Annabelle Boutet
email: annablle.boutet@telecom-bretagne.eu

Franck Poirier
email: franck.poirier@univ-ubs.fr

Gilles Coppin
email: gilles.coppin@telecom-bretagne.eu

Tulio Santiago Rincon
email: santiago.ruano-rincon@telecom-bretagne.eu

Rojas Curieux

Santiago Ruano Rincón

Tulio Rojas Curieux

HCI as an instrument for strengthening culture and language of a Colombian native community

Keywords: Culture, Language and culture preservation, Nasa native community, HCI

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

Introduction

The main motivation of the project presented in this paper is the impact that HCI and the culture of users may have on each other. We believe that it is a reciprocal relationship, with repercussions in both directions: the development and use of a certain technology is impacted by the users' culture, while, technology may modify cultural characteristics of a society. Through this project, we aim to develop computer tools for a Colombian indigenous community, called Nasa. As technology providers, we would like to avoid, in our users' context, a similar impact to the modifications suffered by the Japanese writing system when "Western" word-processors were introduced in Japan. Furthermore, we would like to take advantage of the possible power of transformation of digital devices. Thus, we address this effort to support the campaigns and policies of the Nasa community to revitalize their language and traditions.

Language-oriented processes seem to be insufficient. An earlier experience showed that the translation of the main computer interface into the Nasa language was highly complex and unsuitable for that time [START_REF] Hurtado | Guidelines for the development of graphical user interfaces suitable for the Nasa Colombian indigenous community[END_REF]. Internationalization/localization processes commonly used for other languages and contexts were unfruitful when dealing with the Nasa language. That experience also concluded that the adaptation or the development of information tools should be done taking into account other cultural particularities. Our first challenge was to comprehend this culture, and select from it the elements that may have an impact on interaction with computers.

Before going any further, we need to come to an agreement about what we understand by "culture." For the moment, we take the definition proposed by Hofstede [START_REF] Hofstede | Cultures and Organizations: Software of the Mind[END_REF], and used by Hoft in her HCI and Culture-related work [START_REF] Hoft | Developing a cultural model[END_REF]. For them, culture is "learned behavior consisting of thoughts, feelings, and actions." Thus, developers should have an understanding of how their users might think, feel and react to their products And further, how their products would affect the environment and context of users.

To achieve our goal, we need to understand the Nasa context, from its social, educational and even political perspectives. Through the paper, we briefly describe our apprehension about the Nasa culture. We introduce the community in the following section, then, we present a short outline of culture and HCI-related work. In sections 4 and 5 we briefly describe our approach: our development framework, based on the design of three different tools, and the cultural characteristics that have impacted them. Finally, we present some user reactions and conclusions.

2T h e N a s a P e o p l e

The Nasa people1 are an indigenous community of the Colombian territory. To be more precise, they inhabit the Southwestern Andes of the country, in the section crossing the Cauca department. There, they live in resguardos2 , communal lands of collective ownership, where Colombian indigenous people can exercise their traditional activities. For most of the Nasa, agriculture is the main economic and living activity. Different kinds of products, such as maize, coffee, potatoes, and sugar cane are produced thanks to the diversity of temperatures found in the mountains [START_REF] Rojas Curieux | Desde arriba y por abajo construyendo el alfabeto nasa. La experiencia de la unificación del alfabeto de la lengua páez (nasa yuwe) en el Departamento del Cauca -Colombia[END_REF].

These mountains have helped to preserve the Nasa's mother tongue: Nasa Yuwe. A unique and complex language, that seems to have no clear relationship with the other 60 native languages exiting in Colombia today. It is important to note that the Nasa were, until recently, an oral-tradition society. As far as we know, there is no evidence of writing systems produced by Amerindian communities before the arrival of Europeans on the American continent. In the case of the Nasa Yuwe, the current writing system was approved by the community in 2001, as the product of the unification process of three different efforts to give the Nasa people an alphabet. It is a rich alphabet based on Latin, formed by 32 vowels and 37 consonants, which is now learned by children in schools. From our point of view, it could be seen as a strategy for preserving this language: now, they can write their own history in their own language.

According to the number of speakers, the Nasa Yuwe is the second language in the country. From around 150,000 people, i.e. the whole Nasa population, two thirds speak the language. Sadly, this number decreases from time to time, especially among young people. According to interviews carried out in the Resguardo de Novirao, adults consider that factors such as a lack of teaching, a lack of importance, social stigma and the influence of technology are some of the reasons why people no longer speak Nasa Yuwe3 .

The Regional Indigenous Council of Cauca (CRIC), the main indigenous organization in the region, and its Education Program (PEBI), manage most of schools in the north of the Cauca department. Among their policies, they demand the revitalization of Nasa Yuwe and Nasa traditions through school [START_REF]? 30 años de construcción de una educación propia[END_REF]. They seek to provide bilingual education, focused on agricultural activities, taking into account the Nasa traditions and methods.

We will show other characteristics of this culture when we describe our work in the following sections.

Related Work

Culture in HCI is a topic that has been taken up in recent years. Since 1996, Elisa del Galdo and Jakob Nielsen identified some cultural issues and variables taken into account by most international products in that time, such as: language, format of dates and numbers, character sets and notations, among others [START_REF]International users interface[END_REF]. Such variables, according to the Iceberg Model presented by Nancy Hoft [START_REF] Hoft | Developing a cultural model[END_REF], are visible and easy to study by an external observer, since they are "above the surface." However, del Galdo and Nielsen proposed to explore more levels of software localization.

To go below the surface of the Iceberg, and take into account other cultural variables, Hoft proposes the elaboration of a Cultural Model. Since then, some work has been done [START_REF] Marcus | Cultural dimensions and global web user-interface design. what? so what? now what[END_REF], including a model for "cross cultural game design" [START_REF] Chakraborty | Cross cultural computer gaming[END_REF]. However, Heike Winschiers-Theophilus affirms that current Cultural Models are missing the impact of culture on some stages of the whole design process [START_REF] Winschiers-Theophilus | The art of cross-cultural design for usability[END_REF]. We have developed our version of a Cultural Model [START_REF] Ruano Rincón | Designing for Other Cultures: Learning Tools Design in the Nasa Amerindian Context[END_REF], that is briefly outlined in this paper.

From a lower level point of view, issues found during interaction between different cultures through the interfaces are clearly explained by semiotics.

Computer interfaces are full of signs, such as words, icons, movements, actions, among others, that make possible the human-computer interaction, and whose interpretation largely depends on the users' culture. According to the Semiotic Engineering theory, proposed by Clarisse de Souza [START_REF] De Souza | The Semiotic Engineering of Human-Computer Interaction[END_REF], HCI is a Metacommunication process, between (a deputy of) the developer and the user. As a consequence, the developer must need to talk the same "language" as the user, selecting suitable signs in the interface design.

Our experience with the Nasa people has driven us towards the development of educational tools for children from that culture. The work of Matthew Kam, Anuj Kumar et al. [START_REF] Kam | Designing digital games for rural children: a study of traditional village games in india[END_REF][START_REF] Kumar | An exploratory study of unsupervised mobile learning in rural india[END_REF] seems to be the most and serious about mobile games design for kids in a rural context. We take some elements from their work, such as the strategies to observe local games and extract from them suitable information to design computer tools. Medhi et al. have done an interesting work on Text-Free interfaces for illiterate and semi-illiterate users in Bangalore slums [START_REF] Medhi | Text-free user interfaces for illiterate and semiliterate users[END_REF]. We have found a couple of similar observations about users' behavior and preferences that we will describe on the text.

Among the work specifically designed for the Nasa people, we found the "Web community to support Nasa ethno-education processes" 4 . It seems that there exist other isolated efforts, for which we have not been able to find documentation.

Our Development and Application Framework

At present, the "tangible" outcomes of the experience described in this paper have been the development processes of three tools, focused on Nasa children and their schools. While the first has reached maturity, the other two are in their first development cycle:

1. C ¸ut pwese'je, the maize game 2. C ¸xuga pwese'je, the spinning top game 3. and, the design of a "global" interface, as an alternative to the Desktop Metaphor.

The main objective of the maize game is to help Nasa children (and adults) to learn the Nasa Yuwe alphabet, identifying its 69 graphemes 5 .Itisahangman-like game adapted to the Nasa context. Instead of a condemned man, çut pwese'je's central stimulus is a field of maize plants, main staple of the Nasa diet [START_REF] Ruano Rincón | Designing for Other Cultures: Learning Tools Design in the Nasa Amerindian Context[END_REF].

The second tool, çxuga pwese'je, is planned to be a competitive game where four children have to make their spinning tops spin for as long as possible. To do so, they have to continuously solve challenges in Nasa Yuwe. However, we have not been able yet to determine the adequate type of questions. We have thought about asking for arithmetic operations in the Nasa language, but the way they should be done is still unclear, and linguistic research is needed first.

Besides these two tools, we have also looked for an alternative interface to the Desktop Metaphor, to be used in the computers of Nasa schools. According to the designs made collectively with Nasa students and teachers, we have decided to adapt the Sugar learning environment, which offers an alternative to traditional office-desktop software. It has been originally developed for the OLPC XO-1 laptop computer and is now supported and maintained by Sugar Labs6 .

Development Processes

The design of the maize game started in 2006, then it followed an iterative process. Each cycle allowed us to comprehend Nasa characteristics, through the design and evaluation of prototypes. The three current cycles are described in [START_REF] Ruano Rincón | Designing for Other Cultures: Learning Tools Design in the Nasa Amerindian Context[END_REF].

The spinning top game and the global metaphor have been designed collectively with students and teachers in two Nasa schools. During an in-field workperiod in the resguardos de Tumbichucue and Caldono, we used blackboards and chalks to design and evaluate the tools' dynamic.

The spinning top game was inspired from local games, played by children in their resguardos. The ideas of Matthew Kam were useful in this design [START_REF] Kam | Designing digital games for rural children: a study of traditional village games in india[END_REF][START_REF] Kumar | An exploratory study of unsupervised mobile learning in rural india[END_REF]. We had the chance to observe different games during a celebration day in Tumbichucue. Rustic and accessible material is used to build different types of spinning tops, carts, and other toys. The spinning tops game is based on phçxukwe çxuga: kids have to repeatedly strike a wooden spinning top with a small fiber whip to make it spin as long as possible. As expected, during a competition, the goal is to make it turn more than the others. At the time of the observations, the local record in Tumbichucue was 1h40m.

5C u l t u r a l D i m e n s i o n s

Through our experience, we have encountered some questions that have directed our research: How to study our target culture?, How to select relevant characteristics that would impact the design and usage of computer interfaces?, How to apply them to the design of human-computer interaction? and Is it possible to highlight them through interaction?

Nancy Hoft deals with similar questions and suggests the modeling of culture as a strategy to answer them [START_REF] Hoft | Developing a cultural model[END_REF]. Following her recommendations, we have developed a Cultural Model based on the work of Kluckholm and Strodtbeck [START_REF] Kluckhohn | Variations in value orientations[END_REF], Hofstede [START_REF] Hofstede | Cultures and Organizations: Software of the Mind[END_REF], Victor [START_REF] Victor | International Business Communication[END_REF], among others. Our proposal takes into consideration six wide cultural variables for the development of computer tools: Language, Space, Environment and technology, Social organization, Notion of time and Nonverbal signs. These characteristics and their relationship with the development of the maize game are described in [START_REF] Ruano Rincón | Designing for Other Cultures: Learning Tools Design in the Nasa Amerindian Context[END_REF]. This model was later evaluated through the design processes of the game of the spinning top and the global interface.

In this section, we summarize our observations about each characteristic, and how they have impacted the tool development processes.

Language

Besides the lack of a basic computer glossary in Nasa Yuwe, we have encountered other language-related challenges. For example, the lack of some Nasa Yuwe characters in available keyboards meant we had to look for a graphical input method for çut pwese'je, described in [START_REF] Ruano Rincón | Designing for Other Cultures: Learning Tools Design in the Nasa Amerindian Context[END_REF]. The current keyboard layout is based on the order in which kids learn the alphabet. The four groups-by-four groups organization is taken from the concept of the rhombus and its relationship with the number four (See Figure 1). Moreover, we have proposed to use the spinning top game as a tool to help children learn arithmetic operations in Nasa Yuwe. However, we have found that it is still unclear, among linguists, how these operations are done. As far as we know, current bibliographic reference about numbers in Nasa Yuwe is limited to numbering [START_REF] Ramos Pacho | Numeración y neonumeración en nasa yuwe[END_REF]. Thus, further research is needed.

Space Structuring

Interfaces may have an essential spatial component, such as the Desktop, used in the common computer interface. We base our alternative interface design on different levels of Nasa space structuring, such as the hearth (tulpa), the house garden (tul)a n dt h eresguardo.

We think that a "collective space" in the interface would fit the collectiveorientation that we think is present in the Nasa culture (see below). Thus, we could take advantage of networking capabilities and make it possible to collectively work through computers. For that, we propose an analogous interface to the hearth (tulpa). The Nasa three-stones tulpa is the central point of "traditional" houses. It is a place where family and close friends spend time together, especially after work journeys. During a collective design session, Nasa students and teachers also proposed to include a metaphor with the resguardo,t oexp an d the area of interaction and be able to work with the whole community.

Environment and Available Technology

The Nasa context is mostly agricultural, so files, folders, desktops, trash bins and the concept of recycling are uncommon in this rural environment. The Desktop Metaphor's foundations are inconsistent with the Nasa mind set, resulting in a misunderstood metaphor by the Nasa people [START_REF] Hurtado | Guidelines for the development of graphical user interfaces suitable for the Nasa Colombian indigenous community[END_REF]. Our tools have been designed with the help of studens and teachers, taking into account the local environment and available material: maize, local toys, space structures, among others.

On the other hand, available technology imposes limitations and conditions the design. To cite two examples: the scarce equipment found in schools strengthens the necessity of sharing a single computer among several children, and the absence of Internet makes it unsuitable to create online tools. However, some computer rooms are equipped with local networks, which make it possible to design networked applications.

Social Organization

The social organization is a cultural dimension that embraces a wide range of variables. Here, we expose two of them: the educational context and the community-orientation.

Educational context. Since we focus on Nasa children and their schools, we needed to understand the particularities of the educational context. Nasa authorities aim to provide bilingual education, in Nasa Yuwe and Castilian, centered on agricultural activities and communal policies.

Community-orientation. It is manifested in, at least, two different aspects: territory and work preferences. The Nasa people live in resguardos, communal and inalienable lands that allow collective ownership. Furthermore, there exist three Nasa traditional types of collective work, more valued than other individual ways of working [START_REF] Ximena Pachón | Los Nasa o la Gente Páez[END_REF]. Therefore, the community is involved in a wide range of aspects of the Nasa way of living, from the construction of a new classroom, to the debate about the creation of a writing system for Nasa Yuwe [START_REF] Rojas Curieux | Desde arriba y por abajo construyendo el alfabeto nasa. La experiencia de la unificación del alfabeto de la lengua páez (nasa yuwe) en el Departamento del Cauca -Colombia[END_REF]. Consequently, we have introduced our projects publicly and had more fruitful designs and evaluations when they were run collectively than with one single individual.

Likewise, we seek to highlight the communal character design tools that encourage the collective use of one single device. For example, the spinning top game is designed for up to four simultaneous players.

Notion of Time

Usability evaluation methods such as Thinking aloud, quantitatively measure time of task completion to evaluate the quality of an interface. However, as Winschiers has found in Namibia, we think that the Nasa people give a minor importance to the time. In a general rule, they would not care to spend a "huge" quantity of time to answer a question in our games. Consequently, we have avoided time limits in their design.

Non-verbal Signs

The rhombus and the spiral are important Nasa symbols, representing, among other concepts, one World view and time/life development, respectively. We use such symbols as layouts, metaphors and other interaction signs. The rhombus is easily visible in both prototypes of Figure 1.

We use the spiral and its relationship between the different social interaction levels, to link the tulpa and resguardo analogies in the interface.

6U s e r R e a c t i o n s

For the moment, we have evaluated our work through qualitative observations of user reactions, which outcome is to summarized here.

"Collectively" works better. Our initial evaluations of the maize game were individually run, using "thinking aloud" based methods. However, kids seemed to be uncomfortable. They called other people around to join in the evaluation, which seemed to be a more natural way. From that moment, designs and evaluations were done collectively. Winschiers [START_REF] Winschiers-Theophilus | The art of cross-cultural design for usability[END_REF] and Medhi [START_REF] Medhi | Text-free user interfaces for illiterate and semiliterate users[END_REF] have found similar reactions in Namibia and India, respectively. Abstract ideas. Nasa people seem to be uncomfortable with abstract ideas, such as disappearing maize plants, used to describe the maize game dynamic, or plants with eyes and nose, intended to be attractive for Nasa kids. When testing the game, a kid said "oh, those bad birds!", when he saw the first maize pop up. Teachers and kids have suggested that it would be better that an animal steals the maize when the user is wrong. Medhi also reports similar observations in this point [START_REF] Medhi | Text-free user interfaces for illiterate and semiliterate users[END_REF].

Good reception. During the design evaluation using the blackboard or when playing with the maize game on the computer, children (and adults) laughed and made jokes about other players' answers. However, they show excitement and concentration when it was their turn. Most people clearly wanted to solve Nasa Yuwe challenges and to write "complex" concepts in their language, especially during the design of the spinning top game.

Moreover, several mayores 7 have expressed their interest in building a physical keyboard like the graphical one used in the maize game.

Conclusions

HCI Researchers have concluded that other cultural dimensions than language have to be taken into account in the design and development of computer tools. In our project, we have considered other variables, such as: Space structuring, Environment and Technology, Social organization, Notion of time and Nonverbal signs to construct tools for the schools of the Nasa Colombian native community. Some of these dimensions might impact not only the interface itself, but also processes like development and evaluation, or even the usage practices. For example, the collectivist character of the culture has improved the development of the tools, students and teachers have collectively participated in the design, evaluated and provided new ideas.

Finally, with those tools we aim at helping in revitalisation efforts of language and culture. We hope that the inclusion of cultural variables in the interaction will help to give value to the culture, and reduce, for example, the social stigma felt by some native people when using their mother tongue.

Fig. 1 .

 1 Fig. 1. C ¸ut pwese'je, the maize game (left). Individual space in our adaptation of the Sugar learning environment (right).

Fig. 2 .

 2 Fig. 2. Nasa kid playing with a spinning top during a competition in the Tumbichucue (left). Collective evaluation of the design of the spinning top game in Caldono (right).

The Nasa are also know as Paez, as they were named by the Spanish. We prefer to use the name they use when referring to themselves.

Resguardos:The Colombian Constitution grants some rights to native communities over these special territorial units.

Personal communication, with Marta Corrales and Tulio Rojas, 2010.

Comunidad virtual de apoyo a los procesos de etnoeduación nasa: http://www.ewa.edu.co

Grapheme: the unit of a writing system. Nasa Yuwe has graphemes of one, two and three letters, i.e: ĩh, aa, çx, pxh.

Sugar Labs: http://sugarlabs.org

Acknowledgments

This work has been possible thanks to the Institut Télécom and its foundation. We would like to thank Abelardo Ramos, Nasa leader and linguist, whose help has been essential. As well as the resguardos of Tumbichucue and Caldono, who kindly accepted to receive and work with us. The founding of the Université Européenne de Bretagne and its International Doctoral College made it possible to carry out the in-field work in 2010. Special thanks to Mary Daley for reviewing the writing of this paper.


Yohan Guerrier
email: yohan.guerrier@gmail.com

Maxime Baas
email: maxime.baas@free.fr

Christophe Kolski
email: christophe.kolski@univ-valenciennes.fr

Franck Poirier
email: franck.poirier@univ-ubs.fr

Comparative Study between AZERTY-type and K-Hermes virtual Keyboards dedicated to Users with Cerebral Palsy

Keywords: Virtual keyboard, text entry, effort reduction, cerebral palsy

published or not. The documents may come   L'archive ouverte pluridisciplinaire

Introduction

Much research has been done on virtual keyboards and the tiny keyboards of mobile devices. Indeed, they are increasingly used in mobile devices such as mobile phones or tablet PCs. In this paper, we focus specifically on virtual keyboards for people with disabilities. It is not possible to deal with all the existing handicaps due to their large number [START_REF]Site about handicaps (particulary Cerebral Palsy[END_REF]. Therefore, this article focuses on users with Cerebral Palsy. These people have suffered neurological damage. For many of these users, their movements lack precision [START_REF]Le site de l'Infirmité Motrice Cérébrale[END_REF], which is why they are likely to use a virtual keyboard for text entry. In this case, a joystick is often used for mouse manipulation (other devices are also possible, such as eye-controlled devices), the clicking is done with a pushbutton. For example, the device used by the first author is shown in Fig. 1. In this paper, we begin with a state of the art on keyboards adapted for users with motor impairments. Then we propose the K-Hermes virtual keyboard. An experiment, the goal of which is to compare it with the Clavicom NG keyboard [START_REF] Clavicom | [END_REF] used by many disabled users, is the subject of the next part. The results obtained are described and discussed.

State of the art on keyboards for people with motor impairments (cerebral palsy)

Many studies have been conducted in the field of text entry for people with motor impairments [START_REF] Martin | État de l'art des claviers physiques et logiciels pour la saisie de texte[END_REF] [START_REF] Schadle | Système de prédiction de lettre pour l'aide à la saisie de texte[END_REF]. Representative examples of virtual keyboards with the goals of reducing mouse movements and increasing the speed of text input are presented below.

Dvorak [START_REF] Dvorak | [END_REF] is an alternative to the standard physical keyboard. On the Dvorak keyboard, consonants and vowels are most likely placed in the midline of the keyboard. This layout makes it possible to perform less complex finger movements and thus offers more comfortable input while reducing physical fatigue. XPeRT [21] has a similar layout to the qwerty Keyboard. Its principle is to group the most frequent diagrams (groups of 2 letters) in order to reduce the distance traveled by the mouse pointer while typing text. OPTI and FITALI [START_REF] Guerrier | Étude comparative entre clavier un virtuel AZERTY et un clavier multitap pour des utilisateurs souffrant d'une Infirmité Motrice Cérébrale de type tétraplégique athétosique[END_REF] offer the most probable letters in the center of the keyboard. They have both multiple space bars on the sides and a large shift bar on the bottom that make input easier and faster. This result is in accordance with Fitts's Law [START_REF] Fitts | The Information Capacity of the Human Motor System in Controlling the Amplitude of Movement[END_REF] that shows that the closer the letters, the faster and the less tiring the input. Métropolis [START_REF] Zhai | The Metropolis Keyboard, An Exploration of Quantitative Techniques for Virtual Keyboard Design[END_REF] is based on the eponymous global optimization algorithm. The letters are grouped according to the attraction between them, while taking into account Fitts's law to shorten the travel distance of the mouse. Sybille [START_REF] Wandmacher | an adaptive system for alternative communication adapting to the context and its user[END_REF] is a predictive keyboard that helps the user to type faster by predicting both the most probable letters and words during text input. It should be noted that most keyboards for users with disabilities possess a word prediction system. Dasher [START_REF] Dasher | site explicatif du clavier : www[END_REF] allows an input exclusively based on mouse movement by always pointing to the next character in the list of probable letters presented on the right close to the current pointer position. KeyGlass [START_REF] Vella | Etude de l'optimisation de claviers virtuels au travers des sujets handicapés versus valides[END_REF] provides, after each letter input, around the key, four semi-transparent buttons representing the most probable following letters.

Chewing Word [START_REF]Chewing Word[END_REF] presents a dynamic keyboard with two rows of letter keys. After each character input, the prediction system rearranges the letter keys according to their probability of occurrence. UKO-II [START_REF] Guerrier | Étude comparative entre clavier un virtuel AZERTY et un clavier multitap pour des utilisateurs souffrant d'une Infirmité Motrice Cérébrale de type tétraplégique athétosique[END_REF] is a keyboard designed for people affected by cerebral palsy. It uses the same principle as T9. There are only four buttons for all the characters. To input a letter, the user must enter the number of the key (from 1 to 4) associated to the letter. Then, a disambiguation algorithm proposes the most probable words according to the sequence of keystrokes. K-Thôt [START_REF] Baas | Système de saisie de texte visant à réduire l'effort des utilisateurs à handicap moteur[END_REF] offers a virtual keyboard for people with motor disabilities, which aims at minimizing movements and user fatigue and to maximize the input speed. The input of special characters, such as spaces, backspaces and capital letters is made particularly easy.

CLAVICOM NG [START_REF] Card | The Psychology of Human-Computer Interaction[END_REF] is an azerty layout keyboard. It has been chosen as a reference for the evaluation of the K-Hermes keyboard for the following reasons:

(1) it is often used in specialized centers for people with disabilities, (2) it uses a prediction system like the K-Hermes keyboard, (3 the keyboard layout is adaptable by the user. With Clavicom NG, the user enters its desired text by directly clicking on letter keys like a standard azerty keyboard. Word proposals appear inside white buttons located on top of the keyboard (Figure 2). Just click on one of these buttons to automatically complete the current input word and add a space. With this method, the user does not have to input a space before beginning the next word.

K-Hermes

The K-Hermes keyboard has been proposed in [START_REF] Guerrier | Étude comparative entre clavier un virtuel AZERTY et un clavier multitap pour des utilisateurs souffrant d'une Infirmité Motrice Cérébrale de type tétraplégique athétosique[END_REF]. K-Hermes is named K for "keyboard" and Hermes was the Greek god in charge of sending messages. K-Hermes is based on the layout of a T9-type keyboard. It has the advantage of enabling entry with only 9 keys. This reduces movement between the joystick and the pushbutton, and therefore reduces the fatigue of the user (which is essential for Neurological Injury) (Fig. 3). To enter the nth letter of a labeled button, the user must click on the button n times. Thus, to enter "b", he/she must double click on the button labeled "abc." In the figure, the left buttons containing the word "proposition" corresponds to the area of lexical prediction. In the current version of K-Hermes, if the user types "a", the keypad will display the first six words in its dictionary that start with "a". The keys are arranged in alphabetical order so that the user memorizes the location of the letters easily, which helps reduce eyestrain. The buttons with the word "proposition" ("proposal" in English), which are located on the left side of K-Hermes, are used to display a set of words in the dictionary. In the current version of K-Hermes, if the user types the letter "a", the keypad will display the first six words in its dictionary that start with "a". Note that further information on the word prediction will be provided later in the subsection "Word Prediction".

For users with cerebral palsy, it is important to clarify in this article that all of these movements if repeated several hundred times a day, can cause muscle pain.

The comparative experiment involving the proposed keyboard and Clavicom NG is the subject of the next part.

Experimentation

The hypothesis is as follows: K-Hermes with a word prediction system allows for less movement (return of the hand between the joystick and push button, visible in Figure 1) for entering text. This consequently leads to a decrease in fatigue.

To prove the hypothesis, we conducted a series of tests with three different types of people:

• A person with cerebral palsy is the subject of reference for the experiments.

• A group of able-bodied people simulating a disability to use the device seen in Figure 1 for handling the pointer on the screen. They use their favored hand during testing. • A group of able-bodied people using a mouse.

People simulating a disability had an additional constraint thus bringing them closer to the extent of physical capacity of a person with cerebral palsy: they had to manipulate the joystick with one hand and a clenched fist. Under these conditions, testers make about the same movements as users with cerebral palsy.

The left joystick is used to direct the mouse pointer. The first four buttons (top two in each row) are used to simulate a left click. The following four (the last two of each line) are used to simulate a right click. This device was designed based on an old joystick which was amended and connected to a box used to translate the electrical impulses emitted by the joystick and buttons into digital data. Click lock is accomplished by holding down the top button of the first line (see Figure 1).

The test was conducted in two sessions for the following reason: Cerebral palsy causes its victims to be plagued with a lot of unwanted movements. Therefore, we decided to conduct only a few sessions. Indeed, when able-bodied people manipulate the joystick for the first time with their fists, they too must undergo a large number of additional movements. Thus making the input conditions close to those of a person with cerebral palsy. Carrying out many of these sessions makes it harder to reach the reality of those conditions, as able-bodied people become used to the constraints, which greatly reduces the involuntary movement.

The time between test sessions was 24 hours. The testers used the following four methods alternately: (1) K-Hermes with word prediction, (2) K-Hermes without word prediction, (3) Clavicom NG with word prediction, (4) NG Clavicom without prediction words. The tests were conducted as follows: (1) the testers filled out a questionnaire about their habits with computers. (2) An explanation was given about the keyboard to use. (3) During a period of 5 minutes, they input a series of 5-letter words. (4) These actions were repeated for the four keyboards over two sessions. (5) A final questionnaire was filled for their thoughts on each keyboard. Some information has been recorded for the purpose of analysis by more: the distance traveled by the pointer, the average distance between two keys, the number of comings and goings of the hand between the joystick and push button, the number of words per minute (WPM: Words Per Minute), the number of characters per second (CPS: Characters Per Second).

Preference: to evaluate the preference of testers for different keyboards, we asked testers to draw a line on an axis of ten centimeters. 0 symbolizes the most negative response (difficult to use or exhausting) and 10 the most positive (easy to use or no fatigue felt). We can see that the Clavicom NG left a better impression with testers, because of their practice with an AZERTY physical keyboard type. In addition, 90% (calculated from the questionnaire) of the participants send their messages from their mobile phones with an AZERTY keyboard (mono-tap). Word Prediction: K-Hermes is more efficient than Clavicom NG. Indeed, the former predicted 1.82 words per session and the second predicted 0.89 word per session over all the sessions with all the users. These results were calculated by summing the number of words predicted by the keyboards, and dividing by the number of participants, based on the extension of the dictionary [7] of 60 000 to 336 531 words. K-Hermes has an additional advantage in this domain: when the user uses the backspace key, the previously suggested words are proposed again. Consider the following example (see Fig. 4).

Category of questions

• the user types on the 'M' key;

• the word prediction proposes the words "Matter","Middle","Mistake".

• the user types on the 'O' key;

• The new list of words proposed: "Mother","Motor","Monster".

• By deleting the letter "o", the words: "Matter","Middle","Mistake" are proposed again. This system is not implemented in the Clavicom NG software. When the user removes a letter, all proposals are deleted. This means that the tester must complete the entry word and generates additional movements. The selection of proposals will automatically add a space as a word separator, the user does not need to enter it. This last principle is implemented in K-Hermes and Clavicom NG.

Number of words per minute:

There is a very important difference between the results obtained for the group simulating a disabled person (see Figure 5) and ablebodied people for Clavicom NG. The cause is the manipulation of the pointer: performing an action with the mouse requires a little more time, just one second (the average mouse pointing time is estimated to be 1.1 seconds according to the Keystrole Level Model(KLM) [START_REF] Card | The Psychology of Human-Computer Interaction[END_REF]), whereas with the joystick the same action may take only a few seconds. However, it was also noted that some of those who used a traditional mouse were much more precise with the pointer. First, we thought it was normal fault (handling a pointer with a joystick is not easy), but we later learned that some of the testers were used to playing video games with a joystick. The gamers had just as much difficulty manipulating the mouse pointer. This is due to the sensitivity of the joystick and the effect of reducing the precision of the pointer.

With K-Hermes, the difference between the three groups of testers is reduced. All of the able-bodied people were slower in their entries because of the disambiguation system, the testers had to make an extra effort to select the desired letter on the buttons contrary to Clavicom NG with which the characters are accessible with one click. For the group who simulated a disability, the typing speed difference between the two keyboards with word prediction for the second session was 0.16 words per minute. The reference subject obtained a lower entry speed than the other two groups. This suggests that the simulation of disability is imperfect. The reference subject made more moves because of his disability during the tests, which reduced the number of words he was able to type.

Error rate per word: for all the groups, the two keyboards are approximately the same (Clavicom NG: 0.003 errors per word; K-Hermes: 0.002 errors per word). The Multitap system in K-Hermes to choose the desired letter did not disturb the users. The fact of having to count the number of clicks to get a letter requires additional concentration and prevents the user from choosing the wrong letter.

Number of comings and goings of the hand between the joystick and button validation: for a specific period of time, assuming that users of K-Hermes and Clavicom NG input as many words as they can, the average difference between both keyboards with word prediction is 15 movements, with fewer movements for K-Hermes. If the prediction system is disabled, the number decreases to 10. Table 2 shows the number projections for a complete day. Indeed, the test lasted 5 minutes. Thus, based on the questionnaire, which was completed by all of the testers, they use a computer for an average of 7 hours per day (including breaks). Consequently, in theory, the number would reach 1260 movements within one day (without considering the break time, for example). Such a number of movements has a significant effect on the user's fatigue level. The length between the joystick and the button used during testing is 8 cm; thus the total length over a day (on such a device) could reach up to more than 20,000 cm (20,160 cm in theory). The difference between the two keyboards for the group simulating a disability with word prediction is 52 pixels. We can come to two conclusions: the user manipulates the joystick less time with K-Hermes, this reduces the movement of the arm. The second observation is on pointing precision. On K-Hermes, the keys are larger because they represent three letters. According to Fitts' law [START_REF] Fitts | The Information Capacity of the Human Motor System in Controlling the Amplitude of Movement[END_REF], the tester needs less precision and he/she performs pointing gestures faster. The testers tend to move beyond the appropriate button with Clavicom NG; the consequence is the necessity of additional operations to correct their actions. With K-Hermes, the consecutive letters in a word and finding the consecutive letters on the same key do not require moving the mouse pointer. This is a very important result for users with cerebral palsy.

In the light of the different results obtained, we can conclude that our hypothesis has been verified.

Conclusion

In this paper, the K-Hermes virtual keyboard has been proposed and described. The purpose of this paper was also to compare the reduction in effort with this T9-style keyboard compared to a QWERTY style keyboard for users with cerebral palsy. Such users greatly benefit from a reduced keyboard to limit their movements during text entry and thus reduce their physical strain. The results obtained during the experiments show a significant decrease in the number of movements. Note that other experiments have reached the following conclusion: a valid user may reach 10.4 words per minute after 10 hours of training with a T9-type keyboard [START_REF] Green | A Reduced QWERTY Keyboard for Mobile Text Entry[END_REF]. We are far from this performance, because we chose to do a limited number of tests to remain as close to reality as possible due to operations performed by users with cerebral palsy. However, through our work it was possible to increase the text entry speed while decreasing the physical effort for people with cerebral palsy, which is very promising. Our perspectives focus on improving the prediction system. We are also thinking about different layouts for the keys.

Fig. 1 .

 1 Fig. 1. Pointing device using the K-Hermes virtual keyboard.

Fig. 2 .

 2 Fig. 2. CLAVICOM NG: (1) propositions of words, (2) AZERTY keyboard.

Fig. 3 .

 3 Fig. 3. K-Hermes: (1) Word proposals, (2) T9-style keyboard (3 letters per key).

Fig. 4 .

 4 Fig. 4. Relationship between backspace and word prediction system in K-Hermes.

Fig. 5 .

 5 Fig. 5. WPM for all configuration to 2 sessions.

Table 1 .

 1 Results of the questionnaire completed by the testers at the end of each test session.

	Average (on 10)

Table 2 .

 2 Average number of movements (Number of comings and goings of the hand between joystick and validation button) during the two sets of tests.

	Keyboards	Average number of moves
	K-Hermes without word prediction	99
	K-Hermes with word prediction	93
	CLAVICOM NG without word prediction	109
	CLAVICOM NG with word prediction	108

Table 3

 3 includes the average distance traveled by the mouse pointer over all the tests carried out.

	Keyboards	Average distance	Average distance G2
		G1 (to pixel)	(to pixel)
	K-Hermes without word prediction	108	116
	K-Hermes a with word prediction	107	114
	CLAVICOM NG without word prediction	164	178
	CLAVICOM NG with word prediction	159	180

Table 3 .

 3 Average distance traveled by the mouse between two keys in the 2 sessions (G1: A group of people simulating a disability G2: group of able-bodied people).