Kasper Rodil

Heike Winschiers-Theophilus

Nicola J Bidwell

Søren Eskildsen

Matthias Rehm

Gereon Koch Kapuire

A New Visualization Approach to Re-Contextualize Indigenous Knowledge in Rural Africa

Keywords: 3D visualization, indigenous knowledge, rural, Africa, design

Current views of sustainable development recognize the importance of accepting the Indigenous Knowledge (IK) of rural people. However, there is an increasing technological gap between Elder IK holders and the younger generation and a persistent incompatibility between IK and the values, logics and literacies embedded, and supported by ICT. Here, we present an evaluation of new technology that might bridge generations and preserve key elements of local IK in Namibia. We describe how we applied insights, generated by ethnographic, dialogical and participatory action research, in designing a structure in which users can store, organize and retrieve user-generated videos in ways that are compatible with their knowledge system. The structure embeds videos in a scenario-based 3D visualization of a rural village. It accounts for some of the ways this rural community manages information, socially, spatially and temporally and provides users with a recognizable 3D simulated environment in which to re-contextualize de-contextualized video clips. Our formative in situ evaluation of a prototype suggests the visualization is legible to community members, provokes participation in design discussions, offers opportunities for local appropriation and may facilitate knowledge sharing between IK holders and more youthful IK assimilators. Simultaneously differing interpretations of scenarios and modeled objects reveal the limitations of our modeling decisions and raises various questions regarding graphic design details and regional transferability.

Partiality in Technology Design

Information Communication Technology (ICT) continuously confronts new challenges in localizing design. Cross-cultural studies reveal Western biases in design and erroneous assumptions about the universality of concepts, methods, theories and models have led to many inappropriate decisions [START_REF] Winschiers | Assumptions Considered Harmful The Need to Redefine Usability[END_REF][START_REF] Evers | The Truth about Universal Design: How knowledge on basic human functions, used to inform design, differs across cultures[END_REF]. But acknowledging cultural differences between users and developers is only the start of a long and demanding design expedition when it comes to building systems to support and extend the local Indigenous Knowledge (IK) of rural people. Beyond social, economic, political and technological disparities between urban and rural, Western and Indigenous people lie deep tensions between the epistemologies of IK and those that underlie technology design [START_REF] Bidwell | Pursuing Genius Loci: Interaction Design And Natural Places[END_REF]. Here, we step forward in this expedition by reflecting on our recent endeavors to build an IK management system with a rural community in Namibia, a Southern African country.

Rural-urban disparities

For many generations, rural communities in Southern Africa have acquired, produced and re-produced knowledge that sustains their lives and their environments. Practices and wisdom that respond to ecological and social contexts, and are locally validated, have enabled communities to successfully husband animals; cultivate and harvest plants; and process and conserve local resources. People share such Indigenous Knowledge (IK) orally by talking, telling stories and by participating in ordinary activities and rituals. However, various changes in Southern Africa, from education over employment to transport, have disturbed the processes of information transfer and threaten the persistence of elements of IK systems. Senior community members, or Elders, die without opportunities to pass on rural practices in ways that are accessible to younger members. At the same time younger members encounter difficulties in undertaking activities that are essential for their well-being and survival and the health of their land without their Elders" supervision or advice.

Namibia"s mandatory education policies mean youth from remote areas are often sent to live with relatives in town where they will remain for years and only return in their holidays [START_REF] Rumble | Open Schooling for Secondary and Higher Secondary Education: Costs and Effectiveness in India and Namibia[END_REF]. This has several consequences for local IK systems. Firstly, formal education curricula and teaching practices differ significantly from the content and processes of IK. That is, knowledge is constituted within the social and ecological rhythms of daily life for the 12% -25% of rural residents who have never been to school; but, constituted in books and classrooms according to subjects and study timetables for those attending school. Secondly, in towns youth encounter modern technology and life-styles that contrast with those in their origin villages, which have poor sanitation, no grid electricity and sparse cell-phone coverage. After graduation some people return to their villages to reassume roles in their origin communities but encounter an increasing divide [START_REF] Chinn | The Determinants of the Global Digital Divide A Cross-Country Analysis of Computer and Internet Penetration[END_REF][START_REF] Fuchs | Africa and the digital divide[END_REF]; for instance, while they have written literacy [START_REF]International Literacy Statistics: A review of Concepts, Methodology and Current Data[END_REF] other community members have a literacy about the land and they might use technology to communicate with the "outside" world while other community members communicate according to local social protocols. Thirdly, many rural-tourban migrants remain in cities for employment but save money in order to establish homes in their rural villages later on. However, ungrounded in the minutiae of rural living, a migrant"s connection to rural habitat is shaped by globalization and urban power-relations; and, again, when they return with urban-generated assets, they recontextualize rural practices. Now, keeping more livestock than before; now, travelling in vehicles not by foot or on horseback; now, listening to a radio and making detours to access a signal to use their phones not listening to a storyteller around the fire [START_REF] Bidwell | The Landscape"s Apprentice: Lessons for Design from Grounding Documentary[END_REF].

It is hardly surprising, given differences between rural and urban literacies, that there are few reports about Southern African rural communities appropriating technologies to record or process their knowledge in text, electronically, graphically or with videos by themselves. There are, of course, many interpretations of IK recorded by outsiders, such as historical and anthropological accounts and documentary videos. However, this type of media use is not constructed within the communication patterns of local people. Indeed, initiatives to locate technologies in rural knowledge practices are generally sparse and the locale of technology production itself, sited in research labs and design studios in cities and industrialized regions, is a conduit for selective interpretations of rural life [START_REF] Bidwell | Pursuing Genius Loci: Interaction Design And Natural Places[END_REF].

Acknowledging an epistemological gap

Various indigenous communities globally have appropriated multi-media technology to convey their local knowledge to wider audiences [START_REF] Bidwell | The Landscape"s Apprentice: Lessons for Design from Grounding Documentary[END_REF]. In doing so they respond to certain types of politics which privilege certain sets of social, technical and literary devices and establish certain design paradigms. Leveraging privileged sets can "give" voice to marginalized peoples but, simultaneously, suppress and distort their knowledge traditions [START_REF] Green | Cultural heritage, archives & citizenship: reflections on using Virtual Reality for presenting knowledge diversity in the public sphere[END_REF]. Consider how to achieve "development" agendas people in "underdeveloped" regions draw on formats derived from English-language journalism and project their lived world onto a 2D-plane according to the affordances of cameras in digital storytelling (e.g. [START_REF] Taachi | Finding a voice: Themes & discussion[END_REF]) or re-present a set of oral stories in hypertext. These systems for inscription evolved beyond the IK systems of communities that share their knowledge orally, by talking and participating in everyday life not by recording in print or electronically. Choices about what to record and how to represent and disseminate it are performative in producing knowledge. They are rarely domesticated into daily practice by rural communities and, thus, neglect, for instance, information residing in the performance, structure and form of oral practices or authoring relationships between teller and audience. Further, few design studies account for the situated dynamics as IK, narrative and representation entwine or the ways people create meanings with, and about, new representations continuous with their cultural values, logics and literacies and their expectations about technology.

The dominant paradigms embedded in ICT solutions re-produce urban and western values, logics and literacies and these are often incompatible with values, logics and literacies of rural African communities. Different knowledge traditions organize and interact with information differently. That is, systems (from chronologies, taxonomies, and cartographies to authorship) do not merely translate knowledge between vocabularies but manifest a community's priorities and assumptions about reality. They draw upon implicit or explicit "theories" which encompass the kinds of relations and dependencies that do, or can, exist and their conditions of existence [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]. For instance, mainstream databases and representation and retrieval systems encode relations inherited from science and certain languages, such as hierarchies and tenses. These relations perpetuate particular perspectives on knowledge, whether that be through the structures embedded, ubiquitously, in computer filing systems to those that represent kin relations in family-trees (e.g. in Facebook) or construct the world visually from an external Point-of-view (e.g. Google Earth). And, through all of these, they are continuously shaped by writing traditions.

Dilemmas in designing technologies and media to serve marginalized knowledge traditions are not about whether local knowledge remains superficially the same but what values, logics and literacies are lost in transformation. Consider an Indigenous Australian Elder"s disappointment with a GPS-system, which was designed to preserve his clan"s knowledge on fire management but did not support the actions involved in "walking country" [START_REF] Bidwell | The Landscape"s Apprentice: Lessons for Design from Grounding Documentary[END_REF]. Consider also how a usability evaluation revealed that a sophisticated decision support system, based on ecological models, neglected the way that Herero farmers often draw upon their lived familiarity with their kinship in determining their trust of recommendations [START_REF] Winschiers | A Bush Encroachment Decision Support System"s Metamorphosis[END_REF]. Over the three years of endeavors with the community mentioned here we have experienced similar incompatibilities between prototype technologies and members" information behavior. For instance, the rural Herero community was unenthusiastic about our attempt to use meta-data, extracted from their accounts, and printed text keywords to organize and retrieve video clips that they had collected [START_REF] Kapuire | A revolution in ICT, the last hope for African Rural Communities' technology appropriatio n[END_REF]. Thus, we seek technologies that better align and reconcile with non-Western episteme and alternative approaches to design for the ways the community normally communicates about knowledge.

Can Visualization bridge the gaps?

Studies on the use of a GUI by rural communities with strong oral traditions suggest that members can more easily identify cultural icons and visualizations than using text-based technologies [START_REF] Parikh | Design studies for a financial management system for micro-credit groups in rural India[END_REF][START_REF] Kuicheu | Iconic communication system by XML language: (SCILX)[END_REF]. Visualizations of culture have a history from the earliest humans (e.g. cave paintings) which suggests that modern visualizations, which go beyond graphic icons, offer opportunities to organize information in ways that are compatible with rural IK systems. For instance, consider how Native Americans explain current situations by drawing upon a collection of stories in which events always relate to places [START_REF] Brewer | Storied spaces: Cultural accounts of mobility,technology, and environmental knowing[END_REF] and, then, consider how a 3-D visualization of the places may offer an organizational structure that is compatible with the information conveyed in those stories. However, as noted in previous sections, for such visualizations to support the practices of IK we must account for the fundamental concepts on which they are built and the ways that community members interact with each other through the visualizations.

While modern visualization tools can combine a plethora of photo-real, surreal and abstract element in diverse visual realities the compatibility of these elements and combinations with IK is only as good as their designer"s understandings about local concepts. Any visualization of a place represents a selective set of abstractions, including logics about location and time and these are by no means universal [START_REF] Brewer | Storied spaces: Cultural accounts of mobility,technology, and environmental knowing[END_REF]. For instance, consider how 3D visualizations that separate geographical locations from temporality inadequately depict Arawakan people"s stories about their journeys in Brazil [START_REF] Green | Cultural heritage, archives & citizenship: reflections on using Virtual Reality for presenting knowledge diversity in the public sphere[END_REF]. Thus, producing a visualization of a place, such as a rural African village, requires compatibility with the local concepts about location and time.

Over the past decade a variety of visualizations have been created to depict IK. For instance, [START_REF] Pumpa | Database and Narratological Representation of Australian Aboriginal Knowledge as Information Visualisation using a Game Engine[END_REF], amongst others, report on an elaborate 3D geospatial representation built for traditional custodians of the land to tell their stories by allowing users to step, virtually, into the Aboriginal dream world. However, this visualization is mediated by design teams and lacks facilities for Aboriginal people to add their own stories [START_REF] Turner | Wanderer Beyond Gameworlds Leonardo Electronic Almanac 16(2-3)[END_REF]. Further, many evaluations of visualizations designed to assist communities assume that a visualization will be experienced by a user alone, rather than be drawn into oral exchanges between several co-present users.

Here, we describe a prototype visualization of a rural village which aims to enable community members to organize information about local practices and wisdom. Our design draws on detailed analyses of our extensive observations of these people"s spatial and temporal logics and literacies and interactions with each other and with media [20, [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF][START_REF] Winschiers | Being Participated -A community approach[END_REF]. We begin by summarizing some of the ways our analysis informed designing the prototype. Then we describe how a 3D scenario-based visualization might enable local community members to upload, organize and retrieve their own video recordings of local stories and practices. Next, we present results from a formative evaluation of the visualization with the community; and, finally, we note insights on challenges of cross-cultural scenario-based visualization design that emerged in this endeavor.

Places and Representation

We developed the 3D visualization prototype as part of a long-term research programme which aims to implement Indigenous Knowledge Management systems to sustain the content, structure and communication of the IK of rural people of the Herero tribe. We chose a village in the Omaheke region in Eastern Namibia as the site for exploring the visualization because we can engage with this community continuously. The village consists of approximately 20 homesteads, each housing about seven people. The Herero include around 240.000 people living in Botswana and Angola as well as Namibia, where they are most numerous and constitute around 9% of the population. Our dialogical and participatory action research approach aims to involve community members in co-evolving the design space and exploring how multi-media technology might serve their knowledge system [START_REF] Winschiers | Being Participated -A community approach[END_REF]. Thus, over the past three years, we have together acquired valuable design knowledge by mutual learning and discovery. We have undertaken a range of research activities including ethnographic observations, contextual interviews, participatory design sessions, technology probes and prototype evaluations. During this process we collected some 50 video clips, some recorded by researchers and some by community members. These videos include members telling stories, describing scenarios, demonstrating local practices and engaged in everyday activities. We have interpreted and reflected upon the videos with community members in various ways and also applied Grounded Theory to analyze their content independently [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]20]. In the following sections we summarize some of our insights on how this rural community manages information, socially, spatially and temporally which has implications for designing the visualization.

Social Significance of Places & Knowledge

Residents in the village identify with social elements of place and refer to locations almost exclusively in terms of social relationships [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]. They build their kin relations into the physical infrastructure (since they construct their homesteads themselves) and linking places to people seems to be a feature of Herero oral traditions and their Otjiherero language. For instance, praise-names or verses describe and pay tribute to the places Herero society inhabited, before the German conquest, and have suggested cartography of the landscape in relation to people or events [START_REF] Bubenzer | Otjiherero praises of places collective memory embedded in landscape and the aesthetic sense of a pastoral[END_REF]. It appears that a familiarity with social relations makes the environment legible. For instance, locations in around villages are neither named nor signposted, although a vehicle registration plate marks some homesteads. We also found that places, flora and other features are intelligible, and experienced, through their associations with social roles and daily activities. For instance, activities are gendered so the fire is a place for men to eat and talk but for women to prepare food. Villagers also described their wisdom in terms of social relationships. They communicated about their knowledge using real or metaphoric or prototypical examples and these always included relationships between people or between people and artifacts or settings. Residents frequently personalized information for the listener, explaining that ""When you are telling a story with the intention of teaching you would want specific people to listen"" and speakers judge the relevancy of information according to a listener"s social roles. Conversely, people indicated that they trusted the integrity of information in relation to recognizing the speaker"s pedigree. Further, those involved in recording video insisted that all clips should bear the village and participants" names.

Determining the relevancy of information to a listener and a knowledge-holder"s pedigree involves a deep acquaintance with an intricate web of trans-generational, kin relations [20]. These trans-generational relations are reproduced in interactions with the environment. For instance, consider links between generations performed with respect to the "holy fire". This feature in some homesteads ritualizes Herero values about their society"s coherence and respect for ancestors" in giving life and guarding descendants. Men use the fire in rites (e.g. ceremonial slaughtering), healing and appealing to ancestors to address social tensions. The fire has distinctive locational characteristics, sited between the house and cattle corral and separated by stones or a hedge but these vary between homesteads. The fire has a vital temporal dimension because men must ensure it is burning continuously to maintain favor with patrilineal ancestors, who may cause misfortune if displeased.

First Person Point-of-View

Community members refer to people and locations using Points-of-view (POV) that are intrinsic, rather than extrinsic, to the world. This was very clear when we asked participants to arrange thumbnail images spatially taken from videos they made [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]. While they walked through dense bush directly to locations, they less confidently created a geospatially accurate, aerial view despite the proximity of these locations. Community members scaled the map to the immediate area of the homestead where they sat and were reluctant to extend or re-scale to include more of the village. They sorted thumbnails to isolate those they wanted to arrange on their map effortlessly, but spent more time gesticulating around the homestead and talking about people and activities in clips than mapping. That is, people related to their environment more acutely from a First-person POV. Indeed, Otjiherero often expresses the land as a continuum in which vegetation increases with distance from the speaker and a colocated listener. We propose that a POV that is intrinsic to the world may also relate to the social-relational space of the knowledge system. People often used spatial metaphors in speech when referring to relationships; such as describing people on ""this side"" or, ""looking in opposite directions"", and this might reflect that their bodies orient spatially in social relations. Certainly, community members" use of cameras to record embodied relations between the cameraman and those recorded [20,[START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF].

Spatial & Temporal Relationships

Villagers" paths inscribe knowledge into settings as they move between and beyond homesteads and we have proposed that their movements structure their narratives [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]. Homesteads are approximately 2 km apart, separated by communally used pasture, and consist of huts within a fenced yard accessed by several gates and corrals. People undertake daily activities on foot or, occasionally, on horseback, and their movements often reflect the role of animals. For instance, men maintain camps to distribute cattle over large tracts of pasturage and thus their movement between camps invests the setting with meanings. Closer to home, people can walk between their huts, the fire, on which women cook farmed animals, and the cattle corral but must pass behind the hut to slaughter goats and cook game. That is, their paths are shaped by patterns of activities and, reciprocally, features and settings are legible via daily rhythms. For instance, a familiarity with livestock and daily and seasonal rhythms enables way finding beyond villagers" permanent homesteads. When uncertain of direction villagers follow passages created by cows" paths, read the movement of cattle between rivers, villages and corrals and recognize individual cows" footprints. [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF].

Often when viewing videos villagers made sense of their contents by drawing on oral cues that referenced to seasonality, movement and sequence. Our analysis suggests that sequencing events, through movement, might enable remembering and recollecting personal and collective history, as villagers sometimes structured relationships between specific features in locations, people, livestock, and events within journeys. We also observed that community members recounted knowledge using spatio-temporal references and sequencing to order events and objects coherently. For example, one Elder referred, spatially, to a fruiting plant growing behind the homestead, before telling how to clean, cut and put its root in a calabash to sour milk and also noted learning about a novel herb: "I went to a second place in the village and was looking after the goats that got lost". [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]. That is, villagers accumulate knowledge within sets of everyday activities not by assembling separate observations at discrete times and locations.

Re-creating context

As noted in the previous section we found that recording relationships between bodies, artifacts and settings is often difficult and this constrains the knowledge a video can represent. Community members often indicated that the videos incompletely depicted knowledge. For instance, in watching a clip which shows, visually, the side on which a cow is milked, Elder-1 said it lacked information to explain ""From what side, left or right?"". Settings were not always legible and villagers often found it easier to identify features from spoken sequences instead. Thus, while video records verbal descriptions, bodily actions and camera-use it excludes much information by projecting the world onto a 2D-plane. Further, the action of recording interrupts social practices in information transfer. Indeed, one Elder reflected later that he should have interviewed more actively than he would have done in an ordinary exchange so that subjects would "explain to the video" what they were doing. Viewing clips provoked community members to note that they needed to record more detailed explanations [20] or they added their own stories and more situational information to enrich the context for understanding. Villagers preferred to view video as a group and their exchanges about the videos further indicated the role of layering context orally to share their understandings.

Scenario-Based 3DVisualization Prototype

Our aim in creating a 3D visualization prototype is to produce a structure in which users can store, organize and retrieve an expanding corpus of user-generated videos in ways that are compatible with their knowledge system. The structure should enable rural Elders, who are considered by community members to be knowledge holders to transfer information, asynchronously, to rural-to-urban migrants, who we consider to be knowledge assimilators. To ensure that the information structure is compatible with the rural knowledge system it must enable Elders who may be textually illiterate and have little access to, and experience of, technology to store and organize videos in ways that persist important elements of social contexts.

We use various mechanisms to afford elements of social context. Firstly, we embed videos in a recognizable 3D visualization of highly familiar features of the users" village and populate this with "generic" models of people. We position videos at locations representing those where the video was filmed and propose that users" familiarity with places in the village means that they will interpret represented locations within a social-relational space. For instance, knowing particular gender protocols associated with locations makes activities in that location intelligible and can guide a user"s search for videos about those activities. Secondly, beyond graphically modeling the village we create scenarios at the locations at which videos are embedded. The scenarios are animated models of people associated with an audio narrative and we propose that by simulating aspects of communication patterns these provide resources for users to make appropriate connections in their social-relational space and restrict multiple interpretations. Thirdly, we did not prescribe paths between scenarios but rather modeled some of the paths that farmed animals follow through the village to provide some of the patterns that villagers use to navigate their setting. In the final system, Elders will position new videos at the appropriate locations in the 3D environment for the younger rural-to-urban migrants to assimilate the content within the appropriate context.

The current prototype was conceptualized and built by two new members of the project team (Authors 1 and 4) during their first visit to Namibia in collaboration with researchers involved in the research programme from its inception, including a Herero man from the village (Author 6). We modeled the village from Author 6"s specifications and by using reference photos and videos depicting specific landmarks [START_REF] Haasbroek | The challenges of utilizing intelligent human-computer interface technology in South Africa and other African developing countries[END_REF], including Google Maps satellite images. We created the visualization using the Unity 3D game engine. The visualization consists mostly of trees and bushes and a few man-made objects, such as houses, fences, water-pump, fire places and car tracks (see Figure 1) which marked specific locations as we saw on photos and videos. We populated the static environment with animals and people.

Figure 1 The visualization including all the 3D objects constructed from references in the village.

Resemblance and animation

We focused on graphical resemblance of objects in the village and geographical positioning to support community members" recognition of locations. We assumed that community members were more likely to recognize homesteads if we modeled huts with high photo-realism, matching colors and shape, and including details like flowers (e.g. see Figure 2). We invested considerable effort in modeling goats and cows as both our ethnography and participants" frequent choice in activities they recorded suggested they are a focus of local knowledge. We attempted to model not only the forms of these animals but also their behavior by animating their bodily movements and simulating the paths they routinely follow through the village. We also modeled more nuanced details, such as smoke from a burning fire.

Figure 2 The house on the left is a 3D visualization of the right.

Scenarios and embedded videos

Scenarios, linking locations in the village to social activities and communication protocols, act as triggers to launch corresponding videos. The videos record community members telling stories, demonstrating everyday practices or engaged in ordinary rural activities. Community members, or various members of the team, recorded these videos over the past three years and community members have reflected on and interpreted all the videos in various ways. Videos are executed on a 2D plane in the visualization (Figure 3). We selected scenarios based on the extensive amount of video depicting these activities. We incorporated video in five different scenarios, which encompassed tending or slaughtering goats, healing a calf, and milking or branding cows. Scenarios respond to some of the ways the local knowledge system contextualizes information in social relationships and particular communication patterns. Each scenario consists of an audio description, recorded by a community member and models of four or five men grouped around the animal of concern. We designed multiple copies of a generic man but each instance of a man behaves a little differently. We modeled the men"s gestures to suggest they are pointing and indicating that a story is being told or actions that are imminent at that location. By clicking on the area where the men are gesturing, the user is presented with the recorded video playing on a 2D plane hovering over the area.

3D Placement and navigation

Users navigate around the village to the different scenarios by using drag-able mouse interaction that controls the camera as a lifted First Person POV. The camera has a tilted angle to provide users with a better view of social context without losing 1st POV. We also carefully positioned certain important objects relative; such as the holy fire, relative to the house and the kraal and the appropriate place for slaughtering.

Evaluation

We explored community members" responses to our 3D scenario-based visualization tool during a three-day trip to their village by Authors 1, 4 and 6 and another member of our project team. We sought to discuss the system with residents and evaluate how accessible the system was for them. More specifically, we wanted to determine whether or not people recognized the graphical representation of their locale and could understand that the behaviors of the people models, within a depicted scenario, connected a location to activities and triggered narrative events. We also sought to gain insight into Elders" opinions about the affordances of the scenario-based visualization and the associated embedded video in knowledge sharing and whether young people"s use of the system might enable them to learn rural wisdom and skills. We scheduled two separate evaluation sessions with Elder residents of the village and younger rural-to-urban migrants who had returned to their village for the Christmas holidays. In both sessions we charged the laptop with a car battery as the village has neither electrical power nor cellphone reception.

Community-based Evaluation

We pursued a community-based evaluation as our studies show the high collaboration in villagers" knowledge practices [20,[START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF][START_REF] Winschiers | Being Participated -A community approach[END_REF]. As with all our work in the village, evaluation activities were spoken in Otjiherero (villagers" native language) and were facilitated by the researcher originating from the village (Author 6). Another Otjiherero-speaking researcher also translated to provide updates on the flow of conversation to the developers (Authors 1 and 4) who cannot speak Otjiherero. We recorded the entire sessions for post-situ analysis with one static camera directed at participants and one free-floating camera. We (Author 6) translated the recorded videos in Windhoek and an external person translated and transcribed the recordings to ensure comprehensive documentation. We framed the evaluation with four main questions. Firstly, we sought to determine if participants recognized that the visualization represented their village and could identify the site of the evaluation within the visualization. Secondly, could participants understand the scenarios in the visualization and relate these scenarios to the activities they represent; for instance, that men gather around a cow that is being milked. Thirdly, did participants understand that the people positioned in the scenarios were event triggers for the video, and did this logic make sense? Finally, we sought participants" specific ideas or reflections on the visualization.

System walkthrough with the youth

Seven younger people, aged 10 to 18 years, agreed to participate in evaluating the system. All live in Windhoek most of the time but return to the village for holidays. The session lasted for 28 minutes and commence outside one of the newer homes in the village [see Figure 4]. We encountered some dilemmas that were due to the setup. While amiable participants were hesitant and stood too far from the laptop to see the application in the sunlight but, when we suggested moving into a house, we were reminded that people never sit and talk inside homes. After a little negotiation participants moved closer and were able to see the visualization; however, they remained reluctant to share their thoughts and during the evaluation only two, younger boys, interacted with the system. Thus, we focused the evaluation on whether participants understood the 3D model and basics concepts about its use. We began by exploring participants" familiarity with computer use and introducing the aim of the system. Some said they have never used a computer before and others said they used computers only in schools in Windhoek. We broached the topic of sharing local knowledge by asking if participants knew what to do if a goat or cow is sick. A youth said: "We never heard a story for that" so we (Author 6) pursued this by saying that the Elders are the holders of this knowledge and asking "if the Elderly die, what happens with this knowledge?". The youth agreed that this knowledge "will die with them as well." .

After their initial shyness the young people began to comment on the system and about what they saw. These suggest that they connected the visualization to their imagery of various objects (or perhaps pictures of objects). For instance, exclaiming "People! Fire! Houses and trees!" We found that participants were able to navigate and "read" the visualization and interpret objects using a tilted camera perspective. For instance, some of the youth recognized the 3D representation of the house outside which we conducted our evaluation: "This is here. It is this house." Afterwards, they explained that they recognized it from the sides of the house and the fires in front of it. When participants panned over the cattle-branding scenario they mentioned, immediately, the branding irons, smoke and cattle, and then watched a video on branding cattle. Thus, we asked if the scenario was a story and they replied that the cattle were in the kraal (corral) and that because a man was pointing this indicated that he (the model) was telling a story. Another interesting discussion ensued after a youth panned over a scenario about slaughtering a goat. To begin with participants vacillated: "It's a goat. It's a sheep." but then suddenly agreed that sheep do not have small tails. We interpret this ambiguity as indicating both the importance of photorealistic quality and, that the users" and developers" emphasis on specific visual details differs. That is, we (Author 1 and 4) emphasized man-made objects but not the very fauna that make for local livelihoods and settings.

Elders' Comments on the System

We conducted a 24 minutes evaluation session with Elders in the shade outside of a home, and 2 village Elders and a group of 3 women aged over 35, and 3 younger people sat around the prototype. The Elders have no experience of computers and did not try to interact with the visualization, perhaps because of the set-up and composition of the group or perhaps because the group has been more used to watching videos on the laptop in our earlier work (Figure 5). The Elders observed the resemblance between the visualization and where the evaluation occurred; however, commented on the visual accuracy of the features. For instance, when discussing the scenario near the cattle in the kraal, the Elders told us that planted trees do not grow inside the kraal and added: "It's not a planted tree, it's a wild tree (Otjindanda), just look the way it grows!" Our (the developers) unfamiliarity with local culture and environment meant we lacked an appreciation of visual differences between cultivated and wild trees or where they might grow and made many assumptions when we drew upon reference images. Our lack of visually differentiating trees made the setting less legible to the Elders. This indicates that they not only understand the visualized objects but also recognized the importance of placing objects. Lack of visual accuracy sometimes caused the Elders" frustration and uncertainty about their own memory of the setting; for instance, based on photos we modeled one block of concrete, where villagers lay their fire, in front of a house. However, this hut has two blocks of concrete.

The Elders also noticed inaccuracies in the behaviors of modeled people. For instance, they understood the scenario about milking the cow but said that it looked as if the person was tying the cow. They also understood the goat slaughter scenario easily but, when we asked them who was telling the story, they said that it was the model in the middle of the group because "He is pointing and showing what to be done." While this reassures us that the Elders reason about the visualized objects it also indicates the need to invest, substantially, in designing and modeling of fauna and objects to match local priorities. At the end of the session we asked for the Elders" general impressions of the visualization and they said "They are good in their look [quality] and in the sense that they will be kept there forever and they will never be forgotten." We also asked their opinion about the system"s potential in teaching; they said: "Very much! Especially those township youth, they don't know village stuff, they will learn from that."

Reflections and the Way Forward

The evaluation suggests that re-contextualizing video clips in a recognizable 3D visualization of a familiar environment can potentially bridge epistemological, ruralurban, technological and generational gulfs. However, simultaneously, the evaluation shows differences between developers" and users" interpretations of visualized scenarios and objects. This leaves us with a number of challenges in the next phases of the research.

The importance of realistic details

Both youth and Elders paid acute attention to specific details such as posture, gesture, animal features and behaviors, trees, and the positions of some objects, such as fire. These details seem to contribute to recognizing places as well as to the integrity of representing IK. In evaluations participants discussed, at length, the "wrong posture" of the milking people who are supposed to kneel rather than stand. Such conversations are critical in designing the system. Community members clearly indicated which details are important which both re-emphasized local practices and that the details that scenarios must include in order that they enable sufficient social framing. References to specific details indicate that some items require greater accuracy but our evaluation did not reveal the importance of photo-real properties, such as the color of houses or the size of the trees. Due to our unfamiliarity with the Namibian landscape the developers (Authors 1 and 4) we emphasized photo-real resemblance for man-made objects (e.g. the communal water pump, huts), assuming that these visually differentiated settings. However, as the Elders indicated, we neglected important features and distinctions between trees. This shows the vital importance of gathering data about people"s interactions with items in their environment, linguistically and visually, and translating this in the visualization.

Interpretations and the need for community-driven design

Interpreting visual representations depends on a viewer"s cultural background. For example, we intended the cow milking scenario to represent people milking cows and others watching. However, the posture of those milking and the gestures of those watching signified to community members that the scenario was about teaching milking. Drawing upon information sources such as photographs, videos and a community member"s description was a practical step in creating the visualizations; but, as indicated by rich ethnographic depictions yielded by extensive stays in the village [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]20] they cannot match direct and collaborative engagement. This resonates with observations in various earlier activities about differences in visual recognition between community members and ourselves and community members comments that video incompletely depicts visual details. Thus, our next design steps are situated in the village developing the visualization with the community members. These prolonged situated development periods will enable us to explore how to design the visualization to respond to the ways community members movements structure their narratives. Like various other visualization endeavors with indigenous groups [START_REF] Pumpa | Database and Narratological Representation of Australian Aboriginal Knowledge as Information Visualisation using a Game Engine[END_REF] our current prototype allows users to explore the setting without forcing a linear narrative between scenarios. However, this might compromise the information contained in the sequences of movement that contextualize knowledge [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]. A situated approach to development not only provides continuous integrity checking but also insight into the dynamics of situated interactions between local IK and the visualization. Our previous analysis of community members" interactions with video showed the narrative structure of people"s comments and stories changed when local people viewed videos [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]20]. Such insights are important to avoid making design decisions that will suppress and distort local knowledge [START_REF] Green | Cultural heritage, archives & citizenship: reflections on using Virtual Reality for presenting knowledge diversity in the public sphere[END_REF].

Further Features & Transferability

Our further development includes focusing on appropriate scenario design and modeling the clothing, posture, gestures and movements of people. We will also explore time-location-activity relations as our earlier, and ongoing, ethnography repeatedly shows the importance of daily rhythms to navigating the village and coordinating activities. We can realize shade movements easily in the game engine and this will enable varying scenarios at locations according to time of day.

We will also layer audio of community members" different interpretations of video clips as our previous studies reveal ambiguity decreases or increases when members add stories and information [20]. Currently, we propose that users click on one of the people in the scenario people to access perspectives. Such a feature might also contribute to personalizing information according to the user; however, we also need to explore differential access to scenarios such that users interact with scenarios based on gender, kinship, age or other criteria [START_REF] Bidwell | Pushing personhood into place: Situating media in rural knowledge in Africa[END_REF]. Access to different layers is increasingly used for various visualization and mapping projects for Australian indigenous people, where the suitability of information transfer depends on place, age, clan and gender [START_REF] Bidwell | The Landscape"s Apprentice: Lessons for Design from Grounding Documentary[END_REF].

Investing in the specific details of a specific village has consequences for the transferability of the application to other villages. Our current prototype serves as a proof of concept and we are eager to explore which features of the visualization can be re-used for other villages and for other regions. We will explore this by running further evaluations in other sites in Namibia.

Conclusion

Designing an appropriate visualization to support IK in rural Africa requires thoroughly understanding situated interactions between knowledge systems and audio-visual representations and the conceptual frameworks bearing upon design.

That is, to design digital infrastructures for currently unserved IK we must account for the transformations that take place as technology interacts with the lived experiences, actions and thought or spoken narratives that constitute knowledge [20].

We have shown the potential of embedding video recorded by, or with, communities within a scenario-based visualization to bridging some of the epistemological, generational, literacies and technological gulfs in Eastern Namibia. We claim that the prototype can help to re-instantiate IK by supporting information sharing. Embedding videos in scenario-based 3D visualization is a first attempt to recontextualize de-contextualized representations in a locally accessible way. Merging information about activities and locations visually appears to be more intuitive for this African rural community than our earlier attempts with text-based and video-only retrieval. Our formative evaluation of the prototype in Namibia indicates that both Elders and younger people relate to the representation and can participate in discussions about improving and appropriating the system. We continue to explore some of the challenges that further development entails, such as the degree of detail, scope of interpretations and transferability between communities. However, we hope our reflections on this novel structure for organizing video, according to a community"s familiarity and priorities, will stimulate international dialogue on the contribution that scenario-based 3D visualizations to other local knowledge systems.

Figure 3

 3 Figure 3 Scenarios act as triggers to launch a video as a 2D plane in the visualization. Here the scenario includes Elders transferring information on branding cows and maintaining the herd.

Figure 4

 4 Figure 4 We demonstrated the system to seven younger rural-to-urban migrants.

Figure 5

 5 Figure 5 We demonstrated the system to 8 rural residents including 2 Elders.

Acknowledgements

We thank the residents of the village in Namibia for evaluating our prototype and their continuous commitment and inspirational participation in the project. The work described in this paper was partly funded by Det Obelske Familiefond.


Andreas Holzinger
email: andreas.holzinger@medunigraz.at

Reinhold Scherer
email: reinhold.scherer@tugraz.at

Martina Ziefle
email: ziefle@humtec.rwth-aachen.de

Navigational User Interface Elements on the Left Side: Intuition of Designers or Experimental Evidence?

Keywords: navigation, graphical user interface design, pseudo neglect, visual attention, performance, selection times

Humans tend to direct their attention toward the left half of their area of vision, which is known as visual pseudo neglect. Most navigational elements are placed at the left side. However, there is neither a theoretical reasoning nor empirical evidence, why these elements should be placed left. In the present study we examined three independent variables (presentation side of elements (left, right), number of elements (one, three, five) and a visual cue prior to selection (with cue, without). Dependent variables were selection times and accuracy of task completion. 50 participants were exposed to elements consisting of single words in bubbles. After clicking on the start element in the middle of the screen a number of elements were presented randomly on the left or right. In 50% of trials the presentation side was announced in advance, by using a visual cue. It was tested, whether and to what extent there is a preference and performance (correct selection time) increase for elements placed on the left side. When the cue was presented, performance increased; without cue information, elements on the left were selected faster. The use of cues resulted in no significant differences between the left and right side. A significantly better performance was found when only one element was presented on the left. With an increasing number of elements, the performance decreased. The results of this study suggest that the presentation of elements on the left side is advantageous for the speed of information processing only in the case of single elements. When selecting between numbers of options (three, five), placing elements on the left does not affect the selection performance.

Introduction and Motivation for Research

It is common practice that user interface designers place navigational elements on the left side of user interfaces. Possibly, they are assuming an elementary benefit in information perception, encoding and cognitive processing.

Moreover, although there is only little empirical evidence (e.g. [START_REF] Kalbach | Web page layout: A comparison between left and rightjustified navigation menues[END_REF]), many design guidelines exist, which recommend to put navigational elements on the left side, e.g. [START_REF] Koyani | Research-Based Web Design & Usability Guidelines[END_REF], [START_REF] Torres | User Interface Design and Development[END_REF], [START_REF] Preece | Interaction Design: Beyond Human-Computer Interaction[END_REF], . However, an underlying theory along with an experimental proof seems not to exist. The "rule to arrange navigational buttons on the left" [START_REF] Johnson | GUI Bloopers 2.0: Common User Interface Design Don'ts and DOS[END_REF] seems to be a well-known designer intuition, not grounded in theory. However, we must be careful with the term "intuitive", which is not properly defined; any common definition of the term makes its use inappropriate in interface design [START_REF] Raskin | Intuitive = Familiar[END_REF].

Interestingly, we experienced that when designers placed navigational elements explicitly not on the left side, e.g. at the right side (as in figure 1), end users expressed that they "intuitively" did not like it -possibly because they are used to have the navigational elements on the right side. Motivated by these practical experiences, we began to think for a possible reason, a theory and for an experimental setting to answer the question.

Consequently, this study aims at a critical investigation, whether and to what extent the positioning of navigational elements does factually benefit selection performance.

In section 2 we provide some related work on which we build our work, in section 3 we provide some necessary theoretical background, in section 4 we present our questions addressed and the research logic of our experiment, in section 5 we describe our methods and materials used, in section 6 we present our results and in section 7 we draw conclusions and provide some future research outlook. end users massively complained that they "do intuitively feel that this is wrong"

2 Related Work Kalbach & Bosenick (2003) [START_REF] Kalbach | Web page layout: A comparison between left and rightjustified navigation menues[END_REF] compared two Web page layouts (see figure 2): one with the main site navigation menu on the left of the page, and one with the main site navigation menu on the right. N=64 participants (44 of them female) were divided equally into two groups and assigned to either the left-hand or the right-hand navigation test condition. Using a stopwatch, the time to complete each of five tasks was measured. The hypothesis that the left-hand navigation would perform significantly faster than the right-hand navigation was not supported. Instead, there was no significant difference in completion times between the two test conditions. However, this work questioned the leading Web design thought as well as the common practice, that the main navigation menu should always be left justified. In their experiments, the participants were asked to carry out 6 different tasks, which required the use of the navigational elements. Interestingly, in average, the time to perform the tasks was about 3.7 seconds shorter when elements were placed on the left side (left M=30.5 SD=34.3; right M=34.2 SD=35.8). Kalbach & Bosenick performed an ANOVA for all tasks, however, again there were no significant difference between both conditions. Van Schaik & Ling (2001) [START_REF] Van Schaik | The effects of frame layout and differential background contrast on visual search performance in web pages[END_REF] empirically evaluated design guidelines according to the arrangement of navigational elements. They wanted to discover possible effects of the frame layout (the arrangement of the navigational elements) along with the contrast of the background on visual search performance. There were two independent variables (background -same and different contrast) and the frame layout (arrangement of the navigational elements: left, right, top, down). As experimental material they used a Webpage, which consisted of two parts: main frame layout and menu frame layout. The latter contained five hypertext links in blue text colour and a word length of 5 to 10 letters. They presented the navigational elements on different areas of the page (left, right, top, down) and measured the accuracy and the time of right and wrong answers and the subjective preference for a certain design.

In their study they observed N=189 participants (146 of them female) and allocated 90 participants to the experimental condition "same contrast" and 99 participants to "different contrast". In the first experimental condition the navigational frame layout and the main frame layout had both a grey background, in the other condition the navigational frame was white and the main had grey colour. Within the experiment they presented at first a blank white screen and then a word (target, black colour). Afterwards, the participants had to find this word out of the five hypertext links. The word was either presented or hidden. Only if the participants found the word they pressed a button.

Van Schaik and Ling analysed the hits and the misses and measured reaction times. A main effect was detected amongst the hits [F(3,561)=4,473, p<0,01], on the right side (M=97,47, SD=6,84) there were less hits as on top (M=98,88, SD=5,79) or on the left side (M=98,77, SD=5,17) (Tukey´s Honestly Significant Difference), p<0.05). The reaction time (in milliseconds) revealed also a main effect [F(3,561)=39,910, p<0,001]; right (M=1371, SD=269) and down much longer times were measured than on top (M=1302, SD=300) or left (M=1305, SD=235) (Tukey´s HSD, p<0,05).

In conclusion the authors recommend arranging navigational elements on the left side or on top and they tried to explain these effects on intercultural influences (e.g. reading culture).

Theoretical Background

Visual Pseudoneglect

It is known that humans primarily attend to objects on the left side of space as could be shown in classic cancellation tasks routinely used during neuropsychological testing (see figure 3, second from the left, and compare figure 4). Neglect and pseudoneglect are asymmetries of spatial attention, which are often assumed to have fundamental theoretical and neurological relationship to each other, although there is much dispute about it.

Basically, when neurologically normal individuals bisect a horizontal line as accurately as possible, they reliably show a slight leftward error. This leftward inaccuracy is known as pseudoneglect [START_REF] Porac | Pseudoneglect: Evidence for both perceptual and attentional factors[END_REF], [START_REF] Jewell | Pseudoneglect: A review and meta-analysis of performance factors in line bisection tasks[END_REF], [START_REF] Mccourt | Visuospatial attention in line bisection: stimulusmodulation of pseudoneglect[END_REF]. [START_REF] Diekamp | A left-sided visuospatial bias in birds[END_REF] [START_REF] Diekamp | A left-sided visuospatial bias in birds[END_REF] (see figure 3 (left) and figure 4) tested birds in a task that closely matches these cancellation tasks: the birds were required to explore an area in front of them and to sample grains. The results showed that birds displayed a clear bias into the left side, as evident in the pecking activity or the order in which pecks were placed in the left or right side. Let's go back to humans: Line bisection tasks are a commonly used procedure for testing spatial attention.

Several studies before have found that patients with a so called left hemisphereneglect, bisect long lines too far to the right, but bisect short lines too far to the left, and some studies reported that normal participants bisect long lines too far to the left, presumably reflecting an over-estimation of the left side due to the role of the right hemisphere in attention [START_REF] Rueckert | Pseudoneglect and the cross-over effect[END_REF]. [START_REF] Jewell | Pseudoneglect: A review and meta-analysis of performance factors in line bisection tasks[END_REF] [START_REF] Jewell | Pseudoneglect: A review and meta-analysis of performance factors in line bisection tasks[END_REF] provide a large-scale review of the literature concerning visual and non-visual line bisection in 2191 neurologically normal subjects. The meta-analytic results indicate a significant leftward bisection error in neurologically normal subjects, with an overall effect size of between -0.37 and -0.44 (depending on integration method).

Fitt's Law and Hick's Law: Human Performance principles

No paper about navigation can ignore to mention these two laws. According to [START_REF] Fitts | The Information Capacity of the Human Motor System in Controlling the Amplitude of Movement[END_REF], [START_REF] Fitts | The Information Capacity of the Human Motor System in Controlling the Amplitude of Movement[END_REF] the average duration of responses is directly proportional to the minimum average amount of information per response.

Fitts also discovered that movement time is a logarithmic function of distance when target size was held constant, and that movement time is also a logarithmic function of target size when distance was held constant; the time to acquire a target is therefore a function of the distance to and size of the target. Fitts' law has been applied to user interface design [START_REF] Mackenzie | Accuracy measures for evaluating computer pointing devices[END_REF]. The time for pointing tp is a function of both the distance d of the reach and the width w of the target object. This relationship can be expressed in the following formula where a and b are empirical constants and vary depending the used device:

tp = a + b * log2 (2d/w)
The expression log2 (2d/w) is, according to Shneiderman (1997), [START_REF] Shneiderman | Designing the User Interface. Strategies for effective Human-Computer Interaction[END_REF] also called index of difficulty (ID). Understanding how manipulations of d and w affect the time tp is of considerable importance in developing efficient user interfaces. For our study, we had, within certain parameters (including the dimensions of the screen), full control over the size of target objects and the distance of the user from the screen, and we had experience from previous work [START_REF] Holzinger | Finger Instead of Mouse: Touch Screens as a means of enhancing Universal Access[END_REF], [START_REF] Holzinger | An Investigation of Finger versus Stylus Input in Medical Scenarios[END_REF].

However, we must emphasize, that the formula a + b * log2 (2d/w) is not quite correct. Consider the case where e.g. your finger happens to be where you wish to touch, when a new screen comes up. In that case d = 0, and log(0) is undefined, so the formula provides no result (it should give a as the time).

Similar to Fitt's Law, the so called Hick's Law [START_REF] Hick | On the rate of gain of information[END_REF], describes the time it takes to make a decision as a result of the possible choices of the end user; consequently it assesses cognitive information capacity in choice reaction experiments. The reaction time (rt) raises logarithmically, if the amount of alternatives raise:

rt = k*log2 (n+1)
Both laws are two surviving human performance principles based originally on Shannon and Weaver's (1949) Information Theory concept [START_REF] Shannon | The Mathematical Theory of Communication[END_REF]. With the advent of user interfaces, these laws were used as the fundamental design principles [START_REF] Card | The psychology of Human-Computer Interaction[END_REF]. A good discussion on the impact of those two laws can be found in [START_REF] Seow | Information theoretic models of HCI: A comparison of the Hick-Hyman law and Fitts' Law[END_REF].

Questions Addressed and Research Logic of the Experiment

We conducted an experiment in which participants were instructed to select a target element, which was either placed on the left or the right side of the display. In addition, we examined if the directing of visual attention (using a cue) facilitates selection performance differentially for elements placed on the left and right side. Also we varied the number of distracting elements (the target stimulus had to be selected as a singleton as well as among three or five elements) and determined whether the number of elements asymmetrically influences the processing of information on the left and right side of the display.

Methods

Independent and Dependent Variables

Three independent variables were examined:

(1) The first independent variable is the side on which the target is displayed, comparing elements on the left and the right side of the display.

(2) The second independent variable is the presentation of a visual cue (directing visual attention), directly before the target had to be selected (both with cue, and without cue).

(3) The third independent variable is the number of elements, which were displayed on either side of the screen, differentiating one, three or five elements. The cuing as independent variable in combination with the side on which navigational elements are presented allows us to understand whether the selection performance on both sides is equally high under the cueing condition (if visual attention is beneficial then we should not find the left side benefit). In the condition without cuing we would expect the left side benefit. The arrow (the cue) did not disappear in the cuing conditions, but was not present in the non-cuing conditions (see figure 5).

Dependent variables included the speed and accuracy of performance. For the speed, the selection times (in ms) were determined (executed by a computer mouse). Regarding accuracy, the percentage of correct answers was counted.

Hypotheses

The following hypotheses were underlying the experiment: I. A significant main effect for the side at which elements were displayed  Faster processing times for elements placed on the left side of the display compared to elements placed on the right side of the display  A higher accuracy of answers for elements placed on the left side of the display compared to elements placed on the right side of the display II. A significant main effect for directing visual attention  Cuing the position of the expected elements prior to displaying it increases performance in terms of speed and accuracy of selection times, independently from the side at which elements are displayed. III. A significant main effect for the number of elements, among which the target stimulus has to be identified  The number of elements displayed on either side (right or left) decreases performance in terms of speed and accuracy of selection times

Experimental Task

The task of each participant was to select a target word, which was positioned either on the left or the right side of the display. They started each trial by clicking on a centrally positioned element (word). In 50% of the trials the central element contained a visual cue (a bold arrow) above the start element, which indicated the presentation side of the target element. After participants clicked on the start element it disappeared and the target element(s) -one, three or five elements -appeared. The trial was finished when participants had clicked on the correct target. In order to meet requirements of ecological validity, no time restrictions were given. Participants were instructed to execute the trails in a normal easy and efficient working speed. In Figure 5, a screenshot of the cue (a bold arrow above the start element) is depicted which indicates the side at which the navigational elements would appear. After selecting, the start element (a word) disappeared and the target element (the same word) on the left or right side appeared and had to be selected. Figure 6 shows the display for a trial without a visual cue, and three elements on the left side (the central element is the target word). The distance from the start element to the first/third element (3-element condition) was 11.5 cm and to the second/forth element (5 element-condition) 12.5 cm. The position of the target word was randomized across trials.

All words were between 4 to 7 letters and represented highly familiar words within the German language. The different word lengths were chosen to meet requirements of ecological validity: Normally, we process different word lengths when using websites and selecting objects. To simulate such a real-life scenario we also presented different word lengths in the study. As all experimental stimuli represented highly frequent words, we can exclude confounding effects of different word frequencies on selection times (which are well known). As all participants received the same stimulus material, word length did not asymmetrically influence the processing across participants. In order to learn if the word length has an impact on reaction times we analyzed this factor. No significant effect of word length was found, therefore we can exclude confounding effects of different word lengths. The distance from the center of the start element to the center of the target element (on the left or right side) was 11 cm and 10.38 degree (visual angle).

Participants

A total of N=50 participants volunteered to take part in the experiment. Simulating the diversity of computer users, the age range varied (between 10 and 64 years of age, M = 32.4; SD = 11.8) as well as the educational level. 16 participants had a graduation from apprenticeship training, 4 persons had a vocational school degree; 22 Participants reported to have a general qualification for university entrance and 8 persons had completed a university diploma.

Participants were surveyed regarding their experience with computers and Internet usage as well as their self-reported computer literacy. All persons reported to be frequent computer users with a satisfying experience when using computers and Internet. 35 persons indicated to use the Internet about 5-7 times per week, 9 persons reported to use the Internet about 1-2 times a week. 6 persons -the older onesreported to use the Computer and the Internet to a lesser extent (about once a month). All persons had a normal visual acuity. 26 out of 50 persons wore their corrective lenses during the experiment. Participants were instructed to use the computer mouse with their dominant hand (all participants were right handed), as tested by a handdominance testing procedure. Participation was voluntarily and the participants were not gratified for their efforts.

Apparatus and Materials

For the equipment, a standard working place was used. Participants sat in front of a computer screen, using a computer mouse (optical Logitech Wheel Mouse). In the beginning of the experiment, participants adjusted the height of the chair according to individual needs. In order to exclude different body movements and sighting conditions across participants, a chin rest was used which did not restrict participants, but allowed to control for comparable viewing conditions (figure 7). The stimulus material consisted of disyllabic (german) words (4-7 letters). The selected words are common in the everyday German language usage; thus we can exclude confounding effects from word processing of difficult or unfamiliar material. Moreover, the stimuli were presented in positive polarity (black letters on a white background).

Experimental Design and Procedure

The experiment was based on a 3 (number of elements) x 2 (presentation side of navigational elements) x 2 (with and without cue) -design for repeated measurements. All participants absolved all conditions.

The navigation side at which stimuli were located (right or left) and the number of elements (one, three or five) was varied randomly across trials. The cuing variable was blocked, with one half of participants starting with the order "with cue, followed by without cue" the other half vice versa ("without cue, followed by with cue"). As checked by ANOVA procedures, the order did not impact visual performance.

Overall, 108 trials had to be carried out (54 trials with and 54 trials without a cue, 27 on the left and 27 trials on the right side). The whole experiment lasted about 30-40 minutes, depending on the individual working speed.

In order to meet the high control demands in experiments, we did not use a real webpage, but used a simulation.

Data were analyzed by analyses of variance for repeated measurements assessing effects of (1) the presentation side, (2) the presence/absence of a visual cue and (3), the number of elements presented on the interface at a time.

The significance of the F-Tests was taken from Pillai values. The level of significance was set at p < 0.05. First, the main effects are reported, followed by interacting effects. The data revealed an accuracy level of 100%: None of participants had difficulties executing the selection of elements and perfectly carried out the tasks. Therefore, in the following, the selection times are focused at.

Main effect of presentation side

Participants needed, on average, 1155.7 ms (SD = 223.6 ms, SE = 30.7 ms) for the selection of the target elements presented on the left side compared to 1181.5 ms (SD = 244 ms, SE = 33.2 ms) for the selection of elements, which are placed on the right side of the display.

The small mean difference of 26 ms revealed to be statistically significant (Figure 8 left) yielding a meaningful main effect of presentation side (F (1,49) = 11.8; p < 0.05).

Main effect of cuing visual attention

Cuing visual attention facilitates the information processing: Conditions, in which a visual cue announced the presentation side of the elements, were significantly faster processed (M = 1102.6 ms; SD = 240.3 ms, SE = 32.22 ms) compared to trials without visual cuing (M = 1234.6 ms; SD = 249.1 ms, SE = 32.74 ms).

The mean benefit of 132 ms represented another significant main effect (F (1,49) = 89.3; p < 0.05). Outcomes are visualized in Figure 8 (right side).

Main effect of the number of elements presented at a time on the screen

Furthermore, the number of elements among which the target element had to be selected also showed a significant impact on the identification and selection of navigational elements (F (2,48) = 378.4; p < 0.05)). The outcomes are visualized in figure 9.

Descriptive outcomes show that selection times were considerably faster for conditions with only one element (M = 978.9 ms; SE = 31.4 ms), compared to three elements (M = 1140.2 ms; SE = 31.9 ms) and five elements (M = 1386.7 ms; SE = 34.4 ms). The interacting effects between the three main factors are of considerable interest, as it shows whether the (small) advantage of the left side presentation of navigational element also holds when the identification and selection of target elements is facilitated by cuing the visual attention and when the number of elements which have to be processed at the same time increases.

On a first sight, we expect that cuing of visual attention reduces the left side benefit and that the left side advantage profits from a small number of elements to be processed at a time. Outcomes of the interacting effects are reported in the next sections.

Interacting effect of visual cueing and presentation side

A significant interaction effect was found for the visual cuing of attention and the side on which navigational elements were positioned (F (1,49) = 11.3; p < 0.05, see figure 10). As can be seen from figure 10, the detrimental effect of having no visual cue that indicates the side of presentation is asymmetrical for the left and the right side: the selection times are slowest in conditions in which no visual cueing is present and the elements that have to be processed are on the right side. In other words this can be referred to as an indirectly evidence for the benefit of the left-side presentation as elements on the left side are disadvantaged to a lesser extent when there is no cuing of visual attention.

Interaction effect of visual cueing and number of elements

In this analysis we examined whether the cuing of visual attention is equally beneficial for the number of navigational elements that are presented at a time. Analyses revealed a significant effect (F (2,48) = 13.7; p < 0.05, figure 11): Performance drastically varied depending on the number of elements and a visual cue. The best performance was given, when a visual cue indicated the presentation of one element only (M = 875 ms; SE = 28.73 ms), the worst performance was found in the condition in which no visual cue was given and five elements had to be processed, among which the target element had to be selected (M = 1439.9 ms; SE = 27.73 ms). Visual cuing facilitates the processing of elements and reduces the detrimental effects of having more than one element.

Interacting effect of presentation side and number of elements

Finally it was analyzed if there is a significant interaction of presentation side and the number of elements among which the target element had to be selected. As can be seen from figure 12, there is a significant effect (F (1,49) = 11.3; p < 0.05). From an ergonomic point of view, this interacting effect is most insightful as it shows that the benefit of the left-side presentation of elements is only valid when one element is depicted (what is rather unusual in real web sites). Whenever the number of navigational elements increases (three, five elements) the benefit vanishes and shows the very same selection times.

Conclusion and Future Research Outlook

The results of the presented center-out selection study show that placing elements on the left side significantly decreases the selection time only in cases were individuals elements have to be selected. When user had to choose between several options, no significant differences between left or right were found. As expected, the use of cues decreases the overall selection time. The availability of the a-priori information on the position, however, eliminates also the enhanced left-sided performance for individual elements. The number of elements was of no direct influence on the performance time. There has been an increase in time to perform task with one, three and five elements.

As described in Hick's law, there is a correlation between the number of reaction alternatives and the reaction time. The more complex one task, the longer one needs for the task. In terms of cognitive performance there were no differences between both sides. This is an important finding as this suggests that the performance of usery that are engaged in a selection task, such as navigating a webpage with several menu elements, is not affected by the side the elements are shown on the screen. Phenomena like the pseudoneglect or the intrinsic turning behavior in right-handers, i.e., turning toward the left side due to hemispheric dopamine asymmetries [START_REF] Mohr | Opposite turning behavior in righthanders and non-right-handers suggests a link between handedness and cerebral dopamine asymmetries[END_REF], may argue against such a behavior.

Possible explanations for the enhanced performance during the perception of individual stimuli on the left side could be the biomechanics of the hand and the influence of the writing culture. As known there are many differences between western and eastern cultures, which have a direct influence on designing user interfaces.

This brings us directly to the limitations of this study, consequently our further research duties: This study was conducted only with German speaking participants; hence the results cannot be generalized to other cultural areas -especially in terms of reading habits. It would be very interesting to conduct a similar study in a language with a completely different orthography (e.g. Japanese). By this, we could learn, whether and to what extend the effects are biased by alphabetical writing systems. Also, as the reading direction could also impact the left-side benefit, it would be insightful to replicate the study in a language with a reverse reading direction (as e.g Hebraic or Arabian language).

A further limitation is that we used a webpage simulation in a laboratory experiment, and thus in real-life there could be a lot of different influences with different additional effects. For example, due to experimental requirements the distance between user and interface was fixed and controlled. In contrast, in real using settings, end users do naturally move in front of the screen, resulting in different distance and angles.

In future work different target elements should be used, e.g. symbols. Currently we have developed an online experimental tool, were we plan to replicate this studies within an intercultural context on a large scale. Summarizing, the best performance was achieved when selecting individual elements on the left side of the screen. Besides from this, when end users have no cue or several options to choose from, the side does not significantly impact on the performance. However, due to the fact that the majority of the population is righthanded, and right-handers tend to focus on the left side, placing navigational elements on the left side may be the most intuitive position. Besides this, end users are accustomed to it and they expect it there; consequently the first designers were intuitively right, and we can conclude, yes, it was proper intuition -and it is not recommendable for "modern designers" to switch to the other side.

Figure 1 .

 1 Figure 1. After the "modern" designers placed the navigational elements on the right side,end users massively complained that they "do intuitively feel that this is wrong"

Figure 2 .

 2 Figure 2. The tested Webpages of the experiment done by Kalbach & Bosenick [1]

Figure 3 .

 3 Figure 3. Left (1-2): Settings to test effects on visual pseudoneglect [8]; Right (3-4): Settings where such effects were observed with humans [9]

Figure 4 .

 4 Figure 4. The results from Diekamp et al. (2005) [8]

Figure 5 .

 5 Figure 5. Start element with a cue for the positioning of displaying side of the target element

Figure 6 .

 6 Figure 6. Screenshot for a trial without a visual cue, and three elements on the left side (the central element is the target word).

Figure 7 .

 7 Figure 7. The Experimental setting including a Tobii 1750 eye tracker with chin rest

Figure 8 .

 8 Figure 8. Left: mean selection time in ms for the left compared to the right presentation side of elements; right: mean selection times in ms for trials with and without visual cue.

Figure 9 :

 9 Figure 9: Mean selection time in ms for one, three and five elements presented on either side of the display.

Figure 10 .

 10 Figure 10. Interacting effect of visual cue and presentation side (mean selection times in ms).

Figure 11 .

 11 Figure 11. Interacting effect of visual cue and presentation side (mean selection times in ms).

Figure 12 .

 12 Figure 12. Interacting effect presentation side and number of elements that have to be processed at a time (mean selection times in ms).

Acknowledgements

We are grateful for the valuable comments of the anonymous reviewers. Many thanks to the students Sylvia Graf and Stefan Mayr for their work on programming and experimenting, and to Prof. Dietrich Albert for his support of this work.