitor and developed a ping pong game for carrying out
an experiment. We collected both game log and questionnaire
data from participants. Our results show that participants whoplayed the game with LED light animations liked the game
more and perceived the computer as better and more humanlike. In addition, no evidence suggested a negative effect on auser’s task performance or lead to additional workload.

In this work, we probe an alternative modality: expressive
light. Light, as an interaction modality, has been widely
studied in different fields. Many previous studies in fields
such as psychology and HCI have investigated the effectof light and color on human perception. Regarding HCI
related studies, a number of researchers used expressive light,
including ambient light and point light, for their systems toeither express affection [6][7][8][9][10][11] or indicate functional states [12][13][14][15][16]. In particular, a handful of
papers discussed affective modulation using light and color[7][17][18]. Therefore, the literature has shown evidence tosupport the idea that expressive light can be effective for
affective interaction design.

I. INTRODUCTION
Electronic devices such as computers are widely usedin our daily lives, either personally or publicly. They areused in various applications such as education, entertainment,
and information services. In all cases, it is important forsuch devices to guarantee their users a pleasant and naturalinteraction experience. Such an objective has become an important research topic in human-computer interaction (HCI)
as well as human-agent interaction (HAI) and human-robot
interaction (HRI).
Many factors are related to this goal. Among them, anthropomorphism has been considered as one key factor forinteraction design as it can affect a user’s perception of adevice substantially. According to [1], people interact withcomputers and new media in much the same way as they interact with other people. Moreover, [2][3] well demonstrated
the intrinsic mechanism of humans to anthropomorphize
objects. For this reason, various studies tried to reach amore natural interaction design by using anthropomorphism
methods such as adding human-like eyes and body parts toa device [4] or providing human-like body movements [5].
Although these studies have shown promising results, their
methods are not applicable to many currently-in-use devices
such as personal computers as most PCs at present use akeyboard, a mouse, and/or a touchpad as input modalities anda display (monitor) and/or a speaker as output modalities.
It can be costly and complex to apply human-like design
methods to such PCs. Thus, it is important to investigate

In our work, we attached a programmable LED strip to
the front-bottom of a monitor. On the basis of previous work[19], we assume that such a place of the monitor is withina user’s peripheral visual field and thus will not distract
him or her. Fig. 1 shows an overview of our system. We
developed a ping pong game for carrying out the experiment.
We designed a set of LED light animations for various events
that happen during the game, for example, the racket hitting
the ball, the racket hitting the walls, and game over. We
collected experimental data using a post questionnaire andgame log data. Our results suggest that participants whoplayed the game with LED light animations liked the game
more and perceived the computer as better and more humanlike. The contribution of this work is to provide a simple
and effective method for improving the human-computerinteraction experience that HCI as well as HRI and HAI
researchers and practitioners could readily use.

Processing
Game Interface

LED Light
Hardware1 Sichao Song is with the Department of Informatics, The Graduate Uni-

versity for Advanced Studies (SOKENDAI), 2-1-2 Hitotsubashi, Chiyoda,
Tokyo, Japan sichaos@nii.ac.jp
2 Seiji Yamada is with the National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda, Tokyo, Japan seiji@nii.ac.jp

978-1-5386-3518-6/17/$31.00 ©2017 IEEE

Fig. 1.

17

Animation
control

System overview

Fig. 2.

Four screen shots of ping pong game.

II. EXPERIMENTA. Ping Pong GameWe developed the ping pong game using Processing. Fig. 2
shows different game screens: an initial screen, ready-tostart screen, in-game screen, and game-over screen. We set
the goal of the game as to bounce the ball (moving theracket by mouse) to reach a high score. Four difficultylevels were designed by setting different racket lengths andhorizontal forces on the ball when it hits the racket tomeet the participants’ different gaming abilities. Basically,
we designed different scoring metrics with regard to thedifficulty levels, where a player gets 1 point each time theball hits the racket in the easy mode, 2 points in the medium
mode, 5 in the hard mode, and 10 in the hell mode. We
observed five events in the ping pong game: waiting for gameto start, ball hits racket, ball hits wall, playing, and gameover. Each event was coded uniquely, and the corresponding
code was sent to an Arduino board to control the LED strip
to display event-triggered light animations on-the-fly.

i1r
 i2r

A(t) =  .
 ..

i1g
i2g
..
.


i1b
i2b 

.. 
. 

i72r

i72g

i72b

(1)

,
where the rows represent the indices of pixels and thecolumns represent the three color channels r, g, and b.
The intensity values are the values of the three channels,
respectively:∀ : 0 ≤ ijck ≤ 255j = 1, · · · , 72; ck = r, g, b

(2)

On the basis of the defined animation space A(t), we
designed a set of four parameterized light animation patterns:
sinusoidal, triangle, swipe, and random (see Fig. 3). Patterns(a)(b) consist of two basic periodic waveforms, sinusoidal
and triangle, and (c)(d) are patterns based on the whole
LED strip. The parameters Imin and Imax are the minimum
and maximum intensity values for the RGB color channels,
and duty ratio D is the ratio of the rise time to period T.
Table I demonstrates the set of light animations for eachgame event. Particularly, the light animation for the gameover event consists of both a sinusoidal pattern (first) andrandom pattern (after).

B. Light Animation Design[20] used expressive lights to reveal their mobile service
robot’s states. As we used the same LED strip, an Adafruit
NeoPixel strip with 144 programmable LED pixels per meter,
we adapted the light animation pattern definitions from theirwork. In order to fit the width restriction of our monitor, weused a half meter of the LED strip (72 pixels).
We define an animation A(t) of 72 pixels as a time-varying
72 × 3 matrix of color intensities:

C. Experiment Setup
Fig. 4 illustrates the setting of the experiment environment.
Basically, a notebook PC was used to run the ping ponggame software developed in Processing. A monitor wasconnected to the notebook PC to display the game. During
18

TABLE I
S ET OF LIGHT ANIMATIONS FOR EACH GAME EVENT
Light Animation
sinusoidal
triangleswipe
randomPeriod (T, second)
2
0.2
0.6
0.6
−
−

Fig. 3.

Duty Ratio (D)
−
−
60%
60%
−
−

Imin
RGB: 0,0,0
RGB: 0,0,0
RGB: 0,0,0
RGB: 0,0,0
RGB: 255,255,255
RGB: 100,100,100

Imax
RGB: 255,255,255
RGB: 255,0,0
RGB: 0,255,0
RGB: 0,0,255
RGB: 255,255,255
RGB: 255,255,255

Eventwaiting for game to start
game overball hits racket
ball hits wall
playing
game overSet of light patterns we designed for ping pong game.

the experiment, the notebook PC’s cover was kept closed, andthe game was played via the monitor in full-screen mode.
A NeoPixel LED strip was attached to the bottom side of
the monitor. The LED strip was controlled by an Arduino
UNO board and powered by a 5-V, 10-A AC adaptor. It
needs to be clarified that the image in Fig. 4 was taken ina dark environment for the purpose of showing the lighteffect clearly. The actual experiment was done in a brightenvironment.

5V 10A AC adapter
NeoPixel LED strip

Arduino board

D. Procedure
We recruited twenty-two Japanese in total (9 males) forthe experiment. Their ages ranged from 20 to 38 years old(M = 28.09, SD = 6.23). We designed two between-subject
conditions: one with light animation and one without lightanimation.
Basically, the experiment was designed in two phases: apractice phase and a compete phase. In the practice phase,
each participant practiced the game freely with access to all
four difficulty levels. No time limit was given, so they wereable to end the practice phase at any time when they felt
comfortable with playing the game. In the compete phase,
each participant selected one difficulty level only and played
three rounds with regard to this difficulty level. His or her
final score was decided as the highest score among the threerounds.

note PC

Fig. 4.

Setting of experiment environment.

The participants were first welcomed by an experimenterand asked to sign some administrative documents. After
this, the experimenter explained the ping pong game to theparticipants. They were asked to practice the game freely
with no time limit before they were ready to “compete”
with the others. When the participants thought that they had
sufficient practice, they were then required to choose one
difficulty mode and play three rounds in the same mode.
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TABLE II
S UMMARY OF EVALUATION RESULTS
Category

Sub-category

perception of gamelikenessanthropomorphism
capability
competitivenessfrustrationstress-perception of computer
rate of gaming performance
rate of perceived workload
final score

With light animation
Mean
SD
5.61
0.57
5.18
0.69
2.99
0.86
3.09
1.51
2.5
1.52
3.14
1.29
4.64
1.43
77.09
92.96

Without light animation
Mean
SD
4.15
1.07
3.59
0.91
2.05
1.02
2.55
1.37
2.64
0.90
2.41
1.34
4.64
1.57
27.55
14.79

p valuep < 0.001
p < 0.001
p < 0.01
n.s.
n.s.
n.s.
n.s.
n.s.

(Fig. 5(a)). Moreover, they also liked (Fig. 5(b)) and anthropomorphized (Fig. 5(c)) the computer more, and particularly,
they were more willing to use the computer further intheir daily lives. However, the participants’ subjectively rated
performance and perceived workload indicated no significant
difference between the two conditions. This suggests thatusing light animations might not affect the participants’subjective ratings of their gaming performance, but more importantly, might not cause them extra frustration and stress.
The final score shows no significant difference between thetwo conditions, which also supports the possibility that theparticipants’ real gaming performance might not be affectedby the LED light animation.

E. Post-Questionnaire
We carefully designed our post-questionnaire on the basisof [21][22][23]. It consisted of 22/21 items in total regarding the two experiment conditions with/without LED
light animation. The questionnaire used for the with-LED
condition contained one more question, “Did you notice
the LED light animation?”, to check for manipulation. Eachquestionnaire had three types of items: yes/no questions, 7point Likert-scale questions, and open questions, where 7point Likert-scale questions were used the most (18 items).
The yes/no questions were used to check for manipulationand for participant-related information.
In particular, the 7-point Likert-scale questions were designed with four main categories: Participant’s

IV. DISCUSSION

perception of game - included questions such as “Do
you like this game?” and “Have you enjoyed playing
the game?”• perception of computer - included questions such as“How much fun did you have using this computer?”,“Do you feel close to the computer?”, and “Do you
think the computer is alive?”• rate of his or her gaming performance - included
questions such as “Do you think you are good at thisgame?” and “How competitive do you think your scoreis compared with others?”• rate of his or her perceived workload - included
questions such as “Did you feel tired when playing the
game?” and “Did you feel pressure during the game?”•Our evaluation suggests that using light animations toimprove a user’s experience with using a computer is promising. Specifically, we show that light animations can havea positive effect on a user’s perception of a computer.
This method is simple and therefore can be readily used
to currently-in-use devices, as lighting components such as
LEDs can be easily embedded to most electronic devices.
Our results reveal interesting phenomena in which people
anthropomorphize devices more when they include lightanimations. Although the link between light animation andanthropomorphism is unclear, we believe that expressive light
can be applied to devices and robots that require affective
interaction abilities. At present, an increasing number ofintelligent devices and domestic robots (such as cleaning
robots) are used in our homes. Applying affective light animations to them will definitely improve their social abilities
and achieve more harmonious interaction with people.
In this work, we mounted an LED strip to the front-bottomof a monitor on the basis of previous studies on peripheral
cognition technology [19]. Our results indicate that setting an
LED strip in such a way will not have a negative effect on auser’s task performance and lead to an increase in workload.
Thus, such a setting is recommended. However, other settings
such as the positions and number of LED strips used todisplay light animations will be explored in future studies.
Although in this work we performed the study using aparticular ping pong game, we believe that our results canbe generalized to other types of tasks. We intentionally madethe game simple and difficult (frustrating) to avoid biases thatcan be caused because of a user’s game preferences. Thus,

III. EVALUATION
Mann-Whitney U tests were used to analyze the experimental data. We first checked whether the participants
perceived the game to be different with regards to difficulty.
We did not find a significant difference between the withlight-animation condition and the without-light-animation
condition (medianwith : 5.45; medianwithout : 5; Z = 0.37;
n.s.). In addition, we also did not find a significant difference
between the two conditions with regard to average practicetime (medianwith : 1m 46.5 s; medianwithout : 1m 39.5 s; Z
= 0.24; n.s.).
Table II summarizes the evaluation results obtained using
the Mann-Whitney U test. The participants in the with-lightanimation condition liked playing the game significantly
more than those in the without-light-animation condition
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7

7

6
1

2

3

4

5

**

0

0

1

2

3

4

5

6

***

withLEDwithoutLED

withLEDwithoutLED(b) Perception of the computer: likeness.

4(a) Perception of the ping pong game.

0

1

2

3

**

withLEDwithoutLED(c) Perception of the computer: anthropomorphism.

Fig. 5.

Results of participants’ perception of the ping pong game, of the computer (likeness), and of the computer (anthropomorphism), respectively.

we believe that our task of playing the ping pong game minimally affected the result. However, investigating other typesof tasks such as reading or typing is of interest, and such
experiments will be carried out in our following research. In
addition, investigation on the appropriate applications is alsoneeded.
In addition, we will use our expressive light method withother devices, particularly appearance-constrained robots [6].
It is essential to uncover how our findings can be generalized
and applied in different fields and scenarios.

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ACKNOWLEDGMENTS
This study was partially supported by JSPS KAKENHI“Cognitive Interaction Design” (No. JP26118005).
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