Social Behavior Investigation of Intelligent Virtual … technologies 3 2011 9 and control Key Words: Intelligent virtual agents (IVA); architecture; social behavior; social scenario;

3 2011 9information technologiesand control

Key Words: Intelligent virtual agents (IVA); architecture; social behavior;social scenario; moral emotions; social emotionw primary and secondaryemotions; needs; rationalities; knowledge; ambivalence; choice;deception.

Abstract: This paper investigates the social behaviour of an intelligentvirtual agent (IVA) with PRE-ThINK architecture with the help of typicalworking student’s life scenario modeling. The program system andthe PRE-ThINK architecture, adapted for this scenario, are proposed,and their components are considered. The dynamics of the decisionmaking process in problem situations caused by the implementationof this architecture is shown, when mixed emotions arise and therealization of what happened reflects on the agent’s temper. IVA’ssocial behavior is shown, during which in the process of communi-cating with the user the agent expresses learned from experiencesecondary emotions, which can be either in harmony or in conflictwith the realized secondary emotions, resulting both from the agent’sgeneralized condition and the events. The investigated secondaryemotions are: relief, confidence, prestige, uncertainty, confirmed fear,disappointment; and also the socially expressed secondary emotionssuch as refrained sadness, refrained anger, businesslike manners,politeness and authoritativeness. The results show that the usersperceive the modeled IVAs as socially functioning persons, recognizetheir real emotional state and are interested in their problems.

1. Introduction

In general, social norms are commonly believed rules insocial interaction. These rules serve as a guide for humanbehavior, and as the basis for their beliefs and expectationsabout others. Without them, communication can break downeasily [Si Mei, Stacy C. Marsella, and David V. Pynadath 2006].

Social interaction is accompanied by social emotions.Social emotions can be defined as one’s emotions projecting onor affected by others. They are “valenced reactions”, which canoccur as a result of how people understand events. The firstmodification to the OCC model, (that define a cognitive approachfor looking at emotions) is to allow for the definition of socialemotions [Ortonty, A., Clore, G. L., Collins 1988].

[Damasio 1994] distinguishes at least two classes ofemotions, namely, primary and secondary emotions, on thebasis of his neurobiological findings. According to them second-ary emotions are more dependent on the agent’s cognitive rea-soning abilities. The appraisal of secondary emotions dependsmuch more on the situational context and an agent’s memorythan that of primary emotions. The releasers of secondaryemotions might be learned based on the history of primaryemotions in connection with memories of events, agents, andobjects. The agent’s facial expressions of primary emotions mayaccompany secondary emotions such that they do not necessar-ily need to be expressed by their own set of facial expressions.Secondary emotions also modulate the agent’s simulated em-bodiment, such as its general level of arousal. The agent ex-

presses its awareness of secondary emotions verbally. Second-ary emotions are based on more complex data structures thanprimary ones. Accordingly, only some general aspects of sec-ondary emotions (such as their respective valence components)are represented in three-dimensional emotion space PAD thatdetermines values of the intensity of the pleasure, arousal anddominance.

Recently a number of investigators distinguish betweenprimary and secondary emotions, underlining the importance oftheir modeling and studying [André, E., Klesen, M., Gebhard, P.,Allen, S. ,&Rist, T. (1999); Pelachaud, C., & Bilvi, M. (2003).;Becker-Asano, C., & Wachsmuth, I (2008)].

[Rehm Matthias and Elisabeth Andre 2005] focus on syn-thetic agents that may express emotions that are in conflict withtheir appraisal processes and they put a question: how to handlesituations in which the agent decides to display an emotionwhich is in conflict with its internal appraisal processes in socialsettings.

Acording to [Benny Ping-Han Lee et.al. 2006] the emotionmodels and architectures for virtual agents are not yet advancedenough to be imbued with coexisting emotions but this is veryimportant because mixed emotions, especially those in conflict,sway agent decisions and result in dramatic changes in socialscenarios.

In order to contribute to further development of the de-scribed problems, this paper investigates the social behavior ofan intelligent virtual agent (IVA) with PRE-ThINK architecture bymeans of typical working student’s life scenario modeling. Theprogram system and the PRE-ThINK architecture, adapted for thisscenario, are proposed. The basic modules of the programmingsystem and the implementation of this architecture are consid-ered. The mechanism of arising of the agent’s thoughts, as wellas their assessment, is cleared out. The dynamics of the deci-sion making process in problem situations is shown, whenmixed emotions arise and the IVA’s behavior changes in a way,allowing achieving all of the goals of the scenario,.

The social behavior, shown by the agent, as well as his/her generalized condition of awareness, which are not always inharmony, is explained and presented. The proposed scenarioallows for modeling and expressing of both primary and second-ary emotions. The social emotions, shown by the IVA, whengiving answers to user’s questions in the experimental on-lineinformation site, are a mixture of primary (spontaneously causedby the current context emotions) and secondary emotions (dem-onstrated - learned from IVA’s experience in a similar situation;and realized - caused by the IVA’s self-esteem related to his/her generalized condition and by all the simultaneous events,hidden for the users).

The IVA aspires to hiding the secondary emotions, causedby the realization of his/her generalized condition when thecondition is not quite good due to a failure, disappointment or

Social Behavior Investigation of IntelligentVirtual Agents

D. Budakova

3 201110 information technologiesand control

overtiredness. The IVA aspires to expressing the necessary socialemotions, learned from experience, when communicating withthe users of the site, regardless of his/her real temper or feel-ings at the moment. The current situations could cause sponta-neous primary emotions, but even they are also influenced by thetemper and by the learned reactions of the IVA.

The rest of this paper is organized as follows: Section 2considers similar developments; the third section presents thescenario for the goals of the experiment; the fourth sectioncomprises the description of the programming system and themodel of IVA with PRE-ThINK architecture, adapted for typicalworking student’s life scenario modeling. Section 5 gives de-scription of the experiments and experimental results. The sixthsection includes discussion and directions for further develop-ment of the programming system; a generalization of the presentwork is proposed at the end.

2. Background

There is a considerable body of work on social norms andnorms in conversations in particular, including formalization ofnorms and obligations [Boella, G., Torre, L.v.d. 2003], hownorms emerge, spread and get enforced in a society [Castelfranchi,C. 1995], levels of cooperation in social communications [Airenti,G., Bara, B.G., Colombetti, M. 1993], discourse obligations indialogues [Traum, D.R., Allen, J.F. 1994] etc.

In Thespian’s decision-theoretic framework [Si Mei, StacyC. Marsella, and David V. Pynadath 2006], conversational normsenable the characters to behave human-like by making relevantresponses, following natural turn-taking patterns, and havingappropriate conversational flow.

[deRosis Fiorella, Catherine Pelachaud et. al. 2003] aswell as Prendinger and colleagues [Prendinger Helmut and MitsuruIshizuka 2001] developed agents that are able to control theiremotional displays if the social situation requires it. For instance,if the social distance between an agent and its conversationalpartner is high, Prendinger’s agent would not show anger to thefull extent.

The virtual tutor COSMO [Lester J. C. et. al. 2000] inten-tionally portrays emotions with the goal of motivating studentsand thus increasing the learning effect.

In the WASABI architecture [Becker-Asano, C., Wachsmuth,I.] use their agent’s cognitive reasoning abilities to model themood-congruent elicitation of secondary emotions as well. Theyexplain how nine primary emotions together with three secondaryemotions-namely the prospect-based emotions hope, fears-con-firmed, and relief -were integrated in such a way that their moodcongruent elicitation can be guaranteed. They discussing resultsof a study on the effect of secondary emotion simulation in a cardgame scenario.

In [Gebhard Patrick, 2005] layered model of affect, calledALMA are simulated three interacting kinds of affect as theyoccur in human beings: 1. Emotions reflect short-term affect,which is usually bound to a specific event, action or object,which is the cause of this emotion. After its elicitation emotionsusually decay and disappear of the individual’s focus. 2. Moodsreflect medium-term affect, which is generally not related witha concrete event, action or object. Moods are longer lasting

stable affective states, which have a great influence on human’scognitive functions.[ Morris W. N. 1989] 3. Personality reflectslong-term affect. Personality reflects individual differences inmental characteristics. A common personality schema is theBig Five model of personality [McCrae R. R. and John O. P.1992]. It specifies the general (affective) behavior by the traitsopenness, conscientiousness, extraversion, agreeableness andneuroticism.

In [Benny Ping-Han Lee et. al. 2006] an improved emotionmodel integrated with decision making algorithms is proposedto deal with two topics: the generation of coexisting emotions,and the resolution to ambivalence, in which two emotions con-flict.

[Rehm Matthias and Elisabeth Andre 2005] model situa-tions in games and monologues in which the agent fails toentirely conceal its “felt” emotions and they investigate theinfluence of such a behavior on the relationship between agentand user.

Many researchers model IVA behaviour aiming at estab-lishing a trust-based relationship between the user and the IVA[Celso M. de Melo et. al. 2009, Jonathan Gratch et. al 2007,Timothy W. Bickmore et. al.2007, Radoslaw Niewiadomski et.al. 2008]. Thus IVA-s are modelled, having capabilities to ex-press the so called moral emotions (pity, gladness, sympathy,remorse) [Celso M. de Melo 2009], and the way in which thefrequency and the moment of sending a positive feedback fromthe user to the IVA [Jonathan Gratch et. al. 2007], influence thetrust between them, is investigated. Agent’s behaviour is mod-elled so that it follows the user’s behaviour [Jonathan Gratch et.al. 2007 ].

A hypothesis has been derived [D.Budakova et. al., 2010]that agents with subjective behaviour could be well acceptedamong users, if this behaviour is a well grounded and fairsubjective behaviour. Only in this case it will lead to users’reactions like sharpening their attention, increasing their trust inthe agent and more natural perception of the IVA. An option forthe user to try to meet the requirements of the IVA and gain itsapproval exists as well. [D. Budakova et. al., 2010].

It is assumed that an intelligent virtual agent (IVA), capableof detecting a critical situation, of analyzing it and choosing thebest possible option to take care of all individuals concerned,would easily gain trust. Such a behavioural model is presentedwith the help of the PRE-ThINK architecture. [Budakova D., 2011].

The PRE-ThINK architecture, proposed in [Budakova D.2011] (abbreviation from the initial letters of the basic compo-nents making it up - Principles, Rationalities, Emotions, Thoughts,Investigations, Needs, and Knowledge) also allows for modellingan IVA, having capabilities to detect and analyze conflicts. Prob-lem situations evoke conflicting thoughts, accompanied by mixedemotions and they are related to a number of different ways ofaction. The agent considers in advance (Pre-Think) in what wayeach possible action in a critical situation would reflect over allindividuals concerned by it. The originated social thoughts areassessed from emotional, rational and needs-related points ofview in accordance with the knowledge, priorities and principlesof the agent. Agent’s behaviour motivators are its needs accord-ing to Maslow’s theory [Maslow A.H. 1970].

In the present paper the agent with PRE-ThINK architecture


is used to investigate social behavior in typical working student’slife scenario.

3. The Scenario

For the purposes of the experiment the behavior of thetypical working student is modeled, that have to follow the politeform of social communication at work; fulfill diligently its dutiesat work; manages to pass all its exams; and manage to attendall meetings and parties, organized by its friends. According tothis particular scenario the IVA is modeled to be an attractive 20-year-old blond student, giving information to the users of anexperimental, especially developed for the experiment site, in therole of an on-line receptionist.

The users can only observe the IVA’s behavior in its roleof an on-line receptionist. The other events, related to its modeledpersonal identity in accordance with the modeled scenario(student’s life, sleeping time, party time) as well as the courseof time, remain hidden for the users of the site and are onlysimulated in a programming way.

The new aspect in the proposed paper is that a situationis modeled, in which the hidden/refrained emotions are causedby events that are outside the current context and not related tothe current events, while the shown emotions are related to thecurrent context but they are well considered and result frompersonal experience as well as from studying of social stan-dards.

The real (realized and refrained) secondary emotions ofthe agent, on one hand, could be: confidence, satisfaction withthe achievements and self-belief. They result from well fulfilledtasks, passed exams, well spent time at parties with friends,high ranking by the users of the site, and they evoke at firsthappiness, relief and pleasure and after their rationalization theyturn in the course of time into self-confidence, certainty andauthoritativeness.

This can be expressed by politeness, energy, friendliness,readiness to help and understand the others, willingness tocommunicate and join both the others and various good causes.

On the other hand, these emotions could also be: inferioritycomplex, disappointment and depression, lack of self-belief,what is caused by failures at the exams, unfulfilled tasks atwork, lowered ranking by the users, and they evoke at first fearand anticipation of failures, as well as confirmed fear and aftertheir rationalization in the course of time they turn into disap-pointment and inferiority complex. They could be expressed byirritability, aggression, dictatorial behavior or shyness, sadness,depression and self-isolation from the others.

The model allows for realization of other scenarios forsocial behavior investigation as well as for observation of theprocess of decision taking.

In order to reach all her goals, the IVA plans her time forstudying, working, sleeping and meetings with friends, so thattheir optimal apportionment is achieved. The scenario allowsobserving how in the course of time, day by day, each deadlineis met and the IVA achieves this perfect time apportionment.

The IVA makes her plans in accordance with her principlesto neglect (only within the thresholds of dissatisfaction) the basicneeds in order to achieve the higher goals. Consequently, new

situations and new choices could be realized in case of chang-ing the relation between the needs and the corresponding IVA’sactions and goals, as well as by setting new actions, differentfrom the already predefined ones.

Studying the way in which an IVA gains experience fromthe communication with the users of the site or the way the IVAlearns to be businesslike and polite regardless of her problems,failures or successes will be a subject of another investigation.

It is presumed that with the further development of thesystem it could be possible to realize a backward investigation,i.e., having given the taken decisions in a problematic situation,to build the model of the investigated person.

The simulated course of time could be quickened or sloweddown.

4. The Program System Description

The basic modules of the program system are:1) interface module; 2) module for simulating the course

of time - days and hours; 3) module for decision making and

defining the agent’s actions by means of the PRE-ThINK archi-

tecture according to her goals, principles, priorities and theassessment of the generated thoughts; 4) module for initializa-

tion of the scenario, comprising the relation need - action,deadlines for achieving goals, related to the different needs andemotions, the necessary number of working hours for success-ful fulfilling of a task, the hours for passing an exam and fornormal attendance of parties, as well as the agent’s luck andabilities (figure 1).

Figure 1. Structural scheme of the program systems

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Database

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Module for initialization of the scenario. Schedule of the events, deadlines and

requirements for achieving the assigned goals. ��

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Module for realization of the scenario and for modeling the IVA with the PRE-ThINK

architecture. IVA’s behavior, decisions making for achieving the goals according to the

agent’s principles, priorities, appraisals and experience.

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Interface with the user Experimental web site, where the IVA are

receptionists. Demonstrated social behavior.

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The Interface ModuleThe interface module includes the experimental web site,

working for the purposes of the experiment, with an IVA - recep-tionist, modeled according to the scenario of personal identityand with the PRE-ThINK architecture. The IVA gives the web site’svisitors information in correspondence with the topics offeredlike forthcoming events at the university and in the investigationgroups at the university; explains the location of the laboratoriesin the building of the university; tells when and where the variousclasses happen. The IVA has social conversational capabilities.She always greets the web site users, asks them how she couldhelp them, how they feel, what is new etc. When in good temper,she speaks a bit highly, uses jokes in her answers; when sad,she tries to hide her sadness, speaks slower and more quietly,gives shorter answers and apologizes.

The experimental site is divided into three frames. The firstone is for choosing the topic in which the user is interested; thesecond - for modeling the IVA’s behavior, for initialization of thescenario, as well as for simulating the course of time; and thethird is for visualization of the agent’s head and realization of theagent’s multimodal social behavior.

The following relation is realized: a chosen question anda corresponding answer, generalized condition of the agent,temper, temperament, self-confidence, emotional but sociallyappropriate pronunciation of the answer by the IVA.

The user can see and ask the IVA questions by means ofthe site only. The rest of events and experiences from the pre-defined scenario remain hidden from him/her.

The Module for Initialization of the ScenarioThe relation need - action is preset as it follows: physi-

ological need - need of sleeping; need of safety - workingposition as an on-line receptionist; need of love and belonging- attendance at parties with friends; need of self-actualization -university course (figure 2).

According to Maslow’s theory the needs in normal humandevelopment are arranged as follows: physiological (ph), safety(s), love and belonging (lb), esteem and self-assessment (es),self-actualization (sa), aesthetics (a). In the architecture consid-ered here the needs are associated with weights Wneed corre-sponding to their priority. Wph, Ws, Wlb, Wes, Wsa, Wa.

When, because of the occurrence of an event, one or moreneeds prove to be unfulfilled, i.e., there is a crisis situation, then

the needs rearrange so that the unfulfilled ones receive firstpriority. The unfulfilled needs arrange in an order, opposite to theorder of needs weights in a normal state of the agent. Theunfulfilled needs are denoted by W

phu, W

su, W

lbu, W

esu, W

sau, W

au.

This concept is illustrated in figure 2 where the predetermined(according to the scenario) simplified relations of the type need- action are denominated both for a normal and for a crisissituation. This is the sequence of the IVA’s priorities when thereare no problems and the activities are arranged according totheir correspondence from the most basic physiological needtowards the higher ones - confidence, love and belonging, self-actualization, on the one hand, and according to their rearrange-ment when a need has remained dissatisfied because of thecircumstances.

The system in the next version is envisaged to be able toprocess the cases in which an activity could be related to adifferent degree with more than one need and just the oppositecase when each need is related to a different degree with morethan one activity.

The dates of the exams, the dates of fulfilling the workingtasks and the dates of the parties are predetermined. The hoursnecessary for the agent to get ready for the exams, the hoursfor a task to be fulfilled successfully, the sleeping hours and thehours to enjoy a party are also predefined.

The IVA’s luck and abilities are predetermined as well andthey can facilitate or slow down the fulfillment of a task, theycan lead to a failure at an exam, they can ruin one’s sleepingor his/her time at a party. The thresholds of dissatisfaction foreach task, related to a particular agent’s activity are also pre-defined.

An initial schedule for realization of the IVA’s goals ispredetermined. It defines the initial apportionment of the hoursin the agent’s day and night and it is as it follows: working timefrom 8.00 to 17.00 - during this time the IVA fulfills the tasksrelated to her job position as an on-line receptionist; after that3 hours are envisaged for meetings with friends; 3 more hoursare distributed for exam preparation and the rest of the hoursfrom 23.00 until 8.00 are for sleeping till morning when she hasto go to work again.

This is the exact initial apportionment of the time whichchanges in the course of the events in the agent’s life and theiroptimum arrangement is a goal of the algorithm for decisionsmaking by the IVA.

The variables, in which every success or failure, relatedto a particular event, will be memorized, are set to zero. Theyare, for instance: success_studying; success_work;success_party; failure_studying; failure_work; failure_party;sufficient_sleeping; insufficient_ sleeping; generalcondition_good, general condition_bad, generalcondition_worsening, general condition_bettering. All of theseassessments are related to the emotions, which are formed,realized and expressed in the course of time in result from theIVA’s successes and failures. They are, respectively: happiness,anticipation of a success, confirmation of a success, satisfac-tion, self-confidence, and prestige, on one hand, and, on theother hand - sadness, anticipation of a failure, confirmed failure,disappointment, depression or anger.

The IVA’s aspiration/goal is to succeed in each of the

Figure 2. Arrangement of the fulfilled and unfulfilledneeds in a crisis situation and their weight together withthe correspondence of the relation need-action according

to the considered scenario

W

WphWsWlbWesWsaWa WauWsauWesuWlbuWsuWphu

10 20 30 40 50 60 70 80 90 100 110 120


directions, to be in good spirits and have self-confidence.

Simulating the Course of Time

The course of time is simulated by means of the compo-nent Timer. Every hour is counted out and the sequence of themorning, the noon, the evening and the night is controlled; it isalso controlled what the IVA is supposed to do according to theinitial schedule in each particular moment; the real agent’sbehavior and actions in a moment are also controlled and theactivities from the schedule and the real behavior according tothe decision made are compared. All the agent’s activities aresaved in the database. The IVA knows how many tasks remainto be fulfilled, how many successes and failures are, to whichactivities they are related.

Modelling of the IVA with the PRE-ThINK

architecture and the process of decision making

for defining the IVA’s behavior

IVA’s principles. Anticipated IVA’s behavior in accordance

with these principles

The IVA takes its decisions based on its principles. Thefollowing IVA principles have been modelled: “Choose the betterpossible action”; “Neglect the basic needs until reaching adefinite threshold of dissatisfaction, giving priority to the highest-order needs”, “Follow a polite form of social behavior regardlessof your personal successes or problems”.

The IVA starts following her initial schedule and realizeswhether she manages to cope with the assigned tasks or not.She also realizes how many tasks from each activity remain tobe fulfilled, e.g., how many exams to pass, how many workingtasks etc. According to the principles if the IVA does not passher exams, for example, she will try to reallocate more hours forstudying at the expense of the sleeping hours at first; if this doesnot help, then the new arrangement of hours is done at theexpense of the working hours; and, last, at the expense of thetime spent with friends. If all of these measures do not help andher physiological need - her needs of safety and friendship areseriously threatened, then, according to her principles, realizingMaslow’s theory and according to the predetermined at theinitialization very simple relation need-action, the IVA will stopher studies in order to redress the balance of the more basicneeds, sacrificed in the name of her assigned highest need/goalin this scenario.

IVA’s thoughts. Process of decision making

Each thought of the agent is related to an emotional (posi-tive (+) or negative (-) sign), rational and need value and receivethe weight of this need.

Each thought is addressed to the situation s be denoted byTh_s. If the importance of the thought Th_s is denoted by I

Th_s,

the weight of the need, related to this thought is expressed byWneedTh_s

, , the emotion implied by this thought is marked byEemot.Th_s

, then, following the formulae for calculating the assess-ment value of the thought O

Th_s corresponding to the situation

s will be [Budakova D., 2011]:

sThsneedThsThemotsTh IWEO ___._ **= .

If a thought is partially related to more than one need then

the sum of the weight percentages of the needs to which it isrelated is taken into account in the formulae.

Each thought is related to an action.The assessment values of the thoughts related to one and

the same action in one and the same situation are put on theone basin of the “thoughts balance”. The assessment values ofthe thoughts for the same situation, but related to another action,are put on another basin etc. Our “thoughts balance” will haveas many basins as the alternative actions considered by theagent in the particular situation are. The module of the assess-ment values is summed and the action from the basin havingthe highest assessment value is undertaken. The emotion, ex-perienced by the IVA in a particular situation is determined bythe prevalent emotion. After an action has been undertaken, theagent keeps track of the effect from it. The IVA’s state andpriorities are changed anew and they depend on whether theproblem has been solved or there is a new conflict situation tobe solved [Budakova D., 2011].

The described mechanism for decision making is adaptedfor the purposes of the considered scenario. Instead of choosingthe action from the basin having the highest assessment value,the action with the lowest ranking is sought for here, i.e., the lessimportant for the moment. The hours used for it will be reducedin order to spare time for other more important activities and,

respectively, for achieving other dissatisfied goals.

Mechanism of origination and assessment of the IVA’s

thoughts

The IVA’s thoughts are generated in 24 hour each clockround and they are related to the events from the agent’s sched-ule, to her generalized condition, to the successful or unsuc-cessful fulfillment of the goals, as well as to the possibilities foraction. Each thought, related to achieving a goal/action, is as-sessed from emotional, rational and need-related point of view.For example, if the IVA has failed at her exam today, her thoughtsare of the type:

I am sad because I did not manage to prepare myself wellenough for the exam. I am a very capable person and I believein myself. (Emotion: uncertainty and anticipation of failure). Ihave to increase my time for studying and I will cope with mytask as always. (Emotion: hope and anxiety). The sleeping hoursare enough and I feel good. (+) The working hours are enoughand I cope with my tasks perfectly well (+). The time for meet-ings with friends is enough and I feel well (+).

Thoughts related to possible actions:

I can increase my hours for studying at the expense ofreducing the sleeping time. Emotion (+); weight of the need forsleeping 10; rational assessment - easy and safe 1; generalassessment of the thought related to this action (+10).

I can increase my hours for studying at the expense ofreducing the working hours. Emotion (+); weight of the need forwork 20; rational assessment - easy and safe 2; general as-sessment of the thought related to this action (+40).

I can increase my hours for studying at the expense ofreducing the hours for meeting friends. Emotion (+); weight of theneed for meeting friends 30; rational assessment - easy andsafe 2; general assessment of the thought related to this action(+60).


The initial choice of action in this situation is to reduce thetime for sleeping and increase the time for studying as this isthe easiest and the safest action related to the need with thelowest weight. All the other possible actions are much harderand they are related to higher needs, which are difficult toneglect.

If the spared hours turn out to be insufficient for thesuccessful passing the exam and it is impossible to reducefurther the sleeping time because of reaching the threshold oftiredness, then the next appropriate action would be to reduce thetime for fulfilling the working tasks and duties in order to in-crease the time for studying a bit more etc.

In addition to choosing an action for improving her gener-alized condition, the agent also generates thoughts about hersocial behavior at her working place. For example:

Today I am sad because of the failure at my exam but Ihave to be polite with the users of the site and give themexhaustive information.

Today I am in perfect temper and in addition to the infor-mation I will give the users I could also be witty, etc.

5. Experimental Settingand the Experiment

I. Investigation of the IVA’s BehaviorAccording to the described scenario the following ele-

ments are predetermined:1. Schedule of the sequence of events/IVA’s goals;2. Schedule for realization of the goals.The schedule of the sequence of events/goals comprises

the events from the first until the last day of the experiment andthe number of hours needed for meetings with friends, sleeping,passing the exams and successful fulfillment of the workingtasks. The days are numbered from first to thirty fifth. In orderto further simplify the scenario it is assumed that the IVA studiesfor every exam until the day of the exam and works over a taskuntil its deadline. Regardless of whether an exam is passed ora task is completed, after their deadlines the IVA starts studyingfor the next exam and working over the next task. Only thesuccess or the failure influence the agent’s generalized conditionand they initialize the process of rearranging the hours in theschedule for realization of the goals.

The days of the parties, predetermined for the time of theexperiment are accordingly on the 2nd, 5th, 12th, 18th and 26th dayof the experiment and the duration of the parties is from 6 to 8hours.

The IVA’s schedule for realization of the goals is alsodetermined initially and it is the schedule which the IVA issupposed to optimize in the course of the experiment dependingon the successes and failures.

The initially determined schedule for the particular experi-ment is the following:

8:00 - 17:00 working time;17:00 - 20:00 time for friends;20:00 - 23:00 time for studying;23:00 - 8:00 time for sleeping.The idea is to give the IVA the possibility to redistribute

these hours, for example, in case there is a party, i.e., insteadof sleeping to go with her friends to the organized party; if shehas failed at an exam, she can increase the hours for studyingat the expense of the sleeping hours etc.

The first experiment illustrates the consequences for theIVA if she follows the schedule without changes. The IVA studiesless than needed and correspondingly she fails at the exams.The working time turns out to be sufficient for fulfilling the tasksand duties perfectly.

The sleeping hours are also sufficient and the IVA does notmiss a party.

The second experience shows how the agent tries to copewith her problems at the university by increasing at first thehours for studying at the expense of the sleeping hours and then,at the expense of the working hours.

After she fails at her first exam, the IVA increases the timefor studying at the expense of the sleeping time. After the secondfailure she reduces the sleeping time even more in order tostudy harder. After the third failure she reduces the working time,too, and this is how she manages to pass the fourth and the fifthexams. The success turns out to be sufficient for bringing backher happiness and self-confidence.

II. Investigation of Intelligent Virtual Agents’Social Behavior

For the purposes of the second experiment two IVAs aremodeled with visualized speaking heads. They are called Lilly(figure 3a) and Mira (figure 3b).

The two modeled virtual agents have the same problemsbut show different social behavior. Both virtual agents alwaysgive the users complete, precise and clear information.

The IVA Mira is modeled to be extremely friendly, to ex-press her happiness or sadness in a very open way, to beinclined to sharing her problems comparatively easily. She con-tinuously tries to make friends with the users by asking ques-tions, expressing suggestions, sharing information about theroot of the events they are interested in. When sad, she speaksslower than usual and in a lower voice. Her answers, however,are still complete and exhaustive.

The IVA Lilly is modeled to behave in a more reserved way.Her answers are always complete and concrete but short andquick. She does not want to share her problems and alwaysevades personal questions. She never tries to make friends withthe users and talk to them. She is just polite and always wishesthem success. When sad, she speaks even faster than usualand in a loud voice. Her face expression shows either severityor some boredom and nervousness.

Masking some of the feelings (their restraining) is achievedby introducing mimics, not corresponding to the emotional state,which the IVA tries to express, as well as by changing theloudness and the speed of speaking. The users are expected tocatch and discuss exactly these discrepancies.

The visualization of the IVAs is realized by means of theprogram product Crazy Talk 6.

For the purposes of the experiment the program was of-fered to 30 students at the TU-Sofia, Plovdiv Branch. They hadthe opportunity to get information about forthcoming events at theuniversity from the virtual agents Mira and Lilly. They were


warned that they are expected to treat the IVAs as their col-leagues - classmates, who are at their working place at themoment and who are likely to have personal problems or be very

tired. The task in front of the users was to assess the IVAs’emotional state, to tell whether it changes in the course of theexperiment, to explain the reasons for the showed or restrainedhappiness, sadness, annoyance or uncertainty (in case they areable to notice any). The users were told that the observationshould last about 7-8 minutes per IVA, during which the programsimulates about 50 days in the IVAs’ life and the events happen-ing within these days. Having this in their minds the users couldgive suggestions about what the reasons for the observed emo-tional states were. If they want, the users could ask the IVA’s howthey feel, why they are so happy, whether they have problemsand what the problems are. They can also encourage them orpass remarks.

6. Experimental Results

The users defined Lilly as a girl of action, authoritative,reserved, ambitious and more restrained than Mira.

They defined Mira as extremely friendly, more extrovertthan Lilly, ready to share her problems and sometimes sad ordisappointed with personal problems.

Finding differences in the IVA’s emotional stateAll the users gave a maximum or close to the maximum

assessment mark for the IVAs in relation to their professional-ism, intelligence and truthfulness (figure 4).

The participants in the experiment noticed the differencein the agents’ emotional states during the simulation. They dis-tinguished the days when the IVA were really happy and they justtook pains to show consideration, happiness and politeness

Fig. 3a The IVA Lilly

Figure 3. Modeled IVAs’ heads, expressing emotional statessuch as happiness, uncertainty, pity, disappointment and

sadness

Fig. 3b The IVA Mira

Figure 4. Assessment of the IVA’s truthfulness

Figure 5. Assessment of the agents’ emotional state during thedays of the experiment


Figure 6. Investigation of the users’ opinions about the restrainedemotional states and the possible reasons, causing them

Figure 7. Perception of the IVAs as socially functioning persons

while feeling differently and perhaps hiding disappointment withsomething, sadness, anger or just tiredness (figure 5 andfigure 6).

The users tended to suppose that the restrained emotionalstate is due to the IVA’s personal problems, not related to thepresent context. To a lower degree they suppose that the agentsrestrain their boredom with their work or with the communicationwith the users (figure 6).

Most of the users were interested in the IVAs’ problemsand insisted on finding out what they are. They wished the IVAsto solve them successfully; they sympathized the IVAs and werevery disappointed when Lilly did not share her problems in spiteof their insistence (figure 7). Only one from the users expressedthe opinion that “Lilly’s problem is deeply hidden in her herself”,while expressing at the same time admiration for her authorita-tiveness, self-confidence and he wanted to become friends onlywith Lilly.

The great majority of the participantsin the investigations preferred to makefriends with Mira, five of them wanted tomake friends with both on-line administra-tors. Only one of the participants has pointedthat he is not interested in the IVAs’ prob-lems. Three users have chosen the option“I don’t think the IVAs have problems”.These users are obviously skeptics, whodo not want to perceive the modeled IVAsas really functioning persons and, accord-ing to them this is just a program. How-ever, 90% of the users accept the IVAs associal persons and have expectations re-lated to their behavior and their relation-ships in the process of communication(figure 7).

The conclusion is that the morefriendly and extrovert characters, ready to

share and show their real emotions, speaking more and inter-ested in the problems of the others are preferred and they gainmore sympathy and make more friends.

The higher speed of speaking, the shorter answers, thequickly passing as shade frowning, and the nodding aside arerelated to restrained aggression, distance, and ambition eventhough they are mixed with smiling and positive nodding.

On the contrary, the slower speed of speaking, the sadeyes together with wishes for success, idioms and smiles arerelated to restrained sadness and evoke sympathy and willing-ness to help.

7. Conclusion

The paper investigates the social behavior of an IVA withPRE-ThINK architecture. A scenario is proposed, allowing forclearing out and revealing the following: the agent’s decisionmaking mechanism; the mechanism of origination and assess-ing thoughts, related to the alternative actions for each situation;the mechanism for achieving optimal time apportionment inorder to achieve the best possible coping with the assignedtasks. The origination and the influence of the primary emotionssuch as happiness and sadness is also cleared out for buildingand investigating the secondary emotions such as relief, confi-dence, prestige, uncertainty, confirmed fear, disappointment.The peculiarities of the program system, as well as of the IVA’sPRE-ThINK architecture together with the conducted experimentsare described and explained.

In order to investigate social behavior two virtual agentsare modeled, communicating with the users in a different wayand sometimes hiding their real emotions and temper.

Masking (restraining) an emotional state is modeled byintroducing mimics, not corresponding to the emotional state,which the IVA tries to express, as well as by change in theloudness and the speed of speaking.

What is investigated is: how the users accept the differentsocial behavior, expressed by the IVAs; whether they recognizethe change and discrepancies in their behavior. The results


show that the users can recognize the restrained sadness,happiness, disappointment, distance, authoritativeness, the IVA’swillingness to make friends with them or to stay reserved. Theyprefer a friendlier IVA, clearly showing their real emotional state,ready to share their problems and aspire to making friends withthem.

90% of the users accept the IVAs as socially functioningpersons and have expectations related to them.

The future development of the program system could offerrealization of new situations in which the agent forms newprinciples and new behavioral rules.

Creation of a more complex situation is envisaged, inwhich the IVA’s goals will be related to different needs to adifferent extent. The decision making will be more complicatedand more realistic then.

Tracking the way the IVA gains experience in communica-tion with the users of the site will be a subject of anotherinvestigation together with the way she learns to be polite andbusinesslike regardless of her problems, successes and fail-ures.

It is assumed that, together with the further developmentof the system, it could be possible to realize a backward inves-tigation, i.e., to predetermine the decisions, taken in a problem-atic situation in order to build a model of the investigated person.

The investigation of a collaborative or competitive behaviorin a multi-agent system for similar scenarios would be also ofgreat interest.

Another direction for further development is to investigatehow the various ways of communication with users would influ-ence the ranking of the IVA. Is it better for her to be morebusinesslike if the user is interested in what is going on whenhe has understood from the IVA’s multimodal behavior thatsomething is going wrong or that she is extremely happy?

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Manuscript received on 5.10.2011

Dilyana Budakova received the M.Sc. and Ph.D.degrees from Technical University - Sofia, BranchPlovdiv in 1994 and 2006. Currently she is headassistant professor in the Department of Com-puter Systems and Technologies at Technical Uni-versity - Sofia, Branch Plovdiv. Her interests andpublications are in the areas of intelligences agents,artificial intelligence, affective computing, machinelearning, and generalized nets.

Contacts:Technical University of Sofia, Branch Plovdiv,

61, Sankt Petersburg Blvd., Plovdiv, Bulgariae-mail: [email protected]

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Social Behavior Investigation of Intelligent Virtual … technologies 3 2011 9 and control Key Words: Intelligent virtual agents (IVA); architecture; social behavior; social scenario;