Synchronized Wayfinding on Multiple Consecutively Situated Public Displays

Jorgos Coenen, Niels Wouters, Andrew Vande Moere Research[x]Design, Department of Architecture

KU Leuven, Belgium {firstname.lastname}@asro.kuleuven.be

Figure 1: Our proposed technique of synchronized wayfinding (bottom of displays) on consecutively situated public displays in a

metropolitan railway station, in combination with simultaneous commercial content (top of displays).

ABSTRACT Our built environment is becoming increasingly equipped with public displays, many of which are networked and share the same physical location. In spite of their ubiquitous presence and inherent dynamic functionalities, the presence of multiple public displays is often not exploited, such as to solve dynamic wayfinding challenges in crowded or complex spaces. Hence, we have studied how signage can be animated onto multiple consecutively located public displays in combination with other content. This paper reports on an in-the-wild evaluation study in a real-world, metropolitan train station in order to identify the most promising design strategies to: 1) provide the notion of spatial directionality by way of animation; 2) support concurrent viewing of wayfinding with other content types, and 3) convey a sense of urgency. Our results indicate that spatially distributed animated patterns may be used to convey directions under specific spatial conditions and content combination strategies, yet their impact is limited and highly dependent on the visibility of the animated patterns on individual screens and across multiple displays.

Author Keywords Public display; wayfinding; navigation; advertising; networked public display; public space; evaluation study; in-the-wild field study; railway station

ACM Classification Keywords H.5.1 Multimedia Information Systems (Animations); H.5.2 User Interfaces (Screen design)

INTRODUCTION Navigating in public space poses a range of challenges, especially in underground or indoor places that lack natural affordances or other kinds of spatial cues [3]. Current wayfinding methods typically provide directional cues via well-considered architectural affordances, dedicated graphical signage strategically distributed over space [27] or more display-centric interventions like interactive floor plans [2]. Yet, the lack of dynamic updates to these wayfinding solutions makes them unaware of any changes in contextual or situational circumstances, such as personal needs (e.g. individualized trajectories), collective user requirements (e.g. according to accessibility requirements), or unexpected emergencies (e.g. sudden trajectory changes). Moreover, more dynamic forms of wayfinding may allow for novel kinds of applications to emerge, such as encouraging visitors to aggregate around places based on shared interests or social networks, or offering unique trajectories based on preferred points of interest (e.g. tourism), preferences (avoiding crowds) or physical ability, or the presence of temporary events (e.g. commercial offers, markets).

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PerDis '16, June 20-22, 2016, Oulu, Finland © 2016 ACM. ISBN 978-1-4503-4366-4/16/06...$15.00 DOI: http://dx.doi.org/10.1145/2914920.2929906

Recent technological advances related to indoor localization such as wireless data transfer, Wi-Fi triangulation or proximity sensing (e.g. Bluetooth beacons) have facilitated the use of smartphones to support personalized indoor navigation tasks [20]. While mobile applications like Google Maps or OpenStreetMaps have commenced to provide indoor maps for major locations, they tend to direct human attention towards handheld screens rather than the actual opportunistic context. As a result, users tend to miss out on opportunistic events, like social (e.g. conversations), environmental (e.g. architectural features) or economic (e.g. advertising) opportunities in physical reality. Furthermore, removing the focus of pedestrians from their environment can be potentially hazardous [15][16]. Alternatively, some wayfinding apps and wearable technologies [34][37] now offer wayfinding directions by way of haptic vibration patterns, which however can be ambiguous to interpret, particularly when the context dynamically changes (e.g. differentiating tactile signals during an emergency).

In parallel to these smartphone innovations, the increased affordability of networking and display technology has led to the ubiquitous presence of public displays, particularly in heavily frequented locations. Such displays are however not always successfully integrated into the architectural context [36], and tend to vary in size, technology or mode of presentation. Public displays are commonly steered by a centralized control system to facilitate the synchronization of various playlists and animations, and to allow for regular remote updates. Multiple public displays located within the same physical environment tend to simultaneously show identical content in order to achieve a more consistent, noticeable or overwhelming visual effect. The impact of displaying identical content tends to be reinforced when multiple displays are concurrently visible, such as when they are spatially distributed in a sequential or consecutive way (see Figure 1). In such particular spatial configurations, custom-designed and well-timed animations allow for displaying captivating and spatially interesting visual effects. However, we learned through conversations with display owners and content creators that such multi-display effects tend to be challenging to develop due to the specific demands on content (i.e. each display must show a slightly differing animation) and technology (i.e. each animation needs to start at a slightly differing point in time).

This research explores the still untapped potential of dynamic animations on consecutively situated displays for pedestrian wayfinding purposes. This spatially grounded form of displaying signage exploits the advantages of dynamic or personalized updates and is potentially more intuitive due to its inherent spatial character. Furthermore, it mitigates the need to rely on mobile devices or other peripherals for localizing the exact indoor positions of individual users, or for drawing their attention away from the opportunistic environmental context. Although combining personal devices and public displays has been shown to be suitable for wayfinding [22], a solution that

does not require a personal device is more inclusive, and allows pedestrians to navigate in a more natural, safe and efficient ways by only having to rely on cues from their immediate surroundings [15][28].

Since we believe that ubiquitous displays in public environments may only be realistically funded for advertising purposes, we propose that new strategies for dynamic wayfinding should be combined with commercial content [1]. Therefore, the goal of this study is to gain insight into synchronized wayfinding on consecutively situated public displays, in terms of:

(i) How can animations provide a sense of destination and urgency on consecutive displays?

(ii) How can users identify destinations that are relevant to them?

(iii) How can synchronized wayfinding be integrated with advertising in an efficient way?

RELATED WORK To the best of our knowledge, there exists a lack of HCI studies with a particular focus on the spatial configuration of public displays for wayfinding purposes. However, previous studies have demonstrated how the spatial configuration of multiple public displays can have a significantly impact on a range of audience characteristics, such as user positioning and crowd dynamics. Distinct chained display configurations (i.e. flat, hexagonal, concave) [13] and cylindrical displays [10] have been shown to cause specific changes in user, audience and passer-by behaviors. Configurations that allow audiences and passers-by to more clearly observe the interactions of an active user (i.e. flat configuration) lead to more social learning and attract new users more easily [13]. The natural affordances of spherical displays, on the other hand, make them better suited for individual tasks than collaborative ones [5]. As cylindrical screens promote movement, they seem well suited to entice bodily interactions [10].

Concurrent use of multi-purpose displays Public displays, particularly those on which users do not expect to see interesting content (usually advertising), are known to frequently go unnoticed [23]. Multiple previous studies have explored the nuances of display blindness and ways to combat the blindness phenomenon, e.g. by using personal photographs to foster emotional attachment [17] or physical movement to increase the engagement of passers-by [31]. Consequently, adding utilitarian functions like wayfinding to commercial public displays may generate more interest in what individuals generally perceive to be uninteresting content. The challenge then is to combine both functions without limiting the efficiency of either.

In order for public displays to be used for dynamic wayfinding, a relatively large number of dispersed situated displays is required to achieve sufficient spatial granularity. Yet, since the financial cost is still relatively high, manifestations of digital displays that are solely dedicated

to offering wayfinding are rare [32]. Preceding studies have therefore explored the integration of digital signage with other content, like social [14] or commercial [22].

The collective use of public displays requires that display owners are willing to shift some control over their displays, or at least share its resources (e.g. processing power, screen size), with others. Many public display systems are entirely open to use by any passer-by (e.g. [4][6][35]), but others require display owners to allow or accept what content may appear (e.g. [12][14]). As display owners have specific preferences in regards to how their screens are visually shared for wayfinding purposes [14], a consistent approach of integrating signage on displays owned by various stakeholders may thus be challenging to achieve. Furthermore, many public displays are solely dedicated to advertising [11], which implies strict contractual obligations that may inhibit a decrease in display time or screen size when showing other content types.

Multi-purpose displays are defined as interactive screens that host multiple distinct functionalities [24], enabling the combination of informative content with interactive applications, such as advertising and interactive maps. Such multi-purpose displays rely on playlists that control when and for how long each application is available [8][12][21], require the user to actively request an application to be displayed (e.g. [24]), or ‘multiplex’ the different content types in either time [25], space [8][24] or a visual medium, like through augmented reality [26]. Accordingly, three approaches to combine wayfinding with other content fragments have been identified [14] (see Figure 2):

(i) Overlaying allows for each content fragment to occupy a maximized portion of screen space. Yet overlaying several content fragments can potentially harm the readability when many fragments overlap or contain high information or visual density [9].

(ii) Sequential presentation is based on time-multiplexing by showing multiple content fragments as individual slides in a playlist. Hence, it exploits the full screen resolution and distinguishes separate content fragments. As the fragments cannot be shown concurrently, the sequential presentation suffers in utilitarian value since viewers who are engaged with a particular content fragment need to wait while other fragments are presented.

(iii) Parallel presentation is a space-multiplexed displaying technique that allocates parts of screen space to show multiple content fragments concurrently. For example, advertisements can be combined with informative content, such as a clock. In this technique, all fragments can be used concurrently, yet maintaining utilitarian value becomes more challenging as content fragments need to share the display resolution and physical scale of the display.

Overlaying Segmentation Sequential

Figure 2: Approaches to consolidating signage and other content types. Image adopted from [14].

Identification of relevant signage In contrast to more personal device-centric approaches, navigation by way of public displays requires that users can identify which signage is relevant to them personally, among many others. For instance, if users carry personal devices, they can be notified when relevant signage is shown via crossmodal cues like sounds or vibrations from a personal device that are specifically timed to coincide with the correct signage [25][29].

More inclusive approaches to the identification of relevant signage which do not require pedestrians to posses, hold or pay attention to a personal device include the use of text [15] (such as a name, alias or destination [19]); color, icons or their combination [15]; and personalizing signage, such as by way of sketching on top of a directional arrow [33]. However, using colors to differentiate signage comes with severe restrictions as only a limited number of colors can be readily differentiated, in addition to the challenge of supporting the colorblind [15][33]. However, combining colors with other visual cues like symbols or patterns can expand the range of possible signage identifiers.

STUDY DESIGN We developed a novel wayfinding system for the real-world context of Brussels South, the busiest metropolitan railway station in Brussels, Belgium. It consists of 22 train platforms for regional, national and international traffic, and hosts an average of 61,941 travelers on weekdays [38]. Our study was carried out in the shared underground pedestrian corridor tunnel that connects all train platforms via escalators and staircases. The corridor, which measures approximately 140m in length and 40m in width, also provides access to a metro station, and houses numerous shops, supermarkets, coffee bars and fast food restaurants.

The 32 commercial displays used in this study are marked in red on Figure 3 and are located on both sides of the corridor, next to the escalators and staircases that each provide access to two train platforms. Each display measures approximately 1.78m diagonally (70”) and provides a Full HD resolution of 1080x1920 pixels in portrait mode. All displays are mounted back to back in pairs, and are installed approximately 2.5m above floor level, with 12m in between each pair. Their content is

centrally managed and updated over a wired Internet connection. Since each pair of displays flanks an access route to a platform, we identified the opportunity to employ them for conveying signage towards the platforms.

Signage Design In this section, we describe the design rationale of our novel wayfinding system. We first define design requirements followed by a detailed overview of distinct design strategies for animations to meet these requirements. In addition, this design-oriented analysis illustrates the rationale behind our animated signage approaches and provides the description of the conditions evaluated during the in-the-wild study outlined further on.

We defined five different key design requirements for developing a multi-display, synchronized wayfinding system on consecutive public displays:

1. Content combination. Since public displays are funded for advertising purposes, the signage needs to be functional in combination with other content, and require a minimum of screen space.

2. Directionality. The wayfinding system should exploit the spatial distribution of the displays to provide directions and to indicate the destinations.

3. Concurrent use. The public character of the wayfinding system should support multiple concurrent users and destinations.

4. Recognizability. In spite of concurrent usage, users should be able to confidently recognize their personal signage without needing to glance at (personal) devices to match visual patterns or notice tactile or sonic signals emitted by such a device.

5. Urgency. The time-dependent nature of wayfinding in a public transport context requires the indication of urgency to ensure punctual arrival.

These requirements resulted in an overall design strategy to use animated elements that appear on one side of the displays, slide across them and disappear on the other, resulting in pulsing, spatial navigation cues. Hence, we expected that as the signage includes all the consecutive displays in a shared space, travelers are provided with a more intuitive sense of the direction they have to walk towards, which even allows them to recognize the physical location of their final destination from afar. As travelers are no longer required to take a look at a personal screen or wait for a (haptic) command, such dynamic signage could be less obtrusive, and wayfinding more environmentally-grounded and opportunistic in nature.

Figure 4: Situational overview of the study location in Brussels

South station. This corridor holds 16 displays on each side.

Content combination. We chose the parallel (space-multiplexed) combination strategy in order to mimic a realistic and commercially valid usage scenario as closely as possible, allowing both advertising and wayfinding signage to be present in parallel. Overlaying any content on top of the commercial messages or the train operator advertising was not permitted. Additionally, a time-multiplexing strategy would further decrease the display duration of the wayfinding content since our attempt at ecologic validity, as well as the display owners, required that all content was presented. Strict contractual obligations of the display owners with the advertisers did not allow us to control the commercial content of the displays in any way, except of a short 6 to 12s timeframe (allocated for the advertising of the train station operator), and except of a relatively small zone at the bottom of the display, underneath the advertisement. As a result, during this study, signage occupied approximately 30% of the total display space (1080x560 pixels).

Recognizability. We combined a set of contrast-rich colors with unique bold patterns, to derive a series of distinct graphical combinations that were sufficiently distinguishable to be visually recognized by colorblind users. Adding patterns was favored over symbols (e.g.

Figure 3: Floor plan of the corridor with red symbols

depicting each of the 32 displays used during this study.

arrows), text (e.g. platform numbers) or icons (e.g. elevator), in order to optimally exploit the limited screen space as well as the narrow proportionality of the display area that is left over when the typical advertising was rescaled. For instance, small text becomes unreadable when observed from afar and icons or symbols can only be scaled proportionally, while graphical patterns can be multiplied to fill an entire area regardless of their size or proportion.

Within the context of public transport, each unique combination of color and pattern corresponded to a particular geographical destination. We divided Belgium into eight distinct geographical regions, each approximating the geographical boundaries of the national provinces, as demonstrated in Figure 5. Each group was assigned a unique color, allowing more experienced train travelers to match colors to the general destinations of particular trains. We further subdivided each color by combining them with up to 12 graphical patterns, which each represented a terminus within the railway network in each province or region. As was previously explained by [15], who used spatial subdivisions to augment static signage and help users identify individual destinations; users prefer the use of colored icons over purely textual destination identifiers. While patterns can hypothetically be used across multiple regions, they are rendered unique through the combination with a more dominantly noticeable color (as depicted in Figure 6).

Directionality. The graphical patterns slided over the displays simultaneously to communicate directionality, an approach we refer to as wipe animations. Directions are typically communicated more explicitly by way of lines, arrows, arcs, graphical symbols like pointing fingers, animations or other kinds of movement; or implicitly through color, view direction or visual weighing (i.e. size, shape, position, orientation, negative space). We believe animated signage elements provide particular advantages compared to these more conventional techniques as the synchronized movement on each display has the potential to create a physical sense of direction on a scale that is much larger than the actual size of the displays themselves. Such animations thus could provide for a more situated sense of direction than static or traditional signage alternatives, as the direction becomes mapped in between the displays, and thus within the space itself.

This type of animated signage might retain its directionality better when observed from afar or at a relatively small size compared to small graphical features (e.g. directional arrows), due to how the movement occurs simultaneously and on multiple displays. While the frequency or the dynamic nature of the animations can also convey other useful meanings, the effective use of these animations also comes with particular challenges. For instance, the presentation of multiple directions at once might cause animations to literally ‘collide’ or overlap.

Figure 5: A map of Belgium divided into 8 uniquely colored

regions, each containing markers to indicate the final destination train stations.

Figure 6: The 10 distinct signage patterns that were used

during the in-the-wild field study, which are combinations of contrast-rich colors and graphical pattern designs.

The strategies to deal with content combination outlined earlier can be used to overcome these challenges as individual signage elements can be presented in sequence, in parallel or, less likely, overlayed on top of each other.

A wide variety of possible configurations and compositions of such wipe animations that simultaneously run across multiple displays can be conceived, including, but not limited to, particular strategies that we reference as: a coiling snake (see Figure 7), a cannonball (see Figure 8) or a horizontal wipe (see Figure 9). Each of these animation strategies is able to convey movement in two directions as the graphical elements can be synchronized to travel across the displays in a forward, backward, left or right direction. On displays situated before the destination, signage elements can slide from left to right or front to back to indicate forward movement. On the displays situated behind the destination, signage elements can move in the opposite directions. This way, to whichever display they look, travellers are pointed in the correct direction.

As all other displays simultaneously direct the view of the onlookers to the destination location, the final destination of a trajectory can also be represented in animated ways, such as by pulsating the animated visual element on the destination display, or by simulating a visual impact, such as when the graphical element dissolves into multiple fragments or particles.

The use of multiple displays creates a unique opportunity to show dynamic wayfinding content through animations that occupy the entire available wayfinding space, similar to a texture, without animating in or out of view. We refer to this type of nested animation as a scrolling animation. Here, a sense of direction can be provided through animating the pattern in the direction of navigation (see Figure 10). Whereas the scrolling approach lacks the larger-scale effect of simultaneous movement over each display, its literal duplication across multiple displays may be harder to miss since each pattern is entirely visible on each screen. It might also be easier to understand, since scrolling movement of symbols (e.g. arrows) is a more common form of public signage and wayfinding.

Wayfinding signage commonly includes some form of quantitative indication of the remaining distance towards the final destination. Within our concept of the simultaneous animation sliding across the displays, we considered distance to be a redundant variable since the spatial distribution of consecutively situated displays allows for identifying the destination from a distance. Furthermore, previous research indicates that pedestrians tend not to focus on distance information, but rather benefit from the confirmation of prior navigation choices along their route [20]. Such confirmations are provided through the sequence of displays that the travelers walk past, repeatedly signaling directionality through animations and thus confirming navigation choices.

Concurrent use. Any wayfinding system must be able to communicate multiple destinations, and therefore spatial directions, concurrently. Overlaying multiple signage elements, especially abstract patterns, is challenging due to obvious readability and usability issues. Moreover, the arbitrary use of wipe and scroll animations can cause patterns to clash, move over each other or across displays, making the signage disorienting and hard to understand.

Displaying individual signage patterns in a sequence (similar to signage presentation in [19][28]) ensures that overlap is avoided. However, as a trade-off, directions can only be shown for one destination at a time. As the directional pattern can use the entire screen space dedicated to wayfinding, it is likely to be visually discernable more easily, and the final destination easier to spot from a further distance. However, viewers are likely to have to wait for their directional pattern to be visible, which could mean waiting until the animation sequence recommences.

In contrast, a parallel displaying strategy as depicted on Figure 12, has the advantage that all signage is continuously visible on every display. On the other hand, it suffers from limited visibility due to the necessity to scale down the animated directional patterns to small, narrow strips.

t = 0s t = 0.5s t = 1s

Figure 7: Example frames of a coiling snake animation moving concurrently across three consecutively situated displays

(overlapping rectangles) during the timeframe noted below them. Red arrows indicate the direction of animations.

t = 0s t = 0.5s t = 1s

Figure 8: Example frames of a cannonball animation moving across three consecutively situated displays.

t = 0 s t = 0.5 s t = 1 s

Figure 9: Example frames of a horizontal animation moving across three consecutively situated displays.

t = 0s t = 0.5s t = 1s

Figure 10: A horizontal scrolling signage design, which consists of a graphical pattern (here a diagonal crosshatch) that is

animated sideways.

t = 0s t = 1s t = 2s

Figure 11: A sequential presentation strategy using a scrolling animation. Each display shows identical content consisting of

an animated directional pattern moving sideways. Each pattern is sequentially shown during a fixed time period.

t = 0s t = 0.5s t = 1s

Figure 12: Sample frames from a parallel display strategy for concurrent use.

Urgency. Common wayfinding systems include a notion of urgency, for example by showing the remaining time until a train is departing. Informing onlookers about urgency can also be achieved through a wide variety of visual clues, including quantitative information (e.g. “The train to Antwerp will depart in 10min”), relative placement (e.g. most urgent departure is ranked on top of a list), shapes (e.g. pulsating dots next to destinations) or dimensions (e.g. larger, taller announcements depicting increasing urgency), sound, etc. Varying the pulse rate of auditory and tactile urgency cues has been proven to be effective in conveying levels of urgency [18].

Design-Oriented Pre-study In order to determine the perceived usability of each of the proposed animated wayfinding design strategies, we first aimed to collect qualitative feedback from travelers. As such, we created a collection of 12-second animated videos demonstrating each design strategy within the setting of the train station corridor. These simulation videos showed each design strategy, including both wipe and scrolling animation concepts, different destination-marking techniques (i.e. blinking, impact effects and fading opacity) and urgency indicators (i.e. frequency, speed, size and order). These simulations were based on stabilized video footage edited in Adobe After Effects of the train station corridor, on which the different proposed display contents were digitally overlaid. In order to make it easier for

travelers to imagine the intended result, we conducted this study within the train station corridor itself. Out of 30 randomly approached travelers, ten people participated. Participants were shown the videos on a tablet computer (7.9” display) after which a semi-structured interview of approximately 10 minutes each was conducted. We interviewed train travelers from varying age groups, including foreign travelers.

None of the participants were able to identify the purpose of any of the animations without prior explanation. Often, the animated patterns were assumed to be related to the advertisements that were concurrently shown on the displays. We suppose this may be a result of the novelty of the wayfinding technique, the similar color palette used by the advertisements and our patterns, as well as relatively small display size of the tablet. After a brief explanation (e.g. “The animated patterns are designed to help travelers reach their destinations.”), most travelers were able to confidently interpret the wayfinding. Moreover, as soon as a participant was able to correctly understand a single design strategy, she was able to accurately interpret all other design strategies, indicating that people have little difficulty in mapping wipe and scroll animations to directional clues. Overall, the horizontal wipe animation was understood most frequently, followed by the cannonball animation. This led us to focus on the horizontal wipe animation during the in-the-wild study.

Color was often assumed to denote urgency instead of the intended indicators described above. Participants frequently guessed that signage colored in red was more urgent. Speed was the urgency indicator that was most often perceived correctly. Consequently, the preliminary feedback study provided no definite indications of which urgency indicator was most effective or efficient.

In-the-wild Evaluation Study We conducted an in-the-wild evaluation study in the railway station corridor, during which we aimed to test the effectiveness of the distinct animations, as well as parallel versus sequential design strategies. A total of 35 participants (nine females, three mixed groups, aged 16 to 75) took part in the study over the course of three weekdays. Participants originated from different regions of the country, along with three international travelers. 25 participants were recruited at the location itself and were, due to their time constraints, only presented with a single condition. Ten participants were recruited beforehand via an open call for participation that was distributed through several social media channels as well as a newsletter distributed by a public transportation advocacy group (i.e. TreinTramBus). As these ‘invited’ participants had more time available, they were requested to evaluate two conditions instead of one, including comparing them and explaining their personal preference.

Researchers observed and took notes of all participant activities as they performed a predefined wayfinding task.

These activities were also video recorded, the footage of which was later used as a reference to capture the task completion times as well as for identifying any moments of hesitation and errors, and any needs to search for what pattern to follow. For those participants exposed to two conditions, the quantitative efficiency results were only included for the first condition in order to limit any learning effect impact.

The four distinct conditions we evaluated are summarized in Table 1 and represent a combination of two design strategies in terms of concurrent wayfinding, and the indication of urgency. For each condition, the wayfinding was designed to host ten distinct destinations, and thus the same amount of directional patterns.

WipePar. This condition was based on animating the directional patterns into view on one side of the display and out on the other. All patterns were shown in parallel. Ranking the patterns from top to bottom, similarly to conventional timetabling schedules, showed the urgency.

ScrollPar. This condition used scrolling animations, while the different patterns were shown in parallel. Urgency was conveyed in a similar fashion as in conventional timetabling schedules, i.e. by ordering patterns chronologically from top to bottom.

WipeSeq. This condition used wipe animations, yet showed patterns sequentially. The urgency was depicted by the speed of animation, as patterns were animated faster to direct travelers to trains that were departing sooner. The condition used three urgency levels (i.e. low, medium, high), where each level doubled the animation speed.

ScrollSeq. This condition used scrolling animation, while the patterns were shown sequentially. The urgency of each wayfinding element was shown by its animated speed.

Directions through

Directions shown in

Urgency shown in

WipePar Wipe animation Parallel Order

ScrollPar Scrolling animation Parallel Order

WipeSeq Wipe animation Sequence Speed

ScrollSeq Scrolling animation Sequence Speed

Table 1: Summary of how each wayfinding dimension is encoded in the conditions evaluated during the in-the-wild

study.

Procedure The display content shown on all displays and during the whole study was recurrent: the content that featured our wayfinding system was shown for 12 seconds, and then followed by 60 seconds of regular advertising (i.e. 10 slots of 6 seconds each). During the study, two conditions were shown simultaneously, one on each side of the corridor.

Each condition was thus presented on the 16 back-to-back pairs of displays on one side of the corridor. Accordingly, participants were requested to solely focus on one single side of the corridor, which was relatively easy due to the large width and visual density of the physical environment. Overall, no participant showed any issues with only using a single side. Each pair of two simultaneous conditions was replaced at midday, so that all four conditions could be tested over the period of a single day. In addition, each day the paired conditions and sides of the hallway were alternated to limit the potential influence of any specific characteristics of each hallway side (e.g. presence of escalators, commercial activities) on the performance of participants.

Introduction. First, participants were introduced to the general purpose of the study as “exploring how consecutively situated displays can be used for wayfinding”. Next, researchers gave the participants a fictional scenario in order to convey a hypothetical sense of urgency: “Imagine being on your way to an important meeting that you cannot miss. In order to get to the meeting on time, you need to transfer to a different train in this unfamiliar train station.” The participants were handed a fictitious train ticket (see Figure 13), and were asked to “follow” the pattern printed on the ticket to reach their connecting train. We explained the participants that this pattern was integrated between the commercial content on the large public displays, and informed them that the pattern blinked on the display nearest to the platform of their connecting train.

Figure 13: Example of handout fictitious train ticket, featuring

the wayfinding pattern on the right-hand side.

User Experience. After completing the first wayfinding task, participants took part in a semi-structured interview to capture their experience based on their ratings of agreement on ten distinct statements. These statements aimed to rate their self-assessed ability to correctly interpret the signage, to remember the pattern during the task, to recognize the final destination, to understand how the urgency was represented, and to accomplish these aspects within the given advertising-to-signage ratio. Those participants with more available time were subsequently provided with a secondary navigation task using the concurrently scheduled condition on the other side of the corridor.

Advertising. We further asked participants to recall as many advertisements that were shown in between the wayfinding content as they could. We noted both the descriptions of the specific advertisements and the names of advertisers or products.

RESULTS AND DISCUSSION This section reflects upon the most significant implications of our results, and proposes a range of design considerations for future endeavors in animated, dynamic multi-screen signage

Understanding Wayfinding Our results indicate that no condition stood out in supporting participants to recognize and remember the signage they were assigned (see Table 2). For example, participants 1 and 3 (ScrollPar) mostly focused on the colors instead of the graphical patterns because they considered the patterns to be too small to be distinguished on the displays. Participant 24 (ScrollPar) added that the relative position of his signage in the whole list was the most helpful characteristic to identify it. However, this orientation strategy is challenging as the signage patterns were ordered by urgency and some would be removed from the list if the according trains departed. Another participant (wrongly) considered the order of signage to reflect the sequential order of the platforms in the train station (Participant 15: “I have to walk to platform 3?”, when her pattern was in the third position).

The parallel display technique meant that the signage for each destination became very narrow, and small. Some participants in WipePar and ScrollPar struggled with this relative small size as the contrast between the color and the pattern then became insufficient (e.g. participant 3: “The signage section at the bottom is too small and needs colors that are more different”). Similarly, WipeSeq and ScrollSeq caused less participants to ‘forget’ about what pattern to follow. While the colors and patterns were identical to the

ones in WipePar and ScrollPar, patterns in the sequential strategies took up considerably more screen space.

Design consideration. Maximizing the available screen space that a single signage element takes upon a display increases its: 1) understandability and 2) memorability, particularly when other wayfinding elements are shown simultaneously. The size of the wayfinding elements also plays a role in avoiding ergonomic side effects, such as color contrast.

Understanding Destinations Eight out of nine participants in ScrollSeq successfully reached their destination (avg. 95s, SD 35s). Furthermore, these participants recognized their destination from the furthest away (avg. 48m, SD 8m and avg. 3,83 displays, SD 0,69 displays). However, the uninterrupted visibility of patterns in ScrollPar supported participants more in reaching their destination (approx. 30%) faster than ScrollSeq. WipeSeq proved to be least effective in terms of participants arriving at their destination platform (n=3) as well as the duration required to travel (avg. 228s, SD 6s). Because of the fast-paced movement of the individual signage patterns sliding in and out of view, participants were required to approach the display to distinguish and interpret the animated nature of their signage. In addition, sequential representation makes travelers potentially lose precious travel time, as they may need to wait or slow down in front of a display in order to view their pattern within the signage sequence.

Some participants started walking immediately after they were given the task, probably in order to finish as quickly as possible. Others took some time to observe the displays before venturing further into the hallway. Among them, some (n=5, across all conditions) were able to recognize their destination immediately, even while still standing at their starting point. This naturally desirable outcome for a multi-display setup occurred most frequently in conditions ScrollSeq (n=2). Notably, the destination was typically only

Table 2: Summary of the main quantitative and qualitative results.

WipePar ScrollPar WipeSeq ScrollSeq Quantitative results Participants (n) 9 9 8 9 Successful arrivals (n, %) 4 44% 4 44% 3 38% 8 89% Time to identify destination (avg. s, SD) 81s 17s 61s 43s 228s 6s 95s 35s Distance to identified destination (avg. m, SD) 34m 5m 29m 15m 12m 2m 48m 8m Destination identified (n, SD) displays ahead 2,75 0,43 2,33 1,25 1 0 3,83 0,69 Advertising recollection (avg. n, SD) 0,44 0,68 1,25 1,48 1,14 1,36 0,89 0,99 Qualitative results (questionnaire using Likert, 1 to 10) Patterns are easily recognizable (score, SD) 3.3 3.2 6.0 2.6 3.6 2.4 5.8 2.2 Patterns are easily memorized (score, SD) 5.4 3.2 7.5 1.6 7.8 1.2 8.2 1.2 Destinations are easily recognized (score, SD) 3.0 2.8 4.4 3.0 3.3 2.1 4.6 2.7 Ads harm signage (score, SD) 6.8 3.7 6.4 2.5 4.2 2.9 6.4 2.6 Signage is pleasant to use (score, SD) 3.0 3.2 5.6 3.3 6.5 2.2 5.9 2.7 Urgency is easily understandable (score, SD) 3.2 2.5 2.8 3.2 3.7 3.1 2.7 1.9 Directionality is easy to understand (score, SD) 2.9 2.6 2.9 3.5 3.3 2.0 4.6 3.9

identified when participants paused or waited for the signage to reappear, instead of when they were walking around. This observation seems to indicate that identifying the destination signage could not be processed together with navigating the space, and therefore probably was cognitively hard to understand.

The rather large public space allowed participants to adopt strategic positions to observe the signage on multiple displays. Various spatial behaviors naturally emerged among participants in order to form an overview and understanding of directionality. In conditions WipeSeq and ScrollSeq, participants sought an appropriate position to interpret content on multiple displays ahead. Depending on their eyesight, they looked at between 2 and 6 displays ahead. They also moved sideways to find a suitable viewing angle, inwards (approx. 4m) towards the center of the corridor, to perceive multiple displays at the same time and to virtually connect multiple displays into a single synchronized element. In contrast, the smaller physical size of signage patterns appearing in WipePar and ScrollPar forced participants to stand closer and more directly in front of the nearest display (see Figure 14, approx. 2m).

Participants tended to focus on identifying a destination from afar instead of reading the directions of the animations. However, if a space does not allow for an overview of all screens from a single vantage point (e.g. spaces with small and jagged isovists [7]), animations across multiple displays may still serve to indicate a sense of directionality. As such, travellers could be stimulated to continue towards the subsequent displays and gradually progress and perform their wayfinding task.

Design consideration. In spite of the animated and distributed nature of the wayfinding, particularly the physical size of the signage determines the spatial behavior of onlookers. Accordingly, a sequential animation (dedicating more screen space to signage) is more conductive than a parallel strategy to identify destinations from further away. In the future, an equilibrium needs to be sought between visual legibility and information density.

Understanding Urgency ScrollSeq and WipeSeq mapped the sense of urgency unto the relative speed of the signage animations. While this was considered to be a “good idea” for some (e.g. participants 20, ScrollSeq), some noted that the sequential way of visualizing the signage in ScrollSeq and WipeSeq makes it “hard to compare urgency between patterns” (e.g. participant 2), as the different signage patterns are never simultaneously visible and as such can never be used as points of reference.

Over the course of the study some participants correctly learned that the order of patterns (i.e. ScrollPar and WipePar) indicated urgency, in that the trains at the top of the list departed first. This observation reveals how the contextual environment plays an important role in decoding

visual cues, and how people are able to use previous experience to decipher new visual metaphors. However, the order of patterns also led some participants to believe that it resembled the physical location of platforms (see subsection Understanding Wayfinding).

Figure 14: A participant takes different positions to identify patterns in a parallel condition (top image, close and almost

perpendicular to the display) and sequential condition (bottom image, further away at a spatially strategic vantage point).

Design consideration. Displaying urgency in animated ways requires a frame of reference to be able to interpret the meaning of dynamic cues, like speed. Some meaningful relationships to already familiar strategies helps in interpreting novel visual encodings. Here, a balance needs to be sought between adopting the functionalities of familiar techniques (e.g. order indicates urgency) and the possible confusion that they potentially create (e.g. resembling physical locations).

Integrating Wayfinding with Advertising For some participants, combining signage with advertising “is okay” and “adds value to the advertising”. However, others revealed their personal tendency to attempt to ignore public displays and advertising, a well-known phenomenon coined as display blindness [21]. In WipeSeq participants were most positive about the combination of both content types, because the sequential displaying of wayfinding signage required them to pay attention to the pattern sequence (e.g. participant 23; “I did not really see any advertising. I focused on the signage”). However, because it required considerable attention and patience (e.g. waiting for their intended signage), this condition resulted in the fewest successful arrivals and the highest time to identify

the destination. When participants in this condition were asked how many and which advertisements they remembered, typically only one could be recalled. We learned that participants struggled with the 60-second interruption during which full-screen advertising was shown and the wayfinding signage disappeared. In conditions where participants were more successful in quickly identifying the destination, this advertising duration was commonly perceived to be excessive. Here, participants needed to pay less attention to identifying and interpreting the directionality of their pattern, and thus became more disturbed by its disappearance due to adverts (a contextual constraint we could not avoid).

Most participants expected the continuous visibility of the wayfinding. The intermittent interruption of the wayfinding signage is an obvious harmful requirement in time-sensitive transit environments. Some participants mentioned that there may be a need for finding more optimal signage-to-advertising screen resolution ratios, such as by increasing the overall height of the signage and reducing the overall height of advertising. However, doing so would require content designers to redesign most the available adverts that commonly follow predefined screen resolution standards. Alternatively, one could imagine that wayfinding is shown alongside advertising on a single or few displays, whereas the others show full-screen adverts. The display on which signage is included could then alternate from display to display in an animated fashion.

Design consideration. Combining wayfinding with advertising on public displays is generally positively received, and might be a suitable strategy towards overcoming the issue of display blindness. Different design strategies can be imagined of how such a combination could occur in practice, out of which our study only tested a relative small portion. Our insights reveal the importance visibility on each individual display as well as across multiple displays to support wayfinding in each spatial display configuration and identifying destinations from afar. A suitable screen sharing strategy and an efficient signage to advertising ratio can warrant visibility.

Wipe Animations While we anticipated a positive effect of wipe animations (i.e. in WipeSeq and WipePar) due to their more spatial approach to directions, ScrollSeq proved to be more successful in guiding participants to their destination (success rate of 89% vs. 38% and 44%). ScrollSeq was rated positively in terms of readability of signage directions (avg. 4.6, SD 3.9). The fast moving patterns of the Wipe conditions and the small size of the patterns in both Par conditions made directions difficult to interpret. Participants showed difficulties interpreting what was meant with “reading directions”. However, participant 16 (WipePar) noticed and understood the signage but expressed concerns over the accessibility of the animated patterns: “for my mother, the answers would be very

different.” Another indicated that the fast and pulsating movement of the patterns raised challenges to identify which patterns were blinking; “they’re all going across, so you can’t distinguish which one is flashing” (participant 6, WipePar). These results suggest that aesthetically interesting visual effects to symbolize movement impeded the recognition of the destinations and interpreting the movement as directions.

Design consideration. Our observations and interviews reveal three challenges that come with wipe animations.

1. Functional. Interpreting the directionality of visual elements that move in and out of the display space seems more cognitively challenging than of stationary elements, which appear and disappear, or of elements that continuously scroll about.

2. Spatial. Interpreting animations across multiple public displays may not align well with the actual spatial or contextual configuration, as people or physical structures may interrupt the required sightlines. Scroll animations are less spatial in nature but therefore also less complex and visually intense, which seemed advantageous, especially in case of the conditions with sequential signage presentation.

3. Ergonomic. Identifying a single element between many moving individual elements may be further complicated when these elements are relatively small. In addition, dedicated head or eye movements may be required in order to follow the visual animations over multiple displays. The limited physical movement of Scroll animation as compared to Wipe animations results in more easily identifiable patterns.

Self-reported Qualities Many participants recognized various advantages of using existing public displays to represent wayfinding over using their personal handheld devices. Participant 12 and 9 (ScrollSeq) point at the quality of no longer having to hold a device to navigate a complex space, in particular when “in a hurry and while carrying luggage”. Participant 2 (ScrollSeq) explains that he thinks that “for a simple trip this is easier than a smartphone app” because there is no configuration required, the path to the destination is straightforward, and there are less distractions along the way. Others confirm the “big advantages” such as “being more accessible [than a smartphone]” (participant 2, WipePar), but expound that there is a steep learning curve to overcome (participant 29, WipePar) in order to establish the technique as a new wayfinding system. In contrast, the relatively small screen area containing our signage led some participants to consider a smartphone to provide “more overview” (participant 18, WipeSeq) and being “a very familiar device” (participant 28, ScrollPar).

Multiple participants compared the signage to today’s wayfinding by way of cellphones, mitigating the need for a mobile data subscription (e.g. “I don’t have Internet on my smartphone. Nowadays it’s often required, but I like having

alternatives” (participant 19, ScrollSeq)). Travelers do not need to check a central schedule to verify their platform; they can head straight to the right destination by following the appointed patterns.

While our study involved holding a printed-paper ticket, the same signage pattern could also be displayed on smartphones, smart watches or other digital devices. However, for some participants the introduction of the patterns raises new challenges to support people with particular needs (e.g. restricted eye sight or colorblindness). We envision our approach to be suitable for application in other environments with less fixed schedules or variable wayfinding, such as airports.

Design consideration. Identifying wayfinding signage by way of abstract visual patterns has potential in overcoming the necessity of financially affording, or being distracted by, today’s personal, digital devices. Yet it still necessitates overcoming several important usability and accessibility issues, especially in minimizing the required cognitive effort in terms of remembering and identifying a particular pattern among others, as well as considering how such visual means can include impaired people (e.g. visually impaired).

CHALLENGES AND LIMITATIONS To the best of our knowledge, our experiment is the first to study wayfinding by way of animating signage on multiple, consecutively situated public displays. By executing the whole study in the relatively large, complex and real-life public context of a metropolitan train station, we identified several insights that would have been otherwise overlooked. In addition, we also encountered following challenges.

Wayfinding. As our preliminary study indicated, travelers did not intuitively interpret animated patterns or colors as a form of wayfinding signage. Although more visually distinctive colors and patterns were used during the evaluation study, researchers were still required to briefly explain the use of this wayfinding concept, e.g. “Watch the displays and follow the movement of the pattern on your ticket to where the pattern is blinking”. Yet, we believe our results still demonstrate the impact and value of spatially distributed wayfinding in conjunction with the consecutive placement of public displays on traveler behavior and navigation performance, regardless of how the signage encodes destination, including color, text or symbols, which each carry their own specific disadvantages (e.g. readability, scalability).

Multiplexing. Any in-the-wild field study typically involves a wide range of stakeholders. In this study the numerous stakeholders were comprised of the public display owner, the content provider and designer, the advertising agency, the railway operator, the railway station manager, the local security services, the train station’s public relations department and the health and safety services. We had to collectively align their expectations and

concerns prior to conducting the study, and work within the limitations of their voluntary willingness to collaborate. Content providers needed to alter established procedures to allow for displaying wayfinding signage and cater for the synchronized content: different content had to be programmed for each display and each side of the hallway and a complete change of content at midday had to occur.

While we preferred, and originally had designed for, a continuous space-multiplexing solution, we were confronted with the practical limitation of showing the wayfinding only during 6 (and then after negotiation 12) seconds. In practice, our conditions thus represented a time- and space multiplexed solution. In spite of the relatively short duration during which the wayfinding was usable, we believe this approach was the most optimal and valid within these constraints as well as the ethical concerns of conducting an explorative in-the-wild study within a heavily frequented public context. However, these specific timing and scheduling challenges might be mitigated in future studies as public display advertising becomes increasingly interactive.

While we had thoroughly introduced this constraint to participants, some had expected the signage to reappear more frequently. The intermittent and relatively long disappearance of the signage led some participants to feel disoriented, and some managed to walk across the entire hallway without observing any signage. Hence, the quantitative measurements of the wayfinding performance are likely skewed towards the negative side, particularly when judging the general potential of our wayfinding technique. As this skewedness is shared among all conditions that were evaluated, this study instead describes the qualitative and quantitative differences between the different design strategies, rather than making definitive statements about the value and potential of synchronized signage on multiple consecutively situated public displays in general.

Study Deployment. Recruiting participants in a railway station is challenging since most people walk around with a clear and urgent destination, and thus have a few minutes to spare at most. In addition, our instructions and questionnaires were only available in Dutch and English, which not always corresponded to the preferred language of potential participants who were therefore reluctant to participate. Consequently, this language barrier led some participants (n=5) to take part but quit before finishing the task due to difficulty in understanding our instructions or explanations. Results from those who did attempt to finish the task and took part in the interview (n=4) were included but language skills influenced the quality of qualitative feedback.

Spatial context. We specifically chose to present each condition on a single side of the corridor at a time to increase the number of evaluated conditions in the available timespan and to allow participants to compare them.

Simultaneously presenting the conditions on both sides of the corridor could have had an effect on its usability, experience and performance, yet our results lead us to believe that the influence may in fact be negligible, as participants did not seek other orientation clues and focused solely on a single side of the corridor.

FUTURE WORK We believe that the intrinsic quality of our animated, consecutive display wayfinding concept is particularly suited to the specific architectural layout of the train station corridor and its linear distribution of the public displays. The widespread availability of such architectural layouts should however not be expected to become the new norm. Hence, we believe further research is required to investigate how synchronized signage is possible in other environments (e.g. complex airport environments), under different display configurations (e.g. less distributed displays) or for varying scenarios (e.g. urgent evacuations). Additional research opportunities also exist in unraveling the scalability of our wayfinding strategy, such as in environments where the intended directions are not linear or the physical layout is more complex.

We also imagine that wayfinding animations can be designed and better orchestrated to synchronously run across multiple displays to create the visual illusion of objects moving from one display to the next. The resulting directionality might even become more spatially grounded. While this effect has already been used for specific advertising campaigns (e.g. to simulate a car driving from one display to the next along an escalator [30]), its potential application for wayfinding remains untapped. Both wipe conditions seemingly provided a sense of spatial movement due to their speed and animation timing. Based on our results, we assume that the impact of such well-synchronized cross-screen animations may be relatively limited or even worse than our Wipe conditions. The individual signage elements will be visible even more briefly on each display. Particularly the functional and ergonomic challenges as described for our wipe conditions will probably become amplified, as users will be required to visually track and interpret even more sophisticated and spatially distributed movements. Future research is required to assess this prediction.

We imagine potential use cases of our wayfinding system in combination with indoor location tracking technologies, such as Bluetooth beacons (e.g. iBeacon). For instance, our signage could only be shown on public displays in the immediate vicinity or within viewing or reading distance of each user. These dynamic capabilities have the potential to improve the overall usability, as more space can be devoted to show individual patterns in the parallel conditions or more replays can be run in the sequential conditions. Such usage scenarios could be particularly apt in semi-public spaces such as museums, hospitals or offices, where Bluetooth beacons can be deployed without requiring users

to bring or hold personal devices, and where privacy concerns are relatively limited.

CONCLUSION Wayfinding in public spaces typically relies on identifying and following static, alphanumeric or symbolic elements. We have introduced a novel technique that combines colors and patterns with geographical significance, shown in a synchronized fashion over multiple spatially distributed public displays. This paper reports on how such multiple, consecutively situated public displays can be exploited to provide a new kind of synchronized, animated wayfinding system. We determined the design requirements for such a system and described the design rationale of several suitable signage design strategies. During a three-day in-the-wild study we compared four distinct design strategies that aim to support concurrent use, provide directions and indicate urgency.

No definitive indication was found of which urgency conveyor is more intuitive; either the speed of animating visual elements or the order of their representation. Still, our results indicate that the use of animated graphical patterns is a suitable approach to conveying wayfinding information in a public space under very specific conditions. People are able to remember and recognize these patterns and recognize destinations when signage is visible for a sufficiently long time, when it is large enough to be observed from a distance, and when it is animated without sliding in and out of view.

Due to several contextual challenges and stakeholder requirements we used a parallel signage and advertising combination strategy. While this ecologically valid combination resulted in some negative impact on overall usability and user experience, we believe further research can investigate how to better balance multiple simultaneous content types on public displays.

ACKNOWLEDGMENTS The work presented in this paper is part of TraPIST, a project co-funded by iMinds, a digital research institute founded by the Flemish Government. Partners in this study are Digitopia, TreinTramBus (with project support from IWT), Clear Channel Belgium and NMBS/SNCB.

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