Amalia G Sabiescu
email: sabiesca@usi.ch

Nemanja Memarovic
email: nemanja.memarovic@usi.ch

Participatory Design for Cultural Representation: a cultural transparency perspective

Keywords: participatory design, cultural transparency, cross-cultural design, local communities, cultural representation

Participatory design approaches are being increasingly employed for designing digital artefacts and information systems with and for local communities. These cases require a reconceptualization of PD processes to account for widened knowledge gaps between designers and community members, and new patterns of community-defined design goals. In this paper we provide a perspective on the design process that will help designers to better plan their involvement in participatory projects with local communities. Our analytical stance resides on an interpretation of Étienne Wenger's theory of cultural transparency. Participatory design is analysed as an iterative process of decoding and encoding that involves users/local people and designers having as outcome understanding (through decoding) and representations (through encoding). Cultural transparency, achieved when the two agents advanced sufficient understanding on the other's practices, is the landmark for effective design. The paper argues for the importance of working towards attainment of cultural transparency in community-based projects, in particular when the goal is to create culturally representative artefacts. Examples of activities and suggestions for advancing cultural transparency in these contexts are provided.

Introduction

Participatory design (PD) approaches, traditionally used in work environments [START_REF] Muller | Participatory design: The third space in HCI[END_REF], are being increasingly employed for designing digital artefacts with and for local communities, serving goals defined by community interests, needs, and aspirations. For example, ICTs can be instrumental for preservation and transmission of local knowledge among different generations of the same community [START_REF] Rodil | Enhancing cross-cultural participation through creative visual exploration[END_REF][START_REF] Verran | W: Designing Digital Knowledge Management Tools with Aboriginal Australians. Performative Knowledge Making[END_REF], recovery of memory by appropriation and digital representation of community artefacts [START_REF] Christen | Archival Challenges and Digital Solutions in Aboriginal Australia. The SAAA Archeological Record[END_REF], and networking among disenfranchised indigenous communities [START_REF] Srinivasan | Where Information Society and Community Voice Intersect[END_REF]. These goals can be supported by the design and development of various information spaces, communica-tion artefacts, and repositories, ranging from digital archives to community websites. When using PD in community contexts, three inter-related sets of challenges arise:

1. The knowledge gap between designers and communities is widened. For designers, community settings are characterized by peculiar social and cultural features that need to be understood for creating relevant artefacts [START_REF] Verran | W: Designing Digital Knowledge Management Tools with Aboriginal Australians. Performative Knowledge Making[END_REF]. For community members, digital technology and design workflows, processes and terminology are replete with unknowns that make their informed participation difficult.

A reconceptualization and renegotiation of established design methods and tech-

niques is required for accommodating the participation of community members that may lack digital literacy or even be illiterate. As Winschiers [START_REF] Winschiers | The challenges of participatory design in an intercultural context: Designing for Usability in Namibia[END_REF] argues, even widely accepted PD methods, such as Future Workshop, may be unfit in certain community contexts. 3. The formulation of design goals needs to take into account relations between the features of the digital artefact and the community's long-term goals and bounding cultural protocols. For example, Christen [START_REF] Christen | Archival Challenges and Digital Solutions in Aboriginal Australia. The SAAA Archeological Record[END_REF] reports on the design of an indigenous archive in which different levels of access were defined reflecting restricted access to local knowledge for different community groups.

This paper outlines a theoretical perspective that can shed light on the factors that are brought to bear when employing PD in community contexts. Drawing on an interpretation of Étienne Wenger's theory of cultural transparency [START_REF] Wenger | Towards a Theory of Cultural Transparency[END_REF][START_REF] Wenger | Communities of Practice: Learning, Meaning, and Identity[END_REF], the paper will provide a conceptual mapping of the design continuum highlighting the dynamics of interaction between users and designers in the creation of novel artefacts. PD is analysed as an iterative process of decoding and encoding involving users and designers having as outcome understanding (through decoding) and representations (through encoding). Cultural transparency, achieved when the two agents advanced sufficient understanding on the other's practices, is the landmark for effective design. The paper argues for the importance of working towards attainment of cultural transparency in community contexts, in particular when the goal is to create representative artefacts.

Background and Related Work

The outline of the theoretical perspective exposed herein was shaped by considerations around a participatory project that aimed to explore the potential of ICTs for giving voice to minority groups starting from the grassroots [START_REF] Sabiescu | Exploiting the Intergenerational Connection in Community Media Initiatives for Minority Cultures: A Case Study[END_REF][START_REF] Sabiescu | The Issue of Collective Agency in Community-based Open Content Creation[END_REF]. The project, titled Romani Voices involved two Romani communities in rural Romania. The methodological approach employed placed an emphasis on emergence and people participation in design at two levels: (1) Activity design: people's views were integrated in the design of a content production experience for documenting local cultural practices and collective priorities; and (2) Product design: people participated in designing the information architecture and deciding upon suitable content to be included in a community website for each group involved (www.romanivoices.com).

The study investigated the methodological implications of design interventions in community contexts, and assessed in particular: (1) the conditions, patterns, and impacts of community participation in design; and (2) the challenges of designing cul-turally representative digital artefacts. Drawing on Manovich [START_REF] Manovich | The language of new media[END_REF], culturally representative refers to the quality of a digital artefact or system to properly reflect local ways of knowing and being, and construct in the mind of the onlooker the image of a referent existing in reality, in this case a community's socio-cultural and historical features. In an expanded sense, culturally representative also stands for the capacity of a system or artefact to advance locally defined goals for information, expression and communication.

To investigate these aspects, we surveyed the more generic PD literature, as well as the narrower body of research focusing on community-based participatory design. The PD literature contains a number of contributions that conceptualize the design process around the designers' and the users' inputs. Muller [START_REF] Muller | Participatory design: The third space in HCI[END_REF] describes PD as the third space in HCI, a space in between the developers' and the users' worlds. He makes an overview of "hybrid practices", PD techniques and methods that fall in between the users' and the developers' world. Methods such as workshop, drama, storytelling, and design games contribute to challenging assumptions and driving novel ideas emerged through dialogue and negotiation among users and developers. Kensing and Munk-Madsen's [START_REF] Kensing | PD: Structure in the toolbox[END_REF] model of user-developer communication in PD depicts design as a bridge across two different worlds: the users' (the workplace) and the developers' (the technological options). A third domainthe new systemis created throughout the project.

Community-based design studies are characterized, furthermore, by an increased sensitivity to contextual conditions. It has been argued that designing for local communities involves working with and accounting for two different and at times incompatible ways of knowing [START_REF] Rodil | Enhancing cross-cultural participation through creative visual exploration[END_REF][START_REF] Verran | W: Designing Digital Knowledge Management Tools with Aboriginal Australians. Performative Knowledge Making[END_REF]. When the aim is to create culturally representative and locally useful artefacts, design relies on embracing a local viewpoint and allowing activities and design solutions to emerge from it [START_REF] Rodil | Enhancing cross-cultural participation through creative visual exploration[END_REF]. Community-based design studies, in particular if conducted in indigenous contexts, agree that community participation is the real measure in the development of community-representative artefacts [START_REF] Rodil | Enhancing cross-cultural participation through creative visual exploration[END_REF][START_REF] Verran | W: Designing Digital Knowledge Management Tools with Aboriginal Australians. Performative Knowledge Making[END_REF][START_REF] Srinivasan | Where Information Society and Community Voice Intersect[END_REF]. Community-centric design is not about applying the right method, it rather implies re-interpreting all articulations of the design process in the light of the specific situation [START_REF] Verran | W: Designing Digital Knowledge Management Tools with Aboriginal Australians. Performative Knowledge Making[END_REF][START_REF] Van Der Velden | Design for the contact zone: Knowledge management software and the structure of indigenous knowledges[END_REF]. Design in community contexts calls for the creation of a new space where design approaches and techniques are re-configured during the interaction between local members and the design team [START_REF] Van Der Velden | Design for the contact zone: Knowledge management software and the structure of indigenous knowledges[END_REF].

These considerations frame the position embraced in this paper, and further call for the

central questions it poses: if participatory design in community contexts is an emanation of present interactions between designers and local people, can we identify the most important factors underpinning this interaction? In particular, what are the pre-conditions for effective joint work of designers and local communities in the creation of novel artefacts?

To answer these questions, the next section introduces an analytical model of the design continuum drawing on Wenger's theory of cultural transparency [START_REF] Wenger | Towards a Theory of Cultural Transparency[END_REF][START_REF] Wenger | Communities of Practice: Learning, Meaning, and Identity[END_REF], illustrated by vignettes from the Romani Voices study.

The term community is used in the forthcoming part with two different meanings: (1) the term "community" on its own or in the constructs "designers' community" and "users' community" reflects the meaning invested by Wenger [START_REF] Wenger | Towards a Theory of Cultural Transparency[END_REF][START_REF] Wenger | Communities of Practice: Learning, Meaning, and Identity[END_REF], and indicates a group of people with common interests engaging in shared practices; (2) "Local community" is defined as a construct blending two features: shared geographical space, and members' relatedness [START_REF] Gusfield | The community: A critical response[END_REF], therefore referring to groups of people living in the same space and engaging in social interaction and shared activities.

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The Theory of Cultural Transparency and PD Étienne Wenger's theory of cultural transparency [START_REF] Wenger | Towards a Theory of Cultural Transparency[END_REF][START_REF] Wenger | Communities of Practice: Learning, Meaning, and Identity[END_REF] presents interest for conceptualising PD due to the perspective it provides on the interplay between learning, participation and meaning production. The theory can be summed-up in five core statements: (1) Knowledge is not existing in the abstract but is constantly produced and enacted as part of the practice of communities, taken to be broadly groups of people that engage in shared activities around a profession or common interest; (2) The practices of a community result in the production of objects/representations invested with meaning (from symbols, terms and procedures to gestures and tangible artefacts); (3) Representations are the results of processes of reduction, simplification or meaning investment, meant to facilitate members' joint activities and interaction. They are imbued with meaning, but are at the same time hermetic for a new-comer; (4) Understanding the meaning of representations, or learning, can only happen through direct participation in the practices of a community; (5) Cultural transparency refers to the quality that objects stemming from the practice of communities acquire when their cultural significance is unveiled by an agent. It indicates the successful outcome of a process of learning, on virtue of which a community member can handle representations in a seamless manner. The term "cultural" is used to convey the context-specific and perspective-bound character of knowledge and learning [7, p. 104].

The sections below (1) outline an interpretation and operationalization of Wenger's cultural transparency theory through encoding and decoding meaning, (2) show its relevance for design, specifically PD, and (3) suggest implications for conducting effective PD processes in community contexts.

Encoding and Decoding Meaning

Central to Wenger's theory are two alternate processes that characterize learning through participation in a community of practice: (1) members' regular engagement in activities or practices relying on the production and use of representations; and (2) the new comer's attempt to learn and seize the meanings embedded in these representations. We can look at these alternate processes of creation vs. understanding of representations as a process of encoding vs. decoding meaning and significance. (Note: The encoding-decoding interpretation is part of the authors' approach and was not used by Wenger.) 1. Encoding: Objects and representations are created through abstraction and simplification of the practices in a given community. In this process, they are invested with significance that is invisible to an outsider's eye. 2. Decoding: The attempt to understand the significance of objects or representations of a community equals to a process of decoding, where an outsider tries to make out the hidden layers of meaning in a representation. This understanding is possible, in Wenger's view, only through participation in the practices of a community, and is entirely achieved in full participation. Decoding activities build up understandings until reaching cultural transparency.

The Perspective on Design

Design aims to produce useful artefacts for a certain class or community of users, usefulness which can be determined only in direct relation to the user activities that the artefact will support. Effective design needs to build on a thorough understanding of the user activities that its outcome will serve. In PD, this understanding is advanced by enabling users' direct participation in design activities.

Based on the theory of cultural transparency, participatory design brings together the members of two communities: designers and users, each with a history of past intra-community practices and handling representations created on virtue of such practices. In instantiating PD, a new space of interaction is created, in which the practices and representations of each group are at the outset little known for the other (Fig. 1). PD activities alternate constantly between decoding activities, having as outcome understandings of the other community, and encoding activities, having as outcome new design representations. Decoding activities serve to build up to increased understanding until cultural transparency is reached, indicating the point where each community understands each other's representations sufficiently for engaging in fruitful design activities. The main thesis put forward in this paper is that effective design starts when cultural transparency is reached. The underpinnings and implications of this position are outlined below. Encoding activities serve to create new representations as part of the design process. While Wenger uses the terms "objects" and "representations" interchangeably to encompass all classes of objects resulting from practice, we propose that for being useful in analysing design processes, two distinctions are necessary: 1. Based on level of concreteness, representations can be abstract (e.g. design terminology, work procedures) or concrete (e.g. written codes, manuals). 2. Based on role in the PD process, there can be mediating and final representations. Mediating representations act as intermediary in the relationship between agents (such as a procedure telling agents what each should do) or in the activity performed by agents (as in the use of a mock-up for advancing understanding of the functionalities of the final system). Final representations are those that users will actually be utilizing, such as the final system (Table 1).

Table 1.

Examples of types of representations produced during PD, according to level of abstractness (abstractconcrete) and role in the PD process (mediatingfinal).

Mediating Final Abstract

Design terms, work procedures Workflows based on product usage Concrete Mock-up Final system

Mixed activities, blending decoding and encoding can be employed in order to generate experiential knowledge and showcase or probe preliminary outcomes of design activities. Examples are cultural probes [START_REF] Gaver | Cultural Probes[END_REF], in which users employ low or digital technology to document their context and produce representations that can trigger group discussions and reflections. In Romani Voices, local people used video technology to record snapshots of their life and traditions that were therefore discussed with the field researcher. This served a three fold purpose: (1) local people generated new understandings of their context; (2) the field researcher derived understanding of the local context through people's perspectives; and (3) local people got acquainted with the use of digital technology. Another example is the creation of a community blog and the website mock-up, both of which served to enhance understanding of design-specific terms and artefacts for local people.

A further delineation of activity types can be done by specifying the dynamics of interaction between users and designers in performing either decoding or encoding activities. These activities can be performed separately by each agent (e.g. a designer learning about the local context through non-participant observation) or jointly (e.g. the deployment and joint assessment of an information system). The latter can be referred to by Wenger's concept of boundary practice, indicating the sphere of interaction created through the involvement of users and designers in common activities. A boundary practice is at the same time (1) a fertile field for enhancing understanding of representations commonly grounded in the domain of each community; and (2) the field of production of new meanings. Just as any practice of a community, it can generate its own representations, understood jointly by designers and users. PD activities performed by users, designers, or jointly move constantly between the distinct areas of practice of the two communities and the boundary practice area. The limits of participation. The forms that participation in design can take can be related to Wenger's concept of legitimate peripheral participation -LPP [START_REF] Wenger | Towards a Theory of Cultural Transparency[END_REF][START_REF] Wenger | Communities of Practice: Learning, Meaning, and Identity[END_REF]. LPP as an analytical category refers to learning through increased participation in the practices of a community. However, an agent may participate in practices without attempting to become a member. Her/his position is clearly outlined and so are the limits to her/his participation, based on agreed protocols with the users. In PD, the limits of participation are defined in relation to the degree of knowledge needed by users and designers in order to cooperate effectively in the achievement of the design goals.

Implications for design with local communities

The main argument put forward in this paper is that cultural transparency is the landmark for effective design. In PD, cultural transparency indicates the outcome of a process of learning focused on acquiring knowledge circumscribed to two spheresthe users' context and ICT design. Users will be able to take informed decisions regarding the new system only after having seized the meanings and significance of design representations (terminology, procedures, rules, artefacts). Designers, on the other hand, will be able to put forward adequate solutions when they have reached an understanding of users' practices.

Cultural transparency as landmark for effective design becomes critical when PD is employed in community contexts, aiming to produce artefacts that can advance longterm community goals. When design artefacts are intended to serve cultural representation as defined earlier, there is a need to draw on a common pool of understandings enabling relations between community practices and design solutions. The analytical model introduced drives attention to three aspects to be considered:

1. The types of activities employed in PD, which may fall in three categories: decoding, encoding, and mixed. We argue in particular for the usefulness of mixed activities (e.g. cultural probes), in which mediating representations are created for advancing experiential knowledge and understanding the applicability of design solutions to a specific context. 2. The sequence of decoding, encoding, and mixed activities. Effective sequencing requires sensitivity and attention to the type of knowledge and understandings required for taking informed decisions in design. We suggest that in the beginning of a project cyclic iterations of decoding and encoding activities concerned with the production of mediating representations are effective drivers of understanding on both sides. On this basis, encoding-intensive activities may further be devised. 3. The value of boundary practices. When engaging in joint activities, in particular those blending decoding and encoding (e.g. engaging in the deployment and discussion of cultural probes), users and designers instantiate shared spaces of interaction, with their own production of meaning. These spaces are particularly fruitful for advancing understandings of design, the local context, and design solutions grounded in the needs of the local context.

Conclusion

This paper introduced an analytical model for PD processes, drawing on Wenger's theory of cultural transparency. The model depicts the PD continuum as an alternation of activities in which both users and designers engage, respectively for (1) deriving knowledge and understanding of the other's area of practice and (2) investing meaning in the creation of new representations. The model is proposed as an analytical tool for understanding the factors that are brought to bear and conditions to be taken into account when engaging in PD projects in new contexts, for instance with local communities. The importance of reaching a shared sphere of understandings, indicated by the term cultural transparency, is especially critical when design interventions are aimed to produce culturally representative artefacts that will help to advance a community's goals and can be integrated and used in its practices.

Fig. 1 .

 1 Fig. 1. Participatory design as an iterative process of encoding and decoding involving users and designers.


Mohd Syaheezam

Asyraq Yamin

Eswati Azni Jaafar

Web Design for Science Museum towards Engaging User Experience

Keywords: User Experience, Usability, Web Design, Science Museum

Nowadays, exhibition experience is no longer defined by physical visits. Increasing a person's knowledge about a subject tends to increase their interest in it, thus improve attendance and support for the exhibition. This research analyses and conduct comparison studies regarding website elements featured in 30 science museums around the world. Consequently, this produces an overview of one effective model for Website design; a user-centered process that includes techniques for need assessment, methodology, goal/task analysis, user interface design, and finally pre/post prototyping.

Introduction

As the Internet continues to grow as main sources of information, the design of effective Websites becomes increasingly important. In Malaysia, the level of awareness on issues such as user interfaces and effectiveness regarding website has increased. Some of them even regularly improvise and update their website. However the results are still far from satisfying. Based on the report by "Malaysia Government Portals and Websites Assessment (MGPWA) 2011", only 285 out of the 1,155 websites manage to meet 5-stars rating set by Multimedia Development Corporation (MDEC), a body that oversees Malaysia's Information and Communication Technology initiative. In order to get a 5-star rating, several criteria were put together in MPWGA mostly related to best practice and global standards. This problem also significantly affected other institutions like the Museum and Science Centre. Website is critical as it provides the first impression of an institution. In normal circumstances, Website with great visual design and aesthetic will give more credibility. This report examines the effects of good user interface design for Science Centre Website and whether the implication of user experience design will contribute to number of actual physical visits to the Science Centre.

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Background Nielsen (2000) stressed that there are two basic approaches to web design, which are: the 'artistic ideal' that shows the designer's self-expression and the 'engineering ideal' that delivers solutions to users. Based on that, 3 main areas are considered:

User Experience Issues

Badly designed websites frustrate users and cause them to leave, as they cannot find the required information. Most of them have bad experience when navigating through the website. Reasons cited for the users' negative experience include outdated information, difficult to use and mostly, not finding what they wanted (Nua, 2002). To encourage users to return, website should be designed to facilitate users in finding what they need and increase satisfaction while accomplishing their tasks (N. Abdelmessih, 2001). The website should be able to provide an engaging experience to visitors.

Design Principle

In order to produce a remarkable design, web designer used to manipulate all elements of design and graphic art. Some of these factors range from elements of space, use and size of images, use of animation, colours, audio and many more. A study by [START_REF] Shenkman | Aesthetics and preferences of web pages[END_REF] and Tractinsky et al. (2000) suggests that visual appearance is important in users' preference for website. In similar vein (Tractinsky et al. (2000)) stated that 'what is beautiful is usable'. The design of visual presentation of web pages is based on an imaginative stimulus that, in the intentions of the designer, should represent the best way to implement this strategy. (Visciola, 2000). In order to develop a good visual presentation, designers should be able adapt the design principles to the required design.

Usability

According to ISO 9241-11 (1992) usability is defined as the 'extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use'. Most studies agreed that the measurement of effectiveness of the site normally reflected by the satisfaction level of the users expectations, not the researchers and designers. The quality of user-site interaction is not totally depending on the users' opinion about a website, but also the perception of the identity of the organization providing it, and as well as the evaluation of its efficiency. In this context, each page element has its influence where strategies for access, navigation and orientation are very important aspects. (Mario, 2004)

Method

The authors aimed to investigate two issues. Firstly, to find out the main Design and Multimedia elements that could provide good user experience for a science museum website. Secondly, to explore processes that can provide good website experience. In conducting this research, there are several methodologies employed. The methodological approach in this research is a combination between qualitative and quantitative research as depicted in Table 1 and Table 2 below:

Table 1. The qualitative method used to clarify the issues.

Purpose Method Justification 1.To understand the objectives and goals of PSN

Unstructured Interview

To gain comprehensive Information about targeted type of users. A set of questions were emailed to PSN, followed by interview session with their personnel.

2.To explore the experience of site-visitors.

Observation

Visual observation of site visitors. Visitors are asked to browse the PSN website and perform a few simple tasks.

Table 2. The quantitative method used to clarify the issues.

Purpose Method Justification 1. To generalise groups of people.

Demographics Research

To identify the potential users of the website.

To get more info on the website users (primary data)

Questionnaires

To get the right direction towards the development.

To compare pattern matching trends, gaps and features

Visual Analysis 30 science museums around the world has been analysed based on Design Principles, Usability and Aesthetics factors

Results

In any web development process, the most important step is to understand the users. This is the highest priority during any web design project. Findings is clearly defined below:

Demographic findings

Demographic survey as depicted in Figure 1 showed the number of visitors that visit Pusat Sains Negara (PSN) or National Science Centre in 2011. The survey reveal that most of the visitors come from adults and children category that later can be simplify into 'family category'. Based on this fact, both PSN and researchers agreed to focus on family with children as the main target audience.

Online surveys

According to the surveys, 50% of the participants state, "planning a visit to Pusat Sains Negara" as their main purpose of visiting the PSN website. This is important finding, since their decision to proceed with the visits might depend on the website credibility itself. The participants were then asked to evaluate the current PSN website based on 4 main categories -Design, Features, Ease of Use and Errors Prevention. As expected, the total score of the website is 2.5 out of 5.The survey clearly indicate that the PSN website need improvements, in terms of design, layout and also presentation.

Visual Analysis

For Visual Analysis, the first method use is Screen Real Analysis, which is based on 'Homepage Usability: 50 Websites Deconstructed' (Neilsen And Tahir, 2002). As a One of the most important aspect to compare is pattern matchingtrends, gaps and features. All 'estate' in the websites were scanned properly and then being colourcoded one at a time. Results as depicted in figure 2 below: Visual Analysis on the 30 science centers websites shows that most of the websites have a contrast point (visual differentiation between two or more elements) and also good balance (overall distribution of the visual weight), but most of them suffer badly when it comes to the flow principle which is (the path the users' eyes take through the design). Most of the design failed to combine the design elements in proper manner.

Design and Development

Before starting any design process, it is important to establish a clear direction on the new website. Based on the discussion with PSN and the websites comparison depicted in Table 1, two main attributes are derived based on these keywords: Based on the two attributes above, a design matrix has been composed that is illustrated in Figure 3 below: For the development of a new website, scrolling innovation has been implemented. It enables user to move some of the graphic elements in different way, or change its size, colour or content whenever user scroll down the website. Another effect implemented in order to enhance user experience is parallax effect. It is a technique that featured layered images that moves around the website in different perspectives, which resulting in a nice and interesting 3D illusion. This effect can be achieved using jQuery scripting, CSS3 and HTML5. A pre and post-test is then conducted before proceeding with the final prototype. Pre-test analysis implies that 'Design 2' is preferred as the most smooth and comfortable design. 62% of the participants also agreed with the use of 'scrolling innovation' while 85% believed that the use of parallax effect has improved their experience as stated in Figure 6.

Result

Research findings conclude that it is best to define the elements based on Design Principles, Aesthetics and Usability as stated in Theoretical Framework. The relevant elements then tested either using quantitative or qualitative methods. Based on the Jesse James Gareth's (2003) model of user experience, there are a few processes that have to be conducted starting from strategy, scope, skeleton, structure, to surface. Each process is supporting each other and should be completed one at a time. Based on the questionnaire in Pre Test session, 62.5% from 32 respondents stated that Design 2 would provide them an engaging experience. 85% of them decided that they will visit Pusat Sains Negara (PSN) after browsing the website. In conclusion, an engaging website experience will influence visitors to actual physical visits thus increasing the credibility of the institution. In order to adapt exceptional experience in science museum website, it is always a good practice to consider the latest trends and new approaches in web design. For this research, both innovation scrolling and parallax effect has been integrated into the website design. As a results, the website manage to offer a new dimension in terms of engaging user experience to visitors.

Conclusion

Experiments uncover that the combination of design principles, aesthetic, and usability has the potential to improve the quality of science museum websites. The success of a website is not only judged by aesthetic value but also on its ability to provide an engaging experience to users. In this paper, researchers presented a framework on how to provide an engaging website experience for Science Museum which consists of data from design principles, usability and aesthetics evaluation. Web designers should experiment with lots of new ideas to offer something unique. Continuous research on how to provide best user experience should be encouraged. Hopefully this research will spark more interest from designers or developers to join in the bandwagon in terms of producing a more engaging websites design and development.

Figure 1 :

 1 Figure 1 : Demographics analysis for PSN visitors

Figure 2 :

 2 Figure 2 : Summary of screen real estate for 30 museum websites

Figure 3 :

 3 Figure 3 : Design Matrix for the new website

Figure 4 :

 4 Figure 4 : Sketches and prototypes

Figure 5 :

 5 Figure 5 : Post Test at Usability Lab MIMOS

Figure 6 :

 6 Figure 6: Analysis for user acceptance of prototypes

Table 4 :

 4 Keywords based on feedback from PSN

	ATTRIBUTE	KEYWORDS
	Corporate	Accurate, government agency, formality, MPWGA guidelines,
		Services
	Playful	Imagination, exploration, curiosity, enjoyment, fun, wow factor,
		futuristic


Torben Sko
email: torben.sko@anu.edu.au

Henry Gardner
email: henry.gardner@anu.edu.au

Michael Martin
email: michael.martin@anu.edu.au

Studying a Head Tracking Technique for First-Person-Shooter Games in a Home Setting

Keywords: head tracking, gestural interaction, online studies, games

This paper examines webcam-enabled head tracking for games in a home setting. A new head interaction technique was developed based upon prior laboratory-based research, with a focus on making it robust to the variable conditions of a home setting. Our technique was integrated into a test-bed game and 550 hours of gameplay data was collected from 2500 users, many of whom also provided formal feedback. The head tracking performed creditably and players reported that the experience was more immersive. Head tracking failed to enhance competitive playing performance, perhaps owing to familiarization effects. Nevertheless, the data revealed evidence of learning amongst users, suggesting that performance would improve with continued use. Key lessons that emerged in the home setting in contrast to the earlier laboratory study were a demonstrated need for clear guidance and feedback during system set-up, and greater caution regarding its deployment, having discovered a small population of users who became nauseous.

Introduction

In recent years, webcams have become a ubiquitous form of technology. When placed in a desktop setting -where a user sits up-close to their computer screens -webcams can be used to track the 3D location and orientation of the user's head position. Despite the availability of this technology, head tracking has seen relatively little adoption, even in computer games that have elsewhere seen a significant move towards gestural interaction. Our previous head tracking work [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF] highlighted several barriers to adoption, with the most prominent of these being the perceived reliability of the tracking system. This issue was presented in the context of a laboratory setting and techniques of a prototype quality. Consequently, it could only be hypothesized what the real-world impact of this issue was -when considered in the context of a home setting and a consumer-grade technique. This paper presents the first study of its kind to examine a refined head tracking technique in a household setting. We conducted a remote user study with a built-in logging system to allow us observe how our technique functioned when used by home players. In doing so, we looked to examine whether the technique could work reliably enough within this uncontrolled environment and provide enough benefit that players would adopt it. In examining this adoption, we were also keen to explore what impact our head-tracked interaction technique had on the user's competitive playing performance, as compared to a button alternative. Such an investigation responds to the idea that "hardcore" PC players can be quite dismissive of gestural interfaces on the basis that they do not yield any playing performance benefits [START_REF] Gkikas | The evolution of FPS game controllers: How use progressively shaped their present design[END_REF]. The public exposure the study entailed also provided an opportunity to examine how a large audience of players reacted to the idea of using head tracking in games -a concept that still remains quite novel. This paper examines this reaction in an effort to identify what qualities may help to make a head tracking technique more appealing.

The next section provides some background and further motivates the decision to conduct the study in a home setting. Sections 3 and 4 present a refined interaction technique and detail the study used to assess it. Section 5 presents the results of the study, while Section 6 summarizes our findings as a set of head-tracking guidelines, designed to help others develop their own interaction techniques.

Background

Head tracking was first reported in the literature in the late 1960's by Sutherland [START_REF] Sutherland | A head-mounted three dimensional display[END_REF] who attached a mechanical arm to a user's head to detect their head pose. By contrast, modern head-tracking libraries, such as [START_REF]Seeing Machines: faceAPI[END_REF][START_REF] Garage | OpenCV[END_REF], can now function with just a standard webcam (see [START_REF] Murphy-Chutorian | Head Pose Estimation in Computer Vision: A Survey[END_REF] for a full head tracking review). Following these improvements, researchers have explored the use of head tracking within various desktop applications, including gaming [START_REF] Bradski | Computer vision face tracking for use in a perceptual user interface[END_REF][START_REF] Gorodnichy | Nouse 'Use your nose as a mouse'-a new technology for hands-free games and interfaces[END_REF]. For example, the work of Wang et al. [START_REF] Wang | Face-tracking as an augmented input in video games: enhancing presence, role-playing and control[END_REF] presented a head-based leaning technique in a first-person-shooter (FPS) game that allowed players to dodge bullets. Their work found that the inclusion of head tracking improved a measure of player presence. The commercial game, ArmA 2 [START_REF]Bohemia Interactive Studio: ARMA 2[END_REF], adopted a similar technique that also allowed players to look around independently of their aim. This title required use of the infrared-based hardware system, TrackIR [START_REF]TrackIR[END_REF]. Another tracking system more recently released, is the Kinect [16]. Despite the availability of this hardware, only a few games exist that specifically utilize the head as a gestural controller.

In the absence of any widespread adoption, our previous work [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF] examined the ways in which head tracking could be utilized in an FPS game, by comparing Wang's leaning technique [START_REF] Wang | Face-tracking as an augmented input in video games: enhancing presence, role-playing and control[END_REF] to six other head-interaction techniques. In this work we implemented and evaluated our techniques using focus groups. The general reception was positive, although gamers were also concerned about the reliability and robustness of the tracking system. As this work was conducted in a controlled, laboratory setting, how these concerns might translate to real-world use within a household setting was a matter for conjecture.

Many existing studies have acknowledged the importance of the real-world environment in assessing the usability of new technology. For example, Hartson [START_REF] Hartson | Remote evaluation: the network as an extension of the usability laboratory[END_REF] argues that both the test settings, along with properties of the system itself, are intrinsic factors that impact upon the usage patterns, making it difficult to replicate in a laboratory setting. The work of Brown [START_REF] Brown | Into the wild: Challenges and opportunities for field trial methods[END_REF] similarly points out (in the context of a geolocating tool) that while the lab provides a good setting for exploring the technical feasibility, it provides little insight into user acceptance. These issues, that of the realworld realization and adoption, are particularly relevant when discussing webcambased head tracking given the use of vision-based algorithms. The performance of the tracking is susceptible to environmental factors, such as lighting conditions and physical set up -making it necessary to use a home setting if we wish to know its realworld performance and adoption.

To help deliver studies within remote settings, researchers have increasingly taken to using the Internet. The benefits of online studies include the ability to reach potentially thousands of home users [START_REF] Cooper | Predicting protein structures with a multiplayer online game[END_REF], across a large and varied sample [START_REF] Wood | Online data collection from video game players: Methodological issues[END_REF]. For example, Kittur et al. demonstrated that is possible to utilize existing crowdsourcing systems (i.e. systems where users complete small tasks for monetary incentives) for the purposes of running a user study [START_REF] Kittur | Crowdsourcing user studies with Mechanical Turk[END_REF]. The level of sophistication employed varies dramatically, from simple surveys [START_REF] Evans | The value of online surveys[END_REF] to sophisticated remote studies where the participant and researcher are separated physically and temporally [START_REF] Hartson | Remote evaluation: the network as an extension of the usability laboratory[END_REF]. In these latter studies, a logging system is employed to capture how the user interacts with the study software, which frees the user to engage with the study in their own time [START_REF] Robinson | Unsolicited Narratives from the Internet: A Rich Source of Qualitative Data[END_REF]. For example, the work of Costanza et al. [START_REF] Costanza | Ubicomp to the masses: a large-scale study of two tangible interfaces for download[END_REF] used a logging system to capture the visual and auditory output of their software, allowing them to later replay its use. Some of the other feedback mechanisms that researchers have used include; text and video chat, questionnaires, interviews, forums, and diaries [START_REF] Andreasen | What happened to remote usability testing?: an empirical study of three methods[END_REF]. Our own study employed many of these concepts, as described in Section 4.

Technique Description

The head interaction technique presented in this paper is referred to as the Handy-cam and Leaning (HAL) technique (pictured in Fig. 1). It combines and improves upon the two most promising techniques identified in our earlier work [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF]. The first of these was a leaning technique, which was first explored by Wang et al. [START_REF] Wang | Face-tracking as an augmented input in video games: enhancing presence, role-playing and control[END_REF]. This technique allowed a player to perform an in-game lean movement by physically leaning (that is, tilting and/or offsetting their own head). The resulting in-game action allows players peer out from behind cover so they can spy on enemies and better protect themselves during a gunfight. When featured in an FPS title, this form of control is typically mapped to the 'Q' and 'E' keys. By comparison, using head-movements to perform this form of control is potentially more intuitive [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF] and can provide a finer level of control through its continuous nature [START_REF] Stellmach | Designing gaze-based user interfaces for steering in virtual environments[END_REF]. In Section 5.2, we examine whether this increased level of control can indeed yield a stronger playing performance.

The second technique chosen was the handy-cam effect, which aimed to reinforce the intention that a first-person game is being viewed through the eyes of the protagonist. The technique worked by adding a "wobble" to the virtual camera so that the player's own subtle and involuntary head movements were mimicked by the virtual camera. For example, if the user was pitching their head slightly upwards, the virtual camera was subsequently pitched slightly upwards (likewise for the other head axes). A similar effect is used in modern cinema in films like "The Bourne Identity" (2002), where a subtle wobble is added to the view to make it look as if the action is shot on a handheld camera. This effect can make the viewer feel more present, as if they are viewing the action directly with their own eyes [START_REF] Lombard | At the heart of it all: The concept of presence[END_REF]. Adding a jitter has also been found to make the scene appear more realistic, by increasing the perception of selfmotion [START_REF] Bubka | Natural visual-field features enhance vection[END_REF]. Several studies have examined the effects that a pre-animated jitter can provide, both in pre-recorded video [START_REF] Palmisano | Global-perspective jitter improves vection in central vision[END_REF] and games [START_REF] De Barros | Characterizing Head Movement in First-Person Games[END_REF]. Our earlier work was the first known attempt to create an interactive version of this effect, where it was unanimously well received by the focus group participants [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF].

Technique Implementation

The design of HAL has seen our earlier prototype techniques [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF] greatly matured into a technique designed for mass-use. More specifically, whereas our previous implementations were targeted at a single computer set up, HAL needed to work across a multitude of home computer configurations. To make the technique cope with variations in the set up, the following enhancements were added:

• No assumptions were made about the user's resting position in order to cater for differences in the physical configuration of the home systems. • Time-based smoothing (rather than sample-size based) was used to account for computer speed variability. • Smoothing of the head data was adapted based on the tracking quality, thereby allowing HAL to remain responsive on slower systems. • An easing curve was added to the leaning for finer control over smaller lean movements.

• Several minor tweaks were added to avoid any negative visual impacts the head technique may create. These included constraining the range of head mapped movements and fadding out/in following a head loss/aqausition.

Our HAL technique can be thought of as a mapping from the user's head position to a normalized leaning-amount and a camera offset. The head data was obtained using Seeing Machines' faceAPI (v4) software [START_REF]Seeing Machines: faceAPI[END_REF], which provides both the position and orientation of the user's head. From this data, the leaning-amount was computed using both the roll and sideways head movement (as both axes are typically involved in a leaning action). To derive the leaning-amount the following logic was applied: The bolded variables could be tuned using the settings panel, thereby allowing users to customize how the technique functioned. In lines 01 and 02, the head value is converted from an absolute position into an offset relative to the user's resting position, allowing us to identify how much they have moved. As the head position is stated relative to the webcam, the user's resting position will be a non-zero position vector (e.g. if the user sits 80cm away, the reported depth will be 0.8). There are several sources of variation that will influence this position, including the camera's position, the user's seating position, as well as how the software interprets the user's face. In our earlier work [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF] this position was assumed, which caused the technique to behave incorrectly for some participants. Our HAL technique instead employed a running mean to compute this resting position. To avoid having this position shift too much during play, the mean was only updated when the new head data was within a certain range of the mean (rollRange = 30°, sidewRange = 15cm).

In line 03, the roll amount is normalized over a usage range. This range is scaled (leanScale = 1, sidewScale = 1) in order to control the sensitivity of the technique. A minimum is used (rollMin = 3°, sidewMin = 2cm) to introduce a "dead zone" or nomovement zone. This dead zone ensures subtle head movements avoid invoking a lean movement, which could otherwise interfere with the player's aim. In line 04, the two components of the lean movement are combined and normalized between 1 (ful left lean) and -1 (full right lean). In line 05, an ease-in/ease-out curve is applied to the lean-value based on the easeAmount (= 100%). The leaning value is then smoothed using a moving average (line 06, leanSampleTimeframe = 0.2sec) and faded (line 07) in the event that the user has only started to be tracked within the last two seconds.

The lean-amount obtained from the previous logic was then mapped to a leaning action. In the case of our game, this corresponded to a sideways player movement, a gun movement, and a slight reduction in the field of view (FOV). The gun movement and FOV reduction together recreated some of the look-and-feel of the iron sighting technique, which was well received in the previous focus group studies [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF]).

The other key aspect of HAL was the handy-cam effect. To compute the camera offset, the following logic was applied: ... // Repeat the above for all axes except head depth

cameraPosition += handycamOffset;

As before, the head data is converted into an offset (lines 02 and 03, above). In line 04, the effect is scaled using both a global scale (handycamScale = 1) and an individual scale for each axis (pitchScale = 1, rollScale = 1, etc). These scaling factors allowed the user to control the strength of the technique. In line 05, the offset is potentially dampened during times that the user was leaning (dampenWhileLeaning = 50%). This was included to avoid having the effect interfere with the player's aim whilst leaning. The value was then smoothed (line 06, handycamSampleTimeframe = 0.2sec) and faded (line 07). This was repeated for all the other head axes, except for movements along the forward-facing axis as these were found to negatively impact on the appearance of the weapon model positioned in the foreground of the scene. The computed offset vector was added to camera's position (line 09) to create the handycam effect. A complete implementation of the HAL technique can be found online 1 . It has been implemented using freely available software.

Study Design

To study HAL we wanted to observe; how it performed, to what degree it was adopted by players, and what players thought of it. To achieve this we implemented HAL into the commercial FPS title, Half-Life 2 (HL2). This allowed us to utilize a wealth of existing game content, which provided a rich setting in which to examine our technique. As HL2 does not include leaning as part of its control set, we modified the game to include it. We also constructed a custom lean-centric game mode to explore the hypothesis that a greater focus on head-control would elicit a more positive user response [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF]. This custom mode was called FaceOff Paintball (FOP). The following summarizes the differences in these game modes:

• HL2 mode: existing game levels of Half-Life 2. The levels were not designed with leaning in mind, but can be played with leaning (controlled using either the keyboard or head movements) with our implementation. • FOP mode: a novel paintball game level where players try to survive for as long as possible. The player (and enemies) only take one shot to be "marked" (i.e. eliminated) making it important to use the provided cover, which we felt could be best done through the use of leaning.

We added several mechanisms to both game modes that allowed us to examine how the HAL technique was performing and being used. Firstly, we monitored and logged characteristics of participants' use of the system including their head position, the leaning value, their playing performance (e.g. game score), system performance (e.g. frame-rate), the hardware (e.g. camera model), and potentially a picture of their set up as taken with their webcam. These data were only sent if the user opted into the study aspect of the game. At the time of downloading the game we surveyed the participants (via a sign-up form), asking them about their age, gender, gaming experience and their enthusiasm towards head tracking. We were able to associate this information to the logged data using a sign-in panel within the game.

To collect the player's opinion of the technique, the game was modified to include a post-play questionnaire, made up of 45 questions, most of which requested responses on a five-point Likert scale. We also incorporated an optional comparison test, which provided us a more formalized way of examining the impact head tracking had on the game experience. Within the test, users played the game twice, once with the head tracking enabled, and once with it disabled (randomized order between users). This test could be played under either HL2 or FOP game modes. Under the HL2 mode, players could choose to play with either the traditional control set (without leaning) or with the extended control set (including leaning). This meant there were Fig. 2: A flow diagram for the online experiment (left) and resulting comparison conditions (right). In the flow diagram, the mid-gray boxes represent states where the user is playing. The black dots indicate where the system auto-assigned users to a condition. The 'on' boxes denote the condition where head tracking was enabled, while in 'off' head tracking was disabled. The darkest boxes represent the in-game survey. The system forced the surveys to be viewed but did not prevent users dismissing it without answering any questions. The player could freely switch between any of the game modes and could complete the comparison test multiple times. two conditions: head control (enabled / disabled) and game mode (FOP / HL2standard / HL2-extended). When the playing under the HL2-standard mode (without leaning), only the handy-cam aspect of the head-interaction technique was in effect, allowing us to study its impact on its own. At the end of each condition, an in-game survey was presented to the users. A summary of the study is provided in Figure 2.

Our study system was placed online and promoted through the use of two YouTube videos. The release of the work generated a considerable amount of online discussion, which was found to provide a valuable source of feedback [START_REF] Robinson | Unsolicited Narratives from the Internet: A Rich Source of Qualitative Data[END_REF]. When combined with the open text response taken from the exit questionnaire (479 comments), a collection of over 2000 comments was accumulated. These comments reflected how HAL was both perceived (prior to using) and received (after using it).

Results

Playing data was collected from 2593 users from across 100 countries, with the US, Russia and the UK being the most common countries of origin. The most represented group was young males with "lots" of FPS experience. Through the use of a pre-play survey, administered during the sign-up process, we found that 75% professed to being "excited" about the use of head tracking. The median playing time was 7 minutes. A total of 550 hours of playing data was logged.

The remaining part of this section is split based on the main research goals; Sec. 5.1 examines how the technique performed in an uncontrolled environment, Sec. 5.2 explores how players adopted the technique and its impact on their playing performance, while Sec. 5.3 examines the players' opinion of HAL as a way of identifying the qualities that have most influenced its reception.

Technique Performance

By logging HAL's functional performance, we were able to examine how well it performed in a household setting. Figure 3 illustrates the reliability of the system by binning participants based on the tracking rates during the tracking enabled condition of the comparison test. Of the 726 participants that played under this mode, 62% (452) were tracked for 95% of their playing session or more. By contrast, 2% (17) were never tracked.

When examining the complete participant sample, it was noted that 23% (595) were never successfully tracked. Examining the hardware details of these players revealed that 34% (202) of these non-tracked players did not have a working camerameaning that their camera was incompatible, incorrectly configured, or non-existent. The collected forum comments highlighted that built-in cameras were the most troublesome. The other 66% of the non-tracked players (393 users) did a have recognized camera, but were still never successfully tracked. Several images were collected from the user's own webcams to help explain why the tracking failed. Figure 4 demonstrates that some players used the system under far-from-ideal conditions. Some of the common issues encountered included: partially cropped and obscured faces (e.g. some users wore obscuring apparel, others sat too close); dimly lit settings (e.g. some users were lit via their monitor only); high contrast images (e.g. over-exposure of the image due to bright lighting); blurry/unclear images; and pre-processed images (e.g. with some users featuring partial overlays and virtual avatars). Because many of these issues could have been corrected on the user's side, the software was modified during the study to display an image from the user's own webcam on the main menu of the system in the hope that users would identify and rectify deficiencies in their own setups. As Fig. 3 shows, this had limited impact on tracking reliability, an observation verified by performing a classification of user images based on the apparent issues.

Fig. 4: Some of the webcam images (with faces blurred to protect identities). Many of these images show conditions that would make a user's head difficult to track: dim lighting, overexposure, obscured facial features (e.g. sun-glasses), a highly angled camera. In the case of the alien head and Viking boat, the webcam feed has been pre-processed before being received by the head-tracking library. Explicit permission was sought from users before collecting these images. The study was approved under the ethics protocol, 2010/032.

Player Adoption

The log data from the successfully tracked players provided an insight into how HAL was used by players. The data illustrated that the FOP game mode was successful in encouraging more leaning, with the head leaning being more popular than button leaning under both game modes. As one participant noted, "I rarely make efficient use of the lean function in games because it usually requires some finger gymnastics to strafe and lean at the same time. I found myself leaning much more when all I had to do was move my head. I'm very pleased with this idea." Button-based leaning saw almost no use within the HL2 game mode. As the game content did not encourage leaning, this outcome would suggest that the novelty of the leaning control alone was not enough to encourage players to use it. However, when the leaning control was performed via head tracking its use increased and was well sustained across the users who chose to play for more than an hour under the HL2 mode (30 players).

The playing logs also revealed how much players tended to move while using the technique. Figure 5 shows the amount of head movement under three different control schemes: HAL (both head leaning and handy-cam enabled), handy-cam only and head-controls disabled. In the disabled condition the player's head position was still logged despite having no apparent effect on the game, allowing us to observe the natural head movements that occur during play and establish a control group. The data in Fig. 5 show that players moved their head the least when the head control was disabled. Users appeared to move least in the vertical axis and the roll axis. By comparison, the pitch and yaw axes exhibited a greater amount of movement, making it more likely that they would yield false-positives if used for head controls. This result affirms our decision to develop a technique that predominantly relied on the roll axis.

Fig. 5:

The amount of head movement under different control schemes. The data has been sourced from the HL2 game mode during the comparison test. A half-second smoothing window has been used to account for tracking noise. The control schemes were taken from the different test conditions (see Fig. 2 for a list of conditions). The numbers in parenthesis indicate the number of applicable players, noting that only a few players chose to disable the leaning control, hence why the handy-cam only category is less populated. Nonparametric Wilcoxon tests reveal the disabled/HAL and disabled/handy-cam conditions to be significantly different (p < 0.01). By contrast, the HAL/handy-cam were not found to be significantly different. The data shows that the amount of roll movement increased when the head leaning was enabled, however, even under this condition, this axis still exhibited less energy than the other two rotational axes.

Unexpectedly, the charts reveal that players tended to move most when only the handy-cam effect was enabled. It was expected that the HAL condition would exhibit the most movement, as part of performing the leaning control. By comparison, the handy-cam was intended to utilize the user's subtle and involuntary head movements. This finding suggests that users were trying to pro-actively use the handy-cam effect, presumably to look around, illustrating that its design intention was not well conveyed. When used in conjunction with the leaning, the amount of movement dropped. This may suggest that users were not as inclined to use the handy-cam for practical purposes if a more obvious use of head tracking was also present. For this reason, the handy-cam is probably best used alongside another head-interaction technique.

Returning to the topic of HAL's adoption, another aspect to consider was the impact that head tracking had on the users' playing performance. Past research shows that an interface that provides performance benefits is more appealing to players [START_REF] Gkikas | The evolution of FPS game controllers: How use progressively shaped their present design[END_REF]. To explore HAL's performance impact, our system included an online leaderboard within the FOP mode, which globally ranked players based on their score. By including this indirect competition, it was hoped players would focus on their playing performance. A total of 24,000 attempts were recorded, lasting an average of 36 seconds. It was interesting to note that the top five players consisted three who chose not to lean, one player who mainly used button leaning (3 rd place) and one head-leaning player (4 th ). Three of the top 10 players mainly used head leaning. A mixed-effects model was used to examine how button and head leaning affected the score.

For each attempt the number of marks (i.e. eliminations) was divided by the attempt duration to yield a marks-per-second score. The one-shot-eliminates nature of the FOP mode meant that the scores were not normally distributed, so a log of the marks-per-second score was taken (after removing scores of zero). The resulting "logscore" performance measure was normally distributed. We also added to the model aspects like prior use of the system (e.g. prior duration in FOP mode, prior head/button leaning), information about the attempt (e.g. duration of play, percentage of time tracked), as well as demographic and hardware information. The usernames were fit as a random effect in the model as observations from the same user were likely to be correlated with one another, while observations between users were assumed independent. All other covariates were fit as fixed effects.

After an initial 'full' model fit, all clearly non-significant variables were excluded and reduced model was assessed using both deviance-based criteria and AIC 1. The model indicates that gender (male) had a positive influence on log-score, as did having extensive FPS experience, a faster computer, as well as being reliably tracked.

Our mixed-effects modeling revealed that button leaning had a positive influence on the leaderboard score, but that head-tracked leaning negatively impacted it. With users only playing for an average of seven minutes, it is possible that detrimental effect was the result of a familiarization period. A correlation test found the accumulated duration of play had a significant positive correlation with the score (0.147), illustrating that a learning effect was present. This learning effect was also observed when examining the two forms of leaning. The accumulated duration spent button leaning and head leaning were both found to have a significant positive correlation with the score (0.123 and 0.107 respectively), albeit with the head leaning being harder to learn. This learning effect is encouraging, as it suggests that HAL may be able to eventually facilitate a better performance over time.

To supplement this test, we examined whether the participants' use of the leaning technique changed over time. Little change was observed over a one hour period, suggesting it probably takes several hours of play to become reasonably skilled using HAL. Such an outcome suggests a longitudinal study would be required to properly examine the playing performance impacts of head tracking. Such a study of competitive performance may benefit from adopting a richer control set than that used by us in the FOP mode in order to mitigate the trade-off that occurs between the physical affordance of an input method, the perceived in-game benefit and the reliability of the head tracking system. As one participant noted, "The best keys for leaning are "Q" and "E", but I would rather use those keys for more important actions. If it works right this would free up some valuable real estate." Similarly, having players compete directly against each other in the gameplay may help to address the familiarization performance slump. As one participant noted, "It would be interesting to see if the "I'll stick to my keys" players would change their tune if they started getting owned by head tracking player because of this difference."

Player Opinion

With head tracking remaining a relative novel concept within gaming, we wanted to discover what player's thought of HAL so that we may better understand what influences its appeal. The players' opinions were, in part, collected via the comparison test surveys and the exit questionnaire. An exploratory examination of the data was conducted using a classification tree (CART) approach [START_REF] Breiman | CART: Classification and regression trees[END_REF]. This approach seeks to predict (classify) response variables based on the covariate values by recursively partitioning the covariate space through a sequence of binary splits on individual covariates. Each step in the algorithm chooses a covariate that provides the most homogeneous groups, delivering a tree-like structure for the model. The tree model approach does not require the pre-specification of interaction terms; it allows for complex multi-way interactions; and it caters for a mix of continuous and categorical variables without imposing any particular parametric structure, making it well suited to exploring rich datasets, such as those yielded by online studies [START_REF] Sko | Non-parametric Decision Trees for Online HCI[END_REF]. Some of the covariates included within our tree modeling included: the tracking reliability and the stated prior enthusiasm for head tracking (to help explore the presence of an enthusiasm bias), hardware performance (e.g. frame-rate, to help explore whether a minimum hardware requirement exists), and the prior playing time (to test whether longer exposure improved the player's opinion). For the comparison test questions, the model also included the game mode (to test whether a greater focus on the head-technique yielded a more positive result), and the head tracking condition (i.e. enabled/disabled).

The CART trees for the exit questionnaire and in-game surveys both told a very consistent story. From the exit questionnaire responses, participants were clearly in favor of head tracking. For example, when asked, "What are your thoughts about having the head tracking technique demonstrated in this game incorporated into other first-person-shooters?" the resulting tree, comprising of 899 responses (85% in a positive category), first split on prior enthusiasm, with both first-level nodes classified as a positive response. A similar result was found when asking the more contentious question: "Would you be inclined to use this head tracking technique in more demanding situations, such as when playing on harder difficulties or in competitive online games?" Based on the 825 responses (55% in a positive category), again the tree split on prior enthusiasm. Encouragingly, when examining the response of just the "skeptical" or "undecided" players (i.e. the non-excited players), 65% (72) were still in favor of having HAL included in other games, however, only 26% [START_REF] Wang | Face-tracking as an augmented input in video games: enhancing presence, role-playing and control[END_REF] would use it in a competitive scenario.

For the comparison-test, the head tracking condition (disabled/enabled) was consistently the most dominant factor (primary splitting variable, or best-discriminating covariate) for each of the 18 questions. For example, one of the questions asked players how much they "enjoyed" the game. It received a total of 1276 responses from 888 users (includes responses to the different study conditions and under the different game modes). The resulting tree can in Fig. 6. The tree demonstrates that the tracking condition is the primary predictor, with the prior enthusiasm being a secondary effect relevant for users with tracking enabled, with no improvement in classification for users for whom tracking was disabled.

Although these results show that players liked head tracking, it seems that a prior enthusiasm bias was present. This phenomenon was probably a result of the recruitment approach, which was based on drumming up interest in the work by posting videos on the Internet. With nodes at lower levels of the tree exhibiting high misclassification error rates, this enthusiasm effect appears to have swamped other possible interactions within the data, thus limiting the ability of the model to reveal finer structure. In other words, the preponderance of enthusiastic participants in the study meant that the covariate space was insufficiently heterogeneous for variation within the other covariates to be able to adequately explain variation in the response after the enthusiasm effect was accounted for.

To further explore what people thought of HAL, we examined the written feedback collected via both the exit questionnaire and from the online discourse following the study. The comments helped identify the head tracking benefits that appeared to most appeal to players. Players frequently mentioned its ability to improve the game's immersion and realism. As one player stated, "Even if it doesn't really change gameplay all that much, it certainly enhances the immersiveness of the 3D game environment, more so than higher frames per second, or higher resolution, or better shaders could hope to do at this point." Several comments attributed these qualities to the handy-cam effect, feeling that the technique may be suited to horror style games, with the title Amnesia being repeatedly mentioned. The leaning aspect of the technique was also noted as being very natural; "People have been doing this forever, leaning to the side in a game, hoping for a "better view", but this time your natural movement leads to an in-game result."

There was strong evidence that head tracking appealed to a spectrum of PC players, including those initially skeptical about gestural control. One article about the work opined: "Afraid that new camera-based interfaces herald the death of traditional gameplay? Fear not! This video is whispering in your ear, Core Gamer, and say-Fig. 6: Fitted decision tree model: users were asked to state how much they enjoyed the game experience using a five-point Likert scale ("extremely", "fairly", "moderately", "slightly", "not at all"). The tree initially splits on tracking condition (enabled/disabled), with users for whom tracking was disabled classified as enjoying it only "slightly". For users for whom tracking was enabled, predicted enjoyment depended on their reported prior enthusiasm for head tracking (categorized as "very excited" to "very skeptical"), with "excited" tracked users predicted to "extremely" enjoy it, and non-excited tracked users predicted to only "fairly" enjoy it. The details recorded at each node are the predicted classification, the proportion of data at the node consistent with that classification (x out of y, the classification at the node being the result of a majority vote) from which a classification rate can be calculated, and the proportion of the entire data at that node. The terminal nodes represent the final fit. ing, 'Don't be afraid. Everything is going to be alright.'" 2 In another example, the popular YouTube user, Robbaz: The King of Sweden, placed a self-narrated video of himself playing the study software onto YouTube. As dedicated FPS player -as evidenced by his 300 odd videos, most of which feature FPS games -he is very praising of the technique, stating at one point, "Oh my god. Oh that's satisfying … it feels amazing. Like the first piss in the morning." One explanation for HAL's acceptance is the design decision to augment traditional controls, rather than replace them. As one player noted, "I'd rather see more touches like this that augment controls in hardcore games than having control schemes that are all-or-nothing in the motion control department." In another example, a gamer appealed to other players: "…you do realise that this isn't so much motion controls so much as an addition to a traditional control scheme on the PC?… If you're a PC fan, you may actually want to check it out."

Although the response to HAL was mostly favorable, several recurring concerns were noted. For example, several commentators feared that the use of head tracking could cause neck strain. This perceived issue was, however, scarcely reported by our study participants, with only three noting any actual strain, one of whom stated; "My neck hurts, but in a good way!" Although the study did not explore the use of head tracking over the very long durations that some players claim to play for, encouragingly, none of the 30 participants who played for more than an hour complained of any neck strain. Another health concern pertained to HAL's ability to induce feelings of motion sickness. As one participant stated, "Dizziness! My main complaint is that the head tracking almost made me sick!" This comment was reflected by a few other participants, with some specifically attributing these feelings to the handy-cam effect: "Possibly being rid of the camera shake. It makes me dizzy fast." Notably, these concerns were not raised in our previous focus group studies [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF]. With only a small percentage of the participant sample raising the issue, its occurrence may be a result of the high probability of even a low prevalence event happening amongst a very large participant sample. The issue appears to have some precedent in the literature; with the work of [START_REF] Oman | Motion sickness: a synthesis and evaluation of the sensory conflict theory[END_REF] finding the inclusion of visual jitter can increase the realism of a scene at the cost of hastening the onset of motion sickness. The experiential benefits of the handy-cam were also noted to have a tradeoff with playing performance. One participant noted, "I liked head tracking, it added a sense of more realism and immersion into the game. But sadly it was kind of frustrating to use since my accuracy greatly decreased."

Head Tracking Guidelines

To help summarize many of the findings discussed in the previous section, we present a set of head tracking guidelines. These guidelines extend upon those presented in our earlier work [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF] to reflect the insights we have gained in having examined head tracking within a real-world setting. Their intention is help other researchers with the design and creation their own head tracking techniques.

Provide Motivation and Alternatives:

A game experience designed around the use of head tracking and its benefits (i.e. the ability to perform partial movements alongside traditional controls) will see its use increase (see Sec. 5.2 for more details). Despite this, potentially quite a large proportion of players (up to a quarter) will still not use head tracking, either through choice (e.g. for playing performance reasons) or circumstance (e.g. inadequate lighting), so proper consideration still needs to be given to non-gestural alternatives.

Make it Adaptable:

A home setting introduces a very large amount of variation with regards to the tracking quality and hardware performance. The following can help make a technique more consistent: convert the user's absolute head position into one relative to a mean position, use time-based (rather than sample-size-based) logic, make the logic more conservative under less-than-desirable conditions, and clamp the head data to a desirable range (see Sec. 3).

Not All Head Movements Are Equal: Avoid using the pitch or yaw axes for critical controls as these are noisy and, at extremes, make observing the screen awkward. By contrast, horizontal and roll movements are natural to perform and are more reliably tracked (see Sec. 5.2). Experimenting with the tracking software will help you determine which movements (i.e. axes and speeds) are better tracked than others [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF].

Know Your Audience: Techniques that utilize a natural movement will be better received, remembering that some movements might not be natural to all users (e.g. cocking your head to peer down the barrel of a gun -see [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF]). Consider what properties attract a player to a game and whether your technique enhances these (e.g. the handy-cam effect could probably enhance the immersion of a horror game, but interferes in a performance driven game). If players are particularly skilled in using a traditional control scheme, try to avoid replacing them entirely (sec 5.3). Finally, only by observing players use your technique will you know whether its intention has been properly conveyed (sec 5.2).

Put the Health of the Player First: Avoid long awkward movements and quick snapping actions as these may place the player under duress [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF], as well as reduce the perceived appeal of the game (sec 5.3). Be mindful that a technique that alters the view perspective may cause some players to feel nauseous. Consider making the player have to proactively enable a technique to use it (sec 5.3).

Guide the Player: Guide the player through the set up of the head-tracking system. Written instructions and demonstrative images may be ignored by some players, so consider having the system dynamically highlight less-than-desirable issues as they arise (sec 5.1).

Conclusion

The new contribution of this research is two-fold. First, we extended and refined our earlier work [START_REF] Sko | Human-Computer Interaction-INTERACT 2009[END_REF]. This development required significant effort to modify the earlier prototype techniques to make HAL robust to the highly variable environment of home use. The home-use context set a rich background for assessing HAL, raising many challenges not found in the laboratory. These challenges led to new insights, which we have presented here. Foremost among these is the importance of the user's set-up in determining the effectiveness of the technique. Figure 4 is a simple illustration of the extent of the challenge facing widespread adoption of this technology -users, either intentionally or not, often present conditions that are almost insurmountable for reliable head tracking, and so coaching users to optimize their set-ups appears a necessary precursor to widespread use. The use of the home setting and the consequent large sample of participants also allowed us to identify a small but meaningful group of users who experience nausea while using our software, an result that did not occur during small-scale laboratory testing. The use of online recruitment and survey tools allowed us to amass a large amount of data quickly and easily, and our analyses revealed structure that showed that users were enthusiastic about head tracking and that even initially-skeptical users were swayed by its effectiveness in immersing them in the game. Head tracking did not produce an immediate performance boost -in fact, performance declined, perhaps because of users' unfamiliarity with the techniquealthough there was evidence of improvement with learning. This encourages us to consider a future longitudinal study to examine the long-term effectiveness of head tracking in home gaming.

Fig. 1 :

 1 Fig.1:A user performing a right lean. The amount the player needs to tilt is kept very subtle to ensure the interaction technique is not too strenuous. During the lean the screen and gun model are both rotated and the player shifts sideways.

Fig. 3 :

 3 Fig. 3: System reliability: the players have been binned based on the percentage of time they were successfully tracked during the tracking enabled condition of the comparison test. Two versions of the study software were distributed, with one including an image of the user featured on the main menu -in the hope it would help them recognize deficiencies in their set up. No improvement can be observed when this image was included (as supported by a statistical comparison).

  movement (degrees/sec) Head control disabled (1245) Head leaning and handy-cam enabled (1294) Only handy-cam enabled (61)

rollMin, rollMin + rollRange * leanScale);

	01. rollResting = UpdateMean(rollResting, headData[ROLL], rollRange);
	02. roll = headData[ROLL] -rollResting;
	03. roll = Normalize(roll, ... // Repeat the above for sideways movements
	04. lean = Normalize(roll + sidew, 0, 1);
	05. lean = lean * (1 -easeAmount) + Ease(lean) * easeAmount;
	06. lean = MovingAverage(lean, leanSampleTimeframe);
	07. lean = FadeIn(lean, 2);

Table 1 :

 1 The coefficients of the mixed-effects model. The percentage of time spent head leaning includes the periods where the user performed only a partial lean movement. Information Criterion). This reduction process was continued, until a final model was reached for which the remaining model terms were significant. The estimated coefficients, with standard errors, for the final model are shown in Table

			Attempt	Time	Head	Button	Computer speed	FPS experi-	Sex:
		(Intercept)	duration	tracked (%)	leaning (%)	leaning (%)	(frame-rate)	ence: "lots"	"male"
	Estimate -2.6673	0.004	0.3273	-0.2456	0.5304	0.0008	0.0479	0.1627
	Std. Err	0.0942	0.0002	0.0176	0.0166	0.0255	0.0001	0.0216	0.0918

https://github.com/torbensko/HAL, accessed Apr'13

http://www.joystiq.com/2009/07/01/a-peek-and-head-tilt-into-the-future-head-tracking-in-fpsgam/, accessed Apr'13

Acknowledgements. The authors would like to thank Seeing Machines for the use of the FaceAPI software. No commercial funding was received for this research.