The final publication is available at
http://dl.acm.org/citation.cfm?id=1957656.1957819

Effect of Robot’s Active Touch on People’s Motivation
Kayako Nakagawa1,21Masahiro Shiomi1 Kazuhiko Shinozawa1
Hiroshi Ishiguro1,2 Norihiro Hagita1

ATR IRC Labs.
Kyoto, Japan2

Reo Matsumura1,2

Osaka University
Osaka, Japan

kayako_nkgw@atr.jp m-shiomi@atr.jp shino@atr.jp reo@atr.jp
ishiguro@sys.es.osaka-u.ac.jp hagita@atr.jp
ABSTRACTThis paper presents the eﬀect of a robot’s active touch for
improving people’s motivation. For services in the education and healthcare ﬁelds, a robot might be useful for improving the motivation of performing such repetitive andmonotonous tasks as exercising or taking medicine. Previous research demonstrated with a robot the eﬀect of user
touch on improving its impressions, but they did not clarify whether a robot’s touch, especially an active touch, hasenough inﬂuence on people’s motive. We implemented an
active touch behavior and experimentally investigated its
eﬀect on motivation. In the experiment, a robot requested
participants to perform a monotonous task with a robot’s
active touch, a passive touch, or no touch. The result of experiment showed that an active touch by a robot increased
the number of working actions and the amount of working
time for the task. This suggests that a robot’s active touch
can support people to improve their motivation. We believethat a robot’s active touch behavior is useful for such robot’s
services as education and healthcare.

Figure 1: Does active touch from a robot improve
motivation?

Categories and Subject Descriptors
H.5.2 [Information Interfaces and Presentation]: User
Interfaces-Interaction styles

General Terms
Design, Experimentation

Keywords
Haptic interaction, Active touching, Motivation improvement

1.

INTRODUCTION

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As the human-robot interaction (HRI) ﬁeld advances, social robots have started to work in daily environments. For
example, robots have been developed that provide guide information at museums [34][38] and shopping malls [22][13].
Moreover, recent social robots are working at schools foreducation purposes [15][4][20] and providing health support
through conversations [26][29]. For such daily supports, social robots must increase the motivation of people who haveto perform such repetitive, monotonous but important tasks
as exercising or taking medicine.
Can a robot improve the motivation for such tasks by interaction? Some past works have reported the possibility
for such increases by a robot’s physical body, e.g., physicalpresence or haptic interaction. For example, a robot withphysical presence aﬀects human decision making more thana screen agent in the real world[32]. Wada et al. reported
that haptic interactions had beneﬁts for therapy purpose[40]. Moreover, in human-human interaction (HHI), actively
touching others in haptic interaction (e.g. lightly touchingothers’ arm) increases both feelings of friendliness and persuasive eﬀect [9][14]. These reports indicate the possibilityof positive eﬀect for improving the motivations of people

The final publication is available at
http://dl.acm.org/citation.cfm?id=1957656.1957819

by robot’s haptic interaction, such as an active touch, eventhough such eﬀects have not been explored yet.
However, from another point of view, robot’s haptic interaction might discourage people’s motivation because robots
are perceived as diﬀerent from humans. For example, Takayama
et al. revealed that people want humans rather than robots
for relation-based jobs that require interaction both insideand outside an organization with such people as producers
and directors [36]. Some researchers concluded that a robot
was perceived as “social others” that is a diﬀerent being fromhuman beings [19][25]. They reported that people did notgrant intrinsic moral rights to humanoid robots, even though
they interacted with them socially. Such diﬀerent perceptions might change the eﬀect of a robot’s active touching.
Cramer et al. reported that touching by a robot negatively
aﬀects its dependability [6][5]. Thus, it remains unknown
whether people prefer active touching from a robot that isperceived as diﬀerent beings.
In this paper, we investigate whether a robot’s active
touching behavior improves people’s motivation. For thispurpose, we implement an active touch behavior that a robot
puts its hand on participants hand and stroke it. To test theeﬀect of active touching from a robot in the context of improving people’s motivation, we conduct an experiment andreport how haptic interaction changes people’s motivations
and impressions.

2.

RALATED WORKS

2.1 Physical Interaction in HRI
Recent research topics using physical interaction in social
HRI can be generally divided into commands to a robot andthose for healthcare purposes including therapy.
The former was well studied and surveyed by [3]; developed a robot with a direct physical interface (e.g., leading
people by hand) to control its movements. Other researchers
used a physical interface to demonstrate a task to the robot[2], handing objects to people [8] and adjusting a person’s
posture with a robot for such tasks as dance instruction [37].
Goller et al. developed a cart robot that can be controlled
by haptic interactions [12].
The use of the latter is especially growing to meet thedemand for assisting the increase of senior citizens. For example, nursing-care assistant robots have been developed inJapan that can move a person from a bed to a chair [28][31].
Physical interactions are used not only for physical assistance but also for therapy purposes. Paro, a robot that
resembles a seal, is one famous successful case for robotics
therapy including physical interaction in the real world [40].
The research of Paro presented that the attitudes of elderly
people were improved by interaction with robots, and urinary tests showed that their ability to overcome stress was
also improved.
Thus, even though the former research successfully developed robust physical interfaces to give commands to robots
from people, it failed to focus on the psychological eﬀect ofactive touches from robots. The latter research also showed
the usefulness of physical interactions for physical assistancein therapy, but the psychological eﬀect of active touching by
a robot has not been explored yet.

2.2 Persuasion in HRI
Captology [10][39] (Computer as Persuasive Technology)(a) Overview(b) Link mechanisms

Figure 2: Desktop-sized robot: robovie-mR2

is one well-known area of research in the ﬁeld of persuasionin human-computer interaction(HCI). This ﬁeld’s research
focus is expanding from HCI to HRI.
Researchers originally focused on whether a robot’s physical presence improves persuasive eﬀects [32][30][24][1]. For
instance, Shinozawa et al. reported that a real robot could
aﬀect people’s decision making more eﬀectively than computer agents in real world environment[32]. Bainbridge etal. investigated how people respond to a request to throw abook by comparing humans, agents, and robots [1].
Based on the research ﬁeld’s progress, not only the robot’s
physical presence but also such social physical behaviors as
whispering and touching are being explored [33][6][5]. For
example, Shiomi et al. concluded that a whispering gestureof a robot increases people’s motivation during annoying
tasks [33]. On the other hand, some research reported anegative eﬀect of haptic interaction with a robot. Cramer
et al. investigated the eﬀectiveness of touching by a robot
and found that it decreases machine-likeness but negatively
aﬀects dependability [6] [5].
In the context of improving motivation for performing
such repetitive, monotonous, but important tasks as exercising or taking medicine, social robots have been deployedin such real environments as schools [15][4][20] and nursing
homes [26][29] for daily support. Thus, as cited in Section
2.1, a robot’s physical presence is used not only for improving the persuasive eﬀects but also its physical assistance inthe real world.
These previous works mainly reported the eﬀectiveness ofa robot’s physical presence without focusing on the eﬀectof active touching from a robot for improving motivation.
Some reported the negative eﬀects of touching by a robot. In
this study, we unveil how haptic interaction changes people’s
motivations and impressions.

3. IMPLEMENTATION OF ACTIVE TOUCHING
3.1 Robot
To investigate the eﬀectiveness of a robot’s active touch,
we used “robovie-mR2,” an interactive humanoid robot characterized by its humanlike physical expressions (Fig.2). It

The final publication is available at
http://dl.acm.org/citation.cfm?id=1957656.1957819(a) Initial screen(b) Dragging

Figure 4: Screenshots of the experimental task(a) Passive touch(b) Active touch

Figure 3: Touch behavior

has four DOFs in its arms, three in its head, and four in
its eyes. It stands 42cm tall. Such a robot is often used
as a table-style, conversational partner in natural-HRI studies [33][17][27]. We used a corpus-based speech synthesis togenerate speech [23].
To ensure safety when the robot touches a person, soft
sponge balls were used for its hands. To control the movement of its arms during touching, we installed an atmospheric sensor on its hand to detect pressure; it enables therobot to prevent touching a person too strongly.

3.2 Active touching from robot
We prepared two touching behaviors for the experiment:a passive touch behavior that the robot asks participants totouch it, and an active touch behavior that the robot touches
participants itself.
To safely realize active touching by the robot, we designed
the robot that asks a person to touch its hand ﬁrst, andthen it actively touches the person’s hand that is touching
the robot. For this purpose, we designed the following two
behaviors to request a passive touch from the person and toactively touch him/her:[Behavior requesting a passive touch]: The robot extends
its right hand and says, “Please hold my hand while I talkto you (Fig.3(a)).”[Behavior for touching the person]: When the person touches
the robot’s right hand, it moves its own left hand until it
touches the person’s hand. Then the robot strokes the person’s hand with its own left hand (Fig.3(b)). Because people
have diﬀerent touching styles, might hold the robot hand
diﬀerently, and so on, the robot must control a stroking gesture that realizes identical touch behavior. So we installed
an atmospheric sensor in its left hand as written in Section
3.1.
The following is the active touch behavior:
1. Robot asks a participant to hold its right hand.
2. Robot extends its left hand to the right hand until it
touches the participant’s hand.
3. Its left hand moves out to horizontally widen the space
between both of its hands until the sensor value drops
below the threshold.

4. The left hand repeatedly moves vertically to the righthand. (stroking)We conducted pre-trials to investigate the adequate threshold values of sensors that enable consistent touching of participant hands. Based on the result, we determined thatthe threshold value was 32 millibar higher than the value
without touch.

4. EXPERIMENT
To evaluate the eﬀectiveness for improving a motivation
for a monotonous task, we conducted a laboratory experiment. In this section, we describe its details.

4.1 Participants
The participants were thirty university students (14 men
and 16 women whose age averaged 21.0, S.D. is 2.3) wererecruited on the web regardless of faculty or specialty, so
their backgrounds were various and most of them were notfamiliar with robots. They were paid 1,000 yen (roughly $10
U.S.) for one hour of participation.

4.2 Task
To investigate the eﬀect of a robot’s touch to improve
motivation, we adopted a monotonous task whose degree of
eﬀort was objectively measured. For this purpose, we prepared an on-screen task by referring to a study of behavioral
economics [16]. Fig.4(a) shows the initial screen of the task.
The participants dragged the circle on the left side to thesquare on the right side on the screen (Fig.4(b)). When thelight gray circle is dragged into the dark gray square, thecircle disappears, and a new circle appears on the left side
(Fig.4(a)). Participants can repeatedly drag as many circles
as possible. Since the termination method is displayed on
the screen during the task, participants can terminate whenever they want. The task ends after the participants press
the ESC key or the maximum time (10 minutes) has expired;
participants are not informed of the maximum time.
The following is the procedure of the task: 1. Participants
read the task instructions on the screen. 2. They practicedragging for 10 seconds. 3. If they have no problem performing the task, they start.

4.3 Conditions
To evaluate and compare the eﬀectiveness of with/without
robot touch, we used a between-participant experiment design with three conditions:• No touch : robot asks participants to perform the task.

Participant

Table 1: The flow of the experimentPartition

PC

The final publication is available at
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Speaker

Speech and behavior

Robot

Hello! I’m robovie-mR2. Thank you
for coming.

Operator

2.3 m

Participant

Robot

control

You’re welcome.

Robot

Well, I’d like to ask you a favor. Pleasehold my hand while I talk to you.
(Robot extends its right arm)

Participant

OK. (Participant holds robot’s hand)

Robot(Robot starts stroking the participant’s hand. The pressure for the handis automatically controlled.)

Robot

I’d like you to do the following task aswell as you can. The task procedure
is displayed on the computer screen on
your right.

Robot(Robot stops stroking the participant’s
hand)

Robot

Do you understand?

PC[*1, *2]

4.8 m

Figure 5: Experimental settings• Passive touch : robot requests a passive touch fromparticipants and then asks them to perform the task
(Fig.3(a)).
• Active touch : robot ﬁrst requests a passive touch fromthe participants and then touches thier hand while it
asks them to perform the task (Fig.3(b)).

4.4 Experiment procedure
The experiment was conducted in a laboratory room (Fig.5).
Robovie-mR2 was placed on a table, and a laptop computer
for the task was placed on the other table. Before the session, participants were given a brief description of the experiment’s purpose and procedure. They were randomly
assigned to the experiment conditions; thus ten participants
were assigned to each condition. The gender ratio in eachcondition was counter-balanced.
First, participants sat in front of the robot. In the interaction, the robot requests participants to perform the task.
After the request from the robot, they start it. As describedin Section 4.2, the participants can terminate the task whenever they want. Table 1 shows the ﬂow of the robot speeches
and behaviors. The trigger of each behavior was sent by theoperator in the Wizard of Oz method [7].

4.5 Measurements

Participant
Robot

[*2]

[*2]

Yes.
Thank you. OK, let’s get started!
*1: passive touch condition*2: active touch conditionpose a hypothesis that active touch increases the participant motivation to do the monotonous task. Moreover, active touch is preferred by the participants more than passive
touch and no touch. Thus, we made the following hypothesis:
Hypothesis 1: active touch will increase the number ofactions and the amount of working time more than passive
touch and no touch.
Hypothesis 2: active touch will be rated higher than passive touch and no touch for feelings of friendliness.

4.5.1 Objective measurement

5. RESULTS

To investigate whether an touching behavior improve a
motivation for the monotonous, we measured both the number of actions (dragged circles) and the working time (timespent on task).

We note that all the participants in the active/passive
touch condition kept holding robot’s hand while the robot
asked them to perform the task. To test our hypotheses, we
conducted the analyses below.

4.5.2 Subjective measurements

5.1 Verification of hypothesis 1

To measure the subjective impressions of the participants,
we prepared a questionnaire that addressed feelings of friendliness, authority, and trust. After the session, participants
answered a browser-based questionnaire on a 1-to-7 point
scale where “7” is the most positive and “1” is the most negative.

We analyzed the number of actions (Fig.6) and the amountof working time (Fig.7).
To test the hypothesis, we conducted a one-factor between
subjects ANOVA for the number of actions. There was asigniﬁcant diﬀerence between conditions (F (2,27)=6.044,
p=0.007). Multiple comparisons with the Scheﬀe method
revealed signiﬁcant diﬀerences: active touch > passive touch(p=.022), active touch > no touch (p=.018); but there wasno signiﬁcant diﬀerence between no touch and passive touch(p=0.996). This means that active touch signiﬁcantly increased the number of actions.

4.6 Hypothesis
The eﬀect of robot’s active touch on people’s motivation
remains unrevealed in HRI, though haptic interaction increases friendliness and persuasive eﬀect [14][9]. So, we pro-The final publication is available at
http://dl.acm.org/citation.cfm?id=1957656.1957819

400

7
6

300

5

250

Scale

Number of actions

350

200

4

150

3

100

2

50

1
No touch0

Passive touch Active touch

No touch Passive touch Active touch

Figure 8: Feeling of friendliness
Figure 6: Number of actions

5.3 Did the impressions of the robot affect the
motivations for the task?

600
500

Seconds

400
300
200
100
0

No touch

Passive touch Active touch

Figure 7: Working time

Moreover, we conducted a one-factor between subjects
ANOVA for the amount of working time. There was asigniﬁcant diﬀerence between conditions (F (2,27)=5.238,
p=0.012). Multiple comparisons with the Scheﬀe method
revealed signiﬁcant diﬀerences: active touch > passive touch(p=.032), active touch > no touch (p=.032), but there wasno signiﬁcant diﬀerence between no touch and passive touch(p=1.000). This means that active touch signiﬁcantly increased the working time. Thus, these results support hypothesis 1.

5.2 Verification of hypothesis 2
We further analyzed feeling of friendliness (Fig.8) to investigate how the participants perceived the robot.
We conducted a one-factor between subjects ANOVA for
feeling of friendliness. There was a signiﬁcant diﬀerence between conditions (F (2,27)=3.669, p=0.039). Multiple comparisons with the Scheﬀe method revealed a signiﬁcant difference: active touch > no touch (p=.050); but there was nodiﬀerence between active touch and passive touch (p=.158),
and between passive touch and no touch (p=.838). These
results mean that active touch signiﬁcantly increased the
feeling of friendliness more than no touch, but it was not
rated higher than passive touch. Thus, hypothesis 2 waspartially supported.

The impressions of the robot for participants might caused
the positive eﬀects on the number of actions and working
time. Thus, we analyze relationships between the number ofactions/working time and three kinds of participants’ evaluations: friendliness, authority and trust. Spearman’s correlation analysis showed that there was no signiﬁcant correlation between the impressions and both of these variables([friendliness] the number of actions: r = .27, p = .16, working time: r = 0.28, p = .14, [authority] the number of actions: r = −.02, p = .93, working time: r = .02, p = .93,
[trust] the number of actions: r = −.02, p = .92, working
time: r = −.01, p = .96). The results showed that there
was no signiﬁcant relationship between the impressions of
the robot and the motivations for the task.

5.4 Are responses to the robot’s touch different between males and females?
Gender is an considerable factor that inﬂuences persuasive eﬀect and motivation improvement. In order to investigate gender’s eﬀects in our experiments, we conducted twofactor between subjects ANOVA. Two factors were touchcondition and gender. The results showed that there wasno signiﬁcant diﬀerence between male and female for boththe number of actions (F (1, 24) = 1.9, p = .18) and working
time (F (1.24) = 2.1, p = .16). Therefore, at least in the experiment, the robot’s active touch increased the motivation
irrespective of gender.

6. DISCUSSION
6.1 Design implication
Our result revealed that a robot’s active touching behavior improves people motivation and showed a positive eﬀect.
In the past, some research argued that active touching froma robot had a negative eﬀect[6]. On the other hand, ourresult agrees with the work of many researchers who are investigating the positive eﬀects for haptic interaction in HRI[40][21]. This study supports the research and developmentof a social robot that interacts with people by such haptic
interactions as actively touching others.
As an example of an application for active touch, we havealready developed a counseling robot for lifestyle diseases
in the healthcare ﬁeld that provides health information andThe final publication is available at
http://dl.acm.org/citation.cfm?id=1957656.1957819

advice for users[35]. The problem is that the motivations of
the users dynamically change when they are seeking to theirlifestyles, so it is important how they overcome periods when
their motivation becomes low. Therefore, we believe that acounseling robot can support user’s lifestyle improvement
by encouraging him/her using touch behaviors at such atime. Moreover, there would be many situations that touch
interactions between humans and physical robots are natural and acceptable. So, we believe that this study provides
important ﬁndings for many applications toward long-term
human-robot interaction that changes people’s lifestyle.

6.2 Why did an active touch result in positiveeffects?
Our experimental results indicated that active touch increased a motivation for a monotonous task and friendliness.
Such positive eﬀects of touch behaviors show similar trends
in the researches of haptic interaction in HHI or a part ofresearches in HRI [40][21]; however, other part of researches
in HRI show a contradictive result (i.e. a negative eﬀect for
dependability) of touch behaviors from a robot [6][5].
It is not easy to make clear why active touch from ourrobot showed positive eﬀects by comparing our study withthose researches [6][5], because there are many diﬀerences
between them: appearance, the feel of hands’ material, character, task, cross culture eﬀect, touching behavior and so on.
Mixing of these diﬀerences might considerably change perceived impressions for a robot. One of the future works thatcomes from these considerations is to investigate what kindsof features will change the eﬀects of active touch from therobot.
The results in 5.3 indicate that the psychological indicesthat were measured in the experiment could not explain thereason why the robot’s active touch improved participants’motivation. We think that these results are quite interesting, that will make worthy discussions. Basically, past
research works claim that some psychological indices, suchas friendliness or trust, would relate to persuasive eﬀects;
however, our experimental results cannot be explained in
the points of view of psychological indices’ eﬀects. Thus,
it is still unknown as to what kind of psychological factors
increased motivations of the participant. Some physiological measures might be helpful for that analysis. In fact, aprevious work investigated the eﬀect of shaking hands witha robot for decreasing a person’s perception of stress withphysiological indices [18]. As a future work, we will investigate whether a robot’s active touch physiologically aﬀects
humans and their behaviors by conducting experiments withphysiological measurements.
On the other hand, robot’s appearance is one of key design
issues for HRI. The robot’s appearance might contribute toits foundation, and then active touch might cause positiveeﬀects on user’s motivation. Our robot was designed to give
positive impression with cute appearance; such design policy
would be common policy for almost all communication service robots (e.g., AIBO[25], Paro[40], Robovie-II[21]). The
experiment results with our robot cannot be extended to different types of robots, however, they show that our designof active touching behavior have possibility to increase forsuch various communication service robots.

6.3 Influence of foot-in-the-door effect
The foot-in-the-door eﬀect [11] is a famous manipulativetechnique for persuasion, achieves agreement to a large request by ﬁrst getting agreement to an easy request. Perhaps
our experimental design was aﬀected by this tactic; the robot
makes an easy request, “Please hold my hand while I talk toyou,” and is touched by the participants before it requests
the monotonous task.
However, the experimental results did not show signiﬁcantdiﬀerences between passive touch and no touch for both thenumber of actions and the amount of working time. Therefore, at least in the experimental settings, we consider that
only easy request from the robot did not make a signiﬁcantdiﬀerence in the context of improving motivation.

6.4 Ethical issues of persuasion
Ethical issues will play an important role based on theadvancement of social robots, particularly when such robots
persuade or change human behavior. Past examples of persuasive research in HCI [10] focused on promoting the widely
held conceptions of “good,” but they also pointed out that
persuasive research in HCI can be used for “bad” purposes.
Such problems will continue to appear in the future, andthey must be considered.
On the other hand, for daily support, we must increase
the motivation of people who face repetitive, monotonous
but important tasks such as taking medicine. In our society, many simple services to improve motivation have already been replaced by machines, including mobile phoneschedulers and reminder systems on web mail. Especiallyfor senior citizens living alone who rarely have a chance toget support for such tasks, the current computer/internetbased helper devices are diﬃcult to use. One possibility isusing robots for such daily support instead of machines or
web services.

6.5 Limitation
One of the goals of this study was to reveal that people’s
motivation in repetitive and monotonous tasks could be improved using active touching robots. This study showed positive results for a short term interaction, however, this result
cannot be easily extended to long term interactions. The ongoing study in the healthcare ﬁeld referred in 6.1 would help
us for investigating the eﬀects of active touch behavior on
improving motivation in case of long term interactions.
Since the experiment was conducted with an existing robot,
robovie-mR2, robot generality is also limited. We cannot
ensure that our ﬁndings can be applied to all interactive
robots, particularly unhuman-like robots. However, we believe that the setting is adequate to oﬀer critical knowledge
for researchers interested in improving motivation with interactive robots.

7. CONCLUSION
We focused on the eﬀect of a robot’s active touch for improving people’s motivation. Even though previous research
reported the positive eﬀects of haptic interaction in HRI,
the eﬀect of a robot’s touch for improving motivation remains unrevealed. To investigate the eﬀect of a robot’s active touch, we conducted a between-subjects experiment inwhich a robot requested a participant to perform a repetitive
task with an active touch, a passive touch, or no touch. The
experimental results indicate that the robot’s active touch
increased the number of actions and the amount of working
time with the task, showing its eﬀectiveness for improving

The final publication is available at
http://dl.acm.org/citation.cfm?id=1957656.1957819

motivation in human-robot interaction. We believe that a
robot’s active touch behavior is useful for such robot services
as education and healthcare that require motivating people
to do monotonous but important tasks.

8.

ACKNOWLEDGMENTS

This research was supported by the Ministry of Internal
Aﬀairs and Communications of Japan.

9.

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