Do You Follow Angel Agent’s Advice?
A Pilot Study for Decision Making Support by Multiple Animated Agents
Masahide Yuasa and Daiki Morimoto
Department of Applied Computer Science
Shonan Institute of Technology
Fujisawa, Kanagawa, Japan

Abstract—With the increased use of information technologies,
the importance of information services that assist us in one's
daily decision-making has also increased. However, this is notenough to help in all our daily choices. When conditions areconflicting or complex, it is difficult to make appropriate
decisions. In the case of conflict situation of decision-making,several films, television or manga shows often depict internal
conflict by showing an angel and a demon characters that offer
competing recommendations. The expression of two different
characters may be used in the decision-making tool by using two
types of animated agents that can induce suitable decisionmaking. Therefore, we proposed the decision support animatedagents of angel and demon. In this study, we developed animatedagents of both the angel and the demon that expressed their roles
and promoted suitable decision making. The angel and demon
agents responded against the user’s utterance. The user may
understand both for and against aspects in a conflict situationand then the make better decisions. We conducted two
experiments: one using utility function without animated agent
and the second one using only animated agent. The experimental
results showed that when the angel and demon agents were used,
the participant selected good choice. This is a useful way to use
multiple characters with different characteristics in conversation.
Keywords—animated agent; character; mood engineering

I. INTRODUCTION
With the spread of Internet and increased use ofinformation technologies, information services have become
important as they assist us in our daily decision-makings, suchas in the choice of dinner, clothes, and works. For example,
the restaurant guide helps people find the best restaurant
according to their desired requirements [1, 2]; the fashion site
provides fashion advice that fits the customer's characteristics;
and the weather forecast site helps people to decide whether
they should carry an umbrella.
However, these are not enough to help in all our daily
choices. New technologies, such as e-mail and smartphones,
exacerbate multi-tasking [3] and increase the scenes ofdecision-making. Supporting decision making has been crucial
in archiving many sorts of multi-tasking; however, in complex
and conflicting conditions, it would be difficult to makeappropriate decisions.
Traditionally, this difficult situation of decision-making
has often been depicted by several films, television or mangashows as a whispering angel perched near one’s ear and ademon at the other ear, offering competing recommendations[4]. These characters express conflict dilemma; the angel says
what one should do, and the demon implies what one wants todo. This expression of using two different kinds of characters
can be applied to decision-making support tool by using two
types of animated agents that induce suitable decision-making
for the user.
Therefore, we proposed the decision support animatedagents to use the metaphor of angel and demon. In contrast to
the conventional decision-making tools, a user will be able tosort out the conflict by interaction with the angel and demon
agents who play the role of advocates. In this study, wedeveloped both angel and demon agents that expressed theirroles. The angel and demon agents responded against theuser’s utterance. The users may be able to understand bothsides of opinions and can compare the two types of advices
sufficiently to make appropriate decisions. Moreover, the finaldecisions will be convinced for the user, and the method may
also be effective in producing a suitable decision. In addition,
it will be useful to use multiple characters that have different
characteristics in interaction [5].
In the next section, we describe the overview of our
proposed system, and in the third section, we explain theexperiment performed to confirm the effectiveness of our
proposed system. Furthermore, we also describe the discussion
and the conclusion.
II. OVERVIEW OF THE PROPOSED SYSTEM
A. Developing Animated Agents of Angel and Demon
To develop the angel and demon animated agents, we used
SSP (Sakura Script Player) [6], which can display an animatedagent and control it on the PC screen. Multiple animatedagents and their word balloons can be also displayed on thescreen. Moreover, we used SSTP (Sakura Script TransferProtocol), which is a mark-up script for SSP to control eachagent’s behaviors, such as movement of rip, blink, andpostures. The agent can utter based on the prepared sentences,and the utterance control is also available by using mark-up
description in SSP. For example, the mark “/i5” means
executing an agent’s animation pattern 5, and “/w9” is“waiting time (level 9)” between previous utterance and next
utterance. Fig. 1 shows animated agents of angel and demon inthis study. We drew images and patterns of both charactersand implemented them using SSP. The animations of thesecharacters can be controlled by using SSTP.

(a)

(b)

it is raining outside now?” However, this setting is very simple
and cannot make the participants image conflicting situations.
Therefore, we requested the volunteers to collect details on
conflict situations through discussions. Consequently,additional conditions were; “first lecture of the day,” “the lastpart of November,” “The attendance point is a little over theborderline” “Tardiness will not be tolerated in the lecture(loose the attendance point),” “It takes 5 minutes from hometo station.” By using these conditions, we enabled a participant
to believe that a conflict situation requires a choice of one of
the two alternatives. Moreover, in this experiment, we usedthe conventional method of decision-making using the utility
function ． The participants are required to write down nomore than five advantages and disadvantages in the sheet (Fig.
2). They were also asked to score the level of importance foreach item such that the total score is no more than 100. Afterthe participants had given their scores, the experimenter
estimated the weighted average and judged whether aparticipant selected “should do” or “want to do.” Fig 2. shows
an example of descriptions and scores. In this case, the scoreof “should do” is 55 points and the score of “want to do” is 45
points, indicating that the participant should choose “shoulddo”; thus he/she should attend the class.

Fig. 1.
(Top) Animated Agents of Angel (a) and Demon (b)(Bottom) Interface for Animated Agents.

B. Interaction between Agents and a UserIn Fig. 1, the animated agents are showed at the top and on
both sides of the PC screen. The agents’ utterance in wordballoon is also displayed, but this pilot system does not use thesound of utterance. The system has a microphone and receives
a user’s voice as responses against the agents’ utterance, basedon prepared utterance patterns autonomously. As we will
discuss later, both agents can be controlled in a separate room
by using SSTP, so that we make the participants believe them
to be autonomous, even if the utterances are inputted by theexperimenter.
III.

Fig. 2. An example of descriptions and scores.

EXPERIMENTSTo confirm the effectiveness of animated agents, weconducted two experiments; the first experiment is aconventional decision-making method using utility function
without any animated agents, and the second one is aninteractive experiment between agents and the participant.
A. Experiment using Utility Function as Conventional
Decision-Making Method
For the experiment, we asked the participants to imagine asituation where they have to decide whether to go to theuniversity or not when it is raining outside. The participants
are showed the description “Do you go to university, althoughFig. 3. The number of choice of “should do” or “want to do” (N=13)

B. Result in the Case of Utility Function
Fig. 3 shows that the results of the judgment using theutility function for 13 participants. As can be seen, there are
six participants who should attend the class, four participants
who should not attend the class, and three participants with thesame scores. We will compare the results with the next
experiment that uses animated agents.
C. Experiment with Animated Agents
To confirm the effect of animated agents, we prepared thesame question and conditions (“Do you go to university,
although it is raining outside now?”). Moreover, the angel
agent and demon agent respond against the user’s utterances.
The participants were instructed about the situation and thatthey were required to talk to the angel and the demon. In theexperiment, we used the WOZ (Wizard-of-OZ) method [7];the participants believed that the agents were autonomous.
However, these were actually operated by the experimenter ina separate room. In this experiment, the participant’s voices
are sent to the separated room, and both the agents can
respond from the room using SSTP. The experimenter inputs
the utterance or selects the sentence as a response; however,
the experimenter does not induce a certain result, he/she
infatuates the flow of conversation as evenly as possible. For
example, when a user says “I don’t go to university,” the angel
responds “Don’t cut the class…” On the other hand, when theparticipant says, “I will go to university, today,” the demon
responds, “No problem, if you cut the class. You do not needto go to the school.”
For the experiment, we added one more topic similar to thetopic about the previous one. After the angel or demon agents
had given their advices, the participants were required toanswer which advice they agree with.

participants preferred the utility function method than theanimated agents.
IV. DISCUSSIONAs described above, the first experiment revealed that
there are more participants who should attend the class thanthe participants who need not attend and who had the same
scores. On the other hand, in the second experiment, there
were more participants who agreed with the angel than theparticipants who agreed with the demon who advised not toattend the class.

Fig. 4. The number of approval for angel or demon (N=15)“T1-1” means first topic and first advice of angel or demon agent.

D. Result in the Case of Animated AgentsThe experiments involved 15 participants, including the 13
participants who attended the previous experiment using theutility function. Fig. 4 shows the answers after the angel agent
or demon agent gave the first and second advices, respectively.
In Fig. 4, the term “T1-1” means first topic and first advice. In
the case of T1-1 and T2-2, all the participants answered thatthey agreed with the angel agent.
In the case of T1-2, only one participant chose the demon’sadvice, and in the case of T2-1, six participants selected thedemon’s advice. We conducted Binomial test for them, whichshowed a significant difference in the case of T1-2 (p < 0.01);
however, there is no significant difference in the case of T2-1(p = 0.30).
Fig. 5 shows the average values of total answers,
indicating the advice chosen by the participants. We
conducted a t-test for them with a significant level of p < 0.01,
and so the case of selecting the demon is significantly low.
After both the experiments, the participants were required
to answer which advice method (utility function or animatedagents) was useful, on a scale of −3 (utility value) to +3(agents). The average value was “−0.33” (N=15), and theFig. 5. Average values of choice of angel or demon (N=15, ** p < 0.01)

It is interesting results that the more selections of “shoulddo” (angel) than the case of using utility function, even thoughutility function may induce more cool judge. The animatedagent may be able to induce calm judgment of thecircumstances. In general, when people talk to someone about
one's problems, they can sort out one's standpoint on theproblem logically and calmly by talking with others. Even
though the interaction system has only a non-human agent, thesystem may have a similar effect on humans.
In addition, these experimental results indicate that oursystem influenced the participant’s decision-making, eventhough the adviser is an artificial animated angel and demon
agent. Visualizing angel and demon may be useful fordeveloping decision-making tool.
Furthermore, as shown in the last question after both theexperiments, the participants preferred the utility function
method. The reason they did not prefer the animated agentswas investigated by free descriptions of the answer. The
reasons were “the response is late” and “sometimes I was
afraid that the system can recognize my voice, because there
was time lag.” This is due to the WOZ method, which requires
the participant to input sentences manually, which leads to atime lag. Future experiments should focus on improving theresponse time.
In the experiment using agents, we used the interaction
among angel, demon, and participants. It may be need theexperiment using only single character (only angel or demon).
By conducting an experiment using a single character, theeffectiveness of multiple characters can be confirmed. In
addition, the difference feature of angel and demon should beconsidered [8, 9]. In this study, we prepared the features ofangel and demon subjectively; however, we should take into
account the features suitable for angel and demon. Moreover,
we should focus on the difference of abstractness. Previousstudies described the difference in effectiveness for each
abstractness [9, 10]; therefore, the additional experiment bydeference of features and abstractness should be conducted in
the future to confirm the detailed effects of animated angeland demon agents.
In the usual TV programs and comics, both the angel anddemon agents expressed their own opinions about the user'ssituation. However, in this system, both the angel and thedemon responded to the user's utterance, without expressing
their opinions. We focused on the interaction between the user
and the agents who responded to the user. We intend todevelop those agents who will express their opinions first andconfirm the effect of the other settings.
Moreover, in our experiment, both agents gave advice
twice on different conditions (the user does not want to go touniversity because of two reasons; “heavy rain” or “traindelay”). We used the same topics for these two conditions, andthe characters’ talks were adjusted by the interview results ofseveral volunteers. We thought that there were few
differences; however, there is a possibility that the results willchange for other topics and conditions. Thus, this requires
additional experiments.

According to the order of the experiment, the tests ofutility functions were carried out first, followed by that of theanimated agents. In this experiment, since this order had a few
impacts, we believe that the reverse order may have a more
impacts because the user had received the character’s advice
before the test of utility functions. We will confirm theinfluence of the order or conduct an experiment in which theparticipants would be divided into some groups based on theorder.
V. CONCLUSION
We proposed the decision support animated agents using
the metaphor of angel and demon. We developed animatedangel and demon agents demon that expressed their roles andpromoted better decision making. We conducted the two
experiments: one using utility function without any animatedagents and second using only animated agents. The
experimental results showed that when the angel and demon
agents were used, the participants selected “should do” choice.
In the future, multiple characters that have different
characteristics can be useful in creating an interactive systemor multiparty conversational system [5].
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