Katrin Wolf
email: katrin.wolf@acm.org

Prof Sebastian Möller
email: sebastian.moeller@telekom.de

Michael Rohs

Anja Naumann

Microinteractions to augment manual tasks *

Keywords: microinteraction, gestures, dual-task, multitask, interaction style

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

Research focus

Human actions in the real world are usually a set of tasks solved in parallel and people have the ability to multi-task with respect to motor and cognitive resource handling in many everyday situations. Normally, human-computer interactions are designed as separate tasks and synchronous tasks are understood as multitasking situations with two competing tasks when considering their motor and cognitive resource requirements. Microinteractions are a promising technique that can be done in parallel to manual actions with less competitive motor resource effort.

Ashbrook defines microinteractions as short-time interruptions of primary tasks for controlling mobile devices [START_REF] Ashbrook | Enabling Mobile Microinteractions[END_REF]. These interaction techniques have the beneficial potential of allowing mobile application control in parallel with ongoing everyday tasks. This could significantly enrich the quality of tasks that we could perform onthe-go and fundamentally alter the way we view ubiquitous computing [START_REF] Saponas | Enabling Always-Available Input with Muscle-Computer Interfaces[END_REF]. In this context a microinteraction can be designed as a support or subtask of an everyday task or contextual independent, like mobile communications.

I aim to investigate the potential of microinteractions that are a subtask of a primary interaction. In this field several research projects have recently been conducted to develop tracking interfaces [START_REF] Ashbrook | Enabling Mobile Microinteractions[END_REF][START_REF] Li | Blindsight: eyes-free access to mobile phones[END_REF][START_REF] Loclair | PinchWatch: A Wearable Device for One-Handed Microinteractions[END_REF][START_REF] Saponas | Enabling Always-Available Input with Muscle-Computer Interfaces[END_REF] and a few projects have been conducted that are driven by the human side of interaction [START_REF] Holz | Understanding Touch[END_REF][START_REF] Karlson | ThumbSpace: generalized one-handed input for touchscreenbased mobile devices[END_REF][START_REF] Wimmer | Grasp Sensing for Human-Computer Interaction[END_REF]. I see a research gap on the human-centric side of microinteractions, my motivation is to investigate the design space of these interactions; mainly their affordances and constraints regarding usability aspects, such as ergonomic and hedonic qualities. This work will guide the next step of my research, developing a framework for sub-tasking microinteractions that support grasp tasks. Subtasks in this context could include automotive control interactions such as stopping a turn signal or opening the window while driving. Realizing these subtasks through microgestures allows for performing them in parallel to steering a car while keeping the steering wheel fully grasped.

I believe that synchronous microinteractions allow for the possibility of supporting every-day tasking in an ergonomic and hedonic manner. Therefore my hypothesis is: Microinteractions have the potential to increase the perceived ergonomic and hedonic qualities of contextually related tasks that are performed in parallel.

Understanding microinteractions

To help understand microinteractions, I did an expert evaluation [START_REF] Wolf | A Taxonomy of Microinteractions: Defining Microgestures based on Ergonomic and Scenario-dependent Requirements[END_REF]. I asked sports therapists and physiotherapists to use props (as shown in figure 1) while performing given microgestures, but also they could use any new gestures that they created spontaneously. The gestures should be easily performable without interrupting the primary task, without needing high cognitive effort, and without taking any risk of being mixed up with natural movements. From the expert interview results I developed a taxonomy (see figure 2) for classifying these gestures according to their use cases and assessed their ergonomic and cognitive attributes, focusing on their primary task compatibility. I defined 21 gestures, which allow for microinteractions within manual dual task scenarios. In expert interviews I evaluated the gesture's level of required motor or cognitive resources under the constraint of stable primary task performance. This study was supervised by three researchers (one psychologist and two computer scientists) of the research group I am associated with at the Quality and Usability Laboratories of TU Berlin and that are named as co-authors.

Research plan and status quo

My Ph.D project is planned to consist of three parts and I am currently working on the first one. This part investigates the fundamental understanding of microinteractions. Within the second part, I will -based on the expertise of part 1 -develop novel microinteraction techniques and evaluate them regarding their usability, such as ergonomic and hedonic qualities. The third part will be dedicated to develop a framework for microinteractions that will serve as seamless sub-tasks to support in parallel continued grasp-based tasks.

My first experiment [START_REF] Wolf | A Taxonomy of Microinteractions: Defining Microgestures based on Ergonomic and Scenario-dependent Requirements[END_REF] serves as an initial analysis basis for understanding microinteractions and will be continued to generate a fundamental description of the design space for out-of-grasp microgestures. In this initial study, attributes that have a relevant effect on the gesture performance are defined. These are the grasp type, the grasped objects, ergonomic and bio-mechanic aspects, as well as the cognitive effort that is required for the pure gesture performance. The benefit of microinteractions on the usability of the grasp tasks was valued by experts as useful augmentation for many grasp-based tasks but they also brought up the fact that the degree of benefit might be influenced by pragmatic aspects, such as the task length and by ergonomic parameters of the grasped object.

Guided by the conclusion of the expert study, I currently plan a user study to investigate how users grasp an object like a pad and the effect of physical object attributes (use, size, and shape) on the way users grasp it and on their finger gesture feasibility. The expected outcome of this study is a deeper understanding about users' naturally chosen grasp for holding a pad (e.g. iPad) while performing certain device interactions as well as an evaluation of users' ergonomic skills of performing gestures while grasping the device. To measure the limitations of the grasp performance I will choose certain tasks that have to be done under different conditions (with one or two hands / with or without releasing other fingers). A generic set of finger gestures that are performable by a grasping hand are given by the Taxonomy of Microinteractions [START_REF] Wolf | A Taxonomy of Microinteractions: Defining Microgestures based on Ergonomic and Scenario-dependent Requirements[END_REF]. To measure the specific gesture limitations while grasping an object, we ask users to perform guided gestures while holding an iPad sandwich.

Contribution and expected benefit of the doctoral consortium

Within the student consortium I will present my previous research [START_REF] Wolf | Microinteractions beside ongoing manual tasks[END_REF], [START_REF] Wolf | Touching the Void: Gestures for Auditory Interfaces[END_REF] and the results of my first study [START_REF] Wolf | A Taxonomy of Microinteractions: Defining Microgestures based on Ergonomic and Scenario-dependent Requirements[END_REF] shortly for explaining my current work in greater detail.

In my actual project I measure objective and perceives pragmatic qualities as well as perceived hedonic qualities of microinteractions using SMEQ, NASA TXL, and AttrakDiff. In the student consortium I would appreciate to discuss this approach.

Because I aim to develop a framework for microinteractions, another question to ponder would be how to get valid measurements that are scalable for various graspbased task types and for grasped objects with different parameters.

Fig. 1 .

 1 Fig. 1. The participants are testing the feasibility of finger gestures while (1) holding a steering wheel (2) targeting a cash card, and (3) drawing with a pen.

Fig. 2 .

 2 Fig. 2. The expert-defined and evaluated gesture set. The experts found 17 gesture types for the driving scenario (A). The card targeting scenario (B) and the stylus scenario (C) just contain 2 gesture types each. Most gesture types have several sub-types by performing them with different fingers (index, middle, ring, and little finger). Moreover the same gesture results in a different sub-type (e.g. touch, tab, or press), if it is performed with different acceleration or duration.


Patrick Oladimeji
email: p.oladimeji@swansea.ac.uk

Harold Thimbleby
email: h.thimbleby@swansea.ac.uk

Anna Cox
email: anna.cox@ucl.ac.uk

Number Entry Interfaces and their Effects on Error Detection

Keywords: number entry, data entry, error detection

A significant amount of interaction involves number entry. The purpose of any number entry interface is to accurately select or set a numeric value. There are two main styles of number entry interfaces found on medical devices: serial interfaces like the ubiquitous 12-key numeric keypad, and incremental interfaces that use a knob or a pair of keys to increase or decrease numbers. We report an experiment that investigates the effect of interface design on error detection in number entry. The initial findings show that the incremental interface produces more accurate inputs than the serial interface, and the magnitude of errors suggests that the incremental interface could reduce the death rate relative to the numeric keypad.

Introduction

Number entry is perceived to be a very simple and mundane task -yet numerical drug dosing errors account for a significant portion of adverse drug events (ADEs) in hospitals, particularly in paediatrics [START_REF] Jani | Paediatric dosing errors before and after electronic prescribing[END_REF][START_REF] Vicente | Programming errors contribute to death from patient-controlled analgesia: case report and estimate of probability[END_REF]. Number entry errors can be as a result of a combination of user errors, poor interaction design and hardware defects. Hardware defects on keypads (e.g., key bounces) have been reported by the Institute for Safe Medication Practices (ISMP) as a source of error in medical device programming [START_REF]ISMP: Double key bounce and double keying errors[END_REF].

A key bounce occurs when physically pressing a key once causes a repeat of the same key; this is different from a double keying error where a user accidentally presses the same key twice. If a key bounce is undetected, it might lead to an overdose, which in turn might lead to patient harm or death.

In many user interfaces, number entry is implicit; for example, adjusting sound levels by rotating an unmarked dial, or moving a scroll bar adjusts a hidden number -but the user copes because of direct feedback (direct manipulation). In this paper we are concerned with numbers that are displayed by the user interface as precise Arabic numerals (e.g., 123, 6.5, etc) rather than as abstract values (e.g., colors), or even as numbers indicated by pointers on numeric scales (e.g., analog meters). This style is prevalent in safety-critical applications such as drug rate control in healthcare.

Number entry interfaces may be grouped into two main categories: • Serial number entry: A familiar example of serial entry is the 12-key numeric keypad used on calculators. The user enters the desired number typically using a keypad. The number is entered serially, digit by digit starting from the leftmost digit. There are two main variations: those with a decimal point key and those without. When there is no decimal point key, a decimal point is inserted in a fixed position, typically giving 2 decimal digits (so keying 1234 would input 12.34).

Serial entry provides the quickest method for arbitrary number entry, and its use also coincides with how numbers are spoken in many Western languages. • Incremental number entry: In an incremental interface, the user is only able to increment or decrement the number, using fixed actions, typically a pair of up/down keys, rotary dials, or pressure sensitive controls. As a result, the number entry is about changes to a current number. The user may be able to influence the rate of change of the number by exerting more pressure on the control (in the case of a pressure sensitive interface) or by the speed with which the control is manipulated (e.g., turning a knob), or by the length of time the interaction is prolonged for (e.g., holding down an increment key longer to invoke faster or larger changes on a number). User interfaces typically refine these styles, for instance to impose numerical limits and by varying key layout.

Unfortunately, errors are eventually inevitable when using interactive systems and these can be in the form of mistakes, slips or lapses [START_REF] Reason | Human Error[END_REF]. Sometimes, errors are detected by users and corrected. When errors go undetected, the consequences can be very serious. In a safety critical and dependable system, it is important that users realise when they commit errors and correct the errors. We believe that the differences in the design of number entry user interfaces place different demands on users in terms of what part of the user interface they focus most of their attention on and as a result whether they notice that an error has occurred and correct the error.

In this paper, we investigate the behaviour of users performing a routine task of number entry using serial and incremental user interfaces. We report our findings on the relative accuracies of both styles and a classification of the types of errors committed by users.

Experiment

Because interaction on the incremental interface requires users to monitor how the value on the display changes based on what key the user is interacting with, we hypothesize that users will more likely detect and correct errors when using an incremental interface as opposed to when using a serial interface. We also anticipate that users will pay more visual attention to the display than to the input when using the incremental interface and pay more visual attention to the input than to the display when using the serial interface. Finally, we expect that there will be types of errors that are unique to each class of interface.

Participants

22 participants (12 female) aged 18-55 years took part in the experiment. All participants were regular users of computers. None were prone to repetitive strain injury. One was dyslexic. Each participant was compensated for their time with a gift voucher.

Apparatus

A computer with an integrated Tobii eye-tracker was used to present the instructions and the number entry interfaces. Interaction with the computer was with a mouse, which was used to click on "keys" on the screen. 100 numbers were generated randomly for the experiment with the following constraints: all numbers were between 0 and 10, all numbers had a decimal point, all numbers had at least one nonzero significant digit after the decimal point and all numbers were different.

The serial interface was based on the Graseby 500 infusion pump. It allowed number entry using a full numeric keypad in the calculator style layout. This interface had a decimal point key and had a cancel key for deleting the rightmost character on the display. This interface allowed a maximum of 5 characters in its display, which may include only one decimal point.

The incremental interface was based on the Alaris GP infusion pump. It had four keys (Fig. 1.). The first two keys, with the upward pointing chevrons, increased the value displayed and the last two keys decreased the value. For each of the two sets of keys, one key (with the double chevron) caused a bigger change while the other caused a change that is ten times smaller. This interface allowed two modes of interaction. The user could click the keys or press and hold the keys. Clicking the keys changed the displayed value as specified above. Pressing and holding the keys changed the displayed value at a rate proportional to the duration the key was held down for. Users were expected to press and hold for faster increments or decrements. This interface always showed a decimal point and two digits after the decimal point.

A key bounce was triggered for the 84th, 88th, 92nd and 97th entry for both interfaces to see if users will detect and correct the errors. The experiment logged mouse actions to obtain accuracy and performance data on the number entry tasks.

Design

The experiment was a within-subject repeated measures design. Each participant used both number entry interfaces. The number entry interface style was the independent variable and it had two levels: the incremental and serial interfaces. The order in which the interfaces were tested was counterbalanced for all participants. The dependent variables were the number of undetected errors, number of corrected errors, total eye fixation time on the input and display part of the interface and task completion times.

Procedure

All participants were tested individually. The eye tracker was calibrated for each participant and they were briefed about the stages and purpose of the experiment before starting.

The experiment itself was in two parts: one for each interface. Prior to each part of the experiment, the participant got a training session where they could enter 10 numbers and get familiar with the interface. When the participant was comfortable with how the interface worked, they were allowed to proceed to the experiment.

For the experiment, each participant was required to enter 100 numbers using both interfaces in the order defined by the experimenter. The participants were instructed to enter the numbers as quickly and as accurately as possible. An instruction on the right half screen showed what number the participant should enter. The participant had to click a 'Next' key to confirm their entry, and display the next instruction. The process of number entry and confirmation of entry was repeated until all 100 numbers had been entered using the first interface. The participant was allowed a break of up to 5 minutes before proceeding to the second half of the experiment. The interface was then switched and the participant went through the training session for that interface and proceeded to enter the same set of 100 numbers.

Results

Four participants were excluded from the statistical analyses. One participant's error rate was more than two standard deviations from the mean of error rates, and three had very low eye tracking data. Undetected errors were instances of number entry errors that were not caught and corrected by the participants before confirming the entry. These were not limited to the four key bounce errors introduced in the experiment. All but two participants had at least one undetected error in the experiment. To check for learning effects on the interfaces over the experiments, we analysed the task completion times from each interface in blocks of 10 trials per participant and we found no significant difference in the mean time per block.

Corrected errors for each participant on the serial interface were calculated as the total number of times they pressed the 'Cancel' button. For the incremental interface, the corrected errors for each participant were calculated as the number of times the participant overshot or undershot the target number. In the incremental interface, overshooting the target number was sometimes intentional especially when entering numbers efficiently using a mixture of continuous and discrete actions. For instance, entering the value '5.9' efficiently means slightly overshooting the target number using the continuous (hold-down) interaction in order to reach '6', for instance, and refining the value with a down click (a discrete action) to obtain the target number. This type of intentional overshooting did not count as a corrected error.

Undetected Errors

Analysis of the total undetected errors for both interfaces using a paired t-test indicated that the mean undetected errors for the incremental interface (mean=1.56, sd=1.76) was significantly lower than that of the serial interface (mean=3.61, sd=2.38), t(17)=-4.15, p<0.001.

The total undetected forced errors per participant on the incremental interface (mean=0.28, sd=0.46) was significantly lower than that of the serial interface (mean=1.72, sd=1.23), t(17)=4.74, p<0.001.

Corrected Errors

The number of corrected errors per participant on the incremental interface (mean=74, sd=17.31) was significantly greater than the number of corrected errors in the serial interface (mean=7.1, sd=9.6), t(17)=17.22, p<0.001.

Visual Attention

The total visual fixation duration on the input of the serial interface (mean=271.16secs, sd=80.01), was significantly greater than the total fixation duration on the display of the device (mean=26.28secs, sd=19.31), t(17)=13.35, p<0.001. Conversely, the total fixation duration on the input of the incremental interface (mean=185.82secs, sd=87.78) was significantly lower than the fixation duration on the display (mean=553.47secs, sd=276.25), t(17)=7.34, p<0.001.

Speed of entry

The speed of entry per trial for the incremental interface (mean=8.2secs, sd=2.32) was significantly slower than the speed of entry per trial for the serial interface (mean=1.65secs, sd=0.33), t(17)=12.71, p< 0.001.

Error Types

Keystroke logs from all participants were analysed for this section. Below, we report a selection of the undetected error types that occurred in our experiment. Wiseman, Cairns and Cox have developed a taxonomy of number entry errors [START_REF] Wiseman | A Taxonomy of Number Entry Error[END_REF] and have independently reported and classified these errors. As well as reporting error types, we report the prevalence of certain error types between the two number entry interface styles. The frequency of each error type is shown in Figure 2. For each error type we quantify the severity of the errors by reporting the mean and standard deviation of the difference between the intended number and the transcribed number.

Missing Decimal Point Errors

This error occurs when a decimal point is absent from the transcribed number but is present in the instruction. There were 28 instances of this error on the serial interface and none on the incremental interface. On average, this error changed the intended number by 260.77 (sd=240.85).

Transposition Errors

Transposition errors occur when the user swaps two adjacent digits in a number. For instance instead of entering 5.84, a user might enter 5.48. The majority of these were committed on the incremental interface. The dyslexic participant committed no transposition errors. Most of the transposition errors occurred after the decimal point.

In our data, a special case of the transposition error occurred when the decimal part of the transcribed number was exactly 10 times more or less than the decimal part of the intended number. For example, instead of entering 7.4, a participant entered 7.04. Although one participant committed 17 of these errors, the potential causes make it a concern for further investigation. It is possible that the display of the numbers on the incremental interface was responsible for this error: the display always shows three significant digits. For instance if the numeric value is 7.4, the display shows 7.40. It may be confusing that the 40 after the decimal point is perceived to be greater than 4. It is important to note that this participant did not commit any transposition errors on the serial interface. It seemed that the incremental interface had an effect on their transcription of numbers specifically for numbers of the form 'd.0d' where 'd' is a numeric digit. In other words, the interface design might have affected their perception of numbers of a certain format.

Transposition errors were more serious on the incremental interface. On average this error changed the intended number by 0.54 (sd=0.35) on the incremental interface compared to 0.31 (sd=0.18) on the serial interface.

Wrong Digit Errors

Wrong digit errors occur when one of the digits in the transcribed value is incorrect. This error was more common in the incremental interface. The most serious cases of the wrong digit error happened whenever the whole number part of the number is wrong. For instance a participant entered 4.87 instead of 5.87. Wrong digit errors were more serious on the serial interface but more frequent on the incremental interface. On average, this error changed the intended number by 0.81 (sd=1.27) on the serial interface compared to 0.28 (sd=0.40) on the incremental interface.

Missing Digit Error

This refers to instances of errors where one digit from the intended value is missing from the transcribed value. For instance a participant entered 0.3 instead of 0.43. On average, this error changed the intended number by 3.36 (sd=8.92). The incremental interface was free of this error.

Discussion

The results show a significantly higher number of undetected errors on the serial interface in comparison to the incremental interface. This relative accuracy however comes with a slower data entry speed on the incremental interface, which may in itself account for the more accurate performance on the incremental interface. The higher level of visual attention paid to the display of the incremental interface is another possible reason for its higher accuracy. A third reason could be that participants expect to make errors on this interface. Indeed, the results show a significantly higher number of corrected errors on the incremental interface in comparison to the serial interface. Some participants had a number of tries overshooting and undershooting for the intended number before precisely setting the number. Some deliberately overshoot the intended value and correct the error in a few clicks because that is the optimal way to enter the intended number.

For the incremental interface, the visual attention placed on the input was significantly lower than that on the display. This supports our original intuition, as the interaction on the incremental interface requires the user to monitor how the value on the display changes based on what key the user is pressing. The input part of the incremental interface requires little visual attention and is only used to switch direction and precision of change. However, despite the high attention paid to the display of this interface, the mode of interaction introduced errors that were less likely on the serial interface e.g., the wrong digit errors and the transposition errors.

The results also show that the visual attention placed on the input in the serial interface was significantly higher than the visual attention on the display. This could be because participants did not feel the need to verify their entry. It is possible that most participants trusted the visual feedback they got from the labels on the keys and felt little need for an extra mode of feedback by checking the display.

By design, the numbers specified on a serial interface require parsing to obtain a numeric value valid in the application space. As a result, serial interfaces are prone to syntax errors. Rather than alert users to errors, this parsing process often produces incorrect and unpredictable results whenever the user commits a syntax error [START_REF] Thimbleby | Interactive systems need safety locks[END_REF][START_REF] Thimbleby | Reducing number entry errors: solving a widespread, serious problem[END_REF].

Syntax errors are however impossible on an incremental interface since the application guides the user through a valid range of numeric values. It is also plausible that numbers are perceived as a string of characters when using a serial interface whereas using an incremental interface forces users to be aware of the numeric values and the relative order of numbers.

In a safety critical context like healthcare, the incremental interface is safer. It allows better error detection and the severity of errors is much lower than on the serial interface. The missing decimal point and the missing digit errors are the most serious errors and they were both more likely to occur on the serial interface. Overall, the errors on the incremental interface had a much lower deviation from the intended number as shown by the difference of intended value to transcribed value (serial interface: mean=70.91, sd=166.94, incremental interface: mean=0.93, sd=1.41).

Conclusions

There are significant differences in the error rates for the two experimental conditions of number entry: number entry interface styles do affect error rates -and, by implication, medical outcomes. The speed of the serial interface comes at a price: errors are more likely to go undetected due to significantly less visual attention on the interface and undetected errors like the missing decimal or missing digit are more likely to have serious outcomes typically producing numbers out by a large factor (10 or more) from the intended values. In a medical context, such errors can be fatal.

The result suggests that it should be a priority to research number entry styles and their relation to error rates, behaviour and performance. There is a wide variety of number entry styles in medical devices (where errors cause adverse events), clearly with no or little empirical justification; we now see useful progress can be made to provide sound guidance for designers of safety critical number entry systems.

Fig. 1 .

 1 Fig. 1. Screen shot of the incremental interface tested in the experiment.

Fig. 2 .

 2 Fig. 2. The distribution of undetected error types in each interface in the experiment. Skipped errors were due to double keying errors on the "Next" key during the experiment.

Acknowledgements

Funded as part of CHI+MED: Multidisciplinary Computer-Human Interaction research for design and safe use of interactive medical devices project EPSRC Grant Number EP/G059063/1. Duncan Brumby provided invaluable feedback on this paper.


Achim Ebert
email: ebert@cs.uni-kl.de

Gitta Domik
email: domik@uni-paderborn.de

Nahum Gershon
email: gershon@mitre.org

Gerrit Van Der Veer
email: gerrit@acm.org

Building Bridges -HCI and Visualization

Keywords: HCI, Visualization, Standardization

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

Workshop objectives

Whenever discussing the relation between HCI and visualization in general or when presenting research results in these areas, questions arise about the differences between these research fields. Aren't both fields just the same? And if not, where is the common ground? Where is one research field dependent on the other? Can we combine the separated viewpoints and paradigms in a unified and complementary approach, or are we forced to choose one or the other? How can we provide the general public (the developers and users of visualization and HCI and the engineers implementing our designs) a precise and practical enough idea about what's happening in these fields and what's not? What are the consequences of the answers on the previous: how and what should we teach? What will be the future? This dilemma is a topic of frequent discussion around the water cooler, lecture halls, as well as in the boardroom.

One of the major issues is that it is not easy to precisely define the terms visualization and HCI and that there are many interpretations of these two fields that appear to be distinct.

In order to better (or at all) answer the questions on similarities, differences, and correlations of HCI and Visualization, in our workshop we want to discuss topics like:

• What is HCI? What is Visualization? What is a working description that is practical highlighting the special features of each of the fields? • Are there other disciplines involved in this struggle (e.g., Visual Analytics)?

• How can we take advantage of the two fields and how can we find ways for people with different inclinations to collaborate and take advantage of the strengths of each other? • What are the similarities of the disciplines? What are the major differences?

• Do we need to really split the domains? Or do we need to join them and provide a joint curriculum for studying and practicing them? We welcome participants from various backgrounds interested in research and application of HCI and visualization, including designers, artists, researchers in visualization, interaction, psychology, and usability, and people from all application fields. The intended length of the workshop is one day. Prospective attendees will submit open position papers from their own areas of interest and also provide short answers to two pro forma questions asking for (i) the participant's views on the most important existing knowledge in the area, including a position statement on possible definitions, and (ii) key research challenges related to HCI and Visualization issues.

The team of organizers is comprised of representatives of both university and industry, giving them a wide multi-disciplinary expertise. They all have significant experience in the main disciplines, as well as in related areas and application domains. Some of the organizers have already worked together in many workshops of the HCIV series [www.hciv.de]. The gained expertise and large number of members will be of a great value for successfully advertising this workshop.

Beside the position papers submitted by the workshop attendances, we plan to start an interactive blog in order to continue the discussions of the workshop. For a better visibility of our actions and progresses made, we will also distribute and discuss them using means of social media like Facebook groups and Twitter. Furthermore, the results of the discussions should form common ground for at least one high-quality conference or journal paper.

•

  Can we give definitions that are better applicable in real situations? • Does one need to further research the ways to make people take advantage of both disciplines in designing interactive visual systems? In that case, what are the research agenda(s) and what are the Top 10 Research Challenges?

Additional information

Additional information (full proposal, first schedule, references, CfP) on this proposed workshop can be found at http://www.hciv.de/interact11


José Ignacio Panach
email: jpanach@pros.upv.es-

Nathalie Aquino
email: naquino@pros.upv.es-

Oscar Pastor
email: opastor@pros.upv.es-

Interaction Modeling at PROS Research Center

Introduction

On the one hand, the software engineering community has provided sound models to represent the structure and behavior of software applications. The Entity-Relationship Model or UML Class Diagrams are examples of structural models, while Sequence or Activity UML Diagrams are examples of behavioral models. On the other hand, the human-computer interaction community has provided several proposals for interaction modeling, but none of them has become widely known or used. Even today, the identification of the conceptual primitives that allow interaction to be properly modeled can be considered a research challenge.

The PROS Research Center (Research Center on Software Production Methods) of the Universitat Politècnica de València, Spain, is devoted to improve traditional software production methods by providing model-driven processes to develop quality software. With this goal in mind, PROS has defined an object-oriented and modeldriven development method, called OO-Method [START_REF] Pastor | Model-Driven Architecture in Practice[END_REF], which automatically generates software systems from conceptual models. PROS recognizes the importance of the interactive perspective and, therefore, sustains that the conceptual model of an information system cannot be considered to be complete after just specifying its structure and behavior. It is also necessary to specify how end-users will interact with the system. Hence, PROS proposes a holistic conceptual model in which interaction is modeled together with structural and behavioral models. In this holistic conceptual model, interaction with the end-user is represented in a Presentation Model.

Achievements: the Presentation Model of OO-Method

The Presentation Model [START_REF] Molina | JUST-UI: A User Interface Specification Model[END_REF] of OO-Method provides conceptual primitives to represent the interaction with a software application. A set of elementary patterns is provided to build interaction units. There are three basic types of interaction units that can be used to represent different interactive scenarios: 1) the execution of a method, 2) the list of the population of a class, and 3) the visualization of details of a specific object. These basic interaction units can be combined to build more complex ones. Furthermore, a hierarchical action tree is provided to organize the access to interaction units, defining the menu of the application.

OO-Method and its Presentation Model are supported by a commercial software suite named OlivaNOVA, which was developed by CARE Technologies (http://www.care-t.com). OlivaNOVA allows the conceptual model to be built and applies subsequent transformations until the final code of a fully functional application (structure, behavior, and interaction) is generated for different computing platforms. The OlivaNOVA tool is currently being used successfully in an industrial environment. Therefore, the Presentation Model of OO-Method can be considered a significant achievement of PROS regarding interaction modeling.

Current Research Challenges

Currently, PROS continues devoting efforts to the research line of interaction modeling with the aim of enhancing the expressiveness of the Presentation Model. These efforts can be grouped into two categories: approaches to generate usable systems [START_REF] Panach | Dealing with Usability in Model Transformation Technologies[END_REF] and approaches to customize user interfaces.

With regard to the first group, a method to include functional usability features [START_REF] Juristo | Guidelines for Eliciting Usability Functionalities[END_REF] in any model-driven approach has been proposed. The method is based on the idea of abstracting the information contained in such usability features in order to include them in a conceptual model. Thanks to this abstraction, a model compiler can automatically generate the code for a specific programming language taking as input the conceptual model. This code supports the functionality of the usability features together with the functionality of the whole system. The proposal supports the existing tendency of addressing the treatment of usability in early stages of the software development process. With regard to the second group, a Transformation Templates [START_REF] Aquino | Transformation Templates: Adding Flexibility to Model-Driven Engineering of User Interfaces[END_REF] approach has been defined in order to diversify the kinds of user interfaces that can be generated. In this way, user interfaces can be customized according to context and user preferences before their automatic generation. This benefits the flexibility of the model-driven approach.


Sara Comai
email: sara.comai@polimi.it

Davide Mazza
email: davide.mazza@polimi.it

Usability Assessment of a Multimodal Visual-Haptic Framework for Chemistry Education

Keywords: Haptics, chemistry education, usability evaluation

In this work, we assess the usability of a virtual environment where the force of interaction between the electrostatic field around the molecule and a charge associated to the proxy of a haptic device can be felt. Feedbacks to user are provided in a multimodal visual and haptic way, and auxiliary information are also rendered.

Introduction

In this work, we assess the usability of a virtual environment described in [START_REF] Comai | A haptic-enhanced system for molecular sensing[END_REF][START_REF] Comai | Haptic and visual rendering for multi-modal exploration of molecular information[END_REF] enabling users to probe the electrostatic field around it with a charge associated with a haptic device. The force of interaction can be felt via the haptic device, and feedbacks are provided in a multimodal way, visual and haptic.

The framework is fully described in [START_REF] Comai | A haptic-enhanced system for molecular sensing[END_REF]. It provides the user with a virtual environment showing a 3D representation of the molecule; different modalities of visualization are possible among the typical chemical representation of a molecule three-dimensional structure, e.g. space-filling, ball-and-stick, van der Walls surfaces, etc. Beside the graphical representation, the framework allows to feel the electronic fields' interactions by means of a haptic device (in our case, the Sensable PHANTOM ®Omni [START_REF]Sensable Phantom Omni[END_REF]). The graphical environment shows the current position of the haptic proxy, as a yellow circle, to indicate which part of the space the user is interacting with. Auxiliary visual elements are shown to provide the user with a multimodal way of interaction, in order to integrate the information received in force, e.g., the plot of the electrostatic field along the direction connecting the proxy position and the center of the molecule, which can help in detecting maximum/minimum points of the electrostatic surface, or the force field on the molecule surface (represented by means of different colors). Figure 1 shows a screenshot of the GUI of the framework. The 3D molecule and the proxy pointer are clearly visible. The plot of the electrostatic field is shown in the upper-left corner of the picture. Further details on framework's visual and haptic capabilities can be found in [START_REF] Comai | Haptic and visual rendering for multi-modal exploration of molecular information[END_REF].

Design of the usability test

Potential users of the application have been identified at first. Among the candidate users (i.e., students attending a university-level chemistry course, teachers, and chemistry researchers), being the framework mainly designed for e-learning activities, only students have been involved in this first evaluation study. The usability evaluation consisted of three stages:

• pre-questionnaire administration, sent to the users in order to collect the background information and knowledge about the topics. Beside providing some personal data on their studies and background, users were asked to rate their knowledge about both inter-molecular forces and haptic devices, on a scale ranging from 1 (I do not know at all ) to 5 (I know it very well ); • tasks' execution session, where each user is asked to individually perform three tasks, consisting in identifying with the framework a set of specified electrostatic properties of a given molecule. While executing the tasks, the participants were asked to "think-out-loud". They were required to fill in a questionnaire regarding the task they are performing (the adopted questionnaire form is ASQ [START_REF] Lewis | Psychometric evaluation of an after-scenario questionnaire for computer usability studies: The ASQ[END_REF]). The following task have been performed, by following a set of instructions provided on paper: o Task 1 -Critical points detection: the charge is used to determine the maxima/minima of the potential in the space surrounding the molecule, giving a sensation of falling into an electrostatic surface "hole" when such points are found. o Task 2 -Detecting polar molecules: different molecules exert a different influence on a positive or negative charge, and in different zones of the surrounding space; o Task 3 -Feeling the anisotropy of the interaction: force effects by the molecule on the charge can change w.r.t. the charge-molecule distance and direction of approaching; Execution of all the tasks has been supervised by us, users' behaviours observed and notes taken about what they said. The time taken by each user to complete each task has been also considered for the evaluation;

• post-questionnaire administration, providing a final evaluation of the application, by the usage of the System Usability Scale (SUS) [START_REF] Bangor | Determining what individual SUS scores mean: Adding an adjective rating scale[END_REF]). Users were asked to answer a questionnaire to evaluate general and haptic-specific features of the application, and to finally provide an overall judgement of the experience. A total of 5 users participated to the evaluation study of the developed chemical framework. All were students of the MSc in Computer Engineering at Politecnico di Milano. The group consisted of 2 females and 3 males with the average age of 21.6 years.

Results and discussion

The pre-questionnaire results show that they have very little knowledge about haptic devices and an average knowledge about inter-molecular forces. With respect to chemistry softwares' background knowledge, only one participant was already using another chemistry application. The mean values of the times taken to complete each task, and the ASQ score, have been calculated. The ASQ score [START_REF] Lewis | Psychometric evaluation of an after-scenario questionnaire for computer usability studies: The ASQ[END_REF] includes the efficiency, effectiveness, satisfaction and use of haptic device usability aspects: the smaller the value, the better evaluated are these aspects by the participants. Users' feedbacks were collected regarding the different modalities of visualization and visual elements added to make haptic effects more intuitive. Based on these feedbacks, the most useful visual clues were determined as well as the problematic ones. Problems can be categorized as follows:

• Semiotic-problems related to the meanings of the messages of the application;

• Cognitive -cognitive effort of the user while using the application;

• Graphics -problems related to the graphical choices of the application;

• Haptic -problems related to the haptic features of the application including spatial problems and a haptic device. Using the post-questionnaire, the score of the haptic features has been calculated using the same method as one for the SUS questionnaire [START_REF] Bangor | Determining what individual SUS scores mean: Adding an adjective rating scale[END_REF]. The mean score of the haptic features of the application (43) is above average which shows that the participants found that the haptic features of the application are useful and allows user to perform the tasks in an effective and efficient way.

The SUS score of the general features of the framework is 81.5 which falls in the acceptability range of the usability of application and it is even higher than the mean score (76.2) of GUI interfaces [START_REF] Bangor | Determining what individual SUS scores mean: Adding an adjective rating scale[END_REF] that were evaluated by SUS. The respondents rated the user-friendliness of the application in average Good, which corresponds also to the results of the SUS score.

Also the score of the final feedbacks is very high (4.3/5), confirming that the users have understood the purpose of the application, they found it attractive and would even recommend it to the colleagues.

During the test administration and as final feedbacks, students reported us the easiness by which they understood the explained concepts, thus leading to an increasing interest in the subject. Teachers also appreciated the improved awareness of the phenomena they usually explain only in theory.

Conclusions and future work

The framework has been tested by different users (students) on various molecules stored in a repository associated with the framework.

All the users recognized as the most important benefit the possibility of combining the typical visualization of chemical data with the rendering of the feeling of nanoscale/atomic interactions that can improve the understanding of real phenomena. As future work, given that students greatly appreciated it and they were literally enthusiastic when facing the novelty of such a tool, we plan to introduce it in teaching activities, i.e. in chemistry course as auxiliary tool to integrate classical lectures.

Fig. 1 .

 1 Fig. 1. A screenshot of the framework.

Acknowledgements

We would like to thank Margarita Lukjanska for her precious contribution on the usability assessment activity.


Kaarina Karppinen
email: kaarina.karppinen@vtt.fi

Kaisa Koskela
email: kaisa.koskela@vtt.fi

Camilla Magnusson
email: camilla.magnusson@f-secure.com

Ville Nore
email: ville.nore@f-secure.com

Experiences of Online Co-creation with End Users of Cloud Services

Keywords: Online co-creation, Owela, Cloud services, End users

This paper describes an online co-creation study done via an online co-creation platform Owela as well as shares industrial experiences and lessons learnt about the study. The Owela study was conducted in order to provide a deeper understanding of users' perceptions of cloud services and their security. By utilising the online co-creation platform it was possible to get quick and easy contact to geographically distributed cloud service users. For the company Owela offered an efficient way to apply online user participation while for the end users Owela enabled convenient participation in various co-creation activities regardless of time and place. As an end result of the study the voice of the cloud service users was turned into several new business ideas.

Introduction

Cloud phenomenon is one of the main global trends washing through the ICT industry [START_REF] Dikaiakos | Cloud Computing: Distributed Internet Computing for IT and Scientific Research[END_REF]. Today the cloud is also reality in consumers' life as typical web users use cloud services daily whether they know it or not [START_REF] Karppinen | Usage of Cloud Services -A Survey for Consumers in USA, Japan and Finland[END_REF]. This novel way of offering software, platforms and infrastructure as a service via the internet opens up new possibilities and advantages for companies such as F-Secure, a provider of consumer cloud security and storage solutions.

In order to create new business opportunities within the cloud security domain there is a need to understand what the user perception of cloud services and their security is, and how it is formed. However, reaching geographically distributed cloud service end users via traditional user involvement methods is challenging. To overcome this challenge, we used an approach where co-creation with cloud service e n d u s e r s w a s d o n e v i a a n o n l i n e c o -c r e a t i o n p l a t f o r m O w e l a (http://owela.vtt.fi/owela/introduction). Owela is an online living lab that builds on social media features for co-creation activities and open innovation [START_REF] Näkki | Online Tools for Co-design: User Involvement through the Innovation Process[END_REF]. It was launched in April 2007 and is administrated by VTT Technical Research Centre of Finland. The conducted four week-long Owela study involved a use of various online co-creation tools enabled by the platform such as discussions, commenting, blog posting, idea posting, and chat sessions. In this paper we are presenting how the study was conducted as well as sharing experiences and lessons learnt from it.

Background

Advances in information and communication technologies give companies new opportunities to include users to their processes [START_REF] Näkki | Online Tools for Co-design: User Involvement through the Innovation Process[END_REF]. According to Swahney et al. [START_REF] Gangi | Getting Customers' Ideas to Work for You: Learning from Dell How to Succeed with Online User Innovation Communities[END_REF] online based virtual environments allow a company to engage a larger number of end users without significant compromises on the richness of the interaction. Virtual environment also increase the speed and persistence of user engagement and the episodic and one way interaction with end users can be transformed into a continuous dialogue [START_REF] Gangi | Getting Customers' Ideas to Work for You: Learning from Dell How to Succeed with Online User Innovation Communities[END_REF]. Through online collaboration users can also be involved in co-creation activities regardless of time and place.

Description of the Owela study

The purpose of the Owela study was to discuss with the cloud service users about how they actually use the services and how the existing services could be improved as well as to co-create ideas for new services. The participants were selected based on their responses to an online survey carried out in June 2010 [START_REF] Karppinen | Usage of Cloud Services -A Survey for Consumers in USA, Japan and Finland[END_REF]. A total of 128 end users were invited to join the Owela workspace. From them 47 registered within one week from the invitation. Also 4 representatives from F-Secure participated actively in Owela during the whole study. The company representatives were separately identified so that the users were all the time aware which actions were made by other users and which by the company representatives. In addition, two VTT researchers facilitated the online co-creation. Table 1 gives more information about the study. In the Owela workspace designed for the study, several specific features were used to achieve continuous communication between the end users and company representatives. First of all, Owela enabled active online discussion. The discussions revolved around predefined theme questions which were given to the participants each week. The participants answered these questions and were able to comment each other's answers thus creating discussion. Also F-Secure's and VTT's representatives were actively involved in the discussions to steer them and to probe emerging interesting topics. Secondly, in the Owela blog section users could write down their daily experiences with usage of cloud services according to each week's theme. The participants were encouraged to e.g. share negative and positive experiences with cloud services, compare different services, consider their network identity, and talk about situations that made them feel insecure. Thirdly, the participants had the chance of posting ideas about new cloud services. When posting an idea the participants were asked to write down both the idea that they had in mind and the problem that the idea would solve. This way also other participants had the opportunity to give solution ideas for the stated problems. Finally, five two-hour chat sessions were organized. The purpose of the chat sessions was to promote the direct and synchronized communication between the participants and the company representatives.

Activation and motivation of participants was considered very important in order to receive as good research results as possible. The primary way of activation was the active company representative participation in the discussions by asking questions and commenting the participants' postings. Another way of activation was to send weekly emails to the participants. The emails included current issues such as the theme and tasks for the week as well as a reminder of the chat session schedule and collecting the activity points. The third way to activate the participants was rewarding. The participants earned activity points for their actions at the Owela workspace and these points could be used as lottery tickets in a weekly movie ticket lottery as well as for earning a product gift in the end of the study.

Experiences and lessons learned

From F-Secure's point of view, online co-creation was seen to be a fruitful new way of interacting with end users. Compared to traditional end user research methods such as focus groups, interviews and usability testing used by F-Secure, this method turned out to be much more flexible, which was a benefit to both the end users and the company. It allowed participating end users to give their input whenever they had a few minutes of extra time, without having to leave their home or office. For F-Secure, it enabled defining various research goals during the study, reacting to feedback, and modifying the goals accordingly. Moving focus to new topics that may emerge from the user community during the study is usually hard to do with traditional, often quite rigid forms of end user research. Online co-creation thus enabled a continuous and rich dialogue between the company and end users.

However, it is important to note that Owela or any other online co-creation tool alone cannot ensure the success of a consumer research project. In order to reach the goals, commitment from the company as well as skilful facilitators, for keeping the discussions going and stimulating participants, were essential. Key factors for achieving success were: 1. active participation of all the parties in online conversations, 2. maintaining an active and encouraging atmosphere throughout the whole duration of the study, which motivated users to login frequently, and 3. enabling users to freely share their creative thoughts without the fear of ridicule or pressure to conform.

For F-Secure, the study produced immediately actionable results. It provided valuable insights into consumers' usage and perceptions of cloud services. It also generated 14 new consumer product ideas, which were entered into F-Secure's idea funnel for further development and evaluation. Some examples of the general themes of the product ideas are 1) providing a more secure online shopping and browsing experience, 2) allowing users to control their privacy online, and 3) securing users' cloud based data in various ways. Furthermore, the study provided a way for F-Secure to obtain feedback on upcoming products from mainstream end users, who may not have enough interest in technology to take part in traditional beta testing communities or company-specific, often quite technical, discussion forums.

Conclusions

The online co-creation study conducted via Owela provided F-Secure with a deeper understanding of users' perceptions of cloud services and their security. By utilising the online co-creation space it was possible to get quick and easy contact to geographically distributed cloud service users. Owela acted as a continuous communication channel between the company representatives and the cloud service users. Active online participation by all parties and energetic and encouraging atmosphere created in Owela were the key factors for achieving successful results. For F-Secure Owela offered an efficient way to apply online user participation while for the users Owela enabled participation in various co-creation activities anytime anywhere. The voice of the cloud service users was turned into several new business ideas that are further explored within the company.

Table 1 .

 1 Details of the Owela study.

	Length	4 weeks (24.9.-22.10.2010)
		47 end users
	Participants	4 company representatives
		2 researchers
		Discussions (320 postings)
	Tools for	Blogs (60 comments)
	communication	Idea posting and commenting (14 ideas, 80 comments)
		Chat sessions (5 x 2 hour sessions)
	Schedule for participation	Schedule for participation was optional (users could participate anytime) except for the chat sessions for which the time was announced beforehand
	Motivation and rewarding	Activity points and rewards Active participation of F-Secure and VTT representatives Weekly email reminders


Christian Wiehr
email: c_wiehr@cs.uni-kl.de

Nathalie Aquino
email: naquino@pros.upv.es

Kai Breiner
email: breiner@cs.uni-kl.de

Marc Seissler
email: marc.seissler@mv.uni-kl.de

Gerrit Meixner
email: gerrit.meixner@dfki.de

Improving the Flexibility of Model Transformations in the Model-Based Development of Interactive Systems

This paper presents an approach that adds flexibility in the varieties of user interfaces that can be generated by processes of model-based user interface development. This approach is used at design time. Ideas from this approach have been extended for use at runtime and have been applied to SmartMote, a universal interaction device for industrial environments.

Introduction

Developers are faced with the problem of having to build user interfaces (UIs) for a plethora of target devices and usage situations. Model-based user interface development (MBUID) methodologies promise to reduce the complexity of this problem by leveraging different layers of abstraction, the respective models for expressing aspects of UIs on these levels, and transformation tools for the development and semi-automatic generation of UIs. Frameworks, such as the Cameleon Reference Framework (CRF) [START_REF] Calvary | A unifying reference framework for multi-target user interfaces[END_REF], have been proposed, which define the different abstraction layers and models to be used for the systematic, user-centered design of multi-target and context-aware UIs.

However, the model-based development of context-aware and runtime adaptive UIs still presents relevant challenges regarding model transformations. When an approach uses a transformation language/model to specify transformations, we say that it has explicit transformation logic. In concepts like DynaMo-AID [START_REF] Clerckx | DynaMo-AID: a Design Process and a Runtime Architecture for Dynamic Model-Based User Interface Development[END_REF] and MASP [START_REF] Blumendorf | Multimodal user interfaces for smart environments: the multi-access service platform[END_REF], model transformations and adaptations during runtime are implemented in the underlying renderers, that is, using implicit transformation logic. While the MARIA language [START_REF] Paternó | A universal, declarative, multiple abstractionlevel language for service-oriented applications in ubiquitous environments[END_REF] uses XSLT for the model transformations, it is unclear how the model adaptation during runtime is specified in this concept.

Approaches with implicit transformation logic have limitations regarding the diversity of user interfaces that can be generated and they might require manual modifications on the generated code in order to deal with UI requirements that are not supported by the automated transformation process. Approaches with explicit transformation logic can be considered complex to be used by UI designers and there is a lack of suitable support for manipulation of models at runtime. Therefore, new transformation mechanisms are needed that support the explicit specification of model transformations and manipulations in order to increase the flexibility of today's engineering processes for context-aware UIs.

In Section 2, we present the Transformation Templates approach, which serves as the initial mapping concept for our transformation approach. In Section 3, we extend our runtime generation approach to improve the flexibility of its transformation process. In Section 4, we discuss results and conclude.

Flexibility at Design Time: Transformation Templates

A Transformation Template (TT) [START_REF] Aquino | Transformation templates: adding flexibility to model-driven engineering of user interfaces[END_REF] aims to explicitly specify the structure, layout, and style of a UI according to the preferences and requirements of the end users as well as in line with the different hardware and software computing platforms and environments in which the UI will be used, i.e., different contexts of use.

A parameter type represents a design or presentation option. Defining a parameter type subsumes specifying the types of elements of a UI model that are affected by it, as well as its value type, which refers to a specific data type or to an enumeration of possible values. A parameter type can be implemented for different contexts of use and usability guidelines are provided in order to support the selection of suitable values by UI designers in different situations. A TT gathers a set of parameters for a specific context of use. Each parameter corresponds to a parameter type and has both a value and a selector. The value of a parameter corresponds to a possible value of the corresponding parameter type. A selector delimits the set of UI elements that are affected by the value of a parameter. We have defined different types of selectors that allow the designer to choose different sets of UI elements.

TTs are used to parameterize model-to-model or model-to-code transformations. A model compiler takes the source UI model and a TT as input. The values and selectors of the parameters of the TT specify how to transform the source UI model into the target UI model. It is important to note that TTs do not replace any implicit transformation logic or explicit transformation languages; instead, they provide a higher-level tier for UI designers to easily specify UI transformations at design time.

TTs add flexibility in MBUID approaches because they externalize the design knowledge and presentation guidelines and make them customizable according to the characteristics of the project being carried out. TTs can then be reused in other projects with similar characteristics. Furthermore, TTs aim to diversify the kinds of UIs that a MBUID approach can generate.

Using TTs to Increase Flexibility at Runtime

In our MBUID approach for runtime adaptive systems, three core models can be identified (see Fig. 1): 1) the Useware Markup Language (useML) [START_REF] Meixner | Model-Driven Useware Engineering[END_REF], which is used to structure the user's tasks; 2) the Dialog and Interface Specification Language (DISL) [START_REF] Bleul | Multimodal Dialog Description for Mobile Devices[END_REF], which is used for describing the dialog behavior of the UI; and 3) the User Interface Markup Language (UIML) [START_REF] Abrams | UIML: An Appliance-Independent XML User Interface Language[END_REF], which is used to define how the content is presented to the user in terms of concrete interaction objects and their layout. These models together with runtime transformation specifications coded in the generator software (implicit transformations) were enough to obtain functional but basic UIs for runtime adaptive systems. In order to improve the flexibility of model transformations in our approach, we took the idea of the TTs as an initial mapping concept and we extended it to refer to dynamic, runtime model data, so the UI can be automatically generated and react to adjusted models.

Therefore, a context model has been integrated to provide access to static context information (such as information about the user or environment that may have a direct influence on the interaction) (see Fig. 1). A mapping model with mapping rules was also integrated as an extension to TTs (see Fig. 1) to refer to model data in addition to the fixed values of the TTs. It is composed of layout mappings, which allow the structure of the UI to be defined according to a hierarchical structure of UI containers and widgets; and widget mappings, which allow the mappings from abstract interaction objects to concrete widgets to be described. Further, in order to support the transformation process in terms of reuse and performance, a repository containing frequently occurring widgets (widget repository) and container-widget configurations (layout repository) was integrated (see Fig. 1), that can be extended easily. Both, the containers and the widgets are specified using UIML -featuring parameters to customize their presentation. At runtime, these parameters are set according to the mapping rules, using either fixed values or references to model data. All of the transformation specification previously coded in the generator software can be formalized using the mappings, which guarantee by definition that the generation will be successful. In order to demonstrate the feasibility of our approach, we developed a functional prototype as an extension to the SmartMote approach [START_REF] Breiner | Automatic adaptation of user workflows within model-based user interface generation during runtime on the example of the SmartMote[END_REF].

For the development of such UIs, the underlying models have to be automatically manipulated during runtime. The TT approach can serve as the underlying concept, but it had to be extended. An extended TT concept was developed that supports the interlinking and mapping of different models during runtime. Mapping rules can use model values as input and manipulate the UI generation process during runtime. To test the feasibility of this concept, a first prototype was developed.

Fig. 1 .

 1 Fig. 1. Transformation process in our MBUID approach for runtime adaptive systems

Acknowledgments

. This work has been developed with the support of MICINN under the project PROS-Req (TIN2010-19130-C02-02), and GVA under the project ORCA (PROMETEO/2009/015) and the BFPI/2008/209 grant, and co-financed with ERDF. We also acknowledge the support of the ITEA2 Call 3 UsiXML project under reference 20080026. Parts of the presented work are result of the GaBi project funded by the German Research Foundation (DFG) which is part of the AmSys research focus at the University of Kaiserslautern funded by the Research Initiate Rhineland-Palatinate.

Discussion and Conclusion

In this paper, we presented a new mapping concept for improving the flexibility of an approach for developing context-aware UIs on the basis of UI models according to the levels of abstraction in the CRF.


Guillaume Besacier
email: guillaume.besacier@limsi.fr

Tablexcel: a multi-user, multi-touch interactive tabletop interface for Microsoft Excel spreadsheets

Keywords: Interactive tabletop, legacy application, spreadsheet, scripting

In this paper, we present Tablexcel, a tabletop interface to Microsoft Excel. Single-user, desktop-based computer applications are pervasive in our daily lives and work. An application like Microsoft Excel, a widely deployed spreadsheet application, is used by a large number of businesses and users. Often, several users will collaborate on the creation of a spreadsheet, for example exchanging Excel files by e-mail. A multi-user, multi-touch interactive tabletop could create better working conditions, but Excel is not compatible with tabletop interfaces. Tablexcel use the scripting capabilities of Excel to extract live data from Excel files, and display them in a tabletop-appropriate way. Multiple users can interact with the Tablexcel interface using tabletop interactions, like gestures or rotating windows. Tablexcel manage the collaborative aspect of the interaction and send the resulting modifications to the original Excel application, which update the formulas, graphs, macros, etc.

Introduction

Single-user, desktop-based computer applications are pervasive in our daily lives and work. Being able to use these applications with novel interactive systems, like multitouch tabletops, is a requirement for a large deployment of these systems in a production environment. Indeed, these applications, whether they are widely used or specialized business applications, are essential to their users.

Microsoft Excel, a widely deployed spreadsheet application, is used by a large number of businesses, either for its own value or as a platform for third-party applications programmed with its macro language. Often, several users collaborate to create a single spreadsheet. This author had received and sent back Excel file by email for such diverse purpose as cooperatively making a planning, drafting a list, or filing forms. Excel files are also edited during face-to-face meeting, for example to tweak the weight given to the various grades during an academic jury. Often, a meeting leader will modify the master file on his or her laptop, while the other participants try to follow and make the same modification on their own laptop. A multi-user, multi-touch tabletop could create better working conditions in both situations.

Researchers have created new applications, designed for interactive tabletops, to fill the role of existing applications. For example, a spreadsheet application [START_REF] Tuddenham | T3: Rapid Prototyping of High-Resolution and Mixed-Presence Tabletop Applications[END_REF] was programmed with the T3 tabletop toolkit. But it is not compatible with existing file formats, and offer only basic functionalities. In addition, it doesn't offer a rich, collaborative multi-user experience, as it uses an off-the-shelf single-user component.

This lack of real-world applications limits the appeal of tabletop computing for businesses and end-users, but it also limits our ability, as HCI researchers, to conduct long term studies and field studies on tabletop usage. The only such study we are aware of was conducted using a single user in a desktop environment using a tabletop to emulate a mouse [START_REF] Wigdor | Living with a Tabletop: Analysis and Observations of Long Term Office Use of a Multi-Touch Table[END_REF].

Implementation

Several technologies have been indentified to use existing applications with innovative interactive systems [START_REF] Besacier | Toward user interface virtualization: legacy applications and innovative interaction systems[END_REF]. In this paper, we describe our implementation of Tablexcel, a tabletop interface to Microsoft Excel. Excel exposes a scripting interface. Its purpose is to facilitate tasks automation and applications interactions. For example, a third-party a word processing application might ask a spreadsheet application for some data to create a mailing. Scripting allows Tablexcel to access Excel raw data without formatting for a particular viewport, with the burden of presenting the data in a visual way delegated to our interface. Excel exposes its data model with Automation objects. Automation is an interprocess communication mechanism based on the Microsoft Component Object Model (COM). It provides an infrastructure whereby applications called Automation Controllers can access and manipulate (i.e. set properties of or call methods on) shared Automation Objects that are exported by other applications [START_REF] Kruglinski | Programming Microsoft Visual C++ 6[END_REF]. The Excel Automation Object Workbook represents a file. It contains Worksheet objects, which contain Range objects representing a cell. Each cell has several properties: the numeric value of the cell, the formula used to compute it, its size, font, color, etc.

We implemented an Automation Controller, called Tablexcel, in C++ and Java, which uses the Automation Objects exported by Excel as its data model (Figure 2). Tablexcel uses the Model-View-Controller (MVC) architecture. The Model is composed of Automation Objects exported by Excel. Excel synchronizes theses objects with its internal state. The Controller and View are implemented using the DiamondSpin tabletop toolkit [START_REF] Shen | DiamondSpin: An Extensible Toolkit for Around-the-Table Interaction[END_REF]. For maximum speed, the rendering is done in OpenGL using a custom algorithm created specifically to display Excel spreadsheets.

Interacting with Tablexcel

Tabletop spreadsheets prototypes developed so far have retained the desktop metaphor, using windows, scrollbar and similar widgets to interact with their users. We think this metaphor is not the most efficient when several users are working on the same spreadsheet. Our inspirations for Tablexcel were the interactions one can have with a large map (which is an area frequently studied on tabletops).

The spreadsheet is displayed on the whole table. Is can be translated and rotated with a finger touch, and zoomed with a pinch gesture. The translation and rotation use a kinetic relation between the finger movement and the spreadsheet movement rather than a direct mapping: the movement starts slowly and then pick up speed. As the spreadsheet is shared by all the users, it can disturb a user work if another user This view of the spreadsheet cannot be modified. The size and resolution of most current tabletops doesn't allow small enough widgets to interact directly with this view, which need to be broad enough that all the users' centers of interest fit in the tabletop surface. Instead, users can open an interactive secondary view (two such views are opened in Figure 1), by delimiting an area of interest between the side of their hands. These views are then managed like windows in other tabletop applications: they can be rotated, moved, zoomed, etc. Each user has their own focus, and a formula bar on the tabletop border next to them (not visible in Figure 1). The focused cell is editable using a physical wireless keyboard per user.

Conclusion

We presented Tablexcel, a multi-user, multi-touch tabletop interface to Microsoft Excel using the scripting capabilities of Excel to extract live data from Excel files. In future works, we plan to use Tablexcel to study users' interactions with an interactive tabletop in field studies using users' actual data and work processes.

Fig. 1 .

 1 Fig. 1. Prototype of the Tablexcel user interface. Each user can have their own focus point.

Fig. 2 .

 2 Fig. 2. Tablexcel MVC architecture delegates the Model part to the actual Excel application.


Marta Kristin

Marta Kristin Larusdottir

Dr Jan Gulliksen
email: gulliksen@kth.se

Usability Evaluation in Software Development Practice

Keywords: Usability, evaluation, agile development, Scrum, practice

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

Description of the Background to the Research Topic

Usability evaluation is one of the core usability activities, defined in the ISO 9241:11 standard and in the ISO 13407 standard [START_REF]ISO 9241-11 Ergonomic requirements for office work with visual display terminals (VDTs) -Part 11: Guidance on usability[END_REF][START_REF]ISO 13407 Human-centred design processes for interactive systems[END_REF]. During usability evaluation the evaluator actively defines the status of the usability of the system being evaluated. He or she often uses methods or techniques to focus the activities. Usability evaluation has proven to be a difficult task for the evaluators [START_REF] Larusdottir | The Focus of Usability Testing in the Software Industry[END_REF] so understanding how different the results are when various usability evaluation methods are used, understanding the context which evaluators work in and the hindrances they are experiencing is important.

Researchers have been interested in estimating the effectiveness of using various usability evaluation methods since early 90's see for example [START_REF] Desurvire | What is gained and lost when using evaluation methods other than empirical testing[END_REF][START_REF] Jeffries | User interface evaluation in the real world: A comparison of four techniques[END_REF][START_REF] Karat | Comparison of empirical testing and walkthrough methods in user interface evaluation[END_REF] to be able to advice software developers which method to use. The effectiveness of using a particular evaluation method has been measured by comparing the number of usability problems found by using various methods.

Comparing usability evaluation methods by counting usability problems that are found by each method was criticized by Wixon [START_REF] Wixon | Evaluating usability methods: why the current literature fails the practitioner[END_REF], were he states that research results on evaluation methods fails the practitioner, meaning people working actively on software development. Wixon [START_REF] Wixon | Evaluating usability methods: why the current literature fails the practitioner[END_REF] states that: -the development of real products is the only context sufficiently rich to produce the kind of nuanced examples that are needed to develop a differentiated and contextualized understanding of methods and techniques needed by practitioners‖. Some researchers have responded to his claim and have done studies that have the goal of supporting practitioners better, for example Uldall-Espersen and collages [START_REF] Uldall-Espersen | Tracing impact in a usability improvement process[END_REF] where they study how useful usability evaluation results are to the practitioners.

Agile processes for software engineering evolved to address perceived limitations of more established, plan-driven approaches for software development and have shown their worth in quickly developing reliable software [START_REF] Beck | Extreme programming explained: Embrace change, 2 nd edition[END_REF]. The most widely used are XP and Scrum [START_REF] Salah | Towards a Framework for Integrating User Centered Design and Agile Software Development Processes[END_REF]. In Scrum the projects are split up in two to four weeks long iterations called sprints, each ending up with a potential shippable product. In Scrum self organizing and well compounded teams are heavily emphasized, typically with 6 -8 interdisciplinary team members [START_REF] Schwaber | Scrum development process[END_REF].

One of the benefits of using agile development processes was claimed to be that customers needs are taken more into account than when developing software using more traditional processes [START_REF] Schwaber | Scrum development process[END_REF]. Traditional Scrum has been criticized for not involving real users in their software process and for not adequately address their usability needs, for example in [START_REF] Singh | U-SCRUM: An Agile Methodology for Promoting Usability[END_REF]. Evaluation of the success of deploying user involvement methods in Scrum has so far only been anecdotal [START_REF] Salah | Towards a Framework for Integrating User Centered Design and Agile Software Development Processes[END_REF].

Description of the Research Topic and my Contribution

My first research question is: Does the use of different usability evaluation methods give different results when evaluating the same software system?

Through this question I have explored if the results of doing usability evaluation with users using the think aloud method and the results of using the inspection methods, heuristic evaluation and cognitive walkthrough are different. I have done two experimental studies on this subject, where the quantity of usability problems found by evaluators using these methods is compared [START_REF] Frøkjaer | Prediction of Usability : Comparing Method Combinations[END_REF][START_REF] Hvannberg | Heuristic evaluation: Comparing ways of finding and reporting usability problems[END_REF]. Furthermore, the quantity of serious problems found was studied. The reason for comparing these methods even though these could be used in different purposes is to understand how different the results are and what the strengths and weaknesses are of using these methods. That understanding will help practitioners to choose an evaluation method when evaluating a system they are developing and academics could use the results to be able to suggest new methods or techniques for evaluation [START_REF] Larusdottir | Listen to your Users -The Effect of Usability Evaluation on the Software Development Process[END_REF].

My results from the first study show that the think-aloud method is the most effective method when comparing the results of using the three methods. Similar quantity of problems were found using the think-aloud method and using the heuristic evaluation, but a large extent of the problems found by using heuristic evaluation were false positive, meaning that these were not found during the think-aloud evaluation. In the second study one third of the problems found by using the thinkaloud method were found by using the heuristic evaluation and again a fair amount of problems were false problems.

Through my second question: How do practitioners integrate usability evaluation in the Scrum development process? I explored how usability evaluation is conducted by software developers using the Scrum process in Iceland. By using a survey I studied how often developers evaluate usability, how that compares to other activities like testing and what the hindrances of doing usability evaluation are. The main findings show that unit, functional, system and acceptance testing are done to a wide extent [START_REF] Larusdottir | The Focus of Usability Testing in the Software Industry[END_REF]. Usability, security, performance, alpha and beta testing are much less emphasized. Interviews were conducted to exemplify how practitioners conduct usability testing and what they describe as the difference of usability and acceptance testing. Many of the respondents said that usability testing can only be done once or twice a year. The respondents did not have time for more frequent evaluation. Some examples from the interviews show that practitioners are willing to do formal usability testing on extensive parts of the system, but because the iterations in Scrum are short and the changes to the system in each iteration are small, formal usability testing does not fit into the project work.

Furthermore through my third research question: What are the challenges for practitioners to integrate usability activities in Scrum development projects? I have studied how other usability activities are integrated into the Scrum process to understand if the challenges of integrating usability evaluation are similar to the challenges integrating other usability activities. To do this we have conducted an interview study with 21 informants from Swedish software companies that use the Scrum process. The analysis of this study is still in progress, but the first results show that formal usability evaluation is not much emphasized. Instead more informal ways of evaluation are used, like observing users, getting feedback on the usability from users through group meeting, blogs or chats. Furthermore informal expert evaluations like peer reviewing are conducted by a number of the informants and evaluation with user representatives. The main obstacle for evaluating the usability formally with users more frequently than once a year is that the team does not have time. Nonfunctional requirements like usability are rarely stated or written. Some informants mention that it is hard to know when the usability of the system is good enough; it is always possible to extend the level of the usability. Furthermore the practitioners have different opinions on who is responsible for that the software system is usable, mentioning the whole team as being responsible, the project leader, the usability expert or actually no one as possible options.

To summarize, my research topic is usability evaluation, which is explored by comparing the effectiveness of using different evaluation methods and by studying how usability evaluation is conducted by practitioners using the software development process Scrum. This research topic is important, because even though usability evaluation methods are widely known in the research community of HCI, the methods are not widely used by the practitioners using the Scrum development process. Understanding how different the results of using various evaluation methods and how practitioners are evaluating their systems is of great importance for the HCI research community to be able to suggest new methods or ways to evaluate the usability of software systems that fit the practitioners.


Paloma Díaz

Tim Hussein
email: tim.hussein@uni-due.de

Steffen Lohmann
email: slohmann@inf.uc3m.es

Jürgen Ziegler
email: juergen.ziegler@uni-due.de

Data-Centric Interactions on the Web

Keywords: Web interaction, user interfaces, data-centric systems, semantic web, visualization, large datasets, interactive systems, data management

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

Workshop Theme

While the original World Wide Web was mainly a web of documents, today's web is characterized by an ever-growing amount of data that is published and linked in structured formats. Data about products or services is increasingly made available for public access by companies (e.g., Amazon A2S API, Google Maps API, etc.). Governments and organizations publish more and more often statistics and other data on the web, usually with the aim to increase transparency and empowering the public to utilize this data (e.g., data.gov, data.gov.uk, etc.). In other attempts, structured data is extracted from Wikipedia (e.g., DBpedia [START_REF] Auer | DBpedia: A Nucleus for a Web of Open Data[END_REF]2]) or from multiple web sources (e.g., Freebase [START_REF] Bollacker | Freebase: a Collaboratively Created Graph Database for Structuring Human Knowledge[END_REF][START_REF]Freebase[END_REF]). Last but not least, huge amounts of data and metadata are created by the web users themselves, either indirectly (e.g., via social tagging) or in directed community efforts (e.g., Open Directory Project, OpenStreetMap, etc.). These are just a few of the many examples where data is published on the web nowadays.

Several standards and best practices for the description, publication, linking, and exchange of web data have been developed in the past. Popular examples are W3C specifications such as XML, SOAP, RSS, and RDF, the recommended best practices of the Linked Data initiative [START_REF]Linked Data -Connect Distributed Data across the Web[END_REF], and various vocabularies that emerged from these approaches (e.g., Dublin Core, SKOS, etc.). A similar line is taken in less formal attempts to structure data, such as microformats [START_REF]Microformats[END_REF] or advanced tagging approaches (e.g., geotagging, hashtags, etc.).

However, the full potential of the data can only be exploited with well-designed user interfaces and powerful interaction techniques that allow an efficient exploration and utilization of the data. Although some early attempts to investigate the interaction with this data have been made in the past, there is still a large number of research questions and practical challenges that are not yet sufficiently addressed. Reoccurring interaction problems are differently solved and more general design recommendations and guidelines are just beginning to emerge. A need for reusable design patterns and interaction techniques as well as novel ideas, tools, and methods to present web data to the users is clearly recognizable. These and related issues of data-centric interactions on the web are addressed by the workshop.

Format and Target Audience

The workshop will be a full-day event consisting of paper presentations, discussions, tool demonstrations, and collaborative activities. It aims to bring together researchers, developers, and designers with a shared interest in data-centric interactions on the web. As several research areas are affected by the workshop theme, participants from various backgrounds and communities are expected to attend. The workshop will provide an interdisciplinary forum to exchange experiences and ideas and to discuss novel research results and future developments regarding data-centric interactions on the web.

The workshop will consist of 3-4 sessions, each focusing on a particular aspect of the workshop theme. Accepted papers will be presented in 15-20 minute time slots. A summarization of all papers at the end of each session will help to identify shared goals and challenges and stimulate an in-depth discussion of the session topics. One session will be dedicated to tool demonstrations and selected design cases. In a final wrap up session, open problems and a roadmap for future research efforts will be identified. Further information can be found on the workshop website at http://dciworkshop.org