Showing Users the Way: Signs in Virtual Worlds

Daniel C. Cliburn1 Stacy L. Rilea2

The University of the Pacific

ABSTRACT In this paper, we report the results of a pilot study designed to evaluate the impact of signs as navigation aids in virtual worlds. Test subjects were divided into three groups (no aid, a dynamic electronic map, and signs) and asked to search a virtual building four times for six differently colored spheres. The spheres were in the same locations each time, and subjects were allowed to locate them in any order. A statistical analysis of the data revealed that on the first and second trials subjects took nearly four times as long to find the spheres with no aid present, compared to with maps and signs. We then compared only the sign and map conditions. Overall, subjects who navigated the world with the aid of signs were significantly faster than those who were provided with a map. While more research into the use of signs in virtual worlds is necessary, these results indicate that for at least some environments subjects are able to locate targets more quickly when using signs than maps. KEYWORDS: Virtual Environment, Signs, Navigation INDEX TERMS: I.3.7 [Computer Graphics]: Three Dimensional Graphics and Realism – Virtual Reality; H.5.2 [Information Interfaces and Presentation (e.g., HCI)]: User Interfaces – Evaluation/Methodology.

1 INTRODUCTION As computers become more pervasive in society and advances in hardware capabilities increase the spectrum of what is feasible with computing systems, the use of virtual worlds for teaching and training continues to increase in popularity. For example, researchers are using virtual worlds to teach children about science and history concepts [11], while others are visualizing environmental data [19] and building applications for military training purposes [10]. In many virtual reality applications, the ability to navigate from one location to another is of paramount importance since, as in the real world, the entire virtual world is not visible from a single vantage point. Thus, learning how to move freely in the world without becoming lost or disoriented is often critical to the success of the application.

However, most users find navigating through virtual worlds to be considerably more difficult than in the real world [14]. Some factors found to improve the navigation skill of users as they move about in virtual worlds include the incorporation of physical body movement into the navigation process [2, 21], and increasing the amount of visual information in the world [9]. Other researchers have investigated the impacts of navigation aids such as trails [16] and landmarks [20].

In this paper, we define wayfinding as the cognitive process of discovering a route between locations. Wayfinding is a critical component of navigation as it guides decision making during the navigation process. Passini [13] defines two types of wayfinding situations: those with no environmental information available, which requires a search strategy; and those with environmental information available, which requires an access strategy. Navigation aids such as trails and landmarks are useful for searching, as they can help users remember places that have been visited previously. In the real world, however, most people avoid naïve searches of a new environment. Rather, they attempt to change the wayfinding task to one of access by locating information about the environment before navigation is to take place. For instance, when planning to tour historic monuments in an unfamiliar city, most people would locate a map, or get directions from someone who has been there before. Access wayfinding can be considerably less frustrating than searching in both the real and virtual worlds.

Unfortunately, users of virtual worlds are often forced to perform searches when attempting to find their way in an unfamiliar place. To simplify navigation by making the task one of access, researchers have explored the use of maps [1, 6, 7, 15] and route recommendations from experienced users [17]. What is missing from the literature is an evaluation of the utility of signs as an access strategy for navigation in virtual worlds. Signs are a fundamental component of effective navigation in the real world. Signs can be found on highways, and in complex buildings such as hospitals and airports. In fact, some real world studies have shown that users prefer signs to maps [4, 12]. However, signs as navigation aids in virtual worlds remain largely unexplored, and to our knowledge, their comparison to other common techniques as wayfinding aids is nonexistent. The next section of this paper describes previous research on the use of signs as navigation aids in both the real world and in virtual worlds.

2 BACKGROUND Moeser [12] examined the mental maps of a hospital developed by student nurses who worked in the building for various periods of time. The study revealed that the nurses failed to develop accurate mental maps of the hospital, even after navigating it regularly for two years. During the study, nurses commented that they never used the posted floor plans of the building because they found them confusing. However, the nurses were all able to navigate successfully throughout the building presumably using well-traveled routes and the directional signs located in the hospital.

Butler et al. [4] studied the difference in wayfinding performance between signs, maps, and no aid at all as subjects searched a complex building for a specific room. Subjects were nearly six times faster when they navigated the building using signs compared to maps. In fact, subjects with no aid at all performed better than those who used the maps. Butler and colleagues concluded that the signs provide clear directions about the direction of travel without imposing additional study time or a high memory load.

1e-mail: dcliburn@pacific.edu 2e-mail: srilea@pacific.edu

Emhardt, Semmler, and Strothotte [8] were some of the first to

implement signs as navigation aids in virtual worlds. In their

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application, an agent tour guide presented signs at various locations that pointed to a destination of interest. When users looked into hallways that did not lead to the destination, a “do not enter” sign was displayed. More recently, Barbosa and Rodrigues [3] developed a cell phone application to aid firefighters as they navigate burning building. Exit signs were provided throughout a virtual model of the building to indicate exit routes.

The work by Moeser [12] and Butler et al. [4] suggest that signs may actually be preferable to maps as navigation aids. However, in both of these real world studies, the maps were static and only provided in fixed locations. To be fair, in virtual reality applications maps can be made dynamic so that they are always available to the user and contain a “you are here” marker that constantly updates to show position and orientation [7, 15]. These features should significantly reduce the cognitive burden of map usage in virtual reality. Thus, the preference towards signs in the real world may not exist in virtual worlds. In the next section, we describe the current experiment designed to compare signs with dynamic electronic maps as navigation aids in virtual worlds. Maps were chosen as the aid with which to compare signs given the extensive literature on map usage with virtual worlds [1, 6, 7, 15, 18] and the number of applications that provide maps as navigation aids.

3 EXPERIMENTAL DESIGN We used an experimental methodology similar to that described by Ruddle [16], to compare signs and maps as navigation aids when users attempt to find objects in an unfamiliar virtual world. Test subjects navigated two worlds (see Figure 1). The smaller practice world was intended to help subjects become familiar with the navigation interface and search task. Subjects first navigated this world with no objective given; subjects were only instructed to move about until they felt comfortable using the input device (a PC gamepad). During the second two visits in the smaller world, subjects attempted to locate four differently colored spheres. The spheres were in the same locations both times. Subjects then navigated the larger world four times searching for six differently colored spheres. Again, the spheres were in the same locations every time. Time, distance traveled, and total degrees of rotation were recorded for each search in the larger maze.

Figure 1. Layout of the virtual worlds. Subjects twice practiced

locating spheres in the world on the left, then performed recorded searches in the world on the right four times.

3.1 Test Subjects Thirty-four subjects participated in the experiment and were divided into three groups: no navigation aid, maps, and signs. Four subjects withdrew from the no aid condition before completing the fourth trial and were excluded from the analysis. This left nine subjects in the no aid group (eight males and one

female), ten subjects in the map group (seven males and three females), and eleven subjects in the sign group (nine males and two females). The average age of subjects who completed the experiment was 21.10 (sd = 3.57), and all had at least twenty hours of previous experience using 3D graphics applications with computer generated virtual worlds. The disparity between numbers of male and female subjects in each condition is due largely to the difficulty in locating females with prior experience using 3D graphics applications. Subjects were either paid an honorarium for their participation or received extra credit in a college course.

3.2 The Test Environment The experiment took place in a display environment with three large projection screens (4 feet wide by 3 feet tall) oriented at 135º angles (see Figure 2). Subjects were kept aware of their search progress through an onscreen display showing the spheres that were yet to be located (see bottom right of Figure 3). As the spheres were collected, they disappeared from the list and a computer generated voice reported the total number that had been found.

Figure 2. The three screen projection environment used to conduct

the experiments.

Figure 3. Base condition with no navigation aid. Subjects in all conditions were provided with a list of the spheres that had yet to

be located.

3.2.1 Maps Subjects in the map condition were provided with a global north up map that contained a dynamic you-are-here (YAH) marker. The marker was designed as a triangle with a colored dot that indicated direction of view. We elected to implement a north up map after surveying the literature [1, 7, 15] and determining that the task we were asking subjects to perform was global in nature (that of finding the shortest path between all the spheres). The

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map was shown as a transparent heads-up-display (HUD) in the lower left hand corner of the front screen (see Figure 4).

Figure 4. Some subjects were provided with a dynamic map

showing position, orientation, and location of the spheres.

3.2.2 Signs Signs were designed to hang from the ceiling in the virtual world and indicate the shortest path to each of the spheres (see Figure 5). Following the suggestions of Butler [4] and Corlett [5], we attempted to minimize ambiguity in our signs and provide them at each decision point along the routes between the spheres. Thus, signs were not provided at every intersection, but only those intersections on designated routes that required a change in direction. One advantage of this approach is that, as long as subjects follow the signs, they can be guided to take the shortest routes between spheres.

Figure 5. Some subjects were provided with signs showing the way

to the locations of the spheres. Signs were located at decision points along the shortest paths between spheres.

4 RESULTS A mixed analysis of variance was conducted for each of the three dependent variables (distance, time, and degrees of rotation). For each of the three ANOVAs, condition was a between-subject variable and trial number was a within-subject variable. Additionally, given that our primary interest was to examine differences in using maps relative to signs, an additional ANOVA was conducted using the same variables that only compared the map and sign conditions.

4.1 Analysis of Distance Traveled Results of the mixed analysis of variance for distance traveled revealed a main effect of trial, F(3, 81) = 4.074, p < .05, with

distance traveled decreasing across trials. There was also a main effect of condition, F(2, 27) = 40.926, p < .001, with participants traveling significantly further in the no aid condition (M = 7824.44, SE = 528.24), relative to the map (M = 2200.53, SE = 501.14) and signs (M = 2035.86, SE = 477.82) conditions. Finally, there was a significant trials by condition interaction, F(2, 27) = 4.084, p < .05. These results suggest that the distance traveled decreased from trial 1 to trial 2 in both the no aid and the map conditions, but not the signs condition (see Figure 6). This improvement across trials continued for the no aid condition, but not for the map condition. When comparing the signs and map conditions only, no significant main effects were observed, and consistent with the previous analysis, there was a significant trial by condition interaction, F(3, 57) = 2.933, p < .05.

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Figure 6. Distance (in feet) traveled by subjects for each trial.

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Figure 7. Time (in seconds) traveled by subjects for each trial.

4.2 Analysis of Time Results of the mixed analysis of variance for time revealed a main effect of trial, F(3, 81) = 6.872, p < .001, with the time to locate the spheres decreasing across trials. There was also a main effect of condition, F(2, 27) = 43.627, p < .001, with participants requiring more time to locate the spheres in the no aid condition (M = 388.90, SE = 24.62), relative to the map (M = 124.06, SE = 23.35) and signs (M = 105.91, SE = 22.27) conditions. Finally, there was a significant trials by condition interaction, F(2, 27) = 5.588, p < .01. Specifically, there was a decrease in time across trials, but only in the no aid condition (see Figure 7).

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When comparing only the sign and map conditions, there was a main effect of condition, F(1, 19) = 5.783, p < .05, with individuals in the signs condition (M = 105.91, SE = 5.21) requiring less time relative to the map condition (M = 124.06, SE = 5.46). There was also a main effect of trial, F(3, 57) = 8.760, p < .001. These main effects were qualified by a trial by condition interaction, F(3, 57) = 4.265, p < .01.

4.3 Analysis of Degrees of Rotation Results of the mixed analysis of variance for degrees of rotation revealed a main effect of trial, F(3, 81) = 6.419, p < .05, with angle of rotation decreasing across trials. There was also a main effect of condition, F(2, 27) = 35.386, p < .001, with the degree of rotation being highest for participants in the no aid condition (M = 11301.94, SE = 721.69), relative to the map (M = 4295.175, SE = 684.66) and signs (M = 3839.46, SE = 652.79) conditions. Finally, there was a significant trials by condition interaction, F(2, 27) = 4.790, p < .05. Specifically, the angle of rotation decreased across trials for the no aid condition, and from trials two to four in the signs condition, but not the maps condition (see Figure 8).

When comparing only the signs and map conditions, there was a main effect of trial, F(3, 57) = 3.043, p < .05, with the angle of rotations decreasing across trials. No other main effects or interactions were significant.

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Figure 8. Total degrees of rotation by subjects for each trial.

5 CONCLUSIONS While more research into the use of signs as navigation aids in virtual worlds is necessary, these results indicate that for at least some situations subjects are able to locate targets more quickly when using signs than maps. Subjects who used maps to locate the spheres took slightly (but significantly) longer than sign users. However, the difference in total distance traveled was not significantly different. This suggests that map users must spend more time to analyze a map and form route decisions while wayfinding in a virtual space, than is required to read and follow signs. In the future, we plan to continue this work with further studies that attempt to classify wayfinding tasks for which signs are most appropriate as navigation aids, and research how to effectively present sign information to users of virtual worlds.

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