Hirohito Shibata
email: hirohito.shibata@fujixerox.co.jp

Kentaro Takano
email: kentaro.takano@fujixerox.co.jp

Shun ' Ichi Tano

Text Touching Effects in Active Reading: The Impact of the Use of a Touch-based Tablet Device

Keywords: Active reading, proofreading, touch-based tablet devices, digital reading devices, text touching, pointing to text, sliding

This paper describes experiments examining the effect of touching interaction with text in active reading through evaluating the impact of the use of a touch-based tablet device. The first experiment compared the performance of proofreading when using paper and when using a touch-based tablet device. Results showed that participants detected more errors when reading from paper than when reading from the tablet device. During reading, when using paper, participants frequently performed the interaction of text touching, such as pointing to words and sliding their fingers or pens along sentences. This fact suggests that touching interaction with text plays an important role in proofreading tasks. To verify this hypothesis, we conducted a second experiment in which participants proofread documents with constrained interaction with paper. Results showed that they detected more errors when they were allowed to interact with text freely than when they were not allowed to interact with text. Considering these results, we discuss practical implications to effectively support active reading with a touch-based tablet device.

Introduction

Tablet devices have rapid ly gained widespread use recently. People use them for various purposes in a variety of situations [START_REF] Muller | Understanding tablet use: A mult i-method exploration[END_REF]. They are also used in work situations such as checking email, searching the Web, and giving presentations [START_REF] Hess | Does the iPad add value to business environments?[END_REF]. However, they are not frequently used for knowledge-intensive reading activit ies such as reading academic papers crit ically or proofreading technical reports thoroughly [START_REF] Liu | Reading behavior in the digital environment: Changes in reading behavior over the past ten years[END_REF]. According to Muller's diary study [START_REF] Muller | Understanding tablet use: A mult i-method exploration[END_REF], v iewing documents that seems to include such reading accounted for merely 1.3% of all activities for which tablet PCs were us ed.

Such knowledge-intensive reading, which includes crit ical thinking or learning, is called active reading [START_REF] Schilit | Beyond paper: Supporting active reading with free form digital ink annotations[END_REF]. Active reading involves not merely reading itself but also underlining a text , annotating, finding informat ion within a text, and summarizing. Our interest in this paper is how touch-based tablet devices affect active reading.

To clarify the motivation of this research, we begin with a description of our experience. After the release of the first version of iPad, one of the authors started to read academic papers using an iPad. However, he found it difficult to read papers using it. When he touched the display panel during reading, the docu ments were often moved or expanded against his wishes and this interfered with reading. He had to touch the panel carefully or g ive up touching documents so that the presentation of documents would not be changed. He realized for the first time that he often pointed to text or slid his finger along text wh ile reading and restrict ing these actions made him uncomfortable.

Fro m this experience, we inferred that these actions, which are performed almost unconsciously, played a cognitively important role in understanding documents. For example, people can impress a certain word on their minds by pointing to the word. By pointing to two words, they can easily compare distant informat ion in documents. By slid ing a finger on sentences, they can control the speed of reading to avoid skipping words or sentences unconsciously. We have noticed that touch-based tablet devices would not promote such interaction with text and wondered whether this might degrade reading performance.

To discuss the issue more p recisely, we classify readers' behavior performed during reading. Interaction with paper documents is divided into two types: interaction with sheets and interaction with contents. The former includes moving docu ments, arranging documents, and turning or flipping pages, which we call document manipulation in this paper. For the latter, i.e., interaction with contents, we div ide them into two types. One is annotation that includes underlining text, drawing symbols such as circles or asterisks, and writ ing text in the margin area. It remains permanent info rmation in the document. The other is a touching gesture for contents without leaving any permanent information, wh ich we call text touching. It includes pointing to text and sliding a finger or a pen along text.

The issue of unexpected behavior of a touch-based tablet device in active reading is caused by the interaction of text touching. However, the effect of text touching for active reading is not investigated as far as we know. Therefore, in this paper, we examine how text touching affect reading performance in active reading.

Related Work

Previous studies that compared reading fro m paper and reading fro m screens have mainly dealt with sequential read ing in which readers read documents fro m beginning to end while turn ing pages one-by-one [START_REF] Dillon | Read ing fro m paper versus screens: A critical review of the emp irical literature[END_REF][START_REF] Dyson | Ho w physical text layout affects reading fro m screen[END_REF][START_REF] Gou Ld | Reading fro m CRT displays can be as fast as reading fro m paper[END_REF]. Ho wever, in a work situation, people often skim a document, move back and forth between pages repeatedly, move and organize documents by laying out multip le documents spatially during reading [START_REF] Adler | A diary study of workrelated reading: Design imp licat ions for digital reading devices[END_REF][START_REF] Marshall | Turn ing the page on navigation[END_REF][START_REF] Sellen | The myth of the paperless office[END_REF]. In the following, we overview studies dealing with such work-related reading, whose characteristics are closely similar to active reading, and we describe how interaction with contents affects reading.

Regarding document man ipulation, O'Hara et al. [START_REF] O'hara | A co mparison of read ing paper and on -line docu ments[END_REF][START_REF] O'hara | Understanding the materiality of writ ing fro m mu ltip le sources[END_REF] reported that paper documents are easy to handle in moving or arranging documents and this effectively supports reading. Paper as a physical artifact allows such easy document man ipulation [START_REF] Morris | Reading revisited: Evaluating the usability of d igital display surfaces for act ive reading tasks[END_REF]. In other words, in some cases, awkward manipulab ility of electronic media sometimes degrades the performance of reading in such reading. In fact, some experiments have shown that reading fro m paper is superior to reading fro m electronic media in reading for learn ing [START_REF] Kirsh | Co mp lementary strategies: Why we use our hands when we think[END_REF], reading to organize or select relevant documents [START_REF] Buchanan | Investigating document triage on paper and electronic media[END_REF], cross-reference reading for mu ltiple documents [START_REF] Shibata | Why is paper superior to computer displays in cross-reference reading for mu ltiple documents?[END_REF], reading with frequent moving among pages [START_REF] Shibata | Co mparison of paper and computer displays in reading including frequent movement between pages[END_REF], and reading for discussion [START_REF] Takano | Do tablets really support discussion? Comparison between paper, a tablet, and a laptop PC used as discussion tools[END_REF].

Regarding annotations, Marshall [START_REF] Marshall | Annotation: fro m paper books to the digital library[END_REF][START_REF] Marshall | Explo ring the relationship between personal and public annotations[END_REF] investigated how annotations are used and how they support reading based on observational studies. O'Hara et al. [START_REF] O'hara | A co mparison of read ing paper and on -line docu ments[END_REF][START_REF] O'hara | Understanding the materiality of writ ing fro m mu ltip le sources[END_REF] observed that annotating is integrated with reading more s moothly when using paper. Johnson [START_REF] Johnson | Marg inalised behaviour: Dig ital annotations, spat ial encoding and the implications for reading co mprehension[END_REF] experimentally showed that annotations are more frequently performed when reading fro m paper than when reading fro m screens, and that annotations help to develop spatial memory of text. In addit ion to these studies, the effect of annotation for read ing has been widely recognized. In fact, many systems to support active reading pay much attention to the support of annotation [START_REF] Chen | Designing a multi-slate reading environment to support active reading activ ities[END_REF][START_REF] Go Lovchinsky | The active reading application[END_REF][START_REF] Hinckley | Situ search for active note taking[END_REF][START_REF] Hinckley | Informal informat ion gathering techniques for active reading[END_REF][START_REF] Matulic | Supporting active read ing on pen and touch -operated tabletops[END_REF][START_REF] Schilit | Beyond paper: Supporting active reading with free form digital ink annotations[END_REF]. Most of them provide a feature of free-form in k annotation like paper and a pen. Morris et al.'s [START_REF] Morris | Reading revisited: Evaluating the usability of d igital display surfaces for act ive reading tasks[END_REF] report, based on their experiment, that current computer environments including tablet PCs do not sufficiently support easy quick annotation.

Regarding text touching, very little research has addressed the effect of text touching for reading. According to microscopic analysis of actions performed during actual reading in a work situation, people were frequently performing pointing to text [START_REF] Hong | Microanalysis of active read ing behavior to inform design of interactive desktop workspaces[END_REF][START_REF] Shibata | Why is paper superior to computer displays in cross-reference reading for mu ltiple documents?[END_REF][START_REF] Takano | Microscopic analysis of document handling while read ing paper documents to imp rove digital reading device[END_REF]. Additionally, based on an informal observation, Kirsh [START_REF] Kirsh | Co mp lementary strategies: Why we use our hands when we think[END_REF] pointed out that people exp licit ly pay attention to a certain part of text by using a finger. These facts bring us an inference that pointing to text supports reading. However, no study has assessed how pointing to text affected reading performance quantitatively, as far as we have found. Moreover, the effect of sliding a finger or a pen has not been addressed even from the perspective of observation.

Considering these facts, we aim at assessing the effect of text touching in active reading. If we can understand its role, we expect that we can provide promising design implications to support active reading in tablet devices.

Text Touching Effects

As we described before, very little research has addressed the effect of text touching for reading. Ho wever, we do not think the reason is because text touching does not play an important role in read ing. At the least, we consider text touching has the following cognitive effects for reading on theoretical grounds:  Paying attention to a certain part. By pointing to a word or a sentence, readers can pay attention to its position explicitly [START_REF] Kirsh | Co mp lementary strategies: Why we use our hands when we think[END_REF]. Th is spatial cue helps strengthen readers' experience and memory for that part of the text [START_REF] Minogue | Haptics in education: Exp loring an untapped sensory modality[END_REF].

 Keeping a reading position. Readers sometimes put their finger or hand at the start of a line o r a paragraph where they are reading [START_REF] Hong | Microanalysis of active read ing behavior to inform design of interactive desktop workspaces[END_REF][START_REF] Kirsh | Co mp lementary strategies: Why we use our hands when we think[END_REF]. In doing so, they can easily move back to the start position of the line. Moreover, they can also easily move to the next line without losing their place in the text.  Comparing different parts. By putting fingers or a pen on different words or sentences, readers can readily co mpare them located in different positions. In this case, the finger or the pen can function as a navigational guide to direct the eye. Sliding a finger or a pen on text brings about the following cognitive effect s:  Reading while devoting attention to each word . By sliding a finger or a pen along text, readers can check words one-by-one carefully. Readers can exp licit ly devote attention to a certain part.  Controlling the reading speed. Readers sometimes make haste unconsciously, especially when they read a docu ment they already know. Sliding a finger or a pen visualizes the speed of reading and helps a reader to avoid skipping words or sentences. Additionally, by touching text constantly, readers are apparently able to continue concentrating on reading activ ities [START_REF] Minogue | Haptics in education: Exp loring an untapped sensory modality[END_REF]. These cognitive effects seem to support reading documents carefully. If text touching is constrained, readers cannot leverage these cognitive effects, which might degrade the reading performance.

When using touch-based tablet PCs, documents might be moved or expanded against readers' wishes. Therefore, readers might think that they must not touch the panel while reading. Additionally, they might refrain fro m touching the panel frequently because the panel surface is too smooth and glassy. They might think that they are reluctant to leave a fingerprint on such a glassy surface. So , the use of touchbased tablet devices might restrain the interaction of text touching, which might lower the reading performance.

To verify this init ial hypothesis, in the first experiment, we co mpare reading fro m paper and reading fro m a touch-based tablet device. We measure the number of text touches that are performed wh ile reading. In the second experiment, to verify the effects of text touching, we examine how the restriction of text touching affects the reading performance.

Basic Framework

In our experiments, we require readers to read a docu ment and detect errors as much as possible. Independent variables are read ing media (paper or a tablet PC) or reading conditions. Dependent variables are error-detection rate and reading speed.

As a first step to examine the effect of text touching in active reading, we select cognitively demanding reading as an experimental task. According to our preliminary observational study, readers performed text touching frequently in cognitively demanding reading. Typical examples of this were reading difficu lt technical documents or documents written in a foreign language. Therefore, we require readers to detect semantic errors such that the term "a cat" must be replaced by "a dog" or the term "increased" must be replaced by "decreased." Classical e xperiments that compare reading among med ia have mainly required participants to detect alphabetical errors during a reading task [START_REF] Dillon | Read ing fro m paper versus screens: A critical review of the emp irical literature[END_REF][START_REF] Gou Ld | Reading fro m CRT displays can be as fast as reading fro m paper[END_REF]. However, readers can detect alphabetical errors with superficial reading and, technically speaking, they do not have to understand the meaning of the document. However, in our task, readers must understand the context of documents accurately to detect contextual inconsistencies. Moreover, we require readers to detect erro rs within a limited time to make them concentrate on proofreading with great caution.

To concentrate on assessing the effect of text touching for read ing, we need to isolate text touching from document manipulation. We use one single-page single document at a time to avoid the operations of arranging documents or turning pages.

Readers usually hold a pen during proofreading. Therefo re, we allo w readers to annotate while read ing of the experiments. However, we analyze text touching and annotation separately and assess the effect of them for read ing performance separately.

In an experiment using a tablet PC, i.e. in Experiment 1, we tried to min imize the effect of different writ ing tools and different writ ing manners for the reading performance. When read ing fro m a tablet PC, we attached a transparent film on the panel of the tablet PC and allow participants to write anything on the film with an oilbased pen in the same way as the use of paper as shown in Fig. 1. The ink does not smear on the hand during reading because the pen is oil-based. The transparent film is similar to a protective film of display panels that many people use. Therefore, we think this film apparently does not change the participants' usual panel-touching behavior for the tablet PC.

Fig. 1. Annotating on the panel of a tablet PC.

In all experiments, we required readers to report the positions of errors orally without correcting them. If we require them to check the error positions using special marks such as underlines or circles, then readers must use other notations to give their own annotation and this might change their annotating behavior. Therefore, we adopted the method of oral reporting to avoid giving any restriction for annotation.

Experiment 1: Paper vs. Tablet PC

In the first experiment, we co mpare reading fro m paper and reading fro m a touchbased tablet PC during proofreading to detect semantic erro rs. In this experiment, we examine the following two hypotheses.

First, we expect that reading from a touch-based tablet device would be inferior to reading fro m paper in reading with frequent text touching. Unexpected behavior of digital docu ments caused by touching the panel would become a factor in degrading the reading performance. In addition, if the tablet device constrained the interaction of text touching, then readers would not make use of the effect iveness of text touching by devoting attention to each word or comparing multiple words or sentences easily.

Second, we expect that people would perform text touching more frequently when reading fro m paper than when reading fro m the tablet device. Most current tablet devices are hard and heavy. Therefore, people less frequently hold these devices during reading and manual interaction with tablet devices would not be pro moted. Moreover, touching of panels might cause unexpected document operations such as expanding, shrinking, or turning pages. Such operations might deter readers from touching panels while reading. Additionally, most panels of tablet devices are a glossy surface. Some users might hesitate to touch the panel because fingerprints can stain the surface when they are touched. Consequently, surface materials might not encourage touching of the panel.

Method

Design and participants. The experimental design was a one-way withinparticipants design. The factor was the mediu m (paper and a tablet device). Each participant performed all conditions of tasks and performed t wo trials in each condition. The order of the media used in the participants' trials was counte rbalanced to cancel the overall effects of the trial order.

Participants were 24 Japanese people (12 men, 12 wo men). Their ages were 23-40 years (avg. 31.3). Each had three or more years' experience using PCs. The vision of each, after correction, was better than 0.7. A mong them, 12 people had their o wn touch-based tablet PCs or s mart phones; 3 people were using these devices in business on a daily basis.

Materials. We created documents for the experiment based on columns of a Japanese-language newspaper. We eliminated colu mns related to current events because the level of understanding differs widely depending on background knowledge related to these events. Additionally, we eliminated metaphorical colu mns or prosy columns because the understanding of them differs widely among individuals.

Each docu ment had five semantic errors. Participants were unable to detect these errors without checking the semantic context of the text carefully, although they were able to detect typographical errors while checking text at a surface level.

The average length of the four documents was 660.0 characters. Task. The experiment task was to detect as many semantic errors as accurately as possible. The time limit was four minutes. For the report of error positions, we required them to read aloud at least five characters around errors to judge the position of errors in the text. The task trials were terminated when participants detected all five errors or when the time limit was reached.

Environments. We used the following two media in the experiment.

 Paper : The documents were printed in b lack and white on one side of B5 paper. They were written horizontally in 14 point font. Regarding the margin of the documents, the side margins were 2.8 mm, the top margin was 2.1 mm, and the bottom marg in was 2.4 mm. Each document had 26 lines, each with 34 characters. The line spacing was 22 point.  Tablet PC: As a typical example of touch-based tablet PC, we selected an iPad (WiFi 16G model; Apple Co mputer Inc.), wh ich is widely used. The documents were converted to PDF files and were presented on an iPad. We used i -Bunko HD (ver. 1.07) as a PDF v iewer, which is widely used as a Japanese e-book reader. We adjusted the electronic docu ment character size to be equal to that of characters on the paper. In both conditions, we allowed participants to annotate using the same oil-based pen. As we described before, in the Tablet PC condition, the panel of the PC was covered by a transparent film (Fig. 1). We provided the same manner of annotation among media so that the difference of the mode of writ ing among media does not affect the reading performance. We used new transparent films for every trial.

In i-Bunko HD, the change of document representation is caused by the following interaction. A document is expanded or shrunk when users pinch out or pinch in the document using two fingers. When the document is expanded, the display area of pages is changed when users drag the document. The display page of a docu ment is changed when users swipe the panel or when users tap the side area of the panel. A menu and a slider are displayed when users tap the bottom area of the panel. Interaction of these types is common and broadly used in touch-based tablet PCs and smart phones. However, because the documents used in the experiment were all onepage, page-turning is not performed to co mplete the task of the experiment. Moreover, these functions do not work by contact with the oil-based pen.

Procedure . Before the experiment, part icipants engaged in training and became accustomed to using the iPad and performing the task. They also adjusted the brightness of the devices according to their preferences.

In performing the task, we allowed part icipants to hold the paper or the device freely. While performing the task, we displayed the count of error-detection that they had found using a paper board. We did not give feedback to participants related to whether the detected errors were correct or not while performing the task.

After the experiment, we conducted a questionnaire survey and an interview. Participants detected fewer errors when using the tablet device. This result supports our first hypothesis: reading fro m touch-based tablet devices is inferior to reading from paper in this cognitive demanding reading.

Results and discussion

In the post-task survey, for four statements (Q1 You were able to concentrate on the proofreading task, Q2 You were able to detect many errors, Q3 You were able to perform the task quickly, Q4 You felt little fat igue), we required part icipants to evaluate two conditions (Paper and Table PC) using a 5 -point rating (1=strongly disagree, 2=disagree, 3=neither agree nor disagree, 4=agree, and 5=strongly agree). Fig. 3 presents the average of the ratings given for each question item. Participants felt that they were able to concentrate on the task when using paper. They were also able to perform the task qu ickly and felt little fatigue when using paper.

Ne xt, why was reading fro m the tablet device inferior to reading fro m paper? One possible reason for this result is a factor of presentation quality of documents. However, it has been verified experimentally that reading performance does not differ between paper and computer displays when using high-performance displays [START_REF] Dillon | Read ing fro m paper versus screens: A critical review of the emp irical literature[END_REF][START_REF] Gou Ld | Reading fro m CRT displays can be as fast as reading fro m paper[END_REF][START_REF] O'hara | A co mparison of read ing paper and on -line docu ments[END_REF]. These experiments were conducted from the late 80s to the early 90s. However, the iPad used in this experiment provided higher-quality presentation than the computer displays used in the earlier experiments. Therefore, it seems that the presentation quality of media did not affect the error-detection rate of reading.

The next possible reason is a factor of document manipu lation and interact ion with the content. However, because we us ed single-page single docu ments in this experiment, there was no document manipulation such as moving docu ments, arranging documents, and turning pages. This allowed us to specifically analyze interaction with the content.

Fig. 4 presents a comparison of the frequency of interacting with the content per minute. The interaction is divided into three types: annotating the document (Annotating), slid ing a finger or a pen along the text (Slid ing), and pointing to the text (Pointing). The latter two correspond to text touching. The type of interaction with text was judged visually by one of the experimenters by referring v ideo data. On judging the type of interaction, sliding and pointing are discriminated based on whether participants move a finger o r pen on the media surface. On counting the interaction with the text, every time participants' finger or pen was released fro m the panel, we considered that a new interaction occurred. We observed several times that participants' finger or pen hovered over the text without touching the panel. Such interaction can be also considered as interaction with text . However, we d id not count such actions because it is difficult to judge whether part icipants are hov ering or just moving their finger or pen in the air and it is also difficu lt to determine the start and the end of each hovering action. Therefore, we can say that the interaction with text was performed more in actual than the figures of Fig. 4. We conducted a paired t-test among media for every type of interaction. Results show that, for annotating, no significant difference was found among media [t(23)=1.40, p>.1]. Regard ing text touching, a significant difference was found regarding the pointing [t(23)=4.00, p<.001] and the slid ing [t(23)=2.17, p<.05]. Therefore, participants performed pointing to text and slid ing a finger or a pen along text more when reading from paper than when reading from the tablet.

Fro m this result, we discuss the following two points. First, participants performed text touching more frequently when using paper than when using the tablet device. This supports our second hypothesis: people perform text touching more frequently when reading fro m paper than when reading fro m a tablet device. In the post task interview, one part icipant reported that when putting their hand on the panel during the training session, a document was expanded unintentionally; thereafter, the person devoted special attention to the hand when touching the panel. Another participant reported that the person hesitated to touch the panel because it was so glassy and smooth. We think that these were main reasons why people performed text touching less frequently when using the tablet device.

Second, no significant difference was found in the amount of annotation among med ia. Prev ious studies revealed that people annotated more on paper than on electronic med ia [START_REF] Johnson | Marg inalised behaviour: Dig ital annotations, spat ial encoding and the implications for reading co mprehension[END_REF][START_REF] Morris | Reading revisited: Evaluating the usability of d igital display surfaces for act ive reading tasks[END_REF]. However, in this experiment, the amount of annotation did not differ among med ia, probably due to the following two reasons. First, part icipants did not have to re-read documents later in this task. Therefore, they did not have to extract info rmation for the next reading. In fact, most of the annotation that participants made in this task was underlin ing or circling error positions. Second, the documents used in the experiment were all single -page documents. Participants were able to view a whole document at one time and they did not have to compare informat ion fro m d ifferent pages. Therefore, p lacing permanent informat ion in the document might not have produced any important benefit in this task.

Considering these results, we developed a new hypothesis: the frequency of text touching affects reading performance. In other words, reading fro m a tablet device is inferior to reading fro m paper in cognitive demanding read ing because the interaction of text touching is constrained when using the tablet. In fact, a positive correlation was found between the error-detection rate and the amount of text touching. Pearson's product-mo ment correlat ion coefficient was 0.451, wh ich is significantly different fro m zero [p<.05]. Therefore, those who frequently perfo rmed text touching made a high score in the error-detection rate. If people are unable to point to text, they might forget to devote attention to a certain part, or it migh t become difficult to compare distantly positioned parts of text. If they are unable to slide a finger or a pen on text, people might skip words or sentenced during reading. It is possible that such inconvenience lowers reading performance. To verify our n ew hypothesis, we conduct another experiment, as explained in the next section.

Experiment 2: Restricting interaction with paper

This experiment examines how reading performance varies when text touching was constrained. The following hypotheses in this experiment are tested with this experiment. Even if people read documents using paper, we expect that reading performance would be degraded when the interaction of text touching is restricted.

Method

Design and participants. The experimental design was a one-way withinparticipants design. The factor was the task condition (Untouchable, Touchable, and Writable). Each participant performed all conditions and performed two trials in each condition. The order of the task condition in the participants' trials was counterbalanced to cancel the overall effect of the trial order.

Participants were the 24 people who participated in Experiment 1. Materials. We created documents for the experiment in the same way as Experiment 1. For the six docu ments used in this experiment, the average length of text was 661.0 characters.

Task. The task of this experiment was identical to that of Experiment 1. In each trial, part icipants were required to detect semantic errors to the greatest extent possible within four minutes. We did not reuse the documents used in Experiment 1.

Task conditions. Each task environment was identical to the Paper condition of Experiment 1. The documents were printed on one side of B5 paper in black and white. We gave the following three conditions related to the interaction with contents.  Untouchable: Participants cannot touch paper documents at all except for setting the initial position of the documents.  Touchable : Part icipants can touch paper documents but cannot write anything on the documents.  Writable : Part icipants can touch paper documents and can write anything on the documents. Procedure . Before the experiment, part icipants engaged in training and became accustomed to each task condition.

After the experiment, we conducted an interview.

Results and discussion

Fig. 5 presents a comparison of error-detection rates among the three task conditions. One-way repeated measures analysis of variance revealed that the main effects of the task condition were significant [F(2, 46)=5.38, p <.01]. We conducted a mu ltiple co mparison using the Fisher's LSD (Least Significant Difference) method. Results show that the error-detection rate in the Untouchable condition was significantly lo wer than that of the Touchable condition and the Writable condition [p<.05]. No significant difference was found between the Touchable condition and the Writable condition [p>.1].

The error-detection rate was degraded when text touching was prohibited. Th is fact supports the hypothesis that reading is deteriorated when the interaction of text touching is restricted, which indicates that text touching is an important factor affecting the reading performance. Many studies support the effectiveness of annotation to understand and re-read text documents [START_REF] Marshall | Annotation: fro m paper books to the digital library[END_REF][START_REF] O'hara | A co mparison of read ing paper and on -line docu ments[END_REF][START_REF] O'hara | Understanding the materiality of writ ing fro m mu ltip le sources[END_REF]. However, in this experiment, writing (i.e., annotating) did not improve the reading performance. As we described in Experiment 1, the reading task of this experiment did not require heavy annotation to perform the task of this experiment. We think that participants were unable to make use of the benefits of annotation in this task. In fact, most annotations that participants made were underlining or circling the positions of errors that they found.

Regarding the effects of pointing to text, many participants reported that they were able to devote attention consciously to a certain part. One participant reported "I was able to remember the rough positions of errors by pointing to them. Therefore, I do not need to check them again in a second reading." This statement indicates that pointing to text strengthens spatial memo ry for a certain part within a page. Additionally, one participant found it easy to compare distantly positioned parts by pointing to a certain word. The person reported "this part is about China, but that part describes Japan. I checked whether this correspondence was correct or not."

Regarding the effect of slid ing a finger or a pen along the text, two participants reported that they were ab le to read text intentionally slowly. One part icipant reported "I am apt to hurry up in reading. By slid ing a finger, I can avoid this problem." In particular, when people proofread a document that they wrote by themselves, they tend to skip read ing because they already know the contents of the document. Sliding a finger along text wou ld help to read text intentionally slowly without skipping each word.

Many participants reported that they were able to concentrate on the reading task better when reading with text touching than when reading without text touching. One participant reported "(in the Untouchable condition) I felt frustrating because I could not touch a document. I felt a sense of distance fro m the document. I felt as if I was looking at a bullet in board." Reading without text touching seems to g ive part icipants a feeling of looking at a document fro m a distance. Text touching might bring about a psychological effect that removes a distance or boundary between a reader and a document and which compels a reader to concentrate on reading.

After the experiment, two part icipants explicit ly reported that they realized that they were usually pointing to text or slid ing a finger on text unconsciously. One reported "Today, for the first time, I realized that it was quite difficu lt to read documents without touching them." The other reported "I realized that I had been frequently performing text touching during reading. I had not been aware of it until I participated in this experiment." These statements indicate that text touching is performed almost unconsciously and that people realize the importance of text touching when it is restricted.

General discussion

Experiment 1 revealed that in a certain type of reading, at least when proofreading to detect semantic errors, people detected fewer errors when reading fro m a touchbased tablet device than when reading fro m paper. Additionally, people performed less text touching when using the tablet device than when using paper. We hypothesized that the use of the tablet degraded the read ing performance because it did not promote the interaction of text touching during read ing. To confirm this, in Experiment 2, we examined how reading performance varies when text touching was restricted. As a result, when text touching was prohibited, reading performance was degraded. This means that text touching contributes to improve read ing performance.

First, we will discuss the generality of this study and present some remain ing challenges. Next, we will discuss design imp lications that may be drawn at this stage to improve digital reading devices used in active reading.

Generality of the study

We need to discuss the generality and the scope of th is study. First, we discuss the specialty of the task. In th is research, we addressed proofreading to detect semantic errors within a limited time. We selected this task because this type of reading seems to frequently include the interaction of text touching. The experiments demonstrated that in such reading, the reading performance was degraded when text touching was restricted. We need to consider how much text touching is performed in other kinds of reading and to verify the effect of text touching in these.

In our previous study, we conducted microscopic analysis of handling paper documents while reading [START_REF] Takano | Microscopic analysis of document handling while read ing paper documents to imp rove digital reading device[END_REF]. We categorized the ways that people interact with paper documents in detail, which is hierarch ically organized and consists of more than sixty actions at a bottom level, and analyzed reading behavior for various types of work-related reading based on these categories. Among them, we focus on two actions: placing a finger or an object on paper (i.e. pointing) and moving a finger in parallel to the sheet (i.e. slid ing a finger along text). Table 1 presents the frequency of these two actions per minute for various types of readin g. In the Paper condition of Experiment 1, part icipants performed pointing to text 0.92 t imes per minute and they performed slid ing a finger or a pen 1.04 times per minute. Therefore, in this table, items of pointing whose frequency is more than 0.92 are co lored in red and items of sliding whose frequency is more than 1.04 are colored in orange.

Table 1. Frequency of text touching per minute while readi ng. Items of pointing whose frequency is more than 0.92 are colored in red and items of sliding whose frequency is more than 1.04 are colored in orange.

According to this table, much work-related reading, except for skimming and preparatory reading for d iscussion, text touching was frequently performed. There is a possibility that reading performance might be degraded if text touching is prohibited in these reading types. We think that the task we selected in the experiments was not so special at least fro m the perspective of the frequency of text touching. However, we need to verify whether read ing performance is actually degraded if text touching is restricted in these reading.

There are two majo r actions in text touching: pointing to text and sliding a finger along text. In this study, we examined the integrated effect of these two actions without separating them. Ho wever, the two d ifferent actions might cause different effects for reading. According to Tab le 1, the frequency of the two actions varies depending on the type of reading. If we could know how each action affects read ing, we can infer how text touching affects the performance of d ifferent type of read ing. Evaluating the effect of each action for reading indiv idually is also an important future challenge.

Next, we d iscuss the issue of participants. Different people have different reading style. Therefore, it is apparent that the frequency of text touching varies depending on individuals. For this point, we have following two important questions. What kind of person performs text touching frequently? Even for a person who does not usually touch text during reading, is the reading performance improved if the person begins to perform text touching frequently?

For the former question, we conducted post hoc analysis for the results of Experiment 1. We co mpared the frequency of text touching in terms of gender (men and women), age (20's and 30's), and owning touch -based devices (owning and nonowning). A t -test revealed a significant difference only for the age [t (22)=2.25, p<.05]. The average value for 20's and 30's were 3.59 and 9.77 respectively. Older people performed more text touching than younger people. No significant difference was found for gender [p>.1] and owning touch-based devices [p>.1]. As other factors that might affect the frequency of text touching, we should investigate the effect of their experiences for read ing and writing. We need to co mpare the frequency of text touching between novice readers and expert readers. If we could understand the type of readers and their reading behavior, then we can p rovide a b etter support for reading depending on users.

For the latter question, we infer that reading performance would be improved if people perform text touching intentionally. That is because there was a positive correlation between the frequency of text touching and the error-detection rate in the first experiment. However, we need to verify this in future work.

Finally, we need to investigate other configurations of a tablet PC or other slatetype reading devices. In this study, we evaluated a touch -based tablet PC that allo wed operating documents by touch gestures. However, users can disable this feature when using it. Disabling this feature, users can avoid a problem that unexpected behavior is caused by text touching. However, there is a possibility that the weight and glossy surface of devices might restrain text touching and we need to investigate this effect. Reading devices with e-paper such as Kindle (A mazon Inc.) are relatively light and does not provide glossy surface. They might pro mote text touching in co mparison with touch-based tablet PCs. We need to confirm this as future work.

Suggestions

The study of text touching is not yet completed. As we described in the prev ious section, there are so me remaining challenges to make clear the effect of t ext touching for various types of reading. In this paper, as a first step, we found that text touching affects reading performance in a certain type of reading. To determine the applicable scope of this phenomenon, we need mo re investigation for various types of reading and devices. However, in the following, we describe design imp licat ions that can be considered at this stage to improve touch-based reading devices used in active reading.

The experiments in this paper revealed three important findings. Firs t, people will read with touching text in a certain type of reading. Second, during such reading, the reading performance may be degraded when text touching is restricted. Third, touchbased tablet devices may work on restricting users' interaction of text touching.

It is desirable that a touch-based reading device should be designed with these findings in mind, if it aims to support active reading. In most current tablet devices, touch gestures are assigned to functions to operate documents such as expand ing or shrinking documents, changing the display area of documents, and turning pages. Therefore, unexpected behavior of documents might be caused by text touching, which may be t roublesome for readers. In addition, if readers avoid touching text, they cannot make use of the effects of text touching such as devoting attention to some parts, comparing different parts easily, controlling the reading speed, and preventing skipping words or sentences.

Therefore, it is desirable that a tablet device used in active reading should not interfere with text touching performed during reading. To achieve this, designers of the reading device need to assign gestures that are not performed in usual reading to functions of operating documents, if the device uses touch gestures. Microscopic analysis of gestures during reading [START_REF] Takano | Microscopic analysis of document handling while read ing paper documents to imp rove digital reading device[END_REF] would help to determine what kind of gesture we should use for handling documents.

Finally, a d igital reading device might be able to promote text touching as well a s prevent interfering with text touching by using visual feedback for users' behavior or by directly prompting text touching. In these cases, we can expect that reading performance might be improved.

Conclusions

On the assumption that text touching such as pointing to text and slid ing a finger or a pen along text plays an important role for understanding documents, we conducted two experiments. The first experiment co mpared reading fro m paper and read ing fro m a touch-based tablet device in proofreading. Results showed that the error-detection rate was higher when reading fro m paper than when reading fro m the tablet device. We inferred that this was because a touch-based tablet device did not promote the interaction of text touching during reading and this degraded the reading performance. To verify this hypothesis, we conducted the second experiment, wh ich restricted text touching during proofreading. Results show that error-detection rates decreased when text touching was restricted. Considering these results, we suggest that a touch-based tablet device should be designed not to constrain text touching if the device is intended to support reading with frequent text touching, where act ive reading typically accompanies frequent text touching.

We are currently investigating the behavior during reading in detail. In this framework, we intend to conduct a detailed investigation of the effects of interaction with text. Moreover, we are currently designing a digital reading device based on the design implication described in this paper.

Fig. 2 p

 2 Fig. 2 p resents a co mparison of the error-detection rate, which is the percentage of answers that participants had detected correctly. The erro r bar shows the standard error of the mean. It is the same throughout this paper. A paired t-test revealed a significant difference among media [t(23)=2.51, p<.05]. Participants detected 17.2% mo re errors in the Paper condition than in the Tablet PC condition. Regarding the task completion time, no significant difference was found among media [t(23)=1.96, p>.1] (the average times were, respectively, 218.5 s and 225.4 s in the Paper condition and the Tablet PC condition).

Fig. 2 .

 2 Fig. 2. Error-detection rate in each medium.

Fig. 3 .

 3 Fig. 3. Subjective evaluation of each media (***, **, and * denote significance at 0.1% , 1% , and 5% levels respectively).

Fig. 4 .

 4 Fig. 4. Frequency of interacting with text (*** and * denotes significance at 0.1% and 5% level respectively).

Fig. 5 .

 5 Fig. 5. Error-detection rate in each condition.

Acknowledgement

We thank Maribeth Back of FX Palo Alto Laboratory for her carefu l check for the final version of this paper.

Trademarks

iPad is a trademark or registered trademark of Apple Co mputer Inc. Kindle is a trademark or registered trademark o f A mazon Inc. All other brand names and product names are trademarks or registered trademarks of their respective companies.


Maria Rauschenberger
email: maria.rauschenberger@offis.de

Silke Füchsel
email: sfuchsel@gmx.de

Luz Rello

Clara Bayarri

Jörg Thomaschewski
email: joerg.thomaschewski@hs-emden-leer.de

Exercises for German-Speaking Children with Dyslexia

Keywords: Dyslexia, iOS, Spelling, German, Children, Gamification

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

Introduction

Dyslexia is a specific learning disability with neurological origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological components of language that is often unexpected in relation to other cognitive abilities. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge [START_REF] Lyon | A definition of dyslexia[END_REF]. Dyslexia is frequent: Worldwide, 10% of the population and from 5 to 12% of the German students have dyslexia [START_REF]Gesundheitsforschung -BMBF -Genetische Ursache für Legasthenie entdeckt[END_REF].

In Germany, only 25% of the poor spellers achieve average spelling performance during the period of primary school [START_REF] Remschmidt | Kinder-und Jugendpsychiatrie: Eine praktische Einführung : 177 Tabellen[END_REF]. In a longitudinal study Esser et al. [START_REF] Esser | Was wird aus achtjährigen mit einer Lese-und Rechtschreibstörung? Ergebnisse im alter von 25 Jahren[END_REF] showed that children with diagnosed dyslexia at the age of eight achieved less school performance and a higher rate of unemployment, than the control group measured afterwards at the age of 25. Schulte-Körne et al. [START_REF] Schulte-Körne | Nachuntersuchung einer Stichprobe von Lese-Rechtschreibgestörten Kindern im Erwachsenenalter[END_REF] showed that it takes longer for children with dyslexia to achieve school grades that are comparable to the others, even if these children have a socio-economic condition above the average.

Overcoming dyslexia means a great effort for children and requires doing language exercises regularly [START_REF] Hornsby | Overcoming dyslexia[END_REF]. Traditionally, these exercises are done using pen and paper. In the case of dyslexia, exercises on paper introduce an added difficulty for some students due to the fact that dysgraphia2 is comorbid with dyslexia [START_REF] Nicolson | Dyslexia, dysgraphia, procedural learning and the cerebellum[END_REF].

More recently, it was shown that computer games are a convenient medium to provide exercises in an engaging way to significantly improve the reading performance [START_REF] Kyle | Assessing the effectiveness of two theoretically motivated computer-assisted reading interventions in the united kingdom: Gg rime and gg phoneme[END_REF][START_REF] Lyytinen | Early identification of dyslexia and the use of computer game-based practice to support reading acquisition[END_REF] and the spelling performance [START_REF] Rello | A computer-based method to improve the spelling of children with dyslexia using errors[END_REF] of children with dyslexia. These methods cannot simply be extended to other languages because manifestations of dyslexia depend on the different orthographies of the languages [START_REF] Goulandris | Dyslexia in different languages: Cross-linguistic comparisons[END_REF].

In this paper, we present a game for children with dyslexia for German. To make the training exercises, this method uses real errors found in texts written by children with dyslexia. To the best of our knowledge, this is the first time that error-based exercises targeted for people with dyslexia are done for German.

The structure of the paper is stated as follows: Section 2 details related work while Section 3 presents how we created the content design of the application. Finally, we draw conclusions and describe our future work in Section 4.

Related Work

There are several approaches of assistive technology for dyslexia [START_REF] Petrie | Personalization, interaction, and navigation in rich multimedia documents for print-disabled users[END_REF]. Following, we only present related games to support and train specific issues of dyslexia.

Lernserver is a tool to diagnose dyslexia in German, define the level of support the child needs, and provide support exercises [START_REF] Höinghaus | Ampelsignale zeigen Förderbedarf -bundesweite Lisa-Bildungskampagne[END_REF]. An evaluation with the Landesinstitut für Schule found out that 78,2 % of the students (N = 3798) improved their writing using this tool [START_REF] Flug | Projekt-Evaluation Bremen: Erprobungsphase des Lernservers an bremischen schulen[END_REF]. Similarly, Klex 11 3 helps to practice vocabulary in German adapted to a certain school degree. These tools only use correct-based exercises in the game. Likewise, CESAR schreiben 2.04 is a strategy and educational game, which includes listening, spelling and vocabulary.

Kyle et al. [START_REF] Kyle | Assessing the effectiveness of two theoretically motivated computer-assisted reading interventions in the united kingdom: Gg rime and gg phoneme[END_REF] compared two computer-assisted reading interventions for English inspired by the Finnish GraphoGame [START_REF] Lyytinen | In search of a sciencebased application: A learning tool for reading acquisition[END_REF]: GG Rime and GG Phoneme. They conducted a user study with 31 children of 6 and 7 years old. While the results show that both games may benefit decoding abilities, no significant effects were found, probably due to an insufficient number of participants or not enough training time. The closest work to us is Dyseggxia or Piruletras for iOS [START_REF] Rello | What is wrong with this word? Dyseggxia: a game for children with dyslexia[END_REF], a game composed of error-based exercises to support writing in children with dyslexia in English and Spanish. During eight weeks, the authors carried out a within-subject experiment with 48 children from 6 to 11 years old. Children who played Dyseggxia for four weeks in a row had significantly less writing errors in the tests than after playing the control condition for the same time [START_REF] Rello | A computer-based method to improve the spelling of children with dyslexia using errors[END_REF]. Our game differs from previous work in being the first tool for German based on written dyslexic errors.

Game Content Design

In this section we explain the steps we followed to create the exercises to be integrated in the application. We decided to use errors written by people with dyslexia as the starting point because they can be used as a source of knowledge. Regarding dyslexia, the errors that people with dyslexia make are related to the types of difficulties that they have [START_REF] Sterling | Adult dyslexic writing[END_REF].

Collecting Texts from Children with Dyslexia

We collaborated with two schools to gather anonymous texts written by students with dyslexia. We collected 47 texts (homework exercises, dictations and school essays) written by students from 8 to 17 years old. A total of 32 texts came from children who have been diagnosed with dyslexia. Teachers collected the remaining texts from children with a high spelling error rate. The children attended primary school, comprehensive school (Gesamtschule), high school (Gymnasium) or a special school (Förderschule).

Classification of German Dyslexic Errors

We analyzed the errors and defined an error classification for German. Except from the categorie capital letter, the rest of the error types are consistent Pedler's classification of dyslexic errors [START_REF] Pedler | Computer Correction of Real-word Spelling Errors in Dyslexic Text[END_REF] 5 :

• Substitution: change one letter by another, *grümeln (krümeln, 'crumble').

• Insertion: insert one letter, *muttig (mutig, 'bravely').

• Omission: omit one letter, *zusamen (zusammen, 'together').

• Transposition: reversing two letters, Porblem (Problem, 'problem').

• Multi-errors: more than one letter different, *Stag (stark, 'strong').

• Word boundary errors: They are run-ons and split words. A run-on is the result of omitting a space, such as nichtärgern (nicht ärgern, 'don't tease').

A split word occurs when a space is inserted in the middle of a word, such as Vogel futter (Vogelfutter, 'bird food').

• Capital letter: in German nouns are written with capital letters, while other kinds of words like verbs, adjectives or articles are not. This leads very often to spelling errors frequently based on the lack of attention [START_REF] Stang | Deutsche Rechtschreibung. Praxis kompakt. Dudenverl[END_REF]. For example *geschichten (Geschichten, 'stories') or *Glücklich (glücklich, 'happy').

Annotation of Dyslexic Errors

We annotated each of the word-error pairs with linguistic features [START_REF] Rello | DysList: An Annotated Resource of Dyslexic Errors[END_REF]. Each of the word-error pairs was enriched with specific phonological and visual features derived from the analysis of the errors and some examples:

• Visual information: for each of the target and the error graphemes we annotate the letters involved in the error with the following visual information, considering handwritten text. As a guideline we chose the Lateinische Ausgangsschrift [START_REF] Topsch | Grundkompetenz Schriftspracherwerb: Methoden und handlungsorientierte Praxisanregungen[END_REF] because it is commonly used in schools where the texts were collected. The tags use for visual information are: (a) the presence of mirror letters (<d> and <b> or <m> and <w>), (b) rotation letters (<d> and <p>.) or fuzzy letters, that is, similar visual letters but not due to rotate or mirror, such as <s> and <z>. • Phonetic information: Each of the error words was tagged using a classification inspired by the error analysis of the DRT [START_REF] Grund | Diagnostischer Rechtschreibtest für 5. Klassen: DRT 5; Manual[END_REF]. This classification is based on traditional articulatory phonetic features [START_REF]Handbook of the International Phonetic Association: A guide to the use of the International Phonetic Alphabet[END_REF] and is divided into the following categories: (a) sound distinction, (b) sound sequence, (c) combination of consonants, words with <v>, (d) umlaut, (e) double consonant / false double consonant, (f) lengthening, (g) words with <s/B>, and (h) derivation. For instance, in (h) derivation, related words are often written the same way or similar but pronounced different. To write these words in the right way, one possibility is to have a look at the plural form so that the right writing can be derivate, e.g. Walt (Wald [valt]; Wälder [vεldɒ], 'forest'). We took these features into account to design the exercises (see next Section).

Exercise Design

First, we analyzed statistically the features of the errors and created a set of linguistic patterns for designing the exercises. Then, we manually created 2,500 exercises for German. The types of exercises were defined according the kind of errors found in our resource. These are:

• Insertion: A missing letter is shown and the child need to insert a letter from a set of possibilities displayed on the screen, e.g. *Geburstag, (Geburtstag, 'birthday'). • Omission: The child is given a word with an extra letter and is asked to identify and remove it, e.g. *Abennd, (Abend, 'evening') (Figure 1, right). • Substitution: A word with a wrong letter is displayed and the user is asked to identify and substitute the wrong letter by another letter from a set of possibilities displayed on the screen, e.g. *Muntag, (Montag, 'monday') (Figure 1, left).

• Separation: A set of words, normally composed of a lexical word and a small word or/and functional word are displayed on screen without spaces. Lexical words (e.g. Hund, 'dog') form the basic elements of a language's lexicon. They have a lexical meaning which is less ambiguous than the grammatical meanings expressed by functional words e.g. zu, bei ('at, by').

The user is asked to separate the character chain into different words, e.g.

*ausVersehen, (aus Versehen, 'by mistake'). • Transposition:

The child needs to rearrange the letters or the syllables of a word, e.g. *Zugbürcke, (Zugbrücke, 'drawbridge'). The amounts of types of exercises per class are defined according the real errors percentages found in our error list. For instance, omission errors were the more frequent type in dyslexic texts (28.14%), therefore were created more Insertion exercises to target this kind of error. The other types of errors were substitution (21.03%), capital letter (10.61%) and no capital letter (7.21%) for Substitution exercises, addition (21.03%) for Omission exercises, run-on (0.29%) and split in (2.73%) errors for the Separation exercises, and transposition (0.88%) for the Transposition exercises. We used the multi-errors (18.31%) for higher levels.

Target Word Selection

To assure that the exercises are useful for the children, we used (1) only valid words in German language, (2) a set of the most frequent words of German6 , (3) words used in books in school in Germany7 , (4) and words from our error list. The final list of words is the intersection of these criteria.

For selecting the words we took into consideration specific difficulties of dyslexia. German words can be very long e.g. Straßenbahnhaltestelle ('tram stop'). Since people with dyslexia have difficulties with very long words [START_REF] Rello | Frequent words improve readability and short words improve understandability for people with dyslexia[END_REF] we included long words but not longer than 20 letters. For the Separation we chose functional words because of the same reason, people with dyslexia tend to have more errors with small and functional words [START_REF] Patterson | Surface dyslexia: Neuropsychological and cognitive studies of phonological reading[END_REF].

Modification of the Target Words

For the exercises that are not derived directly from the incorrect words in the corpora, we apply the linguistic patterns extracted from the errors to the most frequent words or schoolbook words. For instance, when the sound /a:/ is represented by the letters <ah> (Wahl, 'election'), <a> (Tal, 'valley') or <aa> (Haare, 'hair'), these three groups of letters are frequently mistaken between themselves or by other letters such as <e>. By applying these patterns to the most frequent words we cover relevant words that might not appear in our corpora.

Selection of the Distractors

Distractors are incorrect options in a multiple-choice answer, which resemble the correct option to 'distract' the player [START_REF] Mitkov | Semantic similarity of distractors in multiplechoice tests: extrinsic evaluation[END_REF]. We selected distractors for each exercise word taking into account linguistic features. For instance, the most frequent errors involve letters which the one-to-one correspondence between graphemes and phones is not maintained, such as in <sch> pronounced as only on phone [∫]. Another example is similar letters representing similar sounds, such as the occlusive consonants [t, d, b, p, g]. We used as distractors the letters that tend to induce more errors.

Difficulty Levels

The game has five difficulty levels: Initial, Easy, Medium, Hard, and Expert. The levels of the exercises were designed considering the difficulties of people with dyslexia. They have more difficulties with less frequent and longer words [START_REF] Rello | Frequent words improve readability and short words improve understandability for people with dyslexia[END_REF][START_REF] Coltheart | Phonological dyslexia: Past and future issues[END_REF] and words with complex morphology [START_REF] Patterson | Surface dyslexia: Neuropsychological and cognitive studies of phonological reading[END_REF]. Hence, in higher difficulty levels, the target word is less frequent, longer and has a more complex morphology. For instance, only words in Hard and Expert levels have prefixes and suffixes. People with dyslexia also struggle with phonetically and orthographically similar words [START_REF] Ellis | Reading, writing and dyslexia[END_REF]. Phonetically similar words are presented in all levels; orthographically similar words are used in all levels except from Initial level.

Implementation

The application was done in Objective-C by using the Model-View-Controller pattern and a high level abstraction to make it easily portable from iOS to Android and later to any other platform if needed. Since text presentation has a significant effect on reading performance of dyslexic readers, the interface of the game implements the guidelines that -according to the latest findings in accessibility research [START_REF] Gregor | An empirical investigation of ways in which some of the problems encountered by some dyslexics may be alleviated using computer techniques[END_REF][START_REF] Rello | Good fonts for dyslexia[END_REF].

Conclusions and Future Work

In this paper we have presented a method for creating exercises in German to support the spelling of children with dyslexia. The exercises were created on the basis of the linguistic analyses of errors written by children with dyslexia (from 8 to 17 years old) and can easily be transferred to other languages, because it relies on little languagedependent resources. The tool with the German exercises integrated will be soon available in the App Store. 8 Also, the resource with the German errors and all the annotations is freely available. The creation of this tool is the first step of a work-in-progress. Our next and final step for future work is to conduct a longitudinal evaluation to measure the efficiency of the tool in a German school with children with diagnosed dyslexia. We also plan to create more types of exercises, adapt the levels, automatically create exercises and improve the application by tailoring the exercises on the basis of the child's performance.

Figure 1 :

 1 Figure 1: Exercises of Substitution (left) and Omission (right).

https://itunes.apple.com/us/app/dyseggxia/id534986729?mt=8

Dysgraphia refers to a writing disorder associated with the motor skills involved in writing,

Dysgraphia refers to a writing disorder associated with the motor skills involved in writing, handwriting and sequencing, but also orthographic coding[START_REF] Nicolson | Dyslexia, dysgraphia, procedural learning and the cerebellum[END_REF].

http://www.legasthenie-software.de

http://www.ces-verlag.de/deutsch/Schreiben2_0/ schreiben2_produktinfo.php5

Examples with errors are preceded by an asterisk '*'. We use the standard linguistic conventions: '<>' for graphemes, '/ /' for phonemes and '[ ]' for phones.

http://www.lsa.umich.edu/german/hmr/Vokabeln/frequent_words.html

http://bildungsserver.berlin-brandenburg.de/fileadmin/bbb/unterricht/faecher/sprachen/ deutsch/Grundschule/2011_11_25_GWS_1_WEB.pdf

https://itunes.apple.com/us/app/dyseggxia/id534986729?mt=8.