Niels Henze
email: niels.henze@uni-oldenburg.de

Susanne Boll
email: susanne.boll@uni-oldenburg.de

It does not Fitts my data! Analysing large amounts of mobile touch data

Keywords: Fitts' law, mobile phone, touch screen, app store, large-scale

Touchscreens are the dominant input device for smartphones and learning about smartphone users' touch behaviour became even more important. We developed a game for Android phones to collect a truly large amount of touch data from diverse devices and players. A part of the game is designed as what we expected to be a Fitts' law task. By publishing the game in the Android Market we collected 5,359,650 micro tasks from 63,154 installations of the game. Using Fitts' law to find a model for these tasks we found a very weak correlation and an implausible high index of performance across different devices. Further analysis shows a similar correlation between time and distance as with Fitts' law but only a very weak correlation with the targets' width.

Background

Fitts' law [START_REF] Fitts | The information capacity of the human motor system in controlling the amplitude of movement[END_REF] is a model of human movement that predicts the time required to rapidly move to a target. It describes the correlation between the distance to a target and it's width with the time to reach the target. [START_REF] Mackenzie | Fitts' law as a research and design tool in human-computer interaction[END_REF] describes Fitts' law as "one of the most robust, highly cited, and widely adopted models to emerge from experimental psychology" [START_REF] Mackenzie | Fitts' law as a research and design tool in human-computer interaction[END_REF]. The index of performance (IP), that is determined using Fitts' law, enables to compare different input devices and is even proposed by ISO 9241-9 [START_REF] Douglas | Testing pointing device performance and user assessment with the ISO 9241, Part 9 standard[END_REF] for this purpose. Fitts' law has been applied to a wide range of devices, including mouse, touchpads, and trackballs [START_REF] Mackenzie | Fitts' law as a research and design tool in human-computer interaction[END_REF]. The IP was used to compare these devices and we assume that the IP can also be used to assess the quality of smart phones' touch screens.

To collect data from a number of different devices, in a natural usage context, and a sufficient number of participants we developed a game and published it in the Android market. The game requires touching targets and records the players' behaviour. A part of the game is a task that requires to sequentially tapping simultaneously presented circles. Using data from 63,154 installations of the game and considering tapping each but the first of the simultaneously presented circles as a task we collected 5,359,650 tasks.

Collecting Touch Data in the Large

The gameplay of Hit It! is inspired by the task used by Park et al. [START_REF] Park | Touch key design for target selection on a mobile phone[END_REF]. Circles are displayed on the screen (see Figure 1) and the player has to touch these targets. Each level consists of multiple micro levels. Different target sizes are used in each level. In most micro levels, one circle is presented to the player. The player advances directly to the next micro level as soon as the target is hit. If a target has not successfully been hit in a certain time frame it is counted as a miss. Every fifth micro levels consist of multiple simultaneously presented targets. As soon as a target is successfully hit it disappears. The player must hit all targets to advance to the next micro level. To make a game out of the two basic tasks the player must complete a micro level in a certain timeframe. The time is reduced from micro level to micro level while the player proceeds through a level. The player receives a penalty point if a target has not been hit and the game is lost when the player collected three penalty points. The faster players hit the targets the more scores they get. We do not collect data that allows identifying individual players or installations. We still decided to clearly inform players about the fact that data is collected in order to act ethically. A modal popup (see Figure 1) shown when the game is started for the first time tells the players that data is collected for research purpose while the game is played. Data about the used device and the performance of a player is collected by transmitted the data to our server. A unique identifier for each installation is derived by hashing the device's "Android ID". We also collect the user's locale (e.g. "en_GB") and the device's type (e.g. "GT-I9000" for Samsung Galaxy S). Most importantly, we record the position and size of the targets for each micro level. We also record the position of each touch event and the time elapsed since the start of the micro level. We published Hit It! in the Android Market on October 31, 2010. Till April 04, 2011 the game was installed 192,250 times1 .

Applying Fitts' Law

When developing the gameplay we designed two tasks. The first task is just tapping a single target but the second task was designed to be a Fitts' law task. In the following we analyze the data from the second task using Fitts' law and investigate the correlation of movement time with the target's distance and width afterwards.

Correlation and Throughput

In order to apply Fitts' law we use the Shannon formulation proposed by [START_REF] Mackenzie | Fitts' law as a research and design tool in human-computer interaction[END_REF]. We only consider micro levels where multiple circles are presented simultaneously, the device is held in an upright posture (according to the phone's accelerometer), and the level's error rate is below 4%. When the player hits the first circle the touched position and the current time is used as the start for the first task (see Figure 1). MT is the time that elapsed until the second circle is hit. D is the distance from the position of the first tap to the centre of the second circle and W is the diameter of the second circle. Analogical we proceeded with the other targets using the touched position that hit one circle and the according subsequent circle. Thereby multiple tasks are derived from a single micro level.

With the described approach we determined 5,359,650 tasks from 63,154 installations. Using linear regression we determined a (intercept) and b (slope) and found that a=.200 and b=.040. The correlation of the data with the resulting formula is r=.14.

The index of performance (

) is IP=25.01. As the determined IP is implausibly high (highest IP reported by [START_REF] Mackenzie | Fitts' law as a research and design tool in human-computer interaction[END_REF] is 13.7 for an eye tracker) and the correlation is very weak ([3] reports correlations between .70 and .99) we selected the considered data more carefully. Using only data provided by 4,873 installations running on a Samsung Galaxy S (292,515 tasks), the most common device in our dataset, results in a=.207, b=.029, and r=.13. With 34.57 the IP is still implausibly high. Considering only tasks from one particular level (992 installations, 5,328 tasks) results in a=.176, b=.060, r=.33, and IP=16.55.

One reason for the unsatisfying correlation might be the small screen size of the Samsung Galaxy S (4.0in diagonal size) that does not require moving the hand but only one finger. Therefore, we repeated the analysis for the Samsung Galaxy Tab (352 installations, 2,134 tasks) that has a screen with 7.0in. Again only tasks from one level are considered. Using linear regression we determined intercept and slope and found a=.165 and b=.063. The correlation of the resulting formula is r=.33 and the index of performance is IP=15.80. Regardless of the way we constrain the dataset, the IP is unlikely high and the correlation is weak for all tested devices. While the high IP only suggest that the used task might be different from what is commonly used as Fitts' law task, the rather low correlation shows that Fitts' law is not a good model for the used tasks.

Correlation with Targets' Width and Distance

In order to investigate why Fitts' law cannot be used as a model for our data we analyzed the data in more detail. We tested the correlation with the target's width and the distance to the target independently. For a true Fitts' law task one would expect that there is at least a weak correlation with both aspects that are composed in Fitts' law. As the measurement unit is not crossed out when looking at width and distance separately we have to treat each device independently.

Using again the data from one level provided by the Samsung Galaxy S (992 installations, 5,328 tasks), the correlation between time and distance is r=.33. Compared with the correlation using Fitts' law (also r=.33) the difference is very small. This suggests that most of the variance that can be explained by the correlation with ID can also be explained by the correlation with the distance to the target. Determine the Pearson correlation between time and width using the same dataset results in r=.11. Testing different functions (e.g. log 2 (W), 1/W, log 2 (1/W)) does not reveal a higher correlation.

Discussion and Future Work

Analyzing the data that resulted from players that touch a sequence of circles we found only a weak correlation when applying Fitts' law as a model for the data. Furthermore, the IP is implausible high. Further looking at the data we found a similar linear correlation between time and distance as if using Fitts' law. In contrast we found a much smaller correlation between time and the width of the target. Our results suggest that, for our task, the time required to hit a target partially depends on the distance to the target. A target's width, however, has a much smaller effect on the time required to hit a target.

The results presented in this paper are only a fraction of what can be investigated using the collected data. Further analysis showed that touch positions are systematically skewed and a compensation function that shifts the users' touches can reduce the error rate [START_REF] Henze | 000 Taps: Analysis and Improvement of Touch Performance in the Large[END_REF]. An area we consider interesting for future work is investigating touch sequences. How a target is hit might not only depend on the target's size and location but also on preceding touch contacts and the elapsed time. Applying such findings might result in a function that shifts the touch events to improve the users' touch precision that in generally applicable. We would like to share the data with other researchers to enable further analysis2 .

Fig. 1 .

 1 Fig. 1. In-game screenshots of the game (left), information presented to the player when the game is started (centre), and how W & D are derived for Fitts' law (right).

Number of installs according to Google's Developer Console.

The complete dataset can be retrieved from http://nhenze.net/?page_id=673


Paul Gault
email: p.e.gault@dundee.ac.uk

Catriona Macaulay
email: c.macaulay@dundee.ac.uk

Graham Johnson
email: graham.johnson@ncr.com

Judith Masthoff
email: j.masthoff@abdn.ac.uk

Structuring the Collaboration of Multiple Novice Design Ethnographers: Towards a New User Research Approach

Keywords: Ethnography, Crowdsourcing, Fieldwork, Innovation, Methodology, Public Space

This paper proposes a new design research method to support businesses engaging in the innovation of products and services intended for use in public spaces. Increasing numbers of companies are turning to detailed user/consumer research often based on ideas from the design ethnography community. In an increasingly complex and fast moving business world, there is a need for faster user research that also provides a wider focus on the situation under investigation. A potential solution is using a larger number of fieldworkers on one study. As it would be difficult and costly to utilise many experienced design ethnographers, this may also involve the use of novices. This paper describes the development of a method for adapting existing practices to the emerging context outlined above (i.e. large numbers of fieldworkers, not all of whom necessarily have experience in ethnography). We discuss 3 field studies that show how the method can be applied and how it has been fine-tuned based on the outcomes. This method involves multiple groups of fieldworkers situated at a range of public spaces and each assigned with a specific theme of interest. The wealth of material that this fieldwork activity produces is then digested and insights are generated from it to help inform an understanding of existing behaviour within public space. This paper shows that fieldwork can be reduced to a set of simple tasks that can be successfully distributed over a group of novices facilitated by an experienced design ethnographer. This work will be extended further so that it can be applied as part of a toolkit for use in businesses where there is no established culture of utilising this type of user research.

Introduction

We will address the problem of providing ethnographic research for an increasingly complex and fast moving business world. This type of activity usually takes a long time to perform and is very specific in what it is observing. Our aim is to create a methodology to help explore the problem space in a short space of time with people who do not necessarily have a background in design ethnography. An objective of this is to have a broad focus on the subject matter so that there is a wide range of perspectives on what is being observed.

As a case study, we will try to identify opportunities for collaborative technologies situated within public space that encourage social interaction. Some examples of the kinds of new systems researchers and companies are interested in are digital signage, ubiquitous computing and mobile technologies. As public space is such a large context, we require a solution that will help us to understand the huge variety of activity going on there at any one time. Instead of a small number of fieldworkers taking many weeks to understand each of the perspectives of people who inhabit the space, a potential solution is to gain multiple viewpoints from many people making observations at the same time. We created a set of very broad themes that could be interpreted in multiple ways so that there would be a variety of approaches to gathering the fieldwork data. We will discuss the design and evaluation of the materials used to facilitate the fieldwork activity.

In essence, we will suggest a method for distributing fieldwork across a group of novice observers, reducing the fieldwork activity to a set of simple tasks. These tasks will be framed and facilitated by an experienced design ethnographer who will produce the support materials and lead the analysis workshops. The idea of using a group of people in fieldwork has similarities with Open Source development [START_REF] Benkler | Coase's Penguin, or, Linux and the Nature of the Firm[END_REF][START_REF] Weber | The success of open source[END_REF]. In Open Source development, the community is encouraged to apply their skills to extend existing software. Our proposed methodology will provide more structure to the tasks requiring less expertise from participants. The idea of involving non-experts in fieldwork has similarities with crowdsourcing [START_REF] Howe | The Rise of Crowdsourcing[END_REF]. In crowdsourcing, well-defined tasks that are traditionally performed by employees are outsourced to an undefined large group of people via an open call. Our approach will not necessarily use an open call to recruit participants, and will involve more explicit continuous collaboration between the participants.

To illustrate our method, we will discuss a set of studies using observations of the interactions taking place in social spaces such as shopping centres, city squares and railway concourses. The outcomes of these studies provide an insight into how to design for such contexts along with techniques for managing this process.

In section 2 we will describe the other relevant literature that has helped to inform the development of our methodology. In section 3 we provide an overview for each of the main activities that constitute up our method. We explain how the method was first deployed in section 4 then subsequently refined and applied an additional two times in section 5. Finally, in section 6 we will detail the conclusions that were arrived at and indicate potential future work.

Related Work

Design ethnography requires a set of custom techniques that can be adapted from their roots in anthropology to suit the requirements of new product development [START_REF] Salvador | CHI 97 tutorial: Design Ethnography: Using Custom Ethnographic Techniques to Develop New Product Concepts[END_REF]. Previous studies have shown the application of ethnographic techniques using short timeframes [START_REF] Millen | Rapid ethnography: time deepening strategies for HCI field research[END_REF] but the possibility of working with a number of fieldworker observations has not been explored.

We aim to use fieldwork to drive a broad exploration of the problem space. The analysis and synthesis of fieldwork observations will help to uncover new opportunities for the interactive systems we are interested in.

The normal limitations of fieldwork-based techniques include issues related to time, breadth and generalisability [START_REF] Myers | Investigating information systems with ethnographic research[END_REF]. Fieldwork can be a very time consuming approach; doing both the observations and analysing the gathered data. It lacks breadth as it typically only studies one organization or culture in a specific time period, so offering in-depth knowledge only of particular contexts and situations. The generalisations arrived at from one study may be subjective as the researcher may have imposed an interpretation on what has been observed (different people may observe different things). We propose to use this subjectivity to our advantage as a way of channelling the observations from a variety of perspectives.

The initial stage of the methodology is the gathering of the fieldwork data. This will involve sending our participants out into a large public space with a set of themes that can help to guide the observations they make. Similar approaches [START_REF] Zeisel | Inquiry by design: environment behavior neuroscience in architecture, interiors, landscape, and planning[END_REF] have shown that this technique will support the fieldworkers as they gather material by focussing on a specific topic of interest. Each theme will be explained using a reference card alongside a map of the physical space that they must make their observations within. The usage of reference cards to help explain a design methodology is a wellestablished concept [START_REF] Ideo (firm | IDEO method cards[END_REF]. We will use this technique as a way of co-ordinating the observations made by our group of novice fieldworkers.

For the second part of our methodology, we will undertake an affinity-mapping workshop where we analyze the fieldwork data using the initial steps of a grounded theory approach, namely open coding [START_REF] Strauss | Basics of qualitative research: techniques and procedures for developing grounded theory 2nd[END_REF]. This is appropriate, as it will allow new themes to emerge from each fieldworker's individual field notes. The process of combining these themes will also allow us to arrive at a set of new-shared themes derived from all of the participants' fieldwork data.

Bringing together all of the field notes from the individual fieldworkers will involve the creation of an affinity-mapping diagram. Affinity mapping is originally based on the KJ-method [START_REF] Kawakita | KJ method: A scientific approach to problem solving[END_REF], which develops themes into insights and helps identify the relationships among many issues. This technique will enable the group to consider the results of all of the observations made during the fieldwork activity. The outcome of this will be a KJ image that shows an externalized mental map of the fieldwork observations made by the group. This will help to show the broad themes relevant to the problem alongside the data they are derived from. This is a useful process as, by its nature, it is an activity that must be done fast encouraging a systemic response to the overall problem [START_REF] Beyer | Contextual design: defining customer-centered systems[END_REF] instead of slowly going through with point-by-point solutions to each problem that is identified. During the workshops we will use the physical space to support the collaborative analysis work. The ability for large media to support many people collaborating in the same physical space [START_REF] Pang | Thinking Big: Large Media, Creativity, and Collaboration[END_REF] will help our participants arrive at a shared understanding of the fieldwork material they have collected. This will enable them to discuss the detail of each individual's fieldwork notes and relate this to the material that other participants have contributed.

In our method, we ask broad exploratory questions first. When working in an industry setting, it can be very difficult to be very specific at the outset. For example, "find the next killer application" might be the first question that a company asks when exploring a new area. By keeping it as broad as possible initially, this gives us enough space for any potential solutions (including unexpected ones) to be explored. The data analysis may result in more specific questions that can then be investigated in a new round of fieldwork.

Proposed Methodology

We will provide a brief summary of the method and then we will go into greater detail by explaining each of the main stages that were followed. Firstly, we broke down our problem of identifying opportunities for collaborative technologies situated within public space into 4 themes. We prepared materials for the participants to refer to whilst out in the field and assigned 2 person teams to work on each theme and placed them at different locations. The fieldwork observations took place on a single day where a large amount of data was recorded. This material was then brought back into the studio, shared with other group members and consolidated into a secure online space. Finally, a workshop was held where the group ruminated over the material they had gathered and some directions for further research exploration were identified. The four main phases of activity were:

-Materials preparation -Fieldwork observations -Dump & distil -Affinity mapping workshop

Materials preparation

A set of briefing cards was designed for the participants to refer to whilst out in the field making their observations. This gave each of the teams a key area to focus on both conceptually and physically. One side of the card detailed a research theme with a title and a set of questions whilst the reverse of the card had a map marking out where the observations were to be located. The research theme was a title followed by single sentence along with 3 example questions loosely related to the theme. The cards were A5 size so they were small enough for the participants to keep in their pocket and so easily referred to if needed. The cards were also laminated to make them robust in case the weather conditions were not favourable.

Fieldwork observations

This phase of work is where the participants go out into the field and make their observations. The participant group were split into equal numbers of people and each team was given a briefing card containing a specific theme. The whole group were briefed before setting off to make their observations. It was suggested that one person take the role of writing notes and another person of capturing visual material. If it was felt necessary, the team members were free to switch roles at any point during the exercise. The importance of keeping communication flowing between members was stressed so that there was a shared plan of action for what was being observed. The teams were encouraged to take plenty of breaks, as making the observations can be quite an intensive exercise. During these breaks, they were able to use the opportunity to talk about how the task was progressing. The teams were asked to keep any observations in context so that they were mindful of the environmental conditions, time of day and density of people in the space they were observing.

Dump & distil

This is the process of putting all the fieldwork data into a form so that it can be worked with further. It began as soon as the observation activity was completed. The teams were asked to write-up another version of the scratch notes they had recorded immediately after making their observations so that nothing was forgotten, as this would easily happen otherwise. The whole group came together to discuss their observations and reflect upon the process they had gone through whilst out in the field. From the outset, the group were encouraged to remain analytical about their observations by not jumping ahead into thinking about designing new solutions. They were asked to discuss their strategy throughout the task, how they interpreted the individual research questions and how they approached working in each location. The group were guided to create backups of all their notes in case they were lost and also, they could be easily shared with each other. To facilitate this, secure network drives were created where everyone was able to pool their data for further analysis.

Affinity mapping workshop

The final part of our method involved a workshop to help reach a shared understanding of the material that had been gathered. The teams were asked to make a pass through their fieldwork data and extract items of interest onto post-it notes. Each team was guided to use 1 colour of post-its and initial each note so that if necessary, the data could be queried later on in the process. Once the groups had written out their notes, they started to arrange them into sub-groups and used index cards to write headings above the groupings. A photograph of each team's notes was taken at this point so if needed, the layout of notes was saved and would be referred back to later on. The final part of the workshop involved all of the teams pooling their data together to see what overall findings could be arrived at. This involved taking down the sub-headings from each group and arranging these into super-headings across all of the groups. The original post-it notes were pulled into these new super-headings so it could be seen how appropriate they were. It should be stressed that this activity can be repeated a number of times to see if the same or a different understanding is reached.

Field study 1 4.1 Study Design

Following the results of our previous Urban Traces study [START_REF] Gault | Urban Traces -A Pilot Study into Public Space[END_REF], we decided to develop our methodology by creating a number of themes and targeting specific physical spaces related to them.

Questions

The research questions for the fieldwork observations were split into 4 different themes. Each theme was explained using a sentence outlining the focus of the observations and then 3 follow-up questions that the participants were asked to try to answer. The themes, explanations and questions were as follows:

Connections Observe how people navigate their way through physical public space using the way finding systems that are present. How useful are the existing way finding systems? Where do clusters of people and flows of activity occur? What would happen if the way finding system were to fail?

Transactions Observe how the exchange of information, goods & services is facilitated. What are the social norms and practices taking place around self-service kiosks? How are people using public space as a platform for collaboration? Where is technology being used and why?

Interactions Observe how people interact both with each other and with the systems that are present in public space. How does the space affect the way in which people behave? Where is one-to-one & one-to-many communication occurring? What kinds of technology are present and why are they there?

Conversations Observe the patterns in behaviour for ways in which people congregate in public space. What are the differences between how large groups of people behave in comparison to small groups & individuals? How does the physical layout affect places that people gather? Where are the empty spaces and why are they so?

Participants

Fourteen students on a Masters of Design Ethnography (MDE) participated in the study (4 male, 10 female). The course teaches students to perform user research and explore how this is incorporated into the work of companies globally. The participants were grouped into teams of 2 so that the different activities could be shared out within each team.

Location

The city centre of Glasgow was used to carry out the fieldwork activity. Glasgow is the largest city in Scotland so there would be a relatively high volume of activity on the day of the fieldwork. Four separate physical spaces were set out to match the research themes. The connections teams were located in Glasgow Central train station; the transactions teams were located in a shopping centre called The Buchanan Galleries; the interactions teams were located in Buchanan Street and the conversations team was located in George Square. Prior permission was sought to make observations in the train station and shopping centre locations. No permission was given to take photographs or record video in these locations, so these particular teams had to rely on note taking and sketches to record their observations.

Materials

Each group was given a plastic wallet containing: a briefing card, sketchbook, notebook and pencil.

Procedure

The study was split into 3 sessions: -Fieldwork: a trip to Glasgow to carry out fieldwork observations. -Dump & distil workshop: The group discussed the process of carrying out the observations and explored ways of presenting the gathered material. -Affinity mapping workshop: Participants analyzed and synthesized the fieldwork notes and other types of data. The purpose was to arrive at a set of insights based on the observations that each team had made. Following on from this, the group tried to make overall sense of activities that had gone on that day across all of the original themes.

Fieldwork

The fieldwork activity began with a briefing in the city square. Participants were put into pairs, creating 7 teams and then the briefing packs were issued. The teams were given the option of assigning roles themselves but it was suggested that they split up the activity so that one person had the role of keeping notes and the other person the role of drawing sketches visually representing any observations. They were encouraged to keep communication flowing between each other whilst working on this activity. The teams were asked to use the materials provided within the pack to help record their observations. The interactions and conversations teams, who were working outside, were also asked to use a digital camera to take photographs. The transactions and connections teams were working inside so had to rely solely on written notes and drawing sketches.

We scheduled 2 bursts of activity to take place on the day of the fieldwork. The first period lasted an hour and half, which allowed each of the teams to become acquainted with the research questions and familiarised with the locations where they were observing.

After the first burst of activity, the group gathered at a cafe to discuss how the fieldwork was going. This enabled them to talk about any problems that had occurred in the first pass of their separate spaces. Some issues that arose from this discussion were:

-Feeling overly visible whilst note taking and strategies for taking notes discretely.

-Having difficulty to decide what to focus on when there was too much happening at once to be able to record everything. -Pretending to do something else other than observing so that the notes could be memorised and then recorded shortly after.

Once the group had finished their discussion, they split up once again into their individual teams and set off back to their designated spaces. This gave them another hour to make some further observations.

Dump & Distil Workshop

A week after the fieldwork, participants were asked to discuss how they managed the fieldwork process and how they interpreted the research questions that were set. They also answered questions related to the design of the study, the location and their use of the materials provided.

Approaches to Fieldwork

There was a mixture of approaches to making the observations in pairs. The conversations team decided to stay together throughout the fieldwork activity. This gave them the opportunity to have a continual dialog about what was being observed. Conversely, both the interactions teams separated whilst taking field notes and regrouped at set time intervals to discuss strategy about where to focus observations next (Fig. 1). A common approach was to take an initial walk through the space to become familiarised with it and then plan how to break their observations down into manageable chunks of activity. One of the interactions teams did this by splitting the timing of their observations equally for separate parts of the street so that they could systematically move down the street in 20-minute intervals.

All of the participants seemed to follow the instructions to allocate specific roles to each team member. There was commonly someone within each team who was stronger at recording things visually in comparison to taking written notes. Many of the teams switched roles at various points to try and gain a different perspective on the activity although, in relation to their drawing abilities, this meant that some team members were slightly outside of their comfort zone.

Where there were 2 teams working within the same space, they negotiated amongst themselves to try and eliminate the possibility of a crossover. For example, the 2 teams working on the transactions theme inside the shopping centre deliberately went to the highest and lowest floors so that more ground could be covered in the time available. A common insight was the groups finding it beneficial to have a higher point of view for making their observations from. The connections teams made use of the balconies that were available in the train station and the interactions teams used a set of steps outside a concert hall to gain a better vantage point. The teams felt that this provided a better overview of the activity that was occurring.

Many of the participants noted that they would like to return to the spaces again to go over some of the details that they might have missed the first time around. For example, checking on the sequence of events that a person who is interacting with a self-service kiosk has gone through. They also thought that returning at various times of day when the spaces are quieter or busier would be useful.

How to Share Data

The next step was to discuss how to go about sharing the fieldwork data between all of the teams. One of the participants suggested using a large physical map of the location to annotate their observations with over time. This might have been difficult for some of the interior spaces where maps were not so easily available. This also jumped too quickly to a physical space metaphor for understanding the data whereas at this stage, we needed to remain thinking about the data in a more abstracted way.

A secure virtual sharing space was set up for participants to place their fieldwork notes and images into in preparation for the final analysis workshop. This gave the participants an opportunity to see how other teams had approached the problem of how to keep easily readable field notes and the recording of other fieldwork data. The total amount of fieldwork data uploaded to the sharing space was 55 sketches, 175 photographs and 33 pages of notes. Each of the participants used a login name to sign into the shared virtual space so that the ownership of the content could easily be tracked. The fieldwork data was uploaded in a variety of formats ranging from single image files to full PowerPoint presentations. A standard format should have been agreed beforehand to make it easier to sort through the data in preparation for the workshop. Also, it would have been much easier to process the images if the individual instances of the image files were uploaded instead of, for example, embedding them within a PDF.

Affinity Mapping Workshop

In order to make sense of the vast amount of gathered fieldwork data, a final workshop session was held. The aim was to quickly reduce all data into a set of shared insights across all themes from the previous fieldwork activity. Given the time constraints, affinity mapping was selected as a suitable method.

The affinity mapping involved extracting notes and ideas from a larger piece of text or data then writing them onto sticky post-it notes. Once this was done, the next step was to try and organize the notes into sub groups to see if new themes emerge based around the particular notes that have been extracted. The workshop plan was to repeat this grouping process multiple times. Firstly, working within each of the small teams of 2 participants. Then working with both teams across each theme and finally everyone working across the overall themes.

Workshop Materials

There were a number of materials that were necessary to effectively carry out the workshop: a supply of post-it notes in 4 different colours; white index cards for recording theme headings; 8 sheets of A1 black paper; marker pens and drawing pins. Also, the day before the workshop, the group was asked to print out and bring along a hard copy of their fieldwork notes. A selection of the visual material that was uploaded to the shared folder was printed out and pinned onto the walls.

Field Data Tagging

Each of the teams was asked to make a pass through the opposite team's field notes working within the same theme. Each piece of extracted data was written onto a single post-it note and stuck onto a sheet of black paper in no particular order. The teams were asked to stick to one colour of post-its so where the note had come from it could be traced. The purpose of this exercise was to allow the team to offer a different perspective on someone else's field notes. This also meant that the field notes had to be written in a clear enough way so that other people could make use of the data.

Grouping Data

The participants returned to the post-it notes that had been recorded for them by the other team. They were then asked to read through the notes and start grouping these together as they deemed appropriate. Headings for each of the groups were written onto index cards and placed above them.

Grouping Themes

This task involved asking the 2 groups working on the same theme to bring together their notes to see where the commonalities were between them (Fig. 2). The two sheets of black paper were joined together so that there was a shared space for the groups to work within. This exercise allowed the teams to filter out duplicate sets of groupings. It also required the groups to explain the notes that they had written for each other previously and come to a shared understanding about the activity going on in each of the physical spaces they had observed.

The ways in which the groups manipulated the post-it notes in the space available was interesting. One of the groups moved all of their notes onto one side of the black sheets so that they had a clear space to organise them within. They could also be seen placing groups of notes at an angle on the paper as a way to differentiate them from the others. Once each of the teams had finished grouping their boards, they were photographed as a way of saving the layouts so that they could be referred to again later.

Extracting Super Themes

At this stage, we had to zoom out of the original themes and try to arrive at an overall understanding of the activity that was taking place in the city centre on that particular day. The participants were given half an hour to look over the notes and themes that all the other teams had arrived at through the previous set of activities. All of the headings that were written onto the index cards were pulled off the wall and collected into a pile. The participants then gathered around a large table and all of the headings were laid out onto it. This allowed everyone to see where there might be some overall groupings that the headings could fit into. The headings that were duplicates and those that were quite vague, for example "Technology" were removed from the table.

Following a brief discussion amongst the group, it became apparent that there was a clear split between the interactions that people have with each other and their interactions with space and technology. The participants allocated separate areas of the table for each of these groupings and set about putting each of the headings into these spaces. The interactions that people have with each other grouping was given the title "Interpersonal Interactions" and 12 headings were placed under this. The interactions that people have with space and technology grouping was given the title "Ways of Interacting" and 26 headings were placed under this. A photograph of each of the groupings was also taken so that they could be referred to again later on.

Evaluating Super Themes

In order to find out if the themes that we had identified were appropriate, we had to refer back to our original post-it note field data. This would allow us to see how all of this data would fit into the new super themes that we had identified. The participants were instructed to split themselves into 2 large groups and divide the space in half down the middle of the table.

This provided the group with another new space to think about all of the gathered data that had emerged from an attempt to organise it under the super headings. The next stage of analysis for the participants would be to try to map all of the post-it notes along each of these newly identified axes. The workshop had already ran an hour over the original scheduled time at this point so was drawn to a close. Photographs of all the post-it layouts at the end of the session were taken to document how far the participants had progressed with analysing the data. tags -recorded tags capturing any individual ideas based on an initial survey of the source material. -source -the original field notes, sketches, images, sounds or video recorded whilst out in the field. A web-based application was designed to prototype how these levels of information might be interacted with using a screen-based tool (see Fig. 5). The gathered material from the affinity-mapping workshop was used as example content to build this tool around. This prototype was only a sketch of an idea for how such a tool might operate. Future work requires enhancing the interface to allow zooming interaction for the content and adding the database backend to help manage the different types of media. In addition, user evaluation is needed.

Reflecting on the method

The week after the affinity workshop, interviews with four of the participants were held to discuss their experience of working with the fieldwork data in a large group. The outcome of this discussion helped us to identify a number of points that could be explored further with the future iterations of the methodology. The issues we have identified were: -Sharing context -Descriptiveness of field data -Physical access to the affinity boards -Information overload -Working across the different axis 4.6.1 Sharing context As the two teams worked together under each theme, there was a sense of familiarity with the field notes and being aware of where they had come from. An interviewee working on the connections theme noted that the opposite team had observed the same activity from another perspective so this helped to validate their own insights further. This had felt like they were "reading a guide book for a city they had visited before" so there was a clarity that could be gained from analyzing these observations. It helped that the teams were working in the same place in the same time frame so they were able to crossover and relate perspectives. If they had to work with a group that had been located at different locations, it might have taken much longer to explain some of the meaning of what had been observed.

Descriptiveness of Field Data

When reading through other team's field notes, there was a reoccurring need to have set out a standard way for writing clear field notes so that others can make use of it more easily. Some sets of notes were written like a story in the format of long paragraphs. There is a need for a shared format that requires the fieldworker to indicate timings next to each of their pieces of data along with bullet points or sub-headings so that it is easier to derive key ideas from later on.

It was felt that the exchange of field notes was a useful exercise to gain a different perspective on the activity but important pieces of information were sometimes left out. Conversely, a fresh pair of eyes reading through the field notes occasionally pulled out new pieces of data that the original author might not have been able to spot.

When extracting the data onto the individual post-it notes, there was often difficulty with the level of detail that was recorded onto each note. For example, writing a single word that could have multiple meanings depending on how it is interpreted. There needs to be a pre-agreed level of detail for writing each note so that they can be easily shared and discussed.

Physical access to the affinity boards

During the workshop, there was a contrast between the earlier tasks where the participants were working in small groups vertically on a wall and the later stages where the large group was working horizontally on a tabletop. The horizontal layout created a physical barrier of people so some had an advantage over others by it being easier to read the notes based on the position that they were in. This made some people quite dominant so they were blocking the view of others who were trying to read the notes. A solution to this problem would be to break down the large group across multiple tables so there is equal access and people are not continually jostling for the best position.

Information overload

One of the interviewees stated that they had felt almost panicked at the huge amount of information that was laid out on the tabletop and it took real effort to re-engage with meaning behind each note. As there was so much to take in at once, the meaning of all the words had quickly started to disappear. A way to resolve this might be to start turning some of the notes into visual representations. This could help to make some of the concepts more approachable and free up thought process to concentrate on the ideas being represented instead of trying to always understand the meaning of the words.

During the final stages, there was often a lot of duplication in the data. It would be worthwhile to start stripping out some of the extraneous the notes and only work with the most important ones instead. This would help the key ideas come to the surface so they could be concentrated on and not get distracted by things of less importance.

Working across different axis

At the end of the workshop, when the group had zoomed out of the final exercise, a lot of the information had been internalized at this point and lead to constructing a physical model with multiple dimensions of meaning. This started off with 2 dimensions but then it was realized that 3 dimensions would be necessary. The participants thought that it would be too difficult to think in 3 dimensions but they could quite easily work across 2 planes at a time so the analysis could be broken down and then rebuilt again afterwards. For example, with the person to people axis and tech to non-tech, these could be broken down into four separate quadrants and then the teams could work on these individually so they are not trying to think about too many things at once.

Field Studies 2 and 3

The method has been applied an additional two times both in education settings. These were at the University of Arts Zurich, Switzerland and again at the University of Dundee, Scotland with an alternative class. We will briefly describe the different conditions in comparison to the first field study and discuss how the methodology was refined based on our previous understanding.

Field Study 2

In Zurich, the same method was followed although the group who took part had less experience of using fieldwork techniques.

Participants

Eleven students on a Masters of Arts in Design participated in the study (8 male, 3 female). The participants were grouped into 4 separate teams with a theme assigned to each team.

Location

The town centre of Zurich, Switzerland was used as the location to carry out the fieldwork activity. The transactions team was located at the budget shopping centre ShopVille -RailCity; the interactions team was located at the upmarket shopping centre Globus Bellevue; the conversations team was based at the Masoala Rainforest Hall and the connections team was based at the Kunsthaus Zürich Museum for Modern Art. We did not have to seek permission to make observations in any of these locations and we were able to take photographs if required.

Materials

Each group was provided with a briefing card alone instead of the additional note and sketchbooks that were previously supplied. Participants were given additional hints on the briefing cards instructing them to assign roles for each team member between note taking, sketching and taking photographs. The cards also stated that the questions set out were only suggested and asked the participants to note down any additional questions that emerged as their observations progressed. A checklist was provided to the facilitator of the workshop to ensure that all the correct steps were followed for each phase of the methodology.

Fieldwork

The fieldwork phase of activity took place over two days, which allowed the teams to make a first attempt at observing and then return back to the studio to discuss what they had seen. This gave the group an opportunity to reflect on their progress early on and decide how to refine their fieldwork strategy further.

Results

Each of the teams produced a presentation of their findings following the final workshop phase of activity. This was a very useful additional task as it forced the group to consolidate the material they had gathered into a series of insights. The conversations team even went as far as creating a short video featuring footage they had shot whilst out in the field. This video helped to convey their findings in an informative and accessible way.

Field Study 3

The method was applied an additional time with a different set of Design Ethnography students.

Participants

Fourteen students on the Masters of Design Ethnography participated in the study (9 male, 5 female). The participants were grouped into 4 separate teams and a theme was assigned to each team.

Location

The city centre of Edinburgh, Scotland was selected as the location to make the fieldwork observations. The teams were not assigned to any specific locations so they were given the freedom to select where would be most suitable for their particular theme. The only constraints for the participants were they could not go into any interior public spaces (railway station or shopping centre for example) as no prior permission had been sought.

Themes

The themes were altered slightly so the connections theme was replaced with a consumers theme and conversations was replaced with environments. A workshop prior to the fieldwork activity was also held that asked the teams to define their own questions based around each theme before going out into the field. Although this gave the teams greater ownership of the research questions, it made the task significantly more difficult.

Materials

As the teams had to define their own individual locations and themes prior to going out into the field, they were not provided with a briefing card as in the previous studies. However, each team was given a pocket-sized video camera that could be used to help document their observations.

Results

Following the fieldwork, the group was asked to create a short video to communicate their findings based on the observations they had analysed. It was useful to have this final piece of work to help summarise their analysis of all of the gathered material. It was also interesting to contrast how the group progressed without any tangible support materials when going out into the field. They seemed to be too ambitious with how much they were hoping to observe in the space of one day. However, the learning experience was improved greatly as without the support materials, the participants had to consider a lot more about how they planned their observations prior to the fieldwork activity.

Conclusion and Future Work

The method we have proposed sets out a new way of using multiple novice fieldworkers and so gaining multiple viewpoints when engaging with a design problem. We have been able to initially break down our problem into smaller parts and divide these up amongst a large group of novice fieldworkers. Such a group can explore the field setting and gradually co-create a rich understanding that cannot usually be gained by lone fieldworker observing in such a short time frame.

There is a clear need for tools to help collect, manage and analyse the fieldwork data when there is such a large group of people involved in the process. We have used an affinity mapping method with physical post-it noting sessions to do this but this has a number of limitations in relation to providing context around each of the pieces of data. Some existing tools, such as Prezi (prezi.com), offer some of the functionality required but lack the ability to manage multiple sources of material and deal with a variety of configurations of the gathered data.

There has been work investigating the use of tablet PCs [START_REF] Mohamedally | Categorization Constructionist Assessment with Software-Based Affinity Diagramming[END_REF] as a replacement for the existing lo-fidelity material in affinity diagramming. Another potential solution could be to use a multi-touch, multi-user technology platform that enables many people to work around the problem at the same time. This would help to alleviate some of the issues that we have identified and also enable sessions to be both colocated and take place between different locations.

Of course it should be noted that this method would not suit all types of problem. For instance, our approach to field data gathering would not be suitable for going into a small space such as a home with 14 people all observing the same thing. This would be uncomfortable for both the fieldworkers and subject! It would also completely disrupt the normal activity going on in such an intimate setting. Working across different types of public spaces provides enough room for a large number of fieldworkers to make their observations without continually overlapping with each other. Also, it is easier for the fieldworkers to make their observations without having too much effect on the normal behaviour of people within such a large space.

As our methodology has been greatly refined using the three field studies we have discussed in this paper, the next logical step is to apply it in anger within an industry context. It is here that the method could be of real benefit as the issues related to limited time and resources for carrying out lengthy field studies are much more pronounced. This is also the setting where any insights the methodology generates can be robustly evaluated to see how much value they can bring to the organization through gaining an understanding of their end users.

Fig. 1 .

 1 Fig. 1. One of the Interactions teams working out a strategy.

Fig. 2 .

 2 Fig. 2. The Transactions team's board showing their integrated data headings.

Fig. 3 .

 3 Fig. 3. Arranging the data into the super themes.

Fig. 5 .

 5 Fig. 5. A screenshot of the prototype tool.

Acknowledgments

This research project is jointly funded by industry sponsor NCR and the Northern Research Partnership. We are grateful to the MSc Design Ethnography students who participated in the study. We thank the reviewers for their constructive comments.

The groups were then asked to pull all of the notes off the wall and place them under each of the super themes (Fig. 3). This enabled the groups to start from scratch again in relation to how they perceived the individual pieces of data. This introduced them to the idea of not being too precious about the original groupings they had set out and start thinking in new ways about organising the data.

This exercise enabled the group to see how valid each of the super headings were. The team working on the "Ways of Interacting" super theme split their groupings up again into 2 which were "Interactions with Technology" and "Interactions with Space". Also, some of the notes were split between the 2 super themes so were placed along a line down the middle between the spaces.

Identifying Axis

Due to the limitations of the tabletop space, the group quickly started to run out of room. In order to lay the data out more coherently, one of the participants suggested the need to arrange the data along different physical axis. Coincidentally, within the studio space there was a set of wooden exhibition stands. The participants used masking tape attached to them to mark out separate axis. These axes were 'person' to 'people' along the X-axis, 'tech' to 'non-tech' along the Y-axis and 'macro space' to 'micro space' along the Z-axis (Fig. 4).

Navigating the Data

Once the workshop had been completed, there was a vast amount of data that would help to map out the problem. These were: the raw fieldwork notes & sketches; the digitised written up notes, photographs of the affinity boards at different stages of the workshop, the axis model, the unsorted post-it notes and index card themes.

When looking through this data, there seemed to be a regular need to zoom in and out of the different levels of material that was gathered. The different levels of information that are regularly accessed include:

themes -top level providing colour-coded groupings of all themes created during the affinity mapping process. -groupings -themes that have grown out of the arrangement of the individual tags.


Gerhard Weber
email: gerhard.weber@tu-dresden.de

Helen Petrie
email: helen.petrie@cs.york.ac.uk

Jenny Darzentas
email: jennyd@aegean.gr

Accessible Design in the Digital World

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

Background to the Workshop

Many approaches for developing user interfaces are based on the concept of user centered design (UCD). If UCD is applicable, the capabilities of users, analysis of tasks and contexts are the basis for all further work including the evaluation of some interactive system. An approach for designing accessible user interfaces is much harder to implement as in all steps users with large variations of capabilities and preferences have to be considered.

Communities of users have unique ways of addressing issues and different approaches for solving problems arising from lack of accessibility. Web 2.0 addresses communities of users specifically and allows authoring of content in flexible ways. But authoring of Web 2.0 content by users with different disabilities is still difficult and new approaches to implement assistive technologies will be needed to ensure successful integration of these users.

2Goals and Issues

The workshop aims to develop a better understanding of the varied communities of users in the digital world, how accessible design solutions benefit from collaboration of users having possibly different if not contradicting requirements, systems that support such collaboration and evaluation methods allowing better insight by experts into the limitations of assistive technologies while using services in the digital world collaboratively.

Web 2.0 has arrived with a plethora of possibilities to contribute information through many types of media. The workshop is interested in studies accessibility issues related to usage of such services.

Mobile devices combine social platforms with location based services. Thereby the digital and the physical world may be bridged while taking the physical context of services and applications into account. In this context, lack of mobility adds to the possible of accessibility of mobile services. Reporting about obstacles, collaborative pre-journey systems, finding accessible routes and rating places from the perspective of users with a disability or who are elderly are topics of this workshop.

Novel cyber-physical systems [START_REF] Lee | Cyber Physical Systems: Design Challenges[END_REF] integrate computational with physical design, propose more natural user interfaces, may be multimodal, and are implemented as embedded systems. Accessibility of cyber-physical devices is much harder to ensure as embedded devices lack assistive technologies by and large. Tangible user interfaces are one example. Access by physically impaired people to collaborative tangible interaction for example on large multitouch tables cannot easily be ensured by writing software and must be designed from the beginning on. Submissions to this workshop should address solutions for designing accessible cyber-physical systems.

Support tools and methods in all stages of user-centered design are to be considered in Web 2.0 application domains such as education, location-based services, and egovernment. Cloud-based computing and collaborative accessibility are examples for new technologies which may be utilized for better integration of all users.

Organisation

The Accessible Design in the Digital World conference was conceived by the University of Dundee's Digital Media Access Group, which was held in Dundee in 2005. ADDW 2008 was hosted by York University and brought an international group together, who were presenting their papers over two days (Petrie, 2008). ADDW 2011 is supported by IFIP Working Group TC 13.3 HCI and Disabilities. Organizers of ADDW 2008 and chairs of WG 13.3 are organizing this workshop.


Huimin Qian
email: huimin1@umbc.edu

Ravi Kuber
email: rkuber@umbc.edu

Andrew Sears
email: asears@umbc.edu

A Longitudinal Pilot Study to Evaluate Non-Visual Icons in a Mobile Exertion Application

This paper describes an evaluation of a mobile exertion application, developed to promote physical activity among adult users. To extend previous work, we aimed to identify changes in walking behavior over time, and to determine the efficacy of non-visual cues presented via the phone. Data was gathered using three methods: automated logging, participant-maintained diaries and interviews. Findings revealed that participants were able to respond most effectively to multimodal icons to modify their pace over a two week period. However, their preferences were noted to change depending on the situational context. The study has also highlighted the complexities associated with data collection techniques for mobile evaluations.

Introduction

Mobile persuasive applications, such as MPTrain [START_REF] Oliver | MPTrain: A Mobile Music and Physiology Based Personal Trainer[END_REF] and StepMan [START_REF] Bieber | StepMan -A New Kind of Music Interaction[END_REF] have been developed to address the challenges faced remaining motivated to keep fit. However, these are often evaluated at one fixed point in time, under controlled conditions (e.g. lab-based). In contrast, longitudinal studies can provide a more comprehensive overview of usage and an insight into behavioral patterns. Examples include the threeweek evaluation of Ubifit Garden [START_REF] Consolvo | Activity Sensing in the Wild: A Field Trial of Ubifit Garden[END_REF], where the researchers were able to monitor the type and duration of activities conducted, and how these varied over time. Reis et al. [START_REF] Reis | Multimodal Interaction: Real Context Studies on Mobile Digital Artefacts[END_REF] were able to identify the contexts in which modalities were selected for use when using mobile technologies. User preference was found to change depending on the environment, and other factors such as lightning, movement, and hand usage.

In this paper, we briefly describe the development of a mobile exertion application designed to aid users to maintain and modify levels of pace, through the presentation of non-visual icons. To extend previous work [START_REF] Qian | Maintaining levels of activity using a haptic personal training application[END_REF], and as a first step towards understanding user behavior, a pilot study was conducted where participants used the application over a two week period in locations of their choice. The aim was to identify the following: Which types of feedback are most commonly used to maintain levels of physical activity when walking in uncontrolled environments? Does choice of feedback vary depending on environment and/or context? How do participants behave in response to signals rendered via different modalities?

2

Design of Mobile Application and Pilot Study

A pedometer-style application has been developed for the Nokia N95 mobile telephone. The device is strapped to the waist using a belt. As the user walks around his/her environment, the number of steps are calculated using data gathered from the built-in accelerometer. An optimal level of pace is determined, based on the user's step rate. Auditory, tactile or multimodal (composed of both auditory and tactile effects) prompts (all played at 158 Hz) are presented via the phone, to assist the user in maintaining his/her desired rate of pace by encouraging him/her to modify pace as appropriate. To move faster, the user is presented with icons lasting for 200ms, while to move slower, 800ms icons are played. The non-visual cues are presented every six seconds until the user reaches their target rate of pace. All auditory information was presented at 65dB. To extend our previous work, a study was performed to determine the efficacy of non-visual cues over a two week period while traversing a variety of terrains, rather than being constrained to a controlled environment, such as in [START_REF] Qian | Maintaining levels of activity using a haptic personal training application[END_REF]. We also aimed to identify whether over time, users would react faster to modify their level of pace.

Methodology

Three adults (2 male, 1 female), aged between 50 and 60, were selected from a local community center. No difficulties were reported with levels of hearing or mobility. All participants classified themselves as moderately physically active. However, the time spent weekly on walking would depend on work schedules and other commitments. Participants were each provided with thirty minutes of training with the application, during which time their pace was recorded when walking at a comfortable speed (N). This enabled us to determine a desired level of pace (N * 120%). Non-visual icons would be presented by the application, if participants were unable to maintain their individual target paces. Participants were then asked to use the mobile application at any point over the two week period, and record their walking goals and experience of using the application in an online diary. The distance and time taken for each journey, rate of pace, and how effectively users were able to maintain this pace was automatically logged by our software. We envisaged that recording data in a diary would aid us in gaining a deeper understanding of their walking behavior, by providing an insight into key events within the journey and reasons behind the selection of feedback. It would also reduce the risk of problems associated with recalling past events, as these would be noted immediately after each trial. Online diaries could also be monitored by the evaluator without disturbing the users.

At the end of the first and second week of use, the participants were interviewed to follow-up on events logged within the diaries and to obtain step rate data stored on each mobile handset. The interviews focused on which types of feedback had been used, key events that disrupted any walk, frequency of use, levels of workload experienced, and if participants had faced any difficulties with the application.

Results and Discussion

Ten trials were logged by the three participants, lasting between seven to thirty-five minutes in duration (Table 1). All trials were conducted in outdoor environments, where visual distractions were present (e.g. traffic) on a range of terrains including both flat and uneven ground (e.g. grass, inclines etc). Multimodal icons were self-selected for presentation in seven out of the ten trials. When asked to discuss reasons behind the selection of these cues, participants suggested that combining auditory and tactile feedback together was found to offer a more "noticeable" alert in inclement environments. Participant #1 suggested as the sound of traffic became louder, the audio was more difficult to process, but he was still able to perceive the tactile cues presented while keeping his eyes free to monitor the presence of cars in close proximity to his route. When in quiet environments (e.g. back yard), Participant #3 suggested that she was able to use auditory feedback. However, she suggested in unfamiliar surroundings more feedback would be needed, as more concentration would be spent navigating the paths. It appeared that context and awareness of the environment played a role in selection.

In order to identify how effectively participants were able to react to the non-visual feedback presented, the number of instances when icons were played were calculated for each trial. A total of 120 instances of feedback were presented (11 audio icons, 31 tactile icons and 78 multimodal icons). The majority of feedback was presented towards the beginning of each trial (>85%), mostly aiming to prompt participants to walk faster. This was expected, as participants noted that they would try to walk faster than their comfortable pace, but it was difficult to gauge from memory, what this rate would be. To determine the accuracy of responses to feedback presented, the number of correct responses to the cues, was divided by the total number of six second intervals within each journey. For all walking trials, response accuracy rates were higher than 97%, demonstrating that participants were able to react to all forms of feedback effectively. Due to the small sample of participants, it is difficult to draw conclusions as to whether perception improved during the time period. In all ten trials, the participants walked faster than their desired target pace for certain periods of time. When asked for the reasons behind walking faster than necessary, participants suggested that in order to divide attention between the non-visual cues and the surrounding environment, it was thought to be less cognitively intensive to walk faster. Participant #1 mentioned that he tended to walk faster deliberately to avoid the delivery of signals. However, no participants reported experiencing levels of overload from presentation of the icons.

While participants did not make as much use of the application as initially envisaged, results provided us with awareness of the contexts and environments in which different forms of feedback proved to be useful. In a future study, we aim to enhance the application, to modify the type of feedback presented during each trial, to provide more flexibility when environments change (e.g. when moving from quiet to noisy surroundings). We will then use the longitudinal study to evaluate how users respond to the feedback presented over time.

Practicalities of Conducting the Pilot Study

While laboratory-based studies offer an effective way to gather data, conclusions derived from studies may only pertain to performing tasks under constrained conditions. Diary studies were selected as one method to gather data when performing mobile tasks, as it was thought that participants could undertake activities in the field, and would be able to describe their goals and actions with minimal intervention from the evaluators. By being able to view online diaries, it was noticeable that few entries were made. It also required effort to understand the meaning associated with the comments made. As a result, the evaluators needed to contact the participants to follow-up on certain points. It also proved challenging to cross-reference entries from the diary with the steps taken, as comments were not as extensive as anticipated. Certain events were omitted as they were thought to be trivial by participants, also mentioned by [START_REF] Brandt | txt4l8r: Lowering the Burden for Diary Studies under Mobile Conditions[END_REF]. Findings from our study suggested that follow-up interviews provided a richer representation of events, than relying on the diary study alone.

Table 1 .

 1 Results from Study

	Trial	Duration (Mins)	Cue	Terrain
	1	30	Multimodal	Forest trail
	2	35	Tactile	Uneven terrain
	3	10	Multimodal	Near home environment
	4	10	Multimodal	Uneven terrain
	5	7	Multimodal	Uneven terrain
	6	9	Multimodal	Uneven terrain
	7	15	Tactile	Uneven terrain
	8	20	Audio	Near home environment
	9	20	Multimodal	Near home environment
	10	20	Multimodal	Near home environment


Margarida Silva

Carla Simões
email: m.carla.simoes@gmail.com

Daniel Gonçalves
email: daniel.goncalves@vimmi.inesc.pt

Tiago Guerreiro

Hugo Silva

Fernanda Botelho
email: fernanda.botelho@ese.ips.pt

Margarida Lucas Da Silva
email: margarida.lucas.silva@ist.utl.pt

TROCAS: Communication Skills Development in Children with Autism Spectrum Disorders via ICT

Keywords: Communicative competence, Autism spectrum disorder, Assistive technologies, Computer-mediated communication, Multimedia platform

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

Introduction

Autism Spectrum Disorders (ASDs) are included in the global developmental disorders group, and considered to be severe and precoce neuro-development disorders that have no known cure and persist throughout life [START_REF] Lucas Da Silva | TR. Quick Reference Guide for Diagnosis Criteria[END_REF]. In this study, we have looked for evidence about the benefits of using a novel multimedia platform, designed specifically to develop the communicative competence in children with ASD. We have mainly focused on making it fully customizable, namely in being: (a) Appealing to the target group; (b) Easy to use both by the tutor and by the end-users; (c) Portable and easy to deploy; (d) Adaptable to the severity degree of the target users; (e) Configurable content-wise to the end-user's development stages; and (f) Evolutive according to their age and school grade.

The paper is organized as follows: Section 2 shows an overview of ASD, unveiling the need for tools to promote the communicative competences in the educational context, which led us to the development of a novel platform, presented in section 3, capable of providing the best experience for children and their tutors. In sections 4 and 5 we analyze the experimental results and outline the main conclusions.

Motivation

Communication competences and social interaction are one of the areas where individuals with ASD present a higher compromise. At the education context level, an ASD frame [START_REF] Jordan | ASD in the Early Years: A Guide for Practitioners[END_REF] requires a set of specialized intervention measures that can attenuate the communication and integration difficulties faced by these children. Their communication abilities can be improved through specialized intervention models [START_REF] Hewitt | Specialist Support Approaches to ASD Students in mainstream settings[END_REF].

Currently, there is a lack of assistive technologies for the specific development of the communicative competence in children with ASDs. Existing solutions have been developed in a more enabling and functional perspective, centered in the individual himself. Examples of possible applications are: the Zac Browser, an enabler for Internet access and multimedia activities; and the Grid 2, a tool for Human-Computer Interaction. Both are aimed at different target populations.

The integration and learning difficulties faced by these children in special education schools has led to new guidelines regarding the action models to employ [START_REF]/18: The Salamanca Statement and Framework for Action on Special Needs Education[END_REF]. Currently, these children are integrated in regular education schools where they learn social inclusion. Our work is focused on a real world problem and application, and on the improvement of current practices.

Proposed Approach

Based on the practical needs of children and their tutors, we have created a fully customizable platform, with the resources that are considered beneficial for the learning environments of children with ASD, and with potential to promote the acquisition of new competences at the communication level. Under tutor supervision, the children created the overall software appearance in a way that better relates their perceived visual information with the underlying context information. From the literature revision in the field, regarding communicative competences promotion in autistic children and adequate stimuli, the platform was designed to support: (a) photos; (b) audio; (c) videos; (d) message board; (e) online digital book library access; and (f) connection to a story retell tool, MS Photostory.

All sections allows the preference classification through the "Like" and "Dislike" buttons (Fig. 1). In a very simplified way, the child can express and share his/her opinion with others, which can in turn visualize the opinions and recognize the colleagues that have expressed them. Together with the message board (Fig. 1), these are core and distinctive features of our proposed approach to the problem. The message board was developed so that users can exchange messages among themselves, recurring to writing, to symbols, or a simultaneous combination of both.

The entire platform is supported by Web standards, which makes it customizable and easily adaptable to other needs that children may have. Design considerations have taken into account two different user roles: (a) end-users that use the platform; and (b) tutors that manage the platform. A core aspect of the proposed platform is flexibility, that is, it can be easily adapted and customizable to the needs of each individual. Tutors can fully adjust the platform according to their goals, without the need of special knowledge regarding the use of the computer; contents are managed through the standard OS file management system, just like any other files. Accessing the TROCAS folder, the tutor can add, change, delete, and categorize the different contents through the folders. The platform automatically detects and organizes all content on the visual interfaces. Fig. 3 illustrates this process: in the folder where pictures are managed, the tutor created three categories: Animals, People, and Transportation (Fig. 3a.). The platform automatically detects these folders and organizes them on the visual interface as categories, using the name of the folder used as category descriptor (Fig. 3b.). The fact that the file names are used directly also allows the tutor to easily change the description of each content element, and facilitates the localization to other languages.

Experimental Results

Tests were conducted with 3 children, all with 12 years old; two of them integrated in a 5 th grade class and a third in a 6 th grade class, and all with individualized educational programs. Tutors were in charge of assessing profiles and progression according to his expert opinion. The implementation plan was: (a) a first stage of 2 weeks, which allowed the content fine tuning of the contents, platform operation, and the intervention plan; and (b) a second stage of 12 weeks, in which the established intervention plan was followed. Collected data revealed a consistent set of changes in the students communicative behaviours. The message board used as a way of communicating among the different agents in this process (counterparts and tutors) seems to favour the capability of understanding messages and orders. Students revealed a higher level of initiative and autonomy in exchanging messages, as well as a greater capacity of interpreting information and producing adequate responses.

It is important to enhance the fact that one of the students, in a final stage of the school year, by his/her own initiative brought a set of notes with the favorite TV characters, and asked to build a story using the resources made available by the platform. The communicative interactions between counterparts and tutors also became more frequent; the test subjects spoke frequently about the different contents of TROCAS, issuing their opinion about a given music, video, photo, etc. Of noticeable importance is the fact that one of the children, by listening to a colleague speak while viewing one of the videos expressed that: "R. can speak after all".

At an interpersonal relations level, the tool shows results in promotion of the relation and social interaction between counterparts. In general, students have always shown interest in using the platform, with clear increases in autonomy and proficiency not only using the platform but also using the computer, in general. Several comments and manifestations were registered, such as: (a) Requests to share TROCAS with other colleagues, tutors, and technicians; (b) Requests to use TROCAS event out of their assigned schedule; and (c) Refuse to attend classes to keep using TROCAS.

Conclusions

The use of information and communication technologies (ICT) is extremely important, as it can help reshape the teaching procedures, and make them more adequate to the reality of the subjects with special education needs. The inclusion of children with ASD in regular education schools is growing exponentially. This fact motivates the need to find new educational responses since, through adequate intervention models, the children can develop basic social competences, indispensable for an effective integration in the educational and social contexts. Experimental results collected during the period of deployment of TROCAS, show a clear relation between the intensive and guided use of the platform, and an improvement in the communicative competences among the test population. Future work will focus on implementing the tool in interfaces that may be more natural for the children.

Fig. 1 . 2 .

 12 Fig. 1. Preference classification list. Fig. 2. Screenshot of the message board.

  (a) Folder structure. (b) Content organization in the platform.

Fig. 3 .

 3 Fig. 3. Content management and categorization in the proposed platform.


Michael Zöllner
email: michael.zoellner@uni-konstanz.de

Stephan Huber
email: stephan.huber@uni-konstanz.de

Hans-Christian Jetter
email: hans-christian.jetter@uni-konstanz.de

Harald Reiterer
email: harald.reiterer@uni-konstanz.de

NAVI -A Proof-of-Concept of a Mobile Navigational Aid for Visually Impaired Based on the Microsoft Kinect

Keywords:

We present a proof-of-concept of a mobile navigational aid that uses the Microsoft Kinect and optical marker tracking to help visually impaired people find their way inside buildings. The system is the result of a student project and is entirely based on low-cost hard-and software. It provides continuous vibrotactile feedback on the person's waist, to give an impression of the environment and to warn about obstacles. Furthermore, optical markers can be used to tag points of interest within the building to enable synthesized voice instructions for point-to-point navigation.

Introduction

Wayfinding is a cognitive demanding, error-prone task for visually impaired persons. It is described by Long and Hill as "the process of navigating through an environment and travelling to places by relatively direct paths" [START_REF] Long | Establishing and maintaining orientation for mobility[END_REF]. As such, it depends heavily on both "sensing of the immediate environment for obstacles and hazards" [START_REF] Loomis | Gps-based navigation systems for the visually impaired[END_REF] and "navigating to remote destinations beyond the immediate perceptible environment" [START_REF] Loomis | Gps-based navigation systems for the visually impaired[END_REF]. These two aspects of wayfinding are also called micro-navigation and macronavigation [START_REF] Petrie | User requirements for a gps-based travel aid for blind people[END_REF]. Although both aspects are part of successful wayfinding, there are only few systems that try to integrate them together (e.g. [START_REF]Electronic assistance for disabled and elderly pedestrians and travelers[END_REF][START_REF] Lee | Wearable computer system reflecting spatial context[END_REF]). These systems typically try to substitute their users' limited or missing visual capabilities by giving helpful feedback via different sensory channels. Sound and speech are probably the most frequently used sensory channels in this domain. However, as environmental auditory signals are very important for persons with limited sight, acoustic feedback must be used carefully and is not appropriate in all cases. Especially when it is used for continuous feedback -which is very important in micro-navigation scenarios such as obstacle detection -acoustic feedback can become annoying and distract users from the natural aural environment. In macro-navigation scenarios, speech outputsimilar to that of car navigation systems -seems to be a reasonable choice. However, as different users interpret these signals differently, it is not easy to give unambiguous navigation instructions. Even worse, workload may differ if navigation instructions are given by sighted persons instead of visually impaired persons [START_REF] Bradley | An experimental investigation into wayfinding directions for visually impaired people[END_REF]. It "seems to be a hopeless situation for the ability of language to convey spatial information" [START_REF] Franklin | Language as a means of constructing and conveying cognitive maps[END_REF]. An alternative is vibrotactile feedback that is used for navigation purposes in various ways, ranging from vibrating headbands [START_REF] Cassinelli | Augmenting spatial awareness with haptic radar[END_REF] to shoulder tapping systems [START_REF] Ross | Wearable interfaces for orientation and wayfinding[END_REF]. As vibrotactile signals are less disruptive than sound or speech, they are an appropriate alternative to give continuous feedback. Thus, our system employs a hybrid approach that augments synthesized speech instructions for macro-navigation with vibrotactile feedback for micro-navigation using only low-cost and self-made technology.

System Description

The initial design of our proof-of-concept was created during HCI coursework at our university. Our design goal was to build a system that enables and/or facilitates both micro-navigation and macro-navigation. For this we utilized the Microsoft Kinect sensor, a vibrotactile waist belt built with Arduino LilyPad1 vibe boards and a simple backpack construction that carried the laptop and enabled quick debugging (Fig. 1 e).

For detecting the immediate surroundings, we reversed the standard operating principle of the Kinect. Instead of a static Kinect that tracks moving objects, we track the static environment with a moving head-mounted Kinect (Fig. 1c). To power the mobile Kinect we use a 12V battery pack that lasted for about 5 hours during our tests (Fig. 1 b). The vibrotactile output is provided by a waist belt that contains three pairs of Arduino LilyPad vibe boards (Fig. 1a). These are fixed into plastic bottle caps to amplify the perceived vibration (Fig. 1d). The speech output is provided by an ordinary Bluetooth headset for mobile phones (Fig. 1e).

Micro Navigation -In contrast to Lee et al., who use vibrotactile signals to encode navigation instructions [START_REF] Lee | Wearable computer system reflecting spatial context[END_REF], we use them to inform users of persons or other obstacles in their way, thereby enabling secure micro-navigation. Erp et al. showed that encoding distances on a vibrotactile display is realized best with temporal patterns instead of changes in frequency or amplitude [START_REF] Erp | Waypoint navigation with a vibrotactile waist belt[END_REF]. Based on several informal evaluations with different distance signals, we decided for a simple yet robust distance encoding with just three different outputs: no output meaning no obstacle, a 500ms pulsed vibration for signaling obstacles between 1-2m distance and a continuous vibration for obstacles closer than 1m (Fig. 2). Erp et al. also investigated that spatial information is encoded most effectively by applying the vibrotactile signals to different body locations [START_REF] Erp | Waypoint navigation with a vibrotactile waist belt[END_REF]. Thus we located the vibe boards on the left, right and center of the person's waist to indicate the direction in which an obstacle was detected. Unlike Cardin et al. [START_REF] Cardin | A wearable system for mobility improvement of visually impaired people[END_REF], who detect only the closest obstacle, we are able to detect the closest obstacles in the left, right and center region of the Kinect's "field of view". The signal processing software and the control of the vibe boards is implemented with C#/.NET and uses a managed wrapper of the OpenNI framework 2 . Obstacles in each of the image's regions are identified via a depth histogram. We assume that nearby and large objects are potentially harmful to the person. Thus, the obstacle detection algorithm moves a depth window of 120mm size from left to right (respectively near to far) over the histogram and stops, if the pixel area of that depth window exceeds a certain threshold area (approx. 4% of a region). The average depth value of the current depth window is then mapped to the pulse of the vibe board.

The overall minimalistic design of the vibrotactile output (3 output channels with 3 different signals each) is based on several iterations with informal experiments, where users felt more comfortable and performed better with less sensory information. We therefore chose to minimize the output's complexity thereby also minimizing the users' cognitive load.

Macro-Navigation -We use synthesized voice as feedback mechanism for macronavigation. Since navigation instructions are very short (e.g. "turn left") and don't occur continuously, they only slightly interfere with environmental sounds. Our lowcost solution uses printed augmented reality markers (Fig. 1e) that can be used to tag points of interest on the desired route. We detect the markers via Kinect's RGB camera using a managed wrapper of the ARToolkitPlus 3 . By integrating depth information of the Kinect, we facilitate different navigation instructions based on the person's distance to the marker. For example, when walking towards a door, the instructions will be as follows: "Door in 3", "2", "1", "Open the door" (Fig. 2). Our approach has the drawback that every route has to be signposted individually. While the effort to create and maintain such a relative positioning system is higher compared to a map-based absolute positioning system like GPS, it has the essential advantage of being available inside buildings.

Future Work

In this work we presented a system that facilitates micro-and macro-navigation for visually impaired persons. We plan to iteratively improve this proof-of-concept in the future: [START_REF]Electronic assistance for disabled and elderly pedestrians and travelers[END_REF] We observed that users don't walk straightforward and frequently don't approach markers from the front but from varying angles. This rendered some navigation instructions useless, as they were designed for frontal approaches. Future work should adapt navigation instructions to the angle from which the user is approaching. (2) Like Ram and Sharf [START_REF] Ram | The people sensor: A mobility aid for the visually impaired[END_REF] we would like to discriminate between persons and inanimate objects. This would help to reduce the amount of system output while moving in a crowded environment and could prevent users from sensory and cognitive overload. (3) Finally, we plan to conduct a formative user study with visually impaired users to evaluate navigation instructions and vibrotactile signals. A further summative study could then reveal how NAVI compares to the conventional white cane in terms of navigation effectiveness, efficiency and cognitive load.

Figure 1 :

 1 Figure 1: (a) LilyPad vibe board in a plastic cap. (b) Mobile Kinect camera with battery pack. (c) Kinect helmet. (d) Vibrotactile Waist Belt. (e) Complete setup with backpack.

Figure 2 .

 2 Figure 2. Vibrotactile cues and navigation instructions depend on the distance to the obstacle (left side) or marker (right side).

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