Alissa N Antle
email: aantle@sfu.ca

Joshua Tanenbaum
email: jtanenba@sfu.ca

Allen Bevans

Katie Seaborn
email: kseaborn@sfu.ca

Sijie Wang

Balancing Act: Enabling Public Engagement with Sustainability Issues through a Multi-Touch Tabletop Collaborative Game

Keywords: Public displays, sharable displays, digital tabletops, interactive surfaces, group interaction, multi-touch interaction, public participation, public engagement, social issues, sustainability, collaborative learning, serious games, simulations

Despite a long history of using participatory methods to enable public engagement with issues of societal importance, interactive displays have only recently been explored for this purpose. In this paper, we evaluate a tabletop game called Futura, which was designed to engage the public with issues of sustainability. Our design is grounded in prior research on public displays, serious games, and computer supported collaborative learning. We suggest that a role-based, persistent simulation style game implemented on a multi-touch tabletop affords unique opportunities for a walk-up-and-play style of public engagement. We report on a survey-based field study with 90 participants at the 2010 Vancouver Winter Olympics (Canada). The study demonstrated that small groups of people can be immediately engaged, participate collaboratively, and can master basic awareness outcomes around sustainability issues. However, it is difficult to design feedback that disambiguates between individual and group actions, and shows the temporal trajectory of activity.

Introduction

Multi-touch displays are only just beginning to move from the research lab into public spaces [START_REF] Hornecker | I don't understand it either, but it is cool" --Visitor interactions with a multi-touch table in a museum[END_REF]. The commodification of these technologies provides opportunities to design to support group participation with digital media in public venues, including hotel lobbies, bars, museums, and large scale sport and cultural events. Research about how to design walk-up-and-play style public displays on walls and tables has only just begun [START_REF] Peltonen | It's Mine, Don't Touch!: interactions at a large multi-touch display in a city centre[END_REF]. We do not yet know what design factors will contribute to their success [START_REF] Hornecker | I don't understand it either, but it is cool" --Visitor interactions with a multi-touch table in a museum[END_REF]. What design considerations are critical to support walk-up-and-play group activities in public venues? What are the key design features that will enable public engagement with important societal issues on public displays?

The 2010 Vancouver Winter Olympics provided us with an opportunity to deploy a public display in a field study with hundreds of diverse participants. The topic of sustainable development was a key theme during this sports and cultural event. The topic has several features that make it an appealing choice when investigating the design space of public displays. Understanding the key elements of planning for a sustainable future in an urban area requires that the public understand the views of the different stakeholders involved, recognize the spatial nature of the issue, and have an awareness of the complex trade-offs involved in preserving the environment and developing facilities to support a growing population. In response to our research questions, this opportunity, and our prior work studying interaction on digital tabletops (e.g. [START_REF] Antle | The EventTable technique: Distributed fiducial markers[END_REF]), we developed a digital media application implemented on a custom multi-touch tabletop called Futura: the Sustainable Futures Game.

In this paper, we discuss the problem of designing for engagement and small group interaction with a walk-up-and-play tabletop display in a busy public venue. Our hypothesis is that a multi-touch tabletop interface to a fast-paced, role-based simulation game can support groups of participants to meaningfully engage with content about social issues (e.g. sustainability) in a public space. We report on our field study at the 2010 Vancouver Winter Olympics. The study utilizes observational notes summarizing the reactions, responses and interactions of hundreds of players and a semi-structured survey with 90 study participants that was designed to provide insights and reveal issues with our design solution. Prior research based on the Futura game has included two observational studies focusing on learning [START_REF] Antle | Futura: Design for collaborative learning and game play on a multi-touch digital tabletop[END_REF], and a comparative study focusing on the effects of tangible and multi-touch tools on collaboration [START_REF] Speelpenning | Exploring how a tangible tool enables collaboration in a multi-touch tabletop game[END_REF].

Related Work

This research builds on recent work in the domains of sharable public displays, multitouch tabletops, serious games and computer supported collaborative learning. We provide a summary of relevant articles here, and identify key concepts and issues in this design space.

Shareable Public Displays

Shareable displays are those interfaces that provide for multiple inputs and support group interaction [START_REF] Sharp | Interaction Design[END_REF]. While a large body of work focuses on the ambient nature of public displays (e.g. [START_REF] Vogel | Interactive public ambient displays: transitioning from implicit to explicit, public to personal, interaction with multiple users[END_REF]), this is not our focus. Many other studies of sharable displays have occurred in semi-private spaces and involve groups of participants who know each other (e.g. [START_REF] Huang | Sharable displays: Semi-public displays for small, co-located groups[END_REF]). Several findings are relevant. For example, an early study revealed the importance of supporting a walk-up-and-use style of interaction that is so self-explanatory that first-time users need no prior training [START_REF] Elrod | Liveboard: a large interactive display supporting group meetings, presentations, and remote collaboration[END_REF]. An observational study on BlueBoard, a touch screen display for sketching that uses RFID to identify individuals, highlighted the importance of visibility of actions so that users can learn from watching each other's actions and the challenges of turn-taking [START_REF] Russell | Social aspects of using large public interactive displays for collaboration[END_REF]. While these findings may be relevant, our focus is on small groups of the public (who may be strangers) interacting with displays in large and busy public venues.

Research that focuses on large, multi-user wall displays in public settings is relatively rare due to technical difficulties with lighting and engaging first-time users [START_REF] Peltonen | It's Mine, Don't Touch!: interactions at a large multi-touch display in a city centre[END_REF]. However, several studies have revealed important factors to consider in design. One study raised the issue of how to encourage users to interact with the display in a busy setting [START_REF] Brignull | Enticing people to interact with large public displays in public spaces[END_REF]. The authors suggest positioning the display in a thoroughfare. Hornecker et al. identify entry and access points as important design considerations for displays in public spaces [START_REF] Hornecker | From entry to access --How shareability comes about[END_REF]. Entry points invite or entice people to interact with a display. Access points are interface characteristics that enable the user to interact, participate and join group interaction. Designs for public spaces must include both entry and access points to support walk-up-and-play.

In a detailed enthnographic study of CityWall, the authors identify and address issues of conflict management of digital objects and difficulties in turn-taking [START_REF] Peltonen | It's Mine, Don't Touch!: interactions at a large multi-touch display in a city centre[END_REF]. They suggest that successful designs must be playful, easy to use and novel. In addition, the authors suggest that designers should consider how to support parallel interaction; how to support learning through observing others; how enable a teacherapprentice approach; and the impact of the deployment on the surrounding architectural space. In a follow-up study, the authors identified and addressed several challenges in designing for engagement and parallel interaction [START_REF] Jacucci | Worlds of information: designing for engagement at a public multi-touch display[END_REF]. They suggest using a multiple, 3D virtual worlds metaphor to support parallel interaction, reduce conflict, and help manage territoriality.

Multi-touch Tabletop Displays

Much research has been conducted on multi-touch and surface computing. However, the focus of this work has largely been on the details of touch-based interaction in collaborative workspaces and labs (e.g. [START_REF] Forlines | Direct-touch vs. mouse input for tabletop displays[END_REF][START_REF] Wu | Multi-finger and whole hand gestural interaction techniques for multi-user tabletop displays[END_REF][START_REF] Rogers | Finger talk: Collaborative decisionmaking using talk and fingertio interaction[END_REF]). Some findings are relevant to the design of public tabletops. Hornecker makes the case for the need for immediate apprehendability in public displays for learning [START_REF] Hornecker | I don't understand it either, but it is cool" --Visitor interactions with a multi-touch table in a museum[END_REF]. Scott et al. make recommendations based on Computer Supported Collaborative Work studies concerning personal, group and storage territories [START_REF] Scott | Territoriality in collaborative tabletop workspaces[END_REF]. Global actions should be visible and transparent. Local spaces should be configured according to functionality. Personal territories should be oriented to player location to ease reading. Occlusion that may occur in personal spaces should be considered. Storage territories should be provided for discrete, private objects.

Serious Games

Serious digital games have been designed to support informal and formal learning and training. An excellent overview that we draw on here in presented in [START_REF] Kirriemuir | Literature Review in Games and Learning[END_REF]. Digital games provide visual digital information to one or more players, take input from players, process that input according to a set of programmed game rules, and change the digital information displayed back to players. A defining characteristic of a game is the set of game rules. Developers of serious games have hoped to harness the motivational power of games for learning. However, many educational games appear to be neither entertaining nor particularly successful in teaching players. These games suffer from two fundamental flaws: the people who design them often do not have traditional game design experience [START_REF] Van Eck | Digital game-based learning: It's not just the digital natives who are restless[END_REF] and they do not properly translate knowledge, facts and lessons into the language of games, namely mechanics, rules, rewards and feedback [START_REF] Jenkins | Games to Teach Project[END_REF].

A number of serious games have been developed that have environmentally conscious themes [START_REF] Chang | Playing the environment: Games as virtual ecologies[END_REF]. Games can potentially support an understanding of natural processes due to their use of procedural rhetoric to engage players in problem solving activities. In addition, games facilitate thinking procedurally about the consequences of actions on the environment. Microworlds are a simple but complete model of a domain or system that enables a person to "live" in that domain for some period of time. A simulation is a model of some domain [START_REF] Rieber | Seriously considering play: Designing interactive learning environments based on the blending of microworlds, simulations, and games[END_REF]. An advantage of simulations for learning is that they provide direct access to subject matter or content that might not be readily accessible in the real world. A key assumption behind simulations is that users will "learn by doing". However, there are challenges in using game-based procedural rhetoric for learning [START_REF] Treanor | Newsgames: Procedural rhetoric meets political cartoons[END_REF]. Procedural rhetoric may elicit emotions that are inconsistent with the game's themes and goals, and in some cases the unexpected and emergent properties of the system can undermine the message of the game.

Computer Supported Collaborative Learning (CSCL)

Collaboration has been defined as "a process by which individuals negotiate and share meanings" and "a coordinated, synchronous activity that is the result of a continued attempt to construct and maintain a shared conception of a problem" [START_REF] Roschelle | The construction of shared knowledge in collaborative problem solving[END_REF]. This differs from cooperative activities in which learners may coordinate their efforts, but the work performed is primarily individual and in parallel [START_REF] Dillenbourg | What do you mean by "collaborative learning[END_REF]. Within education, the CSCL community has begun to research how multi-touch tabletops may support collaborative learning. Several studies have found that learners find tabletop interfaces engaging, enjoyable and playful [START_REF] Piper | Tabletop displays for small group study: Affordances of paper and digital materials[END_REF]. However, findings have not always suggested learning gains. For further details of important elements required to support learning through collaboration, see [START_REF] Antle | Futura: Design for collaborative learning and game play on a multi-touch digital tabletop[END_REF][START_REF] Speelpenning | Exploring how a tangible tool enables collaboration in a multi-touch tabletop game[END_REF].

3 Designing the Futura Tabletop Game

Design Challenges

The high level design goal was to create an application that facilitates a shift in awareness or disposition around issues of sustainability in urban planning and development. Specifically, we are interested in helping the public understand the complexity of meeting the needs of a growing population while preserving the environment. We wanted to support the notion that sustainability is not simply achieved by making the right choices, but rather involves a complex negotiation between different stakeholders, in which short term decisions to meet human needs often have detrimental long term effects on the environment. A second important high level goal was that the installation had to be suitable for a fast throughput of large numbers of users at the Olympics cultural site. This type of massive public event introduces design constraints around scale, mobility, robustness and throughput of the tabletop installation.

In order to successfully enable groups to engage with interactive content about the issue of sustainable land use planning for an urban basin, we propose the following five specific design goals that must be met.

Learning: Individual users should gain an improved understanding of the complexity involved in balancing human and natural factors in land use planning for a sustainable future for an urban area. This outcome is conceptualized as something that is gained through a shift in awareness about the complexity of achieving sustainable development. It is not about learning concepts or facts.

Group Participation: The installation must promote active participation by small groups who may be strangers. Collaborative activity should involve equitable participation by each member of each group.

Walk-up-and-play: The activity must be immediately playable by small groups who can simply walk up and interact with the game, regardless of previous experience (or lack thereof) with new forms of interactive media.

Apprehendability: The content must be immediately understandable to people with a range of different knowledge levels about sustainability issues.

Appeal: The activity must appeal to a wide range of ages, cultures and preferences.

In previous work, we presented and discussed our design rationale specific to learning outcomes for the game [START_REF] Antle | Futura: Design for collaborative learning and game play on a multi-touch digital tabletop[END_REF]. In order to avoid duplication, in this paper we do not provide a detailed design rationale. Instead, we provide an overview of the game, and focus on presenting the results from our survey study. We contribute suggestions for generalizable design guidelines and two issues that must be overcome when designing collaborative, tabletop games that enable public engagement with the social issues.

System Implementation

Futura runs on a multi-touch version of EventTable, a custom multi-touch and tangible tabletop prototyping platform (initially described in [START_REF] Antle | The EventTable technique: Distributed fiducial markers[END_REF]). Our system is housed in a modified IKEA wood and metal table with telescopic legs and a custom metal undercarriage that supports the camera, PC and projector hardware. The surface of the table's wood frame supports an Endlighten™ acrylic surface. Our sensing system relies on a diffused surface illumination (DSI) technique with four infrared strips, one on each side of the rectangular surface. We capture touches with a single web camera with an infrared filter on a wide angle lens embedded in a custom mount. The camera can cover an active sensing area of 85 by 68 cm. The camera and firewire cable provides 30 frames per second (fps) data capture. We process camera data using Community Core Vision, an open source finger tacking software. The game application is written using an existing C# multi-touch library called Breezy. A single short-throw projector provides a resolution of 1024 * 768 pixels on the output surface of 103 by 68 cm. We use a velum mat, attached below the Endlighten™ acrylic for the projection surface, leaving the top surface of the acrylic exposed, which results in better touch tracking.

Game Description

Futura is a multi-player simulation game played on a bar height tabletop (Figure 1). The game is designed to enhance people's awareness of the complexity of sustainable development planning for an urban area. The goal of the game is to work with the other players to support a growing population as time passes while minimizing negative impact on the environment. The game can be played by two to six players. The game is suitable for players of 7 years old and above. The game takes place in a locale that resembles the Fraser River basin (near Vancouver, Canada).

There are three distinct roles that players can take: food, shelter, or energy supply. Each role has an individual toolbar oriented to each of the three sides of the table (Figure 2). The goal of the game is to support the population living in the area without having a catastrophically negative effect on the environment. Players must decide what kinds of food, shelter, or energy producing facilities to construct, and attempts to achieve balance in terms of the population support: neither wasting resources nor failing to provide for the population's needs. At the start of the game, there is a small base population present in the area. Over the course of the game, the population gradually grows. To meet the needs of the growing population, players drag facility tokens from the left side of their individual toolbars (e.g. housing, power plants, and farms) onto the map. For example, Figure 2 shows that single dwelling houses have been dragged from the left of the shelter toolbar onto the map. The game is won if players can add facilities in ways that meet the needs of a growing population without compromising the environment.

Each facility has a cost to build, can support a specific number of people and has a specific effect on the environment. Some facilities will produce more as time passes (i.e. will support a larger population), and some will produce less (i.e. support a smaller population). Information about different forms of environmental damage that may be caused by different facilities (e.g., physical waste, atmospheric pollution, chemicals in the water, pesticides in the food) are available through informational screens, which can be accessed before or during game play by touching and holding on each resource token.

The map interface provides both feedback of the global game state and feedback of individual tools. Each role has an icon that represents it on that role's toolbar and in the global display area (Figure 2). Food is a knife and fork. Shelter is a house. Energy is a lightning bolt. Each of the three toolbars has its role icon in the centre (left, bottom and right in Figure 2). A role toolbar is wide enough to be played by 1-2 players. Players use their toolbar to access information about facilities and can drag facilities from the toolbar to the map if they have enough money to pay for them.

As the game progresses, the environmental and population impacts of all the facilities currently on the board add up to a global environmental and a population effect. A global status console area on the fourth side of the table (top in Figure 2) shows this cumulative state of the game in terms of the environment (anthropomorphic tree) and population (face). The cumulative game state is also indicated through the changing colours of the main map interface (Figure 3) and the tone of the ambient soundtrack. Figure 4 shows the three states of global environment feedback. The tree changes its colour (green yellow, red) and facial expression to reflect three levels of environmental damage. The population's facial expression indicates how well the current population is being supported. The global display console also shows each role's status in terms of their individual impact on the environment up to this point in the game (indicated by the colour of role icon under tree) and their support of the current population up to this point in the game (indicated by the colour of role icon under face). For example, the red house on the left of the global display area indicates that the shelter player(s) has had a negative impact on the environment up to this point in the game. The game timer (top, left in Figure 2) shows the game time. The satellite is used to access game controls such as pause and reset.

If the environmental impact becomes too negative, natural disasters and other negative events begin to occur (e.g. Figure 5). While the game runs in real time (there is no turn-taking), there is a time-based cycle to the game. At regular intervals (every 10-20 sec), the players each receive an additional amount of money (shown in Figure 2, right of the shelter toolbar as an orange and black circle with a "$" dollar sign). At the end of the game, a display informs the players of how they did. Summary information about group and individual outcomes is given through graphics and simple text. The game is designed to be played over and over in order to adjust strategies and learn from mistakes. It is possible, but non-trivial to end with a balanced game world. A video of the Futura project is available at http://www.antle.iat.sfu.ca/Futura/.

Field Survey Study

In this paper we focus on the design space of public engagement with tabletop displays and report on our field survey study. The goal of the survey-based field study was to determine if our version of a collaborative simulation game implemented on multi-touch tabletop met our design goals related to public engagement with the social issue of sustainable development planning. We also wanted to identify insights or issues with our design in order to better understand the key design factors that impact public interaction with a social issue through interactive displays.

Participants and Procedure

We collected survey data from 90 participants aged nine and above. The age nine constraint was introduced by our ethics guidelines, not a design constraint. Participants were a convenience sample from the general population of visitors to one of the cultural sites at the 2010 Vancouver Winter Olympics. Our goal was to gather survey information from 80 to 100 players selected to ensure a range of ages, genders, social group configurations (e.g. family, teen groups, older adults) and cultures.

Study Setting

On the Olympics Surrey cultural site, Futura was positioned in a busy and narrow thoroughfare, as suggested in [START_REF] Brignull | Enticing people to interact with large public displays in public spaces[END_REF]. This afforded people walking up to it as part of their traversal of the space and then either playing, observing, asking to play or joining the queue if there was one. The variable lighting conditions meant that the game was only open after dark, roughly 5 -8 pm.

Survey Data Collection and Analysis

Our survey focused on the five core areas based on our design goals. We asked both closed (Likert scale) and open questions to address the following design questions:  Did participants gain a better understanding of the key issues related to sustainable development? What did they learn?  Did participants actively work together to play the game?  Did this type of collaboration help them learn about key issues related to sustainable development?  Did participants "walk up and play" with little instruction? Did participants have usability problems with the multi-touch tabletop?  Did participants understand how their choices impacted the game state in real time without turn-taking?  Did participants of all ages understand the different kinds of information presented through territories on the tabletop interface (e.g. global information, individual player information)?  Did the experience appeal to participants? Did they enjoy playing? Would they play again?

A seven-point Likert scale was used in the survey, where 1 was "strongly disagree" and 7 was "strongly agree". Closed question responses were analyzed using descriptive statistics (mean, median, standard deviation) in order to determine how well our sustainability tabletop game met our design goals. We also analyzed participants' written responses to open questions to search for common themes that would provide context for the quantitative findings. We also informally interviewed participants when the queue wasn't too long. We restrict our analysis to the survey data with the occasional mention of findings from informal interviews in cases where this provides context for our survey results. We searched for insights into what worked and sought to identify issues in areas where participants' responses were less positive.

Limitations

This survey-based study utilizes a convenience sample and may not be generalizable. We also recognize that the Olympics is a specific kind of pubic event that attracts a specific visitor population. The cultural event site was free for everyone but likely only attracted certain types of users. The survey was not validated, although we have used several of the statements in previous work. These factors limit our ability to generalize our results. However, for the purposes of initially studying our design, and identifying important factors and challenges, we feel that the sample and survey instrument were adequate.

Results

Our results focus on providing evidence that we did or did not achieve our five design goals. Results provide validation for some of our design decisions, reveal insights about this design space, and uncover issues that must be addressed. We provide the survey statements and the mean, median and standard deviations of 90 participant responses for each closed question (Table 1). We follow this with quotes of written responses to open questions.

Participant Profile

Ninety participants completed our survey after playing our game one or more times. Forty-three percent of the players were between the ages of 14 and 18 years old, twenty-two percent of the players were between the ages of 9 and 13, and another twenty-two percent were between 19 and 29, making the primary age group those aged between nine and 30 (i.e. youth and young adult). Sixty-four percent of the players were female and the remaining thirty-six percent male.

Overall Attitudes

Overall participants found Futura fun and engaging to play and rated it a median value of 6/7 for enjoyment and repeat play (see statements S12, S13 in Table 1). Just fewer than half of the groups played more than once. This was determined in part by the length of the queue. All ages of audience, including children, teens and adults, enjoyed playing. For example, one adult player wrote, "It was educational yet very hands on and entertaining." A nine year old boy said, "It's fun. It's really challenging and that's why I like it."

Experiences Based on the Survey

Learning Outcomes. Most participants gained a somewhat better understanding of the importance of making sustainable land use decisions over time (S1) and gained a better understanding of how difficult it is to make sustainable land use choices over time (S2). Player's written responses to the question, "What did you learn?" varied. Many related to the theme of the difficulty of balancing human and natural needswhich was a learning outcome for the game. For example, participants responded with the following written responses:

"How difficult it is to actually balance people vs. the environment and how easily the environment is damaged." "It's hard to make both the environment and population happy." "I learned that we need to help the environment and conserve every little thing we have. I also learned that building houses is expensive and difficult." "That it's hard to keep the world in balance."

Group Participation and Interaction. Many participants somewhat agreed that they worked with the other players (S3) but there was some variation in responses.

Participants were neutral about playing the game on their own and there was some variation in responses (S4). Participants somewhat agreed that working with other players helped them learn something new (S5). Most participants enjoyed playing with others (S6). In response to "What was learned working with other players?", one player wrote, "You learned how to act as a team." Another wrote, "The groups responsible for each aspect of development need to communicate frequently and in great detail to make sure everything working well." Others wrote, "Cooperation is key. One person can't make a difference." and "Everyone needs to work together in order to gain some understanding."

We observed that some players who played the game more than once shifted from individual play to collaboration, including discussions with each other about how each player was doing in terms of supporting the population and minimizing the environmental impact, and would work out strategies together to keep the indicators in the green.

Walk-up-and-playability. Most participants could easily start to play by touching the screen and liked the multi-touch aspect of the game (S7). Many participants wrote that they enjoyed it because they could use their fingers to interact directly with the surface. Participants that had difficulty were usually young children, whose fingertips did not always register, or older adults who showed some hesitation to start. The variation in scores likely reflects some inconsistencies in touch tracking due to the angle of the sun in the late afternoon. Many participants understood and liked the real time (no turn-taking) style of game play (S8).

Apprehendability. Many participants quickly understood what the icons and symbols on the food or shelter or energy player toolbars represented and how to use them (S9). Fewer participants also understood the role-based feedback in the global status console (S10) and/or understood how their choices affected the game over time (S11). We note here that this self-report might not be reliable but discuss this finding below (see 6.2 Issues). Although we didn't explicitly ask about it, we observed that most participants quickly understood the world map metaphor. The map acted as a referential anchor for the players [START_REF] Clark | Grounding in communication[END_REF], enabling them to maintain a shared understanding of the game state by determining if they were winning or losing.

Appeal. Many participants wanted to play the game again (S12) and enjoyed playing the game (S13). Participants responded to "I enjoyed the game because __" with the following written responses such as: "Fast, easy, educational." "Graphics and colours, move with fingers." "I got to meet new people." "Fun + thought provoking."

Discussion

Our goals were to understand if a multi-touch surface application in a public space could support groups of users to walk up and engage with an activity about sustainability, and what design factors would be critical for its success. Our survey results are largely positive and provide evidence that it is possible to design a multitouch tabletop game to engage the public with the issue of sustainability at a busy public event. While we find that the survey results are very positive, we interpret this cautiously. It is possible that the nature of the venue for the study combined with the novelty of the game lead participants to be overly positive.

Analysis of previous work in this design space combined with examination of closed and open survey question responses allow us to suggest five design features of importance that can be used to guide future designs, and to identify two issues with our design that must be overcome in future designs.

Important Design Features

Design choices result in specific design features, which in turn provide opportunities for interaction, which in turn create, shape, and constrain opportunities for public engagement with a tabletop game. Specific kinds of interactions ensure that the design meets the design goals related to learning, group participation, walk-up-andplayability, apprehendability and appeal. For example, choices about the approach and model for learning are made and instantiated in the features of the core mechanic of the game (e.g. learning through a simulation) and the user interface design (e.g. feedback providing playful guidance). Choices about the kind of group interaction enabled are made and instantiated in the game mechanic (e.g. cooperative), game rules (no turn-taking), and reward structure (winning requires collaboration).

We propose that the following design features are critical to the success of a learning game that engages the public in a serious social issue such as sustainable development. We also suggest that this unique combination of design features works well together to enable walk-up-and-playability. Completely meeting the goal of apprehendability requires future work.

We summarize some of our design decisions as general guidelines. In line with our exploratory survey methodology, we suggest that these guidelines are meant as considerations rather than prescriptive heuristics. They are also meant to be considered as a set, rather than individually. We suggest that it is the combination of this set of design features that lead to our positive results rather than any one of them.

Entry through Fast Play in a Microworld. Drawing on Rieber's work in blending microworlds, simulations, and games [START_REF] Rieber | Seriously considering play: Designing interactive learning environments based on the blending of microworlds, simulations, and games[END_REF], the game invites people to participate in the issue of sustainable development by directly experiencing a simulated land development game in a microworld. Multi-touch interaction on a horizontal surface enables fast play by multiple players. The action on a colourful map surface draws and sustains attention in a crowded space. The four sides of the table provide entry points [START_REF] Hornecker | From entry to access --How shareability comes about[END_REF] for players (three sides) or spectators (fourth side). A hand icon on the introduction screens may have promoted touching the displays as reported in [START_REF] Hornecker | I don't understand it either, but it is cool" --Visitor interactions with a multi-touch table in a museum[END_REF]. Hundreds of people played Futura during the event. We found that people played when there was no one playing (e.g. when it first opened), after taking a spectator role while waiting for a turn, and even when there was a queue. The only deterrent to entry seemed to be the length of the queue and the crowded space around the table.

Guideline. Combining a simulation microworld style of game on a multi-touch tabletop enables people to quickly and easily enter the play space.

Access through Roles and Territories. Futura invites people to participate in the game by providing access points [START_REF] Hornecker | From entry to access --How shareability comes about[END_REF] through roles and associated personal territories (i.e. toolbars) [START_REF] Scott | Territoriality in collaborative tabletop workspaces[END_REF]. Some participants negotiated roles by referring to toolbars, which act as objects of shared negotiation [START_REF] Suthers | An empirical study of the effects of representational guidance on collaborative learning[END_REF], while others walked up and played the role on the side of the table where they stood. Survey data indicated that most players understood how to use the individual toolbars. Placing toolbars with a static orientation is contrary to the prevailing design guidelines that suggest content should be dynamically oriented to a user's position [START_REF] Scott | Territoriality in collaborative tabletop workspaces[END_REF]. In Futura, a static orientation ensures that each player is responsible for one role and one corresponding toolbar territory in a collaborative activity. Guideline. Providing individual roles and territories through role-based toolbars on three of the four sides of the tabletop enables people to quickly choose a role and access the game through that role and territory.

Encoding Learning in Game Structure, Rewards and Feedback. In the sphere of public engagement in social issues, outcomes are informal and our survey data indicated that our goals were largely met. We suggest that a unique feature of our game is that the design addresses the problem of unreliable learning gain in collaborative games [START_REF] Piper | Tabletop displays for small group study: Affordances of paper and digital materials[END_REF] by encoding learning in the game mechanics as suggested in [START_REF] Jenkins | Games to Teach Project[END_REF]. We use a replayable game structure where winning the game both requires and rewards achievement of learning outcomes. The mechanics of the game were balanced in such a way that it was only possible to win by understanding the impact of different development choices on the environment. However, losing the game also advances learning by confronting players with the complexity of sustainable development planning. The game is currently paced so that it completes within about three minutes of play. This allows players to play and lose multiple times, and to observe the impact of different choices and decisions during this process. By keeping the time investment short, we hoped to reduce the attachment to the outcome that comes from deep sustained play in video games. Our survey showed that many participants wanted to play over and over (S12).

Another important design decision was that losing is not stigmatized in any way. Although most participants lost multiple times, they still responded that they enjoyed the game (S13). The world events, such as crime spree (Figure 5), were viewed as cute and fun, and provided an indication that players were losing the game. The end state feedback is presented in informative displays that support productive discussion about what is required to keep the world in balance in future play (Figure 7). Guidelines. The combination of the following guidelines enabled learning from game play. We suggest that these guidelines are relevant to educational games in general, and that the affordances of a multi-touch tabletop enhances their effectiveness.  Using a fast, repeatable game style encourages repeat play and motivates wanting to win.

 Designing the game mechanic in a way that winning requires learning outcomes to be met and it is easy to determine if learning outcomes are met.  Providing playful feedback reduces the stigma of losing and motivates learning through repeat play.  Designing the game mechanic in a way that losing furthers learning outcomes and ensures some learning even from losing.

Playing without Turn-Taking. A simulation style game supports simultaneous play and avoids the issue of participants having to work out turn-taking protocols [START_REF] Scott | Territoriality in collaborative tabletop workspaces[END_REF][START_REF] Rieber | Seriously considering play: Designing interactive learning environments based on the blending of microworlds, simulations, and games[END_REF].

Participants can drag and drop resources as fast as they can if they have enough money. The survey indicated that most players liked this style of play (S8). However, this style of game play results in some unforeseen effects described under Issues below.

Guideline. Using multi-touch interaction enables fast entry to simultaneous play, which is well suited to walk-up-and-play style games in public spaces.

Facilitating Collaboration through Game Mechanics and Interface Design.

Players do not compete against each other in the game, but must work together. We balanced the game engine so that any one player had the ability to cause the whole group to lose. This meant that players who had mastered one aspect of the system had incentive to talk to other players in order to win. By encouraging the players to explain their learning to each other, we provided them with an opportunity to reinforce that learning. Written comments indicated that some participants found it difficult to win through collaboration. However, the survey results indicated that they did largely work together (S3-S6), although there was variation in responses. Another design choice that supports collaboration is that at any point in the game, any player can look at the global or individual toolbar displays to see how the other players are doing, and how they are affecting the world. No information is hidden between players. In addition, the size of the tabletop makes it possible for most people to reach across the table and interact with each other's toolbars, which creates opportunities for negotiation [START_REF] Suthers | An empirical study of the effects of representational guidance on collaborative learning[END_REF] that we see as central to collaboration. However, the distances between all three toolbars make it impossible for any one player to reach all three toolbars simultaneously and control the game. In these ways, we support learning by observing others and a teacher-apprentice model as suggested in [START_REF] Peltonen | It's Mine, Don't Touch!: interactions at a large multi-touch display in a city centre[END_REF]. We also suggest that conflict was minimized simply by not rewarding it in the game rules. Players who did not collaborate, could not win. Guidelines. The combination of the following guidelines enabled collaboration. We suggest that these guidelines are relevant to collaboration in general, and that the affordances of a multi-touch tabletop enhances their effectiveness.  Requiring each player to individually win for the group to win facilitates collaboration.  Providing toolbars reachable by two of the three players reduces single player "take-over".  Providing a single group display that is visible to all players supports group communication.  Using a single large map world interface supports players to come to a shared understanding of the game state.

Issues

Issues were identified by looking at survey statements with lower mean scores and higher variation, and related written comments that allow us to infer areas that may need improvement. We identified two important issues that must be resolved in this design space and provide some suggestions for resolution.

Balancing Individual and Group Game Feedback. Meeting our design goal of apprehendability requires that we reduce dependence on prior knowledge and make information understandable by players from a broad age range. To address this goal, we used visual symbols and simple images to communicate information. The size of the tabletop (103 by 68 cm) provides ample space for clear symbols and thumbnails, as well as for both individual toolbars and group display spaces. For example, we use interface metaphors including a world map, tree, and face that change colour to reflect cumulative, global game states. We also use house, knife and fork (food), and lightning bolt (energy) symbols to represent how well the population is supported by each role or facility type. While most players understood and used the individual toolbars (S9), not all understood that the global display represented group progress (variation in responses for S10) and each role's individual contribution to group progress. The game requires individual play and rewards group participation. However, the real time style of play made it difficult for players to distinguish between individual and group effects, which is an important meta-cognitive strategy required for collaborative learning [START_REF] Duffy | Critical thinking in a distributed environment: A pedagogical base for the design of conferencing systems[END_REF].

Understanding Short versus Long term Effects. Participants expected to see an immediate effect of each action taken. Many players did not understand the relationship between the history of their actions and the cumulative game state. This may account for the variation in responses for S10. Many participants mentioned this in our informal interviews. However, the correct simulation model is that all actions of the players impact the game state cumulatively over time. We have encoded the correct model into the game mechanic but found it difficult to find a simple way to communicate short term impact and cumulative temporal effects to players through graphical interface feedback. In order to achieve apprehendability by using simple colour changes of the map and by using tree and face symbols to represent game states, we found it difficult to communicate the temporal trajectory of cumulative activity effectively to players. This trade-off may need to be reconsidered.

Conclusion

Research that contributes to understanding how to design for public "walk-up-andplay" tabletop displays has only just begun. Our research contributes to this effort through the design, implementation, and deployment of an exemplar public "walk-upand-play" tabletop game. The use of such displays to engage the public in discussions about issues of societal importance is also a new field of study. Our findings from the field study of Futura demonstrate that a fast-paced, role-based, simulation, tabletop game can effectively engage the public in learning about the complexity of sustainability development. In our approach, we wove together knowledge from multiple domains to make design decisions about learning content, game mechanics, as well as information, interaction and interface design to create a tabletop and application that met goals about learning, group interaction, playability, apprehendability, and appeal. When designing for this space, we suggest that entry points can be achieved by using a colourful map-based microworld on a multi-touch tabletop platform. While previous work suggests dynamic orientation of territories [START_REF] Treanor | Newsgames: Procedural rhetoric meets political cartoons[END_REF], we use static personal territories to enable role-based play, which provides interface access points to encourage immediate playability and eliminates the need for turn-taking. However, our analysis revealed tension between using real time play and effectively supporting learning about how individual versus group actions affected the game outcomes. We encode learning content in the game mechanics of a simple simulation game where both winning and losing enable learning outcomes. We use a predominantly graphical style of information presentation to support apprehendability. We use a map as a referential anchor and shared displays to support collaboration. However, our analysis revealed a tension between using a largely visual approach to information and interface design and effectively supporting learning about the cumulative effects that short term actions have on sustainability. Future work is needed to address these design trade-offs. We suggest that our findings are applicable to researchers and designers involved in public display design and public engagement campaigns using new media channels.

Fig. 1 .

 1 Fig. 1. Sustainability game on our custom tabletop.

Fig. 2 .

 2 Fig. 2. Map with individual toolbars (left, bottom, right) and global display console (top).

Fig. 3 .

 3 Fig. 3. Microworld map feedback states (colour changes).

Fig. 4 .

 4 Fig. 4. Tree global environment feedback states (tree colour and facial expression).

Fig. 5 .

 5 Fig. 5. World Event: Crime Spree (negative).

Table 1 .

 1 Survey results.

	Statement	Mean	Median	Std Dev
	S1. By playing this game I gained a better
	understanding of the importance of making	5.3	5	1.04
	sustainable land use decisions over time.
	S2. By playing this game I gained a better
	understanding of how difficult it is to make	5.8	6	1.05
	sustainable land use choices over time.
	S3. I actively worked with the other players while I was playing the game.	4.9	5	1.62
	S4. I played the game mostly on my own.	3.9	4	1.88
	S5. Working with other players helped me learn something new about sustainable land use planning.	5.1	5	1.34
	S6. I enjoyed playing this game with other players.	5.9	6	1.09
	S7. I liked playing this game because I could use my fingers to move objects around on the tabletop map.	5.7	6	1.52
	S8. I liked playing this game because the game was played out in real time without turn-taking.	6.1	6	0.97
	S9. I used the food or shelter or energy player toolbar on my side of the table to help me play the game.	5.9	6	0.91
	S10. I used the global impact information display at the top of the tabletop map to help me play the game.	5.3	6	1.49
	S11. I could see how my choices affected the game
	over time by using both the toolbar and global impact	5.5	6	1.32
	display.
	S12. If I had the chance, I'd like to play this game again.	5.7	6	1.19
	S13. I enjoyed playing this game.	6.0	6	0.97

Acknowledgments. This research was funded by an NSERC RTI and a GRAND NCE grant (Canada).


Ki Joon Kim

S Shyam Sundar

Does Panel Type Matter for LCD Monitors? A Study Examining the Effects of S-IPS, S-PVA, and TN Panels in Video Gaming and Movie Viewing

Keywords: LCD panel, response rate, contrast ratio, viewing angle, computer literacy

As computer-based devices become the primary media via which users view movies and play interactive games, display technologies (e.g., LCD monitors) have focused increasingly on quality of video fidelity, with much debate surrounding the relative efficacy of different panel types of LCD monitors. A 3 (S-IPS panel vs. S-PVA panel vs. TN panel) x 2 (game vs. movie) between-subjects experiment was conducted to examine the effects of LCD panel type in facilitating regular viewing as well as enhanced interactive TV experiences. Data from the experiment showed that LCD panel and stimulus type as well as computer literacy were important factors affecting users' viewing and interaction experiences. Limitations and implications for theory and ongoing research are discussed.

Introduction

Choosing an LCD monitor that best fits a user's needs and preferences has become relatively difficult in recent years; a number of factors such as screen-size, brand reputation, price, and technical specifications (e.g., response rate, contrast ratio, and viewing angle) are offered as considerations when purchasing a monitor. Although screen-size has been perhaps the most dominant factor affecting consumer's choice since the debut of LCD monitors, recent marketing emphasis on LCD panel types such as S-IPS, S-PVA, and TN has raised the question whether users should factor panel type into their decision-making. Different panel technologies are used in the production of LCD monitors, and manufacturers acknowledge that overall display quality that viewers experience is largely affected by the type of LCD panel to which they are exposed. In other words, LCD panel type is a key factor, according to manufacturers, that determines users' interactive and immersive viewing experiences. Therefore, it should be considered as integral as screen-size and brand reputation.

However, no empirical study has been conducted to examine the effects of LCD panel type on users' viewing and interacting experiences. As a result, it is unclear whether a particular panel is more effective in providing greater satisfaction, presence, and enjoyment while interacting with LCD monitors. The present study is a modest first attempt at investigating the psychology of LCD monitor users when exposed to three major panel types: S-IPS, S-PVA, and TN

1.1

Panel Difference -From an Engineering Perspective TN (twisted nematic) panel has been most widely used due to the advantages of its high transmittance, simple fabrication process, and relatively low production cost [START_REF] Yoon | Electrode Structure for High Transmittance and Aperture Ratio in TFT-LCD[END_REF]. The panel's affordable price and fast response rate have made it the most suitable panel for typical office use and fast-paced gaming. The biggest downside of the TN panel, however, is its severe off-axis image deterioration resulting in the worst viewing angle, color reproduction, and contrast ratio in LCD panel technology [START_REF] Lyu | Recent Trends on Patterned Vertical Alignment (PVA) and Fringe-field Switching (FFS) Liquid Crystal Displays for Liquid Crystal Television Applications[END_REF]. The panel is not recommended for movie viewing because, unlike 8-bit S-PVA and S-IPS panels that are fully capable of displaying 16.7 million colors in 24-bit true color, it only mimics the 16.7 million colors in 6-bit.

To solve the drawbacks of TN panel, IPS (in-plane switching) panel was first developed by Hitachi in 1996 and later enhanced by LG Display with S-IPS (super inplane switching) technology. The basic principle of the IPS panel was "to change the physical behavior of the liquid crystal layer by having the molecules move in parallel to the TFT and color filter layers rather than at oblique angles," which resulted in "significantly lessened light scattering, and thus improved the picture uniformity and color fidelity when viewed from wide angles" [3]. LG Display further developed the original IPS technology into a premium LCD panel with improved viewing angle, color fidelity, response time, and contrast ratio called S-IPS.

Developed and manufactured by Samsung Electronics as an improved alternative to the existing PVA technology, S-PVA (super patterned vertical alignment) is a new display technology providing image quality advantages over S-IPS, including high transmittance, 2300:1 contrast ratio, and wide viewing angle with no off-axis image inversion [START_REF] Lyu | Recent Trends on Patterned Vertical Alignment (PVA) and Fringe-field Switching (FFS) Liquid Crystal Displays for Liquid Crystal Television Applications[END_REF]. Samsung's new technology called "Magic Speed" claims to offer enhanced response time, rendering the S-PVA panel more suitable for gaming and other interactive applications than the traditional PVA panel.

Panel Difference -From a Psychological Perspective

Previous studies on the relationship between perceived viewing quality (e.g., attention, enjoyment, memory, and presence) and display screen have provided empirical explanations for consumers' preference for large screens and highresolution display devices. Reeves, Detenber, and Steuer [START_REF] Reeves | New Televisions: The Effects of Big Pictures and Big Sound on Viewer Responses to the Screen[END_REF] showed participants short clips from action films on 35-inch and 70-inch screens, and found that the larger screen elicited a greater level of attention, sense of reality, and presence. Similar studies conducted by Lombard [START_REF] Lombard | Direct Responses to People on the Screen: Television and Personal Space[END_REF] and Detenber and Reeves [START_REF] Detenber | A Bio-informational Theory of Emotion: Motion and Image Size Effects on Viewers[END_REF] also found that participants experienced greater enjoyment and arousal and remembered content better when exposed to larger screens. High-resolution display is another key factor contributing to greater presence. Bocker and Muhlbach found that participants exposed to higher resolution display in a video conferencing system elicited greater sense of communicative presence [START_REF] Lombard | At the Heart of It All: The Concept of Presence[END_REF]. A later study conducted by Neuman also found that high resolution images evoked a higher level of self-reported presence than standard resolution [START_REF] Lombard | At the Heart of It All: The Concept of Presence[END_REF].

In accordance with these previous studies that explored the effects of display characteristics on viewers' psychology, the goal of the present study is to identify the effects of LCD panel type, another display characteristic that had never been studied before, on viewers' perceived viewing quality. Therefore, we examine the following research question: RQ: For LCD monitor users, controlling for content and time spent on the monitor, what is the effect of LCD panel type and stimulus type (Independent Variables) upon viewers' satisfaction with image quality and technical features (i.e., response rate, viewing angle, and contrast ratio) as well as perceived level of presence and enjoyment (Dependent Variables) of movies and games?

Method

Design & Participants

A fully-crossed 3 (panel type: S-IPS vs. S-PVA vs. TN) x 2 (stimulus type: game vs. movie) between-subjects experiment was conducted to answer the research question. Data were analyzed from 60 undergraduate and graduate students from a four-year university in Seoul who signed up for the experiment through an online registration page posted on the university's main homepage. Exactly 30 men and 30 women (average age of 23) signed up for the experiment. All participants signed an informed consent form prior to their participation.

Apparatus

A 26-inch LG S-IPS panel monitor, a 27-inch Samsung S-PVA panel monitor, and a 26-inch Samsung TN panel monitor were connected to three high-performance desktop computers with identical hardware specifications (i.e., manufacturer, CPU speed, RAM, and graphic card) via DVI connection. Each computer was equipped with a Logitech 5.1-channel surrounding sound headphone. The monitors' brand logos were masked in order to avoid potential effects of manufactures' brand reputation, and the monitors' user-changeable settings (e.g., color tone, brightness, and contrast) were set to the factory standard. Participants in one condition could not see the monitors used in the other two conditions. Above configurations remained the same throughout the experiment.

Stimulus Material

A pursuit scene in downtown Paris from G.I. Joe: The Rise of Cobra was selected for the movie-watching condition. The present study intentionally chose a speedy pursuit scene from the movie, instead of a slow, long-take scene, in order to allow participants to identify potential motion blurs caused by difference in response rate of each monitor. The film was played in 1080p high-definition Blu-ray quality.

The game used for the gaming condition was Burnout Paradise. This racing game was selected because it was easy to navigate the vehicle using a keyboard and its content was similar to the Paris pursuit scene from G.I. Joe. Burnout Paradise allows players to change the point of view (first or third person) and to select a vehicle that the player wishes to drive. The present study instructed participants to play the game in the first-person point of view based on previous game studies suggesting that playing a game in the first-person point of view resulted in greater involvement and immersion [START_REF] Tamborini | Hostile Thoughts, Presence and Violent Virtual Video Games[END_REF].

Procedure

Participants were randomly assigned to one of the six conditions. In the gaming condition, brief instructions about game controls and navigation were provided, along with an opportunity to test drive for one minute in order to build familiarity with keyboard-based controls. Participants were instructed not to change the vehicle and the first-person point-of-view mode while playing the game, but told that they could freely adjust the volume and sitting posture to their comfort level. Once the experimenter finished giving the instructions, participants were told to start playing the game for 10 minutes. The experimenter left the room. After 10 minutes, the experimenter re-entered the room and administered a paper-and-pencil questionnaire measuring participants' level of satisfaction with the monitor they used as well as their perceived viewing/rendering quality.

In the movie-watching condition, participants were told that they were going to watch a scene from G.I. Joe for 10 minutes alone in the room, and instructed not to modify any configurations on the computer while the movie was being played, except the volume and their sitting posture. The experimenter started the movie and then left the room for 10 minutes. The paper-and-pencil questionnaire was administered when the experimenter re-entered the room.

After filling out the questionnaire, participants in both conditions were debriefed, paid five dollars, and asked not to discuss the experiment with others.

User Experience (UX)

The present study created a questionnaire composed of 19 items measuring participants' level of computer literacy and satisfaction with the monitors, as well as perceived level of presence and enjoyment. Participants responded to each item by marking on a 10-point Likert scale (1="strongly disagree," 10="strongly agree").

Results

A series of General Linear Model analyses was conducted with the two manipulated independent variables (panel type and stimulus type) and one measured variable (computer literacy level) on each of the 19 UX variables. The analysis found interactions between stimulus type and computer literacy for perceived realism (measured by "During the game/movie, I felt I was in the world the game/movie created"; F(1,48)=7.65, p<.05), satisfaction with overall viewing experience (measured by "I was satisfied with the overall viewing experience provided by the LCD monitor"; F(1,48)=4.54, p<.05), and presence (measured by "When the movie/game ended, I felt like I came back to the real world after a journey"; F(1,48)=4.62, p<.05). For participants in the gaming condition, computer literacy level was positively related to perceived realism, satisfaction with overall viewing experience, and level of presence regardless of panel type used for playing the game. For participants in the movie condition, however, a reverse relationship was found, such that the computer literacy was negatively related to these three UX outcomes.

The analysis revealed a three-way interaction predicting users' satisfaction with contrast ratio (measured by "I was satisfied with the contrast ratio of the LCD monitor"; F(2,48)=4.12, p<.05). In the gaming condition, the relationship between computer literacy and satisfaction with contrast ratio was dependent on panel type, such that computer literacy was positively related to satisfaction with contrast ratio for those using the S-IPS and TN panel, and negatively related to those using the S-PVA panel (Fig. 1). For those in the movie-watching condition, computer literacy was negatively related to satisfaction with contrast ratio for those using the S-IPS panel, whereas it was unrelated to those watching with the TN and S-PVA panel. Another three-way interaction was discovered in predicting users' satisfaction with overall viewing experience (measured by "I was satisfied with the visual display quality of the LCD monitor"; F(2,48)=3.30, p<.05). For participants in the moviewatching condition, computer literacy was negatively related to overall viewing experience whereas it was positively related for those in the gaming condition. This pattern was found only when using the S-IPS panel monitor. There was no such genre-based distinction in the relationship between computer literacy and viewing experience for those using the other two panels.

A three-way interaction for presence (measured by "The game/movie-generated world seemed to me somewhere I really visited") was also significant, F(2,48)=4.32, p<.05. In the gaming condition, computer literacy was positively related to presence for those using the S-IPS and S-PVA panel (Fig. 2). For participants in the moviewatching condition, however, computer literacy was positively related to presence for those using the S-IPS panel and negatively for those using the S-PVA panel, whereas it was unrelated to those using the TN panel in both conditions. For enjoyment, a main effect for panel type was found, F(2,48)=3.47, p<.05, such that participants exposed to the S-PVA panel (M=8.76, SE=.37) scored significantly higher on the "I enjoyed playing/watching the game/movie" item than those exposed to the S-IPS (M=7.50, SE=.39) and TN panel (M=7.58, SE=.39). Another main effect revealed that participants in the movie-watching condition (M=8.47, SE=.31) scored higher on the item than those in the gaming condition (M=7.43, SE=.32), F(1,48)=5.38, p<.05. Yet another main effect showed that the higher the computer literacy level, the greater the enjoyment, F(1,48)=14.38, p<.001.

In summary, the present study found that computer literacy is a powerful factor (perhaps even more important than panel type) affecting users' perceived level of realism and presence. It also has effects on monitor users' enjoyment and satisfaction with contrast ratio, a key technical feature of LCD monitors. In general, computer literacy was positively associated with viewing experience, presence and satisfaction with contrast ratio when the IPS panel-type monitor is used in an interactive mode, i.e., for playing games. It is however negatively associated with viewing experience and satisfaction when used in a non-interactive mode, i.e., watching movies. As for the S-PVA panel type, computer literacy is positively associated with presence when playing games but negatively associated with contrast-ratio satisfaction.

Although the present study did not find a particular LCD panel that elicited the highest level of satisfaction, enjoyment, and presence under all conditions, our findings suggest important guidelines and insights for future research on psychological effects of display devices. In general, participants in the present study showed a slight preference for the S-PVA panel over the S-IPS or TN panel types in terms of enjoyment; participants who interacted on a monitor with the S-PVA panel perceived higher level of enjoyment than their counterparts in the other two conditions. However, no main effect for panel type was found on other UX measures. This is because the effects of panel type are qualified by users' prior experience with computing technology.

This finding encourages consumers to ask a practical question: Is it worth the money? Monitors with PVA panel are generally more expensive than IPS and TN panel monitors. The PVA panel monitor used in the experiment (MSRP=$1,100) was nearly twice as expensive as the S-IPS (MSRP=$640) and TN panel monitors (MSRP=$480). Whether consumers are willing to pay that much more to buy PVA panel monitors for "supposedly" greater enjoyment is questionable because consumers' preference is largely influenced by a combination of product price and visible differences noticed during in-store demonstrations (which may not always be fair comparisons). Given our findings, only high-end gamers who are highly computer-literate may find the presence afforded by S-PVA to be worth the added expense. But then, our interaction findings indicate that IPS panel, which is half the price, will do just as well for gaming (and presumably other interactive TV experiences) as long as the user is computer-literate.

Unexpectedly, computer literacy turned out to be quite a significant predictor. For gaming, participants with higher computer literacy level were more satisfied with their overall viewing experience while experiencing greater realism and presence and were more satisfied with their overall viewing experience. However, a reverse relationship was found for movie-watching. We may interpret this as follows: individuals with high computer literacy level tend to focus more on active interaction with technology (i.e., playing the game using both mouse and keyboard simultaneously), whereas those with low computer literacy level focus more on the content (i.e., movie) delivered to them. This provides valuable insights for future studies on the relationship between computer literacy and technology acceptance.

The implications of the present study suggest that display engineers and manufacturers should be looking more carefully at how panel characteristics (e.g., response rate, viewing angle, and contrast ratio) affect and interact with users' viewing/interaction experience and overall enjoyment. The main effect for stimulus type suggests that interactive use of TV display systems, such as in games, leads to inherently lower ratings of panel characteristics and reported enjoyment. This means designers of display technologies and related systems that enable interactive TV ought to work harder to satisfy users regarding the fidelity of video rendering on their screen. Newer display technologies such as LED (light-emitting diode) and AMOLED (active-matrix organic light-emitting diode) provide avenues for further research. Researchers from psychology and communication may also examine how individual differences such as computer literacy, educational attainment and age affect user acceptance of display technologies that offer slightly superior quality at a heavy price.

A notable limitation is that the present study allowed first-person point of view in the gaming condition. While playing the game in first-person is likely to result in greater involvement and immersion in the game [START_REF] Tamborini | Hostile Thoughts, Presence and Violent Virtual Video Games[END_REF], the movie was shot and played with the third-person point of view, thus producing a confound. A recent study on game and violence suggested however that playing a game in third person, not in first person, resulted in increased involvement and focus [START_REF] Farrar | Contextual Features of Violent Video Games, Mental Models, and Aggression[END_REF], which might explain why participants enjoyed watching the movie significantly more than playing the game.

Ongoing research will further probe the impact of panel type on viewing-angle satisfaction and content enjoyment, as well as the relationship between these dependent measures. We will also take into account the size of participants' own computer monitors and whether they are aware of LCD panel differences, and analyze these variables as covariates in the relationship between the panel type and viewing experience.

Fig. 1 .

 1 Fig. 1. Three-way interaction for users' satisfaction with contrast ratio.

Fig. 2 .

 2 Fig. 2. Three-way interaction for users' perceived level of presence.

Acknowledgments. This study was supported by a grant from the World-Class University program (R31-2008-000-10062-0) of the Korean Ministry of Education, Science and Technology via the National Research Foundation. The authors wish to thank Sungyeon Kim and Sanghun Kwak, Ph.D. students at the Department of Science, Sungkyunkwan University, for their collaboration in the data collection process.


Stephen Uzor

Lynne Baillie

Dawn Skelton

Fiona Fairlie
email: f.fairlie@gcu.ac.uk

L Uzor

Dawn Baillie

Skelton

Identifying Barriers to Effective User Interaction with Rehabilitation Tools in the Home

Keywords: falls prevention, user interaction, rehabilitation, visual feedback, user workshop

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Rehabilitation is often used to improve a person's ability to cope with physical activities in everyday life. In musculoskeletal disorders associated with ageing, rehabilitation usually involves exercises which are designed to increase functional capacity; elevate confidence and encourage independence in older adults [START_REF] Skelton | Exercise for falls management: Rationale for an exercise programme aimed at reducing postural instability[END_REF].

In rehabilitation for falls (and similar conditions affecting strength and balance performance), patients are often given exercises to perform in the home. However, evidence suggests that there is a problem with uptake and adherence to these exercises in the home setting [START_REF] Robinson | Promoting adherence with exercise-based falls prevention programmes[END_REF]. This could be attributed to a lack of motivation on the user's part [START_REF] Mataric | Socially assistive robots for post-stroke rehabilitation[END_REF]. To inform the design of more useful home rehabilitation tools, it is necessary to understand the limitations of the current tools and explore ways in which technology can be used to encourage users to engage in rehabilitation.

This paper describes the proceedings of a user workshop -facilitated by HCI and health researchers -to investigate the effects of user interaction with current home rehabilitation materials on motivation to exercise.

Current evidence suggests that technology can be used to assist rehabilitation in various settings. A preliminary study -using interactive games -conducted by the makers of the 'SilverFit softkinetic rehabilitation system' revealed that the participants often performed more exercise than was required of them as they found most of the games very addictive [START_REF]Silver Fit Soft Kinetic rehabilitation[END_REF]. This system utilized a depth sensing camera that captured the user's image and placed it in a virtual environment where the users could interact with virtual objects. However, this study was limited to the laboratory setting as the equipment required was expensive and bulky.

The study by [START_REF] Taylor | Group pulmonary rehabilitation delivered to the home via the Internet: feasibility and patient perception[END_REF] revealed how video-conferencing over an internet connection enabled users at home to attend a virtual exercise class with other users during pulmonary rehabilitation. The premise behind this study was that, because many patients lived far away from rehabilitation centers, patients (and in some cases, physiotherapists) were required to make frequent long journeys to the classes (or patients' homes). The technology used in the study enabled active involvement in rehabilitation by the participants, who remained motivated.

Previous research has also investigated the use of visual feedback of clinical data to aid rehabilitation in various settings. The findings from these studies propose that, not only can visual feedback of progress be used during rehabilitation to encourage users to exercise; but it can also inform users about important clinical measures associated with their recovery.

MacDonald et al [START_REF] Macdonald | Towards a design tool for visualizing the functional demand placed on older adults by everyday living tasks[END_REF] investigated the use of visual feedback of biomechanical data to enhance older adults' understanding of mobility problems that they faced in everyday life. Their visualizations included a 'stick figure' with joints that were illuminated -using green, amber and red colors -depending on the amount of functional demand placed on the users' joints during certain tasks that they performed in everyday life. Their findings suggest that this visual feedback enabled clinicians to communicate effectively with the users about their therapy. In this way, the users felt more involved in their rehabilitation.

Methods

In order to investigate how the current rehabilitation tools may affect the users' motivation to exercise in the home, we held a user workshop with older adults. The aim of the workshop was to obtain a wide range of opinions on current rehabilitation tools used in the home, which could highlight possible factors affecting motivation and adherence to the programmes. The tools investigated in this study included illustrations and videos containing exercises for the rehabilitation of muscle strength and balance in older adults.

One exercise -the "sit to stand" (Fig 1) exercise -was chosen as an example. This exercise was available to the participants in both paper and video forms. Participants were recruited through posters and flyers which were placed at different locations around Glasgow Caledonian University. We recruited 9 healthy older adults (8 females and 1 male) between 62 and 75 years of age. The sample size was kept small in order to allow all the participants the opportunity to contribute to each of the phases of the workshop in the two-hour session. All the participants were educated to at least high-school level. The workshop was divided into a number of phases which employed a range of qualitative techniques identified as effective -based on previous research [START_REF] Baillie | The Home Workshop. Home-Oriented Informatics and Telematics International Working Conference[END_REF][4] -in obtaining informative comments from participants. There were three groups of participants with a facilitator in each group. Notes were taken during the different phases by experts in the field of user interaction within the research team. The phases are detailed in Table 1.

User Workshop

Discussions on Past Experiences with Rehabilitation

In this phase of the workshop, we investigated participants' previous experiences with rehabilitation tools similar to the exercise illustrations and videos. It was important to do this, as previous experience with such tools may provide us with some clues regarding the effects of the use of these on their motivation to exercise.

Scenarios

Scenarios are useful in conceptualizing and managing the performance of tasks in certain environments which could improve the usefulness and usability of technology [START_REF] Mckim | Experiences in Visual Thinking[END_REF]. In this phase of the workshop, the users were provided with 2 personas designed to encapsulate the characteristics of typical users of existing rehabilitation tools. The personas, along with the key characteristics of each one are shown in Table 2 below. Each of the personas tackled the use of both of these types of media (illustrations and videos) separately. The participants were asked to discuss the issues and challenges facing each individual persona while they performed exercises in the home according to certain set scenarios. Three scenarios were used in the user workshop:

 Scenario 1 -Home rehabilitation session with illustrations of exercises.  Scenario 2 -Home rehabilitation session with exercise videos.  Scenario 3 -The use of visual feedback to show improvements in mobility during rehabilitation.

Feedback on Visualizations

In this phase of the workshop, the participants were shown a simple animation (created by Glasgow School of Art [START_REF] Loudon | Enhancing dialogues between rehabilitation patients and therapists using visualisation software[END_REF]) of two stick figures walking side by side. One of the stick figures walked with an abnormal gait while the other walked normally. Both figures left a trail of footsteps behind that highlighted the 'Stride Lengths' (an important clinical measure associated with falls risk [START_REF] Hausdorff | Gait Dynamics, Fractals and Falls. Finding Meaning in the Stride-to-Stride Fluctuations of Human Walking[END_REF], [START_REF] Lord | Sensori-motor Function, Gait Patterns and Falls in Community-dwelling women[END_REF]) of both stick figures. Through Scenario 3, the participants observed how this visual feedback could be shown to Agnes (persona 2) during occasional visits to her home by a physiotherapist. The participants were asked to discuss the usefulness of these visuals in showing the persona's improvements in gait over time.

Findings

The numerous comments made by the participants in the various phases of the workshop were analyzed and arranged into themes. The following sections highlight some of the main issues shared by the participants across all the groups.

Discussion Phase

None of the participants had previously used such rehabilitation tools. Approximately half of the participants attended exercise classes in a gym. These participants drew comparisons between the rehabilitation exercises in the home and the exercise classes in the gym. The main issues shared by the participants in this section were related to the passive nature of the home rehabilitation materials. There were comments that music could engage the users better in the video exercises.

Scenario Phase

One of the main issues raised by the participants in this phase was the duration of exercise when using both the paper and video tools. The participants were aware of the fact that rehabilitation exercises needed to be performed for a minimum of 3 hours a week in order to be effective [START_REF] Taylor | The Otago Exercise Program, An evidence-based approach to falls prevention for older adults living in the community[END_REF]. However, they suggested that the exercises be split into shorter sessions as the personas may quickly lose interest while using such passive rehabilitation tools. Table 3 highlights the main issues -facing the personas in the various scenariosidentified by the participants. Exercises with more repetitions will be helpful in later stages of rehab.

2. Progress cannot be tracked using video exercises. Agnes lives alone and needs to be constantly motivated.

Something to interact with would be useful to

Agnes as the video exercises seem passive and dull.

The main themes that emerged from the discussions in this phase of the workshop were related to motivation, interactivity and charting progress during rehabilitation. All the participants agreed that the personas required a more interactive solution to home rehabilitation in order to keep them motivated.

Visual Feedback of Progress

Prior to our explaining the concept behind the visual feedback method described in 3.3.3, the participants were asked whether they understood the purpose of the animation. A majority of them said that they thought it showed a comparison between one person with abnormal gait and another person walking normally. Initially it was not clear to the participants that both stick figures represented the same individual, but rather highlighted progress during rehabilitation. Interestingly, one of the participants mentioned that the video highlighted stride lengths (drawing the attention of the other participants in their group to the footprints left behind by the stick figures). Others identified specific features of abnormal gait such as: poor balance, apparent muscle damage and knee problems. Subsequent to explaining the purpose of the animation; the participants agreed that Agnes' (persona 2) ability to see improved gait over time -during rehabilitation -will improve her confidence and motivate her to exercise. They also mentioned that visuals such as this one would be useful to them if they were in rehabilitation.

Exercise illustrations and videos currently used in home rehabilitation contain exercises which have been shown in previous research to significantly reduce the risk of falling in older adults. It is necessary for the users to perform these exercises regularly in order to obtain the maximum benefit that they can offer [START_REF] Taylor | The Otago Exercise Program, An evidence-based approach to falls prevention for older adults living in the community[END_REF]. The findings from the workshop provided us with valuable information as to why users may not use such materials in the home setting. The three key issues that the users of our workshop felt that we should take into consideration when designing tools for home rehabilitation are: progress, interactivity and motivation. If the tools we design do not have these three factors then we may encounter the same problems as befalls the current tools in that they will not be used.

Our findings also suggest that visual feedback can play an important role in home rehabilitation. We discovered that it is not only important that older adults in rehabilitation are constantly motivated to exercise; but that their ability to receive feedback on progress during rehabilitation can improve adherence to home exercise.

Future Work

One of the limitations of this workshop was that we asked relatively healthy older adults to provide feedback on the use of rehabilitation tools which they had not used previously. We believe that there may be more issues which have not been identified by the scenarios and personas used in this study that we should take into consideration when designing rehabilitation tools for older adults.

In order to identify these issues, we intend to conduct a similar user workshop involving older adults with a history of falls who have previously used exercise illustrations and videos for rehabilitation in the home. By doing this, we anticipate that we will gain a better understanding of the use of these tools; and the factors that contribute to a lack of adherence to exercise programmes. We also intend to recruit a larger sample [START_REF]Silver Fit Soft Kinetic rehabilitation[END_REF] with an equal balance of male and female participants; as we feel that this would improve the quality of the findings in the next workshop.

Furthermore, by addressing the issues identified in 4.2, we aim to investigate how rehabilitation tools can be improved in order to enable effective interaction by users.

Fig. 1 .

 1 Fig. 1. An illustration of a strength training exercise used in falls rehabilitation in the home.

Table 1 .

 1 User Workshop Phases

	Phase	Rationale	Procedure	Duration
	Discussion	To acquire a range of	Participants were shown	10 minutes
		opinions regarding the	examples of illustrations and
		problems with current	videos from current rehabilitation
		rehabilitation tools	tools. They were asked to discuss
			the issues that users may face
			while using them in the home
	Scenarios	To provide participants	User Journey through	15 minutes
		with everyday usage	rehabilitation using two
		scenarios that they can	personas. Participants were
		comment on for their	asked to discuss the issues that
		applicability to a user	the personas may face in the
			relevant scenarios
	Demonstration	To obtain feedback on	Through the use of scenario 3,
	of	the usefulness of	the participants were asked to
	Visualizations	visualizations to	discuss the use of visual
		highlight progress over	feedback, showing the results of
		time	a walking test at different stages
			of rehabilitation

Table 2 .

 2 Personas

	Personas	Name	Key Details
	Persona 1	Jack Bishop	68 year old retired school
			coach; suffered stroke at 65;
			lacks confidence
	Persona 2	Agnes Newman	82 year old retired office
			worker; suffered a minor hip
			fracture; has fear of falling

Table 3 .

 3 Scenarios (with main issues identified by participants)

	Persona	Scenario	Participants Comments
	Jack	Rehabilitation session in	1. The exercises should be broken down into
		the home using exercise	smaller chunks as 45 minutes is too long to keep
		illustrations for 45	motivated.
		minutes	2. The exercise video would be more interactive
			than the booklet and would engage him better.
			3. As a retired coach, having to perform exercises
			in such a passive manner may reduce his
			confidence even further.
	Agnes	Rehabilitation session	1. The pace of the video exercises never changes.
		in the home using
		exercise videos for 45
		minutes

Acknowledgments. I would like to thank Lee Morton, Mobolaji Ayoade, Glasgow School of Art and the Envisage research team, whose help made the user workshop possible. This research was funded by the MRC Lifelong Health and Wellbeing programme (LLHW).