Di Loreto

Gouaich Abdelkader
email: gouaich@lirmm.fr

A FRAMEWORK FOR DESIGNING SOCIAL INTERACTIVE SYSTEMS

Keywords: Digital Natives, Social Web, Design Methods

Digital natives are the potential users of many applications designed and built today. For this generation most of state of the art features related to social interactions and ubiquitous computing will be taken as granted. For this reason, we have to provide design frameworks and methodologies that integrate these features at early design stages. In this paper we propose a framework for designing Social Interactive Systems (SIS) based on four criteria: identity, space, persistence and action. In order to demonstrate the usefulness of the framework the paper will describe an experiment we held with a Social Virtual World developed using the above-mentioned framework.

INTRODUCTION

Our era is characterized by the convergence of social and ubiquitous computing. From one hand we have the emergence of the social web paradigm (with social sites such as Facebook and MySpace, and social 'worlds' such as Second Life). On the other we have the massive use of ubiquitous interfaces that allows computers to live out here in the world with people. It is our opinion that the mix between social and pervasive computing is an issue that prompts us to rethink Interactive Systems Design. In fact, the capacity to integrate social elements at early design stages will make the difference between successful or not applications. For this reason in this paper we propose a framework based on four elements: identity, space, persistence and actions that are the means for building Social Interactive Systems. In order to demonstrate the usefulness of the framework the paper will describe an experiment we held with a Social Virtual World developed using the abovementioned framework.

A FRAMEWORK FOR SOCIAL INTERACTIVE SYSTEMS DESIGN

This section of the paper presents the core elements of the framework that can be used to design Social Interactive Systems (SIS). The framework is based on four elements: identity, space, persistence, and actions. These elements are motivated by an empirical analysis of current and past social software and supported by major findings from psychology and sociology. Actually, these elements represent core features of any Social Interactive Systems (SIS) targeted towards young generations (see Di Loreto, 2010). Hereafter, the semantics of each element of the framework is described more in details.

Identity

Our point of view about Identity is the same as social psychology's approaches [START_REF] Hogg | Social identity and group cohesiveness[END_REF], which consider individual and social identity not as stable characteristics, but rather as a dynamic phenomenon [START_REF] Harré | Varieties of positioning[END_REF]. In these approaches, the choice about what possible self to show is driven by strategic moves (e.g., what features are more relevant and effective for self-presentation) which participants can make within a particular situation. In describing everyday interactions, Goffman [START_REF] Goffman | The presentation of self in everyday life[END_REF] distinguished between two ways of expressing information: information that is given and information that is given off. Information that is given is the conscious content of communication, the voluntary symbolic actions that are mutually understood. For example, a person who describes their anger is giving information about their emotional state. In talking about their anger however, the person also gives off information, through para-verbal characteristics such as tone, volume, the choice of words, and non-verbal cues. While information that is given is considered to be within the actor's control, information that is given off is perceived by the audience to be unintentionally communicated. A classical example of 'identity announcement' that has intentionally and unintentionally elements is avatar personalization. While we will not enter in detail here on its implications the avatar is a visual claim for personal expression that is constantly worked on. This continuous work reinforces the concept of presence and thus social presence. As another example of collateral information, we can use the explicit specification of a social network of acquaintance. While it is true that social networks are built via a series of invitations, usually members also have some control over the visibility of their network for others. This means that, for impression management, a user will show only networks he/she wants to show. For instance, some members can decide to make their social networks visible only to their direct acquaintances. In this case, there is a 'given' information (the user chooses what to show about his/her identity), but also a 'given off' information (derived e.g., from the kind of groups a user showed/joined). From a design point of view, we can say that allowing both the kinds of identity representation becomes the starting point for a social evolving identity.

Space

If we look carefully, the language we use to describe our experience of the virtual environment is a reflection of an underlying conceptual metaphor: 'Cyberspace as Place' [START_REF] Lakoff | Categories and Analogies 3[END_REF]. This means that we are transferring certain spatial characteristics from our real world experience over the virtual environment. The metaphor 'Cyberspace as Place' leads to a series of other metaphorical inferences: cyberspace is like the physical world, it can be 'zoned', trespassed upon, interfered with, and divided up into a series of small landholdings that are just like real world property holdings.

In this little presentation the term space was joined with the term place. In reality, for the good functioning of a SIS it is important to distinguish between the two terms. Actually, the literature about space and place is fairly massive and diverse. A converging definition of the difference between space and place does not exist, however in his book about urban spaces and places, Carmona [START_REF] Carmona | Public places-urban spaces: the dimensions of urban design[END_REF] distinguishes among dimensions of an urban space. While space is divisible, place is not. Place is complex, inextricably multi-dimensional, lived, experienced, meaningful (with of course multi -meanings).

This means that while space is a well-defined topographical entity, place is the result of human inhabitation, (social) interaction, and the like. We are located in spaces, but we act and develop individual and social experiences in places. We claim that in order to design a social application, it is essential to allow by design the creation of public (at different levels) places for aggregation but also the creation of private places [START_REF] Wenger | Cultivating Communities of Practice[END_REF]. Besides, the lever of personalization can be used in order to allow the shift from spaces to places. Only taking possession of the space, and manipulating it to turn it in something we like, we can transform it in a place.

Persistence

As we have seen, in order to create a social identity in an online environment several elements are required. An additional element is persistence (of personal identity in the system). In a non-persistent world, it is not possible to have a history of actions and thus allow, for example, the creation of a reputation like in real life. Moreover, Danet [START_REF] Danet | where's that smoke coming from? writing, play and performance on internet relay chat[END_REF] argued that synchronicity is associated with 'flow experiences', a state of total absorption, and a lack of awareness of time passing. This idea of synchronicity is linked to the idea of temporality, a linear procession of past, present, future. This particular nuance (synchronicity as process) is very interesting if we think that interaction with media and media perception is changed. In fact, advances in technology and the speed of network connections are blurring distinctions between synchronous and asynchronous communications (Joison, 2003). Synchronous and asynchronous communications are thus processes that happen during time. The idea of communication as a process is very consistent with the idea of persistence and is another element supporting social awareness.

Actions

In this part, we discuss physical and psychological mechanisms that regulate human actions in order to understand why the action element has to be considered as a pillar in the design of social software. The first theory we want to describe is the so-called 'thinking through doing'. This theory describes how thought (mind) and action (body) are deeply integrated and how they coproduce learning and reasoning [START_REF] Klemmer | How bodies matter: Five themes for interaction design[END_REF]. Jean Piaget [START_REF] Piaget | The origins of intelligence in children[END_REF] postulated that cognitive structuring requires both physical and mental activity. In a very basic sense, humans learn about the world and its properties by interacting within it. As a second support, we can cite embodied cognition. Theories and research of embodied cognition regard bodily activity as being essential to understanding human cognition [START_REF] Pecher | Grounding Cognition: The Role of Perception and Action in Memory, Language, and Thinking[END_REF]. While these theories address cognition through action in physical environments, they also have important implications for designing interactive systems. In fact, body engagement with virtual environments constitutes an important aspect of cognitive work. For example, one might expect that the predominant task in Tetris is piece movement with the pragmatic effect of aligning the piece with the optimal available space. However, contrary to intuitions, the proportion of shape rotations later undone by backtracking increases (not decreases) with increasing Tetris-playing skill level. In fact, players manipulate pieces to understand how different options would work [START_REF] Maglio | Epistemic action increases with skill[END_REF].

To summarize, because an action is always an action-over-something, the kind of interaction spaces and objects we create in a Social System will influence which cognitive work the user will do over the system.

The Overall Framework

While we presented the four elements in a separate way, their usefulness in the construction and evaluation of social environments is mostly linked to the interaction between these elements.

In a way each element can be thought of as a line (an axis) that starts from the absence of the element to the fulfillment of its presence for a Social Interactive System. For example, for the concept of identity its total absence is anonymity while its fulfillment is social presence (with intermediate points such as personal identity construction). For the concept of space its total absence is topographical space while its fulfillment is social places (with intermediate points such as third places and personal places). For the concept of persistence its total absence is system 'amnesia' while its fulfillment is memory (with intermediate points linked more or less to the concept of persistence). Finally, for the concept of action its total absence is the obstruction of action (i.e., my user can only look at my application) while its fulfillment is social actions (with intermediate points such as public personal actions and the like). Figure1 shows the above-described axis graphically. This way to represent the four elements has an additional value. In fact a designer can create an 'Expected Profile' for an application using the four axis. For example, if he/she decides that his/her to be developed application has to have a high level of selfpresentation elements (an avatar, a profile, and so on) he/she will give a high value for the identity axis. Same thing happens for the persistence axis. For example, a social network based on micro actions such as Facebook, does not require the same level of persistence as a virtual world such as Second Life. In the first case the persistence axis will have a medium value, in the second a high value. And so on.

Note that the total framework is not simply a list of elements (i.e., its application does not mean to put one after the other the four elements in your system) but it is created through the delicate balancing between them. Actually, it is up to the designer to choose which element of the framework to stress or not during the creation of a dynamic experience such as in a social application. In addition, only once the 'Expected Profile' of the application is decided, the designer chooses which features add to the system. This means that what is important is the balancing between the elements not which features the designer puts in his/her system.

THE SCHOOL SOCIETY WORLD

As mentioned in the introduction of this paper social elements really influence the use of an application in our era. In order to support the abovementioned assertion we will describe a Serious Virtual World we developed using the framework: School Society.

From a practical point of view, the environment used in this experiment was able to support our students both in online learning, and in recreational experience. Note that due to the subject of this paper we will not analyze the virtual world as a learning environment, but as a social environment. Apart from studying, there is no final aim in School Society. Each Resident can find his own way to inhabit this word.

The Gameplay for the School Society World:

When the user enters the world for the first time, an animated intro scene describes how the world was created. Sometime in the future mankind has managed to practically destroy the world via magnetic weapons. The world was knocked off its axis and continents have sunk into the ocean. Only small islets remain. Several decades later, the survivors have managed to remodel their lives. They have built homes on the islets, as well as shops and a school. The top, elite students of this school are recognized worldwide as the best people in the world: the Legendary Eagles.

THE FRAMEWORK IN ACTION

The first step in this experiment was to determine an 'Expected Profile' for the to be developed application. In this case the choice was a balanced 'Expected Profile' (see Figure 2. In order to understand how the profile was evaluated see Di Loreto, 2010). This means that the virtual world has to enable deep personalization, in both the space and the identity aspects. The world has to be a persistent one and it has to enable the creation of a community memory.

Hereafter the most interesting elements (both from the framework application and from gameplay point of view) are described in more detail.

Space in action

First of all, as an element of identification, the Resident's home is indicated as 'My home'. In addition, when the Resident reaches a public place, an NPC (Non Playing Character) welcomes him (with 'special attention' if he is the winner of some world competition -an element also linked to identity construction).

At this moment the public buildings in the world are: the Pub, the Market, and the School.

The basic idea was to use the Pub as a potential 'third place' for the world. In fact the Pub is a place where the Resident can 'informally' meet people he does not know. On the contrary, the Market is only a space to buy items for competitions. The school is the more 'formal' space. In this 'space' there is a different section for each different quiz the students can take.

A particular space: The Gazette School Society's world has its own newspaper called the 'Gazette'. The 'Gazette' is the 'voice' of the world. Every interesting event that has occurred in the world can be found in it. This journal is a kind of herald that publicizes 'public' activities (in-world events such as tournaments) but also 'private' activities (what your friends have done). The result is a dynamic public and private space that changes over time and is the 'memory' of the interactions within the world.

Identity in action

Each student can personalize the avatar he chose when he entered the world whenever he wants.

Each avatar possesses the following attributes: Name: When the student enters the world for the first time he is asked to choose a name for his avatar.

Body Attributes: When the student enters the world for the first time, he is asked to construct his avatar that will represent him during the interactions. However, he can change his appearance whenever he wants during the inhabitation of the world.

Finally, a student can use the gold he has earned through quizzes to buy objects in the market that he can use to add personal items on his avatar.

Activity in Action

As said the Pub is a particular space. In fact, in the pub the student can chat with people who are in it even if they are not on his buddy list (i.e., if they are not his friends).

In the School building students can take part in a set of social actions (apart from taking the quizzes the professors have created). In particular they can take part in two interesting social activities: participate in tournaments and challenge the professor.

For the first activity the student is alone against others students. If he can beat all the other participants his success is published on the world journal, the 'Gazette'. In this case the social aspect is driven through competition.

The other activity is literally a social one. If a professor is available, students can organize themselves in groups and challenge the teacher.

Practically, while the students will take quizzes created by the teacher, the teacher will answer to a quiz created by the students. For each answer the team gives, the time available to the teacher to solve the quiz increases or decreases (based on wrong or right answers). If the team is able to leave the teacher no time to solve the quiz, it will be the winner of the contest, rewarded with the Medal of Honor 'Where eagles dare'. In this case their bravery will also be publicized in the 'Gazette' (and so will be publicly visible).

Time in Action

First of all the game's world is a persistent one. This means that each time the player disconnects his account, the game will save his status: his modifications, his avatar's appearance, his experience, and so on. In addition, all old 'copies' of the Gazette are available for consultation. In this way all public events, all competition winners, and the like are stored creating a memory for the community.

EVALUATING THE FRAMEWORK THROUGH USE

In order to demonstrate the assertion stated at the beginning of this paper (i.e., that the presence of social aspect modulated through the framework influences the use of an application) the developed School Society virtual world was given to a group of students to use. Hereafter more details on the experiment.

The General Method of the Experiment

Three (3) groups of students were asked to consistently use the system for about one week. Each group had different 'views' over the systems (i.e., the group could access a different set of features). The different views were created in order to block some aspect of the framework (e.g., identity representation) and then evaluate if this absence impacted on the user's experience in the way supposed while describing the framework.

Subjects

The participants in the experiments were 38 students of the University Institute of Technology (I.U.T.) of Montpellier. The gender distribution of participants was 34 (90%) male and 4 (10%) female, with an average age of 20.

Students were divided into three groups: Group 1: Full vision over the system Group 2: Vision of the system without Identity features Group 3: Vision of the system without social features Note that this means that all the groups were using the same system. They just had different views of it. This kind of division was done in order to demonstrate the effective importance of social features and of the identity factor.

The number of participants in each group (about 13 people) was coherent with the findings that 'with high complexity, a study with more than 15 cases or so can become unwieldy' (Miles el al., 1994, p.30).

Procedure and Materials

At the beginning of class, subjects in all groups were introduced to the virtual world of School Society. The students were asked to use the systems for 7 days.

The interactions were 'free' for the students. They just had to inhabit the world as they liked. The idea was that if the students did not feel the absence of a feature they would not ever look for it (i.e., if they did not feel the necessity to use a chat, they would never open a chat).

Materials:

At the end of the week students were asked to evaluate their experience in School Society. Data on the experiment were collected through two channels.

In fact, the survey method was coupled with tracking methods based on technological features (log files, number of sessions, sessions' length, and the like).

The general idea was that by cross-referencing users' feedback and number of interactions (qualitative and quantitative data) it would be possible to understand if the designed social system really works or not from the social point of view.

Survey and Qualitative Measurements:

The survey was conceptually divided into three parts. Several questions directly addressed students' satisfaction with the social aspects (quality of the interaction). Another group of questions addressed graphic appeal and usage problem issues. A final group of questions provided an overall measure of satisfaction with the entire system (the overall reaction to the system). The different parts of the survey were designed in order to understand if the global satisfaction with the system was influenced by graphic appeal and usage issues, which are not directly linked to social satisfaction. The main idea was to distinguish between attitudes to the system itself and attitudes to using the system in a social way. Questions with Lykert type scales were avoided where possible in order to avoid different subjective approaches to these kinds of questions. In general, a scale of 0-4 was adopted in the process.

Log Files and Quantitative Measurements:

In order to measure sociability from a quantitative point of view the system logged all the actions made by the students. In particular Preece's suggestions (see [START_REF] Preece | Sociability and usability in online communities: determining and measuring success[END_REF] on determining sociability in online communities were taken into account.

Preece says that determinants of sociability include measures such as the number of participants in a community, the number of messages per unit of time, member satisfaction, and some less obvious measures such as amount of reciprocity, the number of on-topic messages, trustworthiness and the like [START_REF] Preece | Sociability and usability in online communities: determining and measuring success[END_REF]. While in this case the number of participants in the community had no significance (the participants were only the students) a list of the other elements taken into account is described in detail hereafter. 2-The amount of on-topic discussion was evaluated only in public discussions and only to understand the relationship between learning topics and strictly social topics (i.e., the topic of the post as not evaluated by its profundity or its real impact on 'community life').

Use of Sociability

3-Reciprocity is concerned with giving to a community as well as taking from it. While this element is normally measured through the number of answered posts, in this case the measure of reciprocity was also determined through the challenge feature (number of reciprocated challenges).

4-Flaming and uncivil behavior, such as abusive language or harassment. In this experience this measurement was not relevant for two main reasons: the presence of teachers who acted as moderators, and the fact that the experience lasted only one week.

Results and Discussion

Before beginning analysis it is important to address a possible limitation of this study. Students of an I.U.T may not necessarily be the 'average user'. This could influence how fast they learn to use the system or its perceived usability, but not the sociability they put into it. In fact, because of their age they can be considered an 'average' Digital Native. In the case of this experiment the measurements were linked to the sociability of the system and not to its usability/ability to learn to use it. For this reason we believe that the composition of the sample did not influence the experiment.

System Usage

Figure 3 shows the general system usage (the number represented in the y-axis is the number of total general actions that impacted over the system, including posting, taking quizzes etc.) for each of the groups. As we can see the group with full features used the application noticeably more than the other two groups. In addition, the group with no identity features used the system more than the one with no social aspects but noticeably less than the one with full features. Global satisfaction and generic issues Parameters linked to system issues or graphic appeal (derived from the survey) are very similar for all the groups. On the contrary the global satisfaction of the system experience shows a difference for group one (Full features-see Figure 4). Interesting enough, the group that was not able to use identity elements rated it in a similar way as the group without social elements.

Sociability Determinants

Figure 5 shows the trends for exchanged messages. Public messages have greatest numbers than the private ones (we will return on this topic later in the paper). This is coherent with the perceived usefulness (derived from the survey) of the two features: while chats rated an average of 3.8, mail rated 2.8 (scale 0-4). It is interesting to note that while Gazette was used more for lurking activities its perceived usefulness is 3.6. This is not a surprising finding. Lurking and contemplating activities are one of the most common actions in social environments [START_REF] Wenger | Communities of practice: Learning, meaning, and identity[END_REF].

Perceived Sociality of the System

The perception of the sociality of the system was obtained through the survey. To the question 'In general, about the fact that someone was playing the same game as you' 90% of participants answered they were encouraged to use the application and the main motivation (derived from another question) was because they play to beat their friends. Only four people answered that the presence/absence of others did not influence their use of the application. Nobody answered that the presence of others was an obstacle to the use of the application.

To the question 'Do you think that leaving messages for your friends in game is' 45% of participants answered they find it useful because they like to comment on what their friends do, 3 people answered they find it useless, and the majority (50%) answered they preferred the public chat (the Pub). This is more coherent with Digital Natives' use of social tools than with the use they did of the two media in the application.

In fact, the Pub had a flow of message very Twitter like (that in our opinion contributed on its success), while the note on mail was given based on the standard use of private messages and not on the ingame use of mail.

In addition, in the Pub participants with no identity features quickly added a nickname to each post. The result was something like: "Guest says: Guillaume: who is in the Guest group?".

CONCLUSIONS AND POSSIBLE IMPROVEMENTS

This paper started asserting that the mix between social and pervasive computing is an issue that prompts us to rethink Interactive Systems Design. In fact, the capacity to integrate social elements at early design stages will make the difference between successful or not applications.

Ending our discussion we can say that the experiment described in this paper supported this assertion. Firstly, the absence of social features deeply influenced the use of the application (as the different usage of School Society demonstrated, see Fig 3).

In addition, the experiment demonstrated that also the identity aspect is very important in a Social Interactive Systems. In fact, not only it influence system usage, it generates a sort of 'need for identity' in the social context (as the Pub example demonstrated).

However, while trends are visible even in this short (in terms of time) experiment, we are aware that more interesting information could be obtained extending the time of the experiment. For this reason we are working on another experiment (on the same system) for a longer amount of time (the idea is to let the world 'live' for at least two months).

Another interesting experiment could be done 'playing' with the Action element. In fact, additional interesting information could be obtained doing a similar experiment that will use Identity, Space, and Time as reference points, and will play with different levels of social actions in order to answer questions such as: More or less to what degree do visible social actions affect social interactions? In addition, we want to demonstrate the importance of the space and the time aspect in the same way as we did for the identity aspect.

Finally, the idea of adapting complex software systems by creating different profiles based on the four dimensions of the framework in order to answer other questions could also be explored. For example, for a large democratic debate application is the right thing to do give all age ranges the same vision as the 'first vision' (i.e., the view they have over the system the first time they enter it)? Would a simplified vision in all aspects be better for older people or would they not need, for example, the space aspect for a good performance? And so on.

Figure 1 :

 1 Figure 1: The graphical representation of the 4 elements as axis

Figure 2 :

 2 Figure 2: The Expected profile for the School Society virtual world

  of messages, messages per member indicate how engaged people are within the community. Number of private messages (i.e., in other friends' mailbox) and number of public messages (in the Pub) were regrouped under the label 'Number of messages' and measured during the experiment.

Figure 3 :

 3 Figure 3: School Society: general system usage

Figure 4 :

 4 Figure 4: School Society global satisfaction

Figure 5 :

 5 Figure 5: School Society: trends for exchanged messages


Di Loreto

Gouaich Abdelkader
email: gouaich@lirmm.fr

Pierre-Alain Laur

FACEBOOK GAMES: THE POINT WHERE TRIBES AND CASUAL GAMES MEET

Keywords: Social games, casual games, tribes, Facebook

The focus on social games in recent years has been generated by the rising number of users of MMORPGs (Massive Multiplayers Role Playing Games) such as World of Warcraft (WoW). However, the rise of social games in social networks has also played an interesting part in social games awareness. In this paper we focus on 'social' casual games in Facebook. Our assumption is that the success of games in the Facebook context is linked to the blending of personal and social aspects. In particular: (i) the engagement in 'fictional' social actions, (ii) the use of asynchronous actions, (iii) the combination of public and private actions within the game. The three above-mentioned aspects contribute to the emergence of particular social groupings, very similar to Cova's tribes. In order to demonstrate the previous assertions the paper will first define a set of basic concepts and will then describe some practical examples from the Facebook context.

INTRODUCTION

2009 was the year social games exploded into the mainstream consciousness. While most of the focus on social games was due to MMORPGs (Massive Multiplayers Role Playing Games) such as World of Warcraft (WoW), a large part of social games awareness was generated by the rise of social games in social networks. Although many social networks (such as MySpace and Bebo) have contributed to the growth of this trend by featuring a growing range of applications, Facebook is the social network where games applications have had the hugest impact. For example, Farmville -a land management game-has 76,677,249 active monthly users, Mafia Wars -a kind of role-playing game-24,650,755 active monthly users. Even though Facebook contains a huge amount of 'recreational' applications, in this paper we are interested only in those that can be defined as 'social casual games' (see Section 3).

As in all real life games, the success of online games is dependent on their playfulness i.e., all the elements of the (digital) design that engage people's attention or involve them in an activity for recreation, amusement, or creative enjoyment [START_REF] Follett | Engaging User Creativity: The Playful Experience[END_REF]. This paper will show that in the Facebook context playfulness is linked to blending of personal aspects and social aspects. In particular, playability is constructed through: (i) the engagement in 'fictional' social actions, (ii) the use of asynchronous actions, (iii) the combination of public and private actions within the game. The three above-mentioned aspects contribute to the emergence of particular social groupings, very similar to Cova's tribes (see [START_REF] Cova | Tribal marketing: The tribalization of society and its impact on the conduct of marketing[END_REF]. Consequently, the social ties created through the game encourage the user to return to use the application.

In order to demonstrate the previous assertions the paper will first define a set of basic concepts to help us understand this trend. The concept of playfulness, the concepts of casual and social games, and the concept of tribe will be defined. These definitions will be used to demonstrate why exactly the above-mentioned elements determine the success of games in the social network. Finally, some practical examples from the Facebook context will be described.

THE CONCEPT OF PLAYFULNESS

While in the introduction to this paper we defined playfulness as simply 'all the elements of a (digital) design that engage people's attention or involve them in an activity for recreation, amusement, or creative enjoyment', the definition of playfulness is actually more complicated. For example, it is important to understand that playfulness is different from 'flow' or 'fun'. In fact, the concept of playfulness does not imply absorption (as for the flow concept), skills, challenges, or even attention. In the same way, playfulness is a mood that lasts much longer than emotions, such as, for instance, 'fun' [START_REF] Parker-Rees | Protecting Playfulness[END_REF].

In a way, playfulness can be seen as an inclination to play. [START_REF] Meire | Qualitative Research on Children's Play[END_REF] identifies this inclination as a preliminary to play that prepares the conditions for the arising of play opportunities and play actions. In addition, the author distinguishes between playful state of mind and actual play activity. Equally interesting, [START_REF] Barnett | The Playful Child: Measurement of a Disposition to Play[END_REF] defines playfulness as a mixture of 'cognitive spontaneity, social spontaneity, physical spontaneity, manifest joy, and sense of humor'. The interesting aspect of this definition is that it addresses both personal and social aspects. This means that both of them are fundamental elements in the creation of requirements for playfulness.

Interestingly enough, Facebook 'recreational applications' also seem to appeal to the sphere of emotions (fun and playful mood) rather than actions [START_REF] Rao | Facebook Applications and playful mood: the construction of Facebook as a "third place[END_REF]. In fact, most Facebook games have a very simple gameplay. For example, the above-mentioned Mafia Wars simply asks the player to push a button in order to go on missions and so acquire experience. While the detailed gameplay for this application is more structured, it's a matter of fact that it is very far from the complex gameplay of Word of Warcraft. On the other hand the millions of users playing Mafia Wars each month are an indicator that there is something apart from the gameplay that encourages its users to play these games.

CASUAL GAMING AND SOCIAL GAMING

Most of the games developed for Facebook draw on 'browser games'. However, because of the environment they are developed in (Facebook) they voluntarily (or involuntarily) include the social aspect.

On December 4 2009, 208 applications were listed as the 'most popular games' on the Facebook site. Between these 208 applications, 100 (44%) can be defined as 'social' casual games (in the sense we will explain hereafter) while the other 116 can be classified simply as casual games. As examples of the latter we can cite Hatchlings and Chain Rxn. We have defined these applications as 'casual games' because of the practically non-existent social aspect (as in the Solitaire application). As a consequence, in Facebook the number of active monthly users of these rarely exceeds 600,000. Actually, there is still much confusion regarding the status of most Facebook applications. Marketed as games of some kind until recently, at the beginning of 2008 Facebook managers introduced the new category 'Just for Fun' to accommodate those applications that didn't fit into the 'Gaming' category. In fact, the ambiguity both categories present is often resolved by indexing the same applications in different categories at the same time. For this reason it is not surprising at all to find very different kinds of applications in the most popular games category 1 . While all the applications listed in Facebook as 'the most used' have been analyzed, in this paper the assumptions made in the introduction will only be demonstrated for what we have defined as 'social' casual games, i.e., games applications that show at least one social feature which is an integral part of the gameplay.

After this introduction it is important to define what we mean in this paper when talking about 'social' casual games.

What a casual game is

Casual games are one of the most popular categories of games played over the Internet (IGDA, 2006). There are various definitions for the term casual game available from different organizations (e.g. IGDA, CGA, GDC) or spokespersons for the industry (i.e. [START_REF] Tams | Online Casual Games Q&A[END_REF][START_REF] Wallace | IGDA 2006 Casual Games White Paper[END_REF][START_REF] Waugh | GDC: Casual Games Summit 2006: An Introduction to Casual Games[END_REF]. For a more in depth discussion of the topic, see [START_REF] Kuittinen | Casual games discussion[END_REF].

According to the Casual Games Association 2007 Market Report, 'Casual games are video games develo ped for the mass consumer, even those who would not normally regard themselves as a 'gamer.' (IGDA, 2009). This definition is also true for Facebook users [START_REF] Rao | Facebook Applications and playful mood: the construction of Facebook as a "third place[END_REF]. In fact, following Rao's analysis Facebook users seem to share the same denial as casual games players, who do not see themselves as gamers.

In general, casual games involve less complicated game controls and less complexity in terms of gameplay than others online games, which make them very popular and accessible. They can be seen as games that are easy to play and their main focus is on entertainment and relaxation.

While there is the perception that casual game players do not play games frequently or only play in very short game sessions, there is a large group of users who do not fit this stereotype. Many of the casual online games sites are some of the stickiest web sites on the Internet. For example, on the AOL Games Channel the majority of its online classic card, board and free casino games average between 20-40 minutes per game session. For example, even Solitaire averages 40 minutes a game session, even though a round can be completed in two minutes (see IGDA, 2009). While these times differ greatly from the MMORPGs ones (on average, each character spends about 10 hours in WoW during that 1-week period-see [START_REF] Ducheneaut | Building an MMO with Mass Appeal: A Look at Gameplay in World of Warcraft[END_REF] surely they are remarkable for a so-called 'casual' game. If we compare these data with the abovementioned assertion that casual games do not see themselves as players, an interesting scenario emerges.

What a social game is

People are inherently social creatures and, for this reason, people are constantly searching for others to share their interests, to solve their problems, to date, to meet people, to have an informal conversation, to ask an expert for some help, as well as other interests.

In his paper 'Why game studies now?' Dmitri [START_REF] Williams | Why Game Studies Now? Gamers Don't Bowl Alone[END_REF] says that there are business and technical reasons for the postarcade era resurgence of social game play, but they do not fully explain the sudden boom in online networked gaming that ranges from casual card games to vibrant massively multiplayer online games. While, it has become obvious that the content of games matters, the social side of what happens to the players, their friends, families, and communities' matters as well and matters a great deal at this particular moment. Endorsing Robert [START_REF] Putnam | Bowling alone: The collapse and revival of American community[END_REF] ideas Williams claims that the backdrop for the rise of social gaming is the decline in civic and shared spaces and a decline in real-world places to meet and converse with real people. Whether or not we agree with this statement the emergence of a social online era is a matter of fact, also supported by the growing development of ubiquitous computing. In addition, we can note the increasing importance of a sense of community for the online gamers. In fact, the social gaming audience is looking for an experience that either is built on connections, or incorporates some interaction with others who like the same kinds of games. Players want to compete, collaborate, socialize, and connect through chat and other forms of online communication [START_REF] Gerhard | Redefining the Online Gamer "Enthusiast Gamers" Open Up a New World of Possibilities for Casual Games Companies[END_REF]. now divided into Action & Arcade Games, Board Games, Card Games, Role Playing Games, Virtual World Games, and Word Games most of the applications are simply classified as 'games'.

However, it's worth noting that games in Facebook (and in general in all social networks) are a particular kind of social game.

A particular characteristic of social casual games: Asynchronous play

Social media have enabled conversations to occur asynchronously and beyond geographic constraints, but they are still typically bounded by a reasonably well defined group of participants in some sort of shared social context (Boyd et al. 2010).

The same asynchronicity in a particular context can be found in games developed for Facebook . The concept of asynchronous multiplay was first introduced by Bogost (see [START_REF] Bogost | Casual as in Sex, not Casual as in Friday[END_REF] to designate those situations in which players play a game 'in sequence, rather than simultaneously', and breaks in the game are a way to 'accommodate real life necessities and game expectations'. In general, asynchronous play supports multiple players playing in sequence, not in tandem. In fact we can talk of 'representation' of multiplay rather than actual interaction between different players. Actually, the space for action in most of those games is personal and not shared. For example, in Farmville -a farm management simulation game -the only farm the user can interact with is their own. Other players' farms are there only for 'visiting' purposes' and the player cannot modify them. The same thing happens in Happy Aquarium , where the user grows and sells fish. Other's interaction spaces (aquaria) are there only to create a sense of 'social presence' (i.e., that someone else is in the same environment at the same time). In the same way, when one user engages in competitive play, the opponent is notified of having being challenged by the first user and of the outcome of the challenge, but in reality the outcome of the challenge isn't affected by either of the players, and the challenged is allowed to respond to the challenge only by initiating a new game, not in the same contest.

Only in rare and particular circumstances do games in Facebook adopt a real collaborative approach. For example in Mobster2 -another RPG like game -in order to complete one of the quests, several players have to be online at the same time.

In this sense, the presence of friends seems more a symbolic representation with the aim of giving a feeling of community and participation without actual co-presence or interaction.

However, this 'fictional' sense of presence becomes more real because of the environment the game is in. First of all, the 'fictional' people you are asked to play with are your friends, so people you know (more or less). In addition, most games share the same pattern. For example, when a user 'visits' someone else's farm or aquarium, the action can be 'public'. In fact, the player can publish on his Facebook wall that he/she has helped his friend, or that he needs some object to progress in the game. Even when the application is played only once, the results of the game can be permanently shown in the user's profile, as boxes or as micro-stories in the mini-feeds (minimal chronicles of every action related to the user or her Friends in Facebook), hence contributing through their persistence to the user's identity, as expressed by the profile. Note that the private aspect is also important. For example, if I like, I can decide not to show my friends the last trophy I won or the last object obtained in the game. In this case, refusing to share some information the player carves out a space for the self in a social environment.

To summarize: the 'space of play' in Facebook can be seen as both private and public. The same happens for actions because each of them can be 'announced' or not to friends in the 'public' space of the wall. On the other hand, the time of play is always asynchronous.

TRIBES AND TIES

All the elements described in Section 3 of this paper (the engagement in 'fictional' social actions, the use of asynchronous actions, and the shift between public and private actions within the game) have as a consequence the creation of links between players.

Cova [START_REF] Cova | Marketing tribale[END_REF] uses the word 'tribe' to refer to the re-emergence of quasi-archaic values: a local sense of identification, religiousness, syncretism, group narcissism and so on. These tribes do not limit themselves to teenage groupings as shown by the number of adult tribes where people gather around shared 'ordinary passions' [START_REF] Bromberger | Passions ordinaires. Du match de football au concours de dictée[END_REF]. In fact, the common denominator of postmodern tribes is the community of emotion or passion. In addition, tribes are inherently unstable, small-scale, 'affectual' [START_REF] Maffesoli | The Time of the Tribes[END_REF] and not fixed by any of the established parameters of modern society. Instead, they can be held together essentially through shared emotion and passion. A tribe is a question of sharing of passions, hobbies, interests, way of being, moral beliefs, with people who recognize themselves in the relationship. The tribe is built on the shared meaning of the sense given to different situations: a noun, an object, an emotion, a tangible experience are all pieces of the same idiosyncratic world -that belongs to the tribe, and whose members contribute in building it. In this way, any object can acquire a special meaning within the borderline of a tribe, and lose it outside them [START_REF] Ripamonti | Tribal marketing and ICT: Post-modern Communities go online[END_REF]. Thus, every behavior, even a gift exchange in a game, may acquire a special meaning within a tribe, contributing to the definition of the self-image within the tribe.

In addition, Scott [START_REF] Feld | The Focused Organization of Social Ties The[END_REF] talks about the power of foci in understanding networks. You and your strong ties have things in common, the foci of the relationship. Often, the closer you are, the more you share in common. This is why you often have things in common with friends of friends. Now, each Facebook game has his focus. 'Selling and buying' friends in Friends for sale, farming in Farmville and Farm Town, growing pets in Pet Society and PetVille, and so on. The players of such games share the focus of the game exactly (there are lovers of Farmville that are haters of Pet Society and the other way round) and also share all the emotions and meanings linked to the game. As a matter of fact, in Facebook we assist in the rise of a group of tribes, one for each (more or less) widely used game.

In addition, the shared focus creates a boundary between insiders and outsiders (we players and the others). For example in Facebook there are many groups grouping people not playing Farmville. The most popular of them, Not Playing Farmville has 2,128,189 fans while the official Farmville Group has 19,677,974 fans. Another interesting example that underlines the we versus the others dichotomy is the spreading of a video called 'Farmville Ad'2 . In reality this is a fake advert that is a parody teasing Farmville addicts. The video has 1,119,088 visualizations on YouTube only (data on this sharing on Facebook are not available).

Therefore, groups of tribes are created, as in other environments, because of the focus of the application and the shared sense of membership to the tribe (because of a shared meaning). However, we cannot forget that one of the levers that push the user to play is the presence of the shared environment with public actions, where my friends are. To summarize, the focus is the first lever that pushes the user to take part in the game of the tribe, and the presence of friends and all the mechanisms described in Sections 3 and 4 of this paper are the levers that push him to return to use the application.

TWO EXAMPLES FROM FACEBOOK CASUAL GAMES

After the above-mentioned theoretical considerations, this section will describe two examples that help to better understand the link between each element and how they affect the creation of ties and the emergence of tribes.

An example of public and private: identities, spaces and actions.

Pet Society (18,726,890 monthly active users) is basically an online version of Tamagotchi3 , where the player can take care of a virtual pet. While it's true that the game itself is Tamagotchi in style, it allows a very in depth characterization that makes the pet you create your own pet.

In fact, in Pet Society the pet starts 'naked'. However, the player can choose what he/she (you can decide whether it'll be male or female) looks like. He/she can pick the color of the pet, and parts like ears, eyebrows, eyes, nose, mouth and head shape (and even a little marking on his snout). Finally the player chooses his/her name. Once in the game, the player can also buy objects to personalize the pet: dresses, shirts, shoes and so on.

It's worth noting that while most Facebook games now allow for such an in depth characterization, Pet Society was the first game to allow for it.

What makes the in depth characterization very interesting is linked to two main aspects: personal identification and immersion, and social presence. The first one is obtained through the pet's personalization elements. The last one is influenced by game design. In fact, one of the objectives of the game is to obtain (virtual) money visiting friends (in this way the player can buy, for example, clothes for the pet). It's not unusual to see a friend's message in a virtual house, commenting on the new look of the pet. In the end, the fact that the player's 'pet' is a special pet that is different from others becomes a topic for conversation. In the same way, the player can personalize the pet's home, buying and arranging things. As for the pet personalization, this means that the house the pet lives in is the player's home. And, as for the pet personalization, this means that when a player is visiting a friend's house, he/she will check out his latest arrangements and make comments on it, thus generating a social behavior.

To summarize, Pet Society shows an interesting blend of personal aspects and social aspects. Firstly, the player carves out a 'private' space personalizing his/her pet and home. Secondly, the presence of friends in the same 'space of play' creates a sense of social presence and collective action. Finally, the social aspect linked to the membership to a tribe goes beyond friendly chitchat. It is not unusual, in fact, to see discussions in forums about pets' appearances and room arrangements.

An example of 'tribe' membership: gift-giving in Farmville

Farmville is a real-time simulation game available as an application on Facebook and MySpace. The game allows players to manage a virtual farm by planting, growing and harvesting virtual crops, trees, and livestock. This is the most popular gaming application available on Facebook and, as said, is reported to have more than 76 million active users playing the game all over the world. The game 'plays' with the ties you already have in the social network: you can 'visit' your friends (i.e., the friends from your network who are already using the application), help them, and give them a virtual gift.

This last kind of behavior is not unusual in social network games. In reviewing 98 game applications with over 100,000 daily active users (DAU), Inside Social Games found that only about 20% of them did not have a gifts component at the start of the game (ISG, 2010 ). While gifts have often been considered social spam, in Facebook games the feature has become a very powerful way to get users to interact around a game.

However, the interesting part of the Farmville example is how the application developers used the power of ties in order to increase the number of 'hits' to the application (and the number of users) over Christmas 2009. Farmville developers did this by adding some particular, 'surprise' Christmas gift to the classical giftgiving feature (another usual type of behavior in social network games).

These gifts cannot be bought. The player has to receive them as gifts from his/her neighbors/ friends (so if he/she does not have enough friends, he/she will have to add some more) and place them under the 'Christmas Tree'. The more presents the user gets, the bigger the Christmas tree grows, and so on. To limit the gift giving, the players are only allowed to send a gift to their friends every 6 hours.

It's easy to foresee the resulting behavior generated by these premises knowing that one of the most common types of behavior in social software is to collect things [START_REF] Porter | Behavior first, design second[END_REF]. First of all, people put the 'sticker collection' behavior into effect (i.e., 'I want them all!'), so they go back to use the application every 6 hours. Now, let's remember that in this game the player can only send the gifts to others. What draws the user back every 6 hours is the expected reciprocation behavior (i.e., their friend will send a gift in return). Gift requests were also made on public walls. In this case the gift exchange allowed the users to feel like they were a part of a whole, a 'tribe' linked to a common practice: the gift exchange. In this way they created a kind of social identity. Moreover, the 'time' variable should not be underestimated. As Bromberger [START_REF] Bromberger | Passions ordinaires. Du match de football au concours de dictée[END_REF] said, time can be seen as 'collective time' under some circumstances. For example the time used for cooking pasta with friends is a collective time (with a bigger or smaller energy investment) that acts as a link with friends.

The place (a social network) and the particular moment (Christmas) determined a particular situation and thus a particular type of behavior4 . This combination allowed the onset of a particular social identity ('the gift sender/receiver').

CONCLUSION AND FUTURE WORKS

This paper has shown that in the Facebook context playfulness is linked to the blending of personal and social aspects. In particular, playfulness is constructed through: (i) the engagement in 'fictional' social actions, (ii) the use of asynchronous actions, (iii) the combination of public and private actions within the game. The three above-mentioned aspects contribute to the emergence of particular social groupings, very similar to Cova's tribes. Consequently, the social ties created through the game and the interest in its foci encourages the user to return to use the application.

Note that the aim of this paper is not to state that only social aspects are determinants for the success of a game application in Facebook. Without a gameplay that appeals to the player's emotional sphere (raising a pet, being a gangster, and the like) no social aspects can catch on. On the other hand, the presence of friends who share the same 'emotional sphere' is a lever to push players to return to use the application. The playfulness, while attributable in part to the design, is heavily reliant upon users and their level of engagement. In the end, users themselves create playfulness. Facebook Applications are a prominent example of this phenomenon because they are used both as individual entertainment and as socialization tools.

After the analysis reported in this paper we can foresee two possible developments. First of all, the three elements that cause the emergence of tribes are strongly supported by the environment the games are in: Facebook has a high level of visibility of actions because of the feed mechanism used in the wall. It would be very interesting to compare the same applications in other environments such as MySpace and Bebo which lack the social features that Facebook offers.

This will help to understand in which measure and in which way the different environments influence the emergence of the tribe linked to the game.

On the other hand, it could be very interesting to apply our findings developing a game for Facebook. To this purpose we will migrate a virtual world we constructed for educational purposes, School Society (http://www.lirmm.fr/~gouaich/schoolsociety/), re-designing it in order to foster sociability in the Facebook contest.

While the analysis for this paper was done before the Facebook interface change in the first week of February, the new classification did not change the above-mentioned observations. In fact, while games are

http://www.youtube.com/watch?v=odBDAcOEKuI&annotation_id=annotation_321740&feature=iv

The Tamagotchi is a handheld digital pet created in 1996 by Aki Maita and sold by Bandai. For further information: http://en.wikipedia.org/wiki/Tamagotchi

Note that the combination of place/moment is essential. Pet Society implemented a virtual 'Stickers album' but it is practically never used because it holds no additional meaning.