Emanuel Felipe Duarte

Edson Oliveirajr

Filipe Roseiro Côgo
email: filiper@utfpr.edu.br

Roberto Pereira
email: rpereira@ic.unicamp.br

Dico: A Conceptual Model to Support the Design and Evaluation of Advanced Search Features for Exploratory Search

Keywords: Design and Evaluation Guidelines, Information Seeking, Exploratory Search, Advanced Search, Search User Interfaces

The design of models and tools to support Exploratory Search acquires more importance as the amount of information on the Web grows. The use of advanced search features is a viable approach for query exploration during Exploratory Search. However, the usage of advanced search features remains relatively low since Web search engines became popular, partially because of design decisions that ignore the complex and flexible nature of search activities. In this paper, we introduce Dico: a conceptual model for advanced search features for Exploratory Search, presenting and evaluating a set of guidelines created to support designers and evaluators to design better advanced search features, promoting its usage. Results from an evaluation activity with prospective designers indicated participants were able to make sense of Dico's guidelines, suggesting the guidelines as a promising artifact to support the evaluation of search engines.

Introduction

According to White and Roth [?], exploration is part of human nature and we aim to expand our knowledge through exploration. Continuous advances in information technology and the advent of the Web have revolutionized the way people interact with information, and the amount of information available to be explored has become abundant. However, the abundance of information became a significant problem in recent years as information consumes the attention of its recipients [?]. Therefore, White and Roth [?] express the need for systems capable of safeguarding users' attention through information filtering.

White, Kules and Bederson [?] discussed how search technologies available in 2005 already provided adequate support for users with well-defined information needs. However, the authors highlighted how these technologies lacked support for situations where users do not have the knowledge or the contextual awareness to formulate queries or navigate on complex information spaces. According to White et al. [?], current search technologies still provide insufficient support for this kind of activity, denominated Exploratory Search: an activity in which users perform a search with open and abstract goals and need to build knowledge about a particular subject. There is a growing need for models and tools to support Exploratory Search.

In this paper we introduce Dico (Latin for "say", "speak", "mean"): a conceptual model for advanced search features for Exploratory Search, presenting and evaluating a set of guidelines created to support designers and evaluators of Exploratory Search tools. These guidelines are intended to support the design and evaluation of advanced search features to provide new possibilities of exploration for people engaged in Exploratory Search activities, such as modifying, refining, restricting, or expanding a search query.

This paper is structured as follows: in Section 2 we briefly present and discuss the literature review; in Section 3 we present Dico, the methodology for creating the guidelines and the guidelines themselves; in Section 4 we present an evaluation of Dico's guidelines and discuss the main results; finally, in Section 5 we present the main conclusions and directions for future research.

Literature Review

According to White and Roth [?], most Web search engines operate by means of a classic query-response paradigm: users formulate a query and the search engine returns a collection of documents for the given query. However, this paradigm represents a narrow understanding about the Information Seeking process and the way people interact with information. Dico is grounded on Information Seeking models because a better understanding of the Information Seeking process can benefit the creation of models and tools for supporting Information Seeking activities, such as the Exploratory Search.

Information Seeking

As a research area, Information Seeking focus on Information Science and benefits from the advances of Computer Science, including Human-Computer Interaction (HCI). According to Marchionini [?], Information Seeking investigates the search for information centered on users and their activities. Attfield and Blandford [?] state that many Information Seeking models have been proposed with focus on temporal and behavioral aspects. However, several studies argue the users' iterative process is transversal to both temporal and behavioral aspects, and need to be considered [?], [?], [?].

Marchionini [?], for instance, describes the Information Seeking process in eight stages where iterations can occur, e.g. when the examination of the query results guides users to formulate a new query. According to Kuhlthau [?], cognitive processes and users' feelings throughout the activity also play an important role. Furthermore, the users' activity of finding meaning from information to extend their state of knowledge about a particular subject is considered in the author's Information Search Process. Negative feelings, such as uncertainty and anxiety, are common when there is little knowledge on the subject.

Bates' Berrypicking model [?] focus on the identification of new search opportunities, proposing a process in which users starts with only an open subject and shape their own path according to their evolving interests by navigating through different sources. The Berrypicking model emphasizes that: both information need and queries are constantly evolving; information is collected gradually and continuously; users perform a variety of search strategies according to the search topic and the proficiency with the involved technologies; and users navigate through various information sources to gradually and continuously build knowledge.

In a biological analogy, Pirolli [?] describes the Information Seeking process in terms of foraging. The author's Information Foraging theory explains how people explore information sources and decide whether to continue exploring the same region or identify a new and more "fruitful" area. This decision is motivated by a perceived information quality indicator named "information scent". In a vast information environment such as the Web, the perceived "information scent" of search results may define, or at least influence, the next steps of users.

To Dervin [?], people interact with an information system to build a "picture" or "model" of a domain. This process, called Sensemaking, can be described as "the deliberate effort to understand events" [?]. According to Zhang et al.

[?], Sensemaking occurs when people face problems in unfamiliar situations where their current knowledge proves insufficient. Sensemaking plays an important role in search, specially when users' current knowledge on the topic is limited. Targeting for a holistic and high-level abstraction model about how people interact with information, Blandford and Attfield [?] created the Information Journey Framework. The Information Journey Framework suggests the design of tools to interact with information, such as Exploratory Search tools, should consider users' cognition process (i.e. the creation of mental models) and the iterative nature of the Information Seeking process, which may accommodate various techniques and interaction styles in addition to a variety of feelings from users.

Exploratory Search

White et al.

[?] argue that Exploratory Search is an elusive concept, suggesting that every search is somewhat exploratory. Marchionini [?] develops a conceptual discussion and proposes a categorization with three types of search activities: "lookup", "learn" and "investigate", whereas Exploratory Search is concentrated on the last two. They are explained as follows:

-lookup: users already know the format of the information and how to find it, therefore well-defined queries are formulated generating accurate results.

Example: a search for weather conditions;

-learn: involves multiple iterations and a greater cognitive effort to handle and interpret the results. Possible goals are the acquisition of knowledge and skills, and the understanding of concepts. Example: a researcher seeking to learn what is quantum physics; and -investigate: it also involves multiple iterations that may occur during long periods of time. This activity has higher-level goals, such as analysis, synthesis and evaluation. Example: a consumer interested in purchasing a television set investigating which model is the most appropriate for his needs.

According to White and Roth [?], Exploratory Search tools should "support querying and rapid query refinement" and "offer facets and metadata-based result filtering", among other features. In practical terms, these tools should support users to (re)formulate their queries, allowing them to constantly explore and filter the obtained results. In the literature, there are related works reporting results from investigations on Exploratory Search tools, such as Flamenco [?] and Relation Browser [?]. Although these tools feature important contributions, both Flamenco and Relation Browser are not suitable for the Web as a whole, they are limited to specific closed sets of documents because they need very carefully structured metadata.

In the sense of frameworks and design recommendations, there are related works such as Wilsons's [?] design recommendations and Campos and Silva's [?] framework. Aiming to propose a framework for search user interface features, Wilson [?] proposes four categories: (1) input; (2) control; (3) informational; and (4) personalisable, and twenty design recommendations distributed between these categories. The recommendations are succinct and direct in order to be easily applied. However, there is little room for discussion on human factors, and there is no clear connection with the domain of Exploratory Search. Campos and Silva [?], in turn, consider Exploratory Search directly and propose a framework with six dimensions that can be addressed in Exploratory Search tools:

(1) documents quality; (2) information presentation; (3) time; (4) cognition and knowledge acquisition; (5) personalization; and (6) collaboration. Initially only time was directly explored with a history tool. Therefore, there is still need for subsequent studies to address other dimensions and their interrelations.

The aforementioned studies feature important contributions, however none of them considered the advanced search features' potential of exploration in the context of Exploratory Search activities. Morville and Callender [?] 1. it displaces users from their context: memorization of filters and operators syntax is problematic for most users, therefore they need to access a separated "advanced search" page to make use of these features; 2. features are difficult to find: the link to access the separated "advanced search" page is usually concealed inside drop down menus or positioned in low visibility areas of the page; 3. features are presented in intimidating form: once users access the separated "advanced search" page, they usually find a long form full of fields with little or no help on how to fill them properly; and 4. the applied logic of the features can be misunderstood: it is common for people to have difficulties to understand the employed logic of some filters and operators, like the ones involving Boolean algebra.

As enumerated, advanced search features usage is relatively low due to several factors, some of them related to how these features are designed. However, because the use of advanced search features empowers users to explore new search possibilities, such as modifying, refining, restricting or expanding a search query, they are a plausible and viable approach to support Exploratory Search. Therefore, there is a need for studies that help to understand how to design better solutions that favour the use of advanced search features. Dico is intended to contribute in this direction and is presented in the next section.

Dico

Dico is a conceptual model for advanced search features to support Exploratory Search. Dico is composed by three principles derived from the four major problems pointed out in Section 2.2: (1) context, (2) presence and (3) simplicity, and has guidelines to promote the usage of advanced search features by addressing one or more of these principles. The conceptual model can be applied to any query-response paradigm search engine, such as Google2 , Bing3 , Google Scholar4 and Springer Link5 . Fig. 1 illustrates Dico's composition and its application, which promotes the creation of Exploratory Search tools that favour the use of advanced search features. The main difference between Dico's guidelines and other examples of design recommendations, such as Nielsen's [?] heuristics or Wilson's [?] search user interface design recommendations, is the focus on promotion of advanced search features usage during Exploratory Search activities, an objective that may not be achieved without specific design recommendations such as Dico's guidelines.

Dico

Context Presence Simplicity

Search Engines

Examples: Google, Bing or Google Scholar

Dico's Instances

Exploratory Search tools that promote the use of advanced search features

Information Seeking

Exploratory Search

Human-Computer Interaction

Guidelines

Fig. 1. Illustration of Dico's composition and its application.

Methodology for Creating Dico's Guidelines

Dico has three key principles that cover the major advanced search features problems identified in the literature: (1) context: provide features when and where they can be useful to users; (2) presence: make features easily found or perceivable by users; and (3) simplicity: present features without intimidating users and in formats they can understand what the feature is, what it does, and how to use it. Grounded on these principles, we carried out four steps to identify and propose guidelines for Dico. The methodology is illustrated in Fig. 2 and detailed in sequence:

-step 1: analyse how the studies discussed in the literature review are related to one or more of Dico's principles. If a study contributes to at least one principle it was a candidate to compose a new guideline or complement an already outlined one. Finally, compile a set of guidelines in which each one must be theoretically justified by at least one study. The guidelines' structure is inspired by Design Patterns [?], containing:

• name: presents an identification number and the guideline name. The number is for reference only and does not indicate importance or priority; • description: presents a more detailed explanation of the guideline;

• theoretical foundation: describes the theoretical foundation used to support the guideline, which may be related studies on Information Seeking, Exploratory Search and HCI; • category: relates the guideline to at least one of three Dico's principles, which are context, presence and simplicity; and • example: presents and discusses an example of the guideline implementation (i.e., how it can be understood and put into practice As a result of this process, we created a set of eight guidelines for Dico, which means we were able to approach Dico's principles with eight different perspectives inspired by our literature review. Due to space restrictions, we present only a summary of the guidelines. The summary contains the number, name and description for each guideline, and can be seen in Table 1. For demonstration purposes, guideline #1 is presented in detail in Section 3.2. A document describing Dico and containing all the guidelines in their complete structure is available at http://din.uem.br/gsii/dico/.

3.2 Guideline #1: Users should be able to reformulate their query at any time in an easy way.

-Description: the search user interface should always allow users to reformulate their query easily according to their evolving state of knowledge on the subject. The query reformulation can be in the format of modification, refinement, restriction, or expansion, and to do so the search field and the current query must always be available to users. -Theoretical Foundation: as evidenced by Bates [?], Marchionini [?] and Blandford and Attfield [?], users go through an iterative process during a # Name and description 1 Users should be able to reformulate their query at any time in an easy way: the search user interface should always allow users to reformulate their query easily according to their evolving state of knowledge on the subject. The query reformulation can be in the format of modification, refinement, restriction, or expansion, and to do so the search field and the current query must always be available to users. 2 Advanced search features must be present in the main search page: advanced search features should not be limited to the fields of a separate and specific page, such features should be included in the main search page which users are already used to operate. More specifically, advanced search features should be included in the search results page, because it is there where they will possibly be more useful. 3 Users should be able to start their search in a conventional search user interface: to take advantage of advanced search features offered by the search engine, users should not be required to access an unfamiliar and possibly intimidating page.

They should be able to start their search in a conventional search user interface they are already used to operate (e.g., the default home page of the selected search engine). 4 Advanced search features should complement information when applicable:

when filters and operators relate to the presented information, interaction elements for advanced search features should be inserted in the search user interface next to the information or even contained in it. Such elements are intended to allow users to directly use the information of their interest to formulate and submit new queries without being moved from their context. 5 The interface should assist users to understand concepts and relationships present in the results: users should be assisted in forming a mental model of the researched topic, because this is an important step in the construction of knowledge in an Exploratory Search activity. The interface can provide a visual representation of the information space in which the main concepts and how they relate to the retrieved documents can be highlighted. Such relationships, for example, may be interactive so that users make further queries with related advanced search features. 6 Advanced search features must be presented in a manner that does not intimidate users: the search user interface should not have the format of a page with several fields to be filled or complex controls, it is necessary to provide search features that are as simples as possible according to the context. The advanced search features should be presented with simple controls, and the presentation of these features must be diluted along the search activity, with different features presented at different times as they become useful for a given context. 7 Users should be able to identify and manage advanced search features easily in the current query: the query must be processed so the features can be identified and presented in a format that highlights them individually. Presenting features individually also facilitates its management, like removing or editing a specific feature present in the query. When presented individually, the features may also receive an individual explanation in a language that makes sense to users, assisting them to associate syntax and functionality. 8 The search user interface should communicate technical information of advanced search features in a manner that makes sense to users: users must be able to understand the logical operation of advanced search features. For this, the visual and verbal communication used to display the features and related technical information must have a simple language that makes sense to users.

search. Among other aspects, this process is characterized by query reformulation according to the new acquired knowledge. Therefore, it is critical the interface does not prevent or make it difficult for users to reformulate queries, because this is a recurring step during Exploratory Search activities. From the HCI perspective, this guideline can be related to Nielsen's third heuristic "user control and freedom", described by the author as "Users often choose system functions by mistake and will need a clearly marked 'emergency exit' to leave the unwanted state without having to go through an extended dialogue. Support undo and redo." Finally, considering the advanced search perspective, freedom and easiness to submit new queries can be incentives for users to explore the provided advanced search features. -Category: context, presence and simplicity.

-Example: the search results page of the Brazilian e-commerce Submarino6 , illustrated in Fig. 3 for the query "seo", makes use of features such as breadcrumbs, faceted navigation and visual highlight of the found terms. However, there are problems considering the scope of this guideline. Although the search field remains present on the Web page, it appears without the current query filled in, making it difficult to reformulate in case users wish to modify only a part of the query. The interface would be in compliance with the guideline if the search field remained filled after submitting a query.

Evaluation

To evaluate Dico's guidelines, we conducted a study to investigate whether prospective designers would make sense of the guidelines' descriptions and their illustrated examples, and whether they would find the guidelines useful to support their practical activities. First, participants carried out an inspection of two Web search engines using Dico's guidelines. This task was designed to introduce the guidelines to the participants, enabling them to subsequently evaluate the applied guidelines based on their experience with them. Both qualitative and quantitative data were collected and analysed, therefore we considered this a mixed evaluation. We used the Goal Question Metric (GQM) template [?] to summarize the nature of the study and the main aspects involved: we evaluated Dico's guidelines; for the purpose of assessing whether they make sense to designers who may apply them; with respect to description clarity and illustrated examples usefulness; from the viewpoint of designers using Dico's guidelines to inspect search engines; and in the context of Computer Science undergraduate students attending to a HCI course.

Study Planning

The study planning consisted of the activities described as follows.

Participant Selection: 15 Computer Science undergraduate students attending to a HCI course in the third semester were invited to participate. Participants were all males, with ages ranging from 18 to 31 years old. They were chosen for knowing basic principles of evaluation by inspection and heuristic evaluation, for being used to conduct Exploratory Search activities on the Web, and for being the target audience of Dico's guidelines: prospective designers who will probably work in the design and evaluation of computer systems. The study was applied as an HCI theoretical and practical activity, however it was up to the students to decide whether they want to anonymously supply their data to this study. A total of 14 students consented, and one of them had incoherent answers with the asked questions and was removed, resulting in a sample N = 13. As the study involved human beings, the applicable ethical aspects were adequately addressed. Participation was voluntary, unpaid, with the possibility to leave the study at any time without justification, and all participants registered their consent.

Planning the Inspection of Search Engines with Dico: two search engines were selected to be inspected: Google (general purpose) and Google Scholar (scholarly literature), and participants were randomly assigned to inspect one of them. Individually, participants inspected whether the search engine was in compliance with each of Dico's guidelines. Participants did not receive any kind of prior training or information about Dico's guidelines beyond what is already presented in the guidelines. For data collection, we selected mandatory multiplechoice questions with three options: (1) "Yes"; (2) "No"; or (3) "N/A", followed by a required text field to justify the answer. This activity was considered sufficient to provide an initial experience with the application of Dico, qualifying the participants to later evaluate its guidelines directly.

Planning the Evaluation of Dico's Guidelines: participants evaluated the guidelines individually. For each guideline they evaluated the clarity of its description and the usefulness of its example. For data collection, we selected the format of an assertion for which participants select their degree of agreement using a five-point Likert scale. The first assertion is "The Guideline #X is clear and can be easily understood", where X is the guideline number. The possible answers were: (1) "Strongly agree"; (2) "Partially agree"; (3) "Indifferent";

(4) "Partially disagree"; and ( 5) "Strongly disagree". Participants have the option (not mandatory due to time constraints and possible fatigue effects) to justify their answer. The second statement is "The given example assists to understand the Guideline #X". Again, participants must select an answer between the same degree of agreement options and optionally justify their answer.

Instrumentation: we created three ad hoc instruments for this study: (1) a document containing an overview of Dico's guidelines with their names and descriptions;

(2) an online form for the inspection of search engines with Dico; and (3) an online form for the evaluation of Dico's guidelines. The first instrument contains a summary of all guidelines in the same page for a holistic view, because they can be viewed only one at a time in the online forms. The second instrument introduces and supports the search engine inspection with Dico, where each guideline along with the respective fields are presented in detail in separated pages. Finally, the third instrument introduces and presents Dico's guidelines evaluation, repeating the format in which each guideline along with the respective fields are presented in detail in separated pages.

Operation

Participation was in person during a HCI class inside a computer lab, and all participants had access to a computer and Internet. The first instrument was handed to each participant, and also contained an anonymous identification code and the search engine to be inspected. The other two instruments were given as URLs to be accessed. The participants were instructed to access them in order, starting with the form for the inspection of the search engines (second instrument), and then, after finishing filling it, accessing the form for the evaluation of Dico's guidelines (third instrument). Participants were instructed the purpose of the study was to obtain their opinion as prospective designers, and therefore there were no "correct" or "wrong" answers. The tasks were performed individually, without exchange of information between participants, and submitted in digital format.

Results Analysis and Interpretation

For the search engine inspection with Dico, Fig. 4 shows the summary of responses for both Google and Google Scholar inspections. (In Fig. 4, "#X" stands for compliance with guideline #X according to participants' responses.) It can be noted that even though both search engines are from the same company, there is a clear difference in responses between them. This difference is positive for this study because both groups of participants had different experiences with the application of Dico's guidelines, enriching the results. As participants inspected the search engines with Dico, this experience properly qualified them to evaluate Dico's guidelines directly. For Dico's guideline evaluation, Fig. 5 illustrate all responses (in the first activity participants 1, 3, 5, 7, 9, 11 and 13 inspected Google, and participants 2, 4, 6, 8, 10 and 12 inspected Google Scholar ), and Fig. 6 a summary of the responses. (In Figs. 5 and6, "#XD" stands for the statement "The Guideline #X is clear and can be easily understood" and "#XE" for "The given example assists to understand the Guideline #X".) Summarizing, there were 155 (74.52%) responses for "Strongly agree", 30 (14.42%) for "Partially agree" (summarizing 88.94% of agreeing responses), 12 (5.77%) for "Indifferent", 8 (3.85%) for "Partially disagree" and 3 (1.44%) for "Strongly disagree" (summarizing 5.29% of disagreeing responses). It can be noted participants 7 and 8 had together 16 of the 30 "Partially agree" responses. Aside from that, responses were relatively equally distributed among participants. The 11 disagreeing responses, for instance, were distributed among 7 participants, therefore we did not detect dramatic differences regarding individual participants. These results indicate participants approved Dico's guidelines descriptions and illustrated examples. Additionally, because participants were all prospective designers, it was expected them to experience some difficulty when using the guidelines for the first time. Only 5.29% of responses indicated difficulty, what is another indication the guidelines were well received and understood. However, a more detailed analysis regarding individual guidelines and differences between the responses of participants who inspected Google and Google Scholar can provide more specific results and highlight opportunities for improvement.

0 1 2 3 4 5 6 7 # 1 # 2 # 3 # 4 # 5 # 6 # 7 # 8 Sum of responses Dico's guidelines (a) Google Yes No N/A 0 1 2 3 4 5 6 # 1 # 2 # 3 # 4 # 5 # 6 # 7 # 8 Sum of responses
# 1 D # 1 E # 2 D # 2 E # 3 D # 3 E # 4 D # 4 E # 5 D # 5 E # 6 D # 6 E # 7 D # 7 E # 8 D # 8 E Sum of
# 1 D # 1 E # 2 D # 2 E # 3 D # 3 E # 4 D # 4 E # 5 D # 5 E # 6 D # 6 E # 7 D # 7 E # 8 D # 8 E
For guidelines #2 and #8, all the participants strongly or partially agreed their descriptions are clear and can be easily understood and the illustrated example assists to understand the guideline. One participant, for instance, justified his "Strongly agree" choice for guideline #8 as "Very easily understood." for description clarity and "Clear and easily understood example." for illustrated example usefulness -all translations of participants answers were made by the authors. Therefore, guidelines #2 and #8 were considered useful and well elaborated by all the participants. It can be noted that among participants who inspected Google there were 3 "Partially agree" responses, while for those who inspected Google Scholar there were 6, indicating these two guidelines were better understood when compared against Google. This result may suffer influence from users' previous experience with the search engine and from specific design decisions. A new study with a larger sample of participants and search engines may offer results of statistical significance to verify these hypothesis.

For guidelines #1, #3, #6 and #7, each received one "Partially disagree" or "Strongly disagree" response for description clarity (guideline #3) or illustrated example usefulness (guidelines #1, #6 and #7). One participant, for instance, justified his "Strongly disagree" choice for guideline #3 description clarity as "I found it very difficult to understand what the guideline means." It can be noted only "Strongly agree" or "Partially agree" responses were provided by participants who evaluated Google, while all occurrences of "Indifferent", "Partially disagree" and "Strongly disagree" responses were from participants who inspected Google Scholar. Guideline #7 description clarity had 3 neutral responses, however the participants did not justify their choices for these responses. Even though we did not identify evident issues with guidelines #1, #3, #6 and #7, the presence of indifferent and disagreeing responses motivated a review of them. Again, it is possible these guidelines are better understood when compared against Google, however further studies are needed for conclusions.

Finally, for guidelines #4 and #5, there were occurrences of more than one "Partially disagree" or "Strongly disagree" responses, being two for guideline #4 and three for guideline #5, both on description clarity. It can be noted most "Indifferent", "Partially disagree" and "Strongly disagree" responses come from participants who inspected Google, contrary to the other six guidelines in which all these type of responses came from participants who inspected Google Scholar. One participant who inspected Google justified his "Indifferent" choice for guideline #5 description clarity as "I was unable to apply the guideline in the search engine." Other, who inspected Google Scholar, justified his "Strongly disagree" for the same item as "No, the guideline is very difficult to understand, I was unable to extract the information the guideline means." Even though the majority of participants still provided "Strongly agree" or "Partially agree" responses for both guidelines, we identified the recurrence of other responses as a result of some participants having difficulty to understand the guidelines #4 and #5 abstraction level, therefore they were improved by a review with focus on description simplicity.

The difference between responses for participants who evaluated Google and Google Scholar indicate designers may understand some of Dico's guidelines differently in different contexts, such as specific domain search engines. It is possible some of Dico's guidelines are prone to make more sense in the context of some search engines than in others. This possibility should be considered and further analysed in future studies. In general, even guidelines with problematic feedback, like #4 and #5, still made sense to the majority of participants, indicating the prospective designers who participated in this study succeeded in making sense of Dico's guidelines and showing the guidelines as a promising artifact to support the evaluation of existing Web search engines.

Validity Evaluation

Following, we present the potential threats to the study's validity we anticipated, and the efforts taken to minimize them.

Conclusion

Validity: the study sample size (N = 13) does not provide results with statistical significance, and participants applied Dico to only two different search engines. However, our objective was to obtain feedback from prospective designers because they are Dico's target audience. Even though a larger sample of participants and search engines is needed for results with statistical significance, the study sample size was considered enough to obtain initial evidence Dico's guidelines descriptions and illustrated examples made sense to the participants. Therefore, sample size was not considered a threat.

Construct Validity: we were very careful for participants to properly understand what should be done in the activity. Instructions for every step were explained clearly and succinctly before the study, the tasks performed by participants were coherent with their qualification and educational level and they were allowed to ask for help at any time if they had questions about how to proceed. To ensure the same treatment for all the participants, questions about how to proceed in the study were answered to the whole class. No participant showed significant difficulty in understanding and carrying out the activity. Therefore, the threat of participants not understanding what should be done was considered under control, not affecting the results.

Internal Validity: we anticipated the following two threats:

1. fatigue effects: participants took between 1h and 1h30m to complete the study, and it required a considerable cognitive workload from them. However, the participants are used to perform similar activities during the 1h40m duration HCI classes in which the study took place, and they could have abandoned the study at any time if they became uncomfortable with it. Therefore, the threat of participants becoming fatigued was considered under control, not affecting the results; and 2. influence among participants: because we requested participants to carry out the activity individually, and no significant interaction between them was observed, the threat of participants influencing each others' responses was considered under control, not affecting the results.

External Validity: the selection of prospective designers as participants does not guarantee experienced designers would show similar responses. However, we intentionally selected prospective designers to evaluate Dico because they are its target audience. Because low experienced prospective designers were able to make sense of Dico's guidelines descriptions and illustrated examples, it is reasonable to expect experienced designers to also be able to make sense of them, possibly even better than prospective designers. Therefore, we did not consider the selection of prospective designers a threat.

Conclusions

Current search engines still lack support for Exploratory Search. Therefore, there is a need for models and tools to support users in Exploratory Search activities.

Even though the use of advanced search features is a plausible approach for Exploratory Search tools because it empowers users with new exploration possibilities, currently the usage of such features is relatively low.

To promote the use of advanced search features we introduced Dico. Dico is composed of three principles and eight guidelines to address the current major problems of advanced search. Inspired by Design Patterns, each guideline has: identification number and name; description; theoretical foundation on Information Seeking, Exploratory Search and HCI; category according to the three principles; and illustrated example demonstrating how it can be applied.

We evaluated Dico's guidelines and provided evidence prospective designers were able to make sense of them when inspecting existing Web search engines. Even though most responses evidenced no problems, the few who did also provided useful insights to further improve some of Dico's guidelines. For further studies regarding Dico, we consider:

evaluate Dico's guidelines with a larger sample and more search engines to obtain results of statistical significance and possibly new insights on how different contexts affect the ability to make sense of Dico's guidelines;

analyse designers using Dico's guidelines to identify problems in search engines and propose design solutions to analyse how differently people may apply the guidelines and, by evaluating the solutions, whether Dico's guidelines are serving their purpose in assisting the design better tools; and instantiate Dico as an Exploratory Search tool based on a search engine and evaluate it both qualitatively and quantitatively to analyse aspects such as how participants feel about using the tool, and measure the usage of advanced search features to compare with data from the literature.

Fig. 2 .

 2 Fig. 2. Illustration of the methodological steps to create Dico's guidelines.

Fig. 3 .

 3 Fig. 3. Guideline #1 example: lack of current query on the search field in the search results page of Submarino. Accessed 01 August 2014.

DicoFig. 4 .

 4 Fig. 4. Summary of search engines inspection with Dico responses.

Fig. 5 .

 5 Fig. 5. Dico's guidelines evaluation responses.

Fig. 6 .

 6 Fig. 6. Summary of Dico's guidelines evaluation responses.

  -step 3: create an illustrated example of how to apply the guideline within a search user interface. Examples consist of an analysis of certain features of search user interfaces from search engines or academic tools. It is discussed how the example satisfies the guideline, or why it does not and what could be done to solve the problem; and -step 4: evaluate the guidelines description and illustrated example with prospective designers. The guidelines were revisited based on the results from their usage and evaluation with a group of prospective designers. The evaluation details and results are presented in Section 4.

	Literature Review		Human-Computer Interaction models, theories and empirical studies	Evaluation with prospective designers
	Information Seeking
	and Exploratory Search models, theories and		2		4
	empirical studies	1	Draft of Dico's Guidelines	Dico's Guidelines	Revised Dico's Guidelines
	Advanced search major problems		3
			Search engine
			interface examples
						).
	-step 2: analyse the composed guidelines and complement the theoretical
	foundation with HCI studies. The considered studies are Nielsen's [?] heuris-
	tics, the communicability concept from Semiotic Engineering [?], and Wein-
	schenk's [?] study on human aspects relevant to design decisions. These
	studies cover a wide range of factors, such as design questions and human
	factors (e.g., memory and cognition);

Table 1 .

 1 Summary of Dico's guidelines.

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http://bing.com/

http://scholar.google.com/

http://link.springer.com/

http://www.submarino.com.br/

Acknowledgements. This study was partially funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). We would like to dedicate this work to Professor Sérgio R. P. da Silva who is dearly missed.


Euan Freeman
email: euan.freeman@glasgow.ac.uk

Stephen Brewster
email: stephen.brewster@glasgow.ac.uk

Vuokko Lantz
email: vuokko.lantz@nokia.com

Towards In-Air Gesture Control of Household Appliances with Limited Displays

Keywords: In-Air Gestures, Household Devices, Multimodal Feedback

Recent technologies allow us to interact with our homes in novel ways, such as using in-air gestures for control. However, gestures require good feedback and small appliances, like lighting controls and thermostats, have limited, or no, display capabilities. Our research explores how other output types can be used to give users feedback about their gestures, instead, allowing small devices to give useful feedback. We describe the Gesture Thermostat, a gesture-controlled thermostat dial which gives multimodal gesture feedback.

Introduction

Our homes are becoming increasingly interactive. Small household appliances, like lighting controls and thermostats, are being enriched with new interaction modalities. Users can now interact with their household environments using their smartphones, speech commands and even in-air gestures. Gesture interaction is especially compelling as users can interact from across the room and without having to first locate their smartphone or a remote control. Unlike speech, gestures do not disturb others and work in noisy household environments, where chatter, music and television may cause speech recognition difficulties.

In-air gesture interaction, like speech, can be uncertain and users require lots of feedback during interaction, so that they can gesture confidently and effectively. Many household appliances have limited ability to give feedback, however. They typically have small displays, or no display at all, meaning visual feedback would be difficult to see from a short distance away. Users would lose the benefits of gesturing from across the room if they had to approach a device first to see feedback about their gestures and the effects they are having.

Changing the form factor of such devices to accommodate a larger screen is undesirable, as doing so increases size, cost and power demands. In our research, we are exploring other ways for household controls to give users feedback during interaction. This paper describes the Gesture Thermostat, a gesture-controlled thermostat dial which gives users multimodal feedback about their gestures. Interactive lighting illuminates the surrounding wall to give visual feedback as users gesture (see Figure 1). We also use sound, from within the device, and vibration, from a smart-watch, to enhance the feedback.

Related Work

Many have found that users are more willing to interact with small devices from a distance than they are to approach them for input. Valkkynen et al. [START_REF] Välkkynen | Evaluating Touching and Pointing with a Mobile Terminal for Physical Browsing[END_REF] found that users preferred to interact with objects by pointing at them, rather than touching them, when more than a step away. Even when on their feet or walking past objects, users would rather gesture than go out of their way to touch them. Rukzio et al. [START_REF] Rukzio | Mobile Interaction with the Real World: An Evaluation and Comparison of Physical Mobile Interaction Techniques[END_REF] also found that distal interactions were more preferred than approaching objects to interact with them. These distal interactions allow what Koskela et al. [START_REF] Koskela | Evolution towards smart home environments: Empirical evaluation of three user interfaces[END_REF] call instant control of household appliances: immediate, convenient access to basic functionality.

Offermans et al. [START_REF] Offermans | User interaction with everyday lighting systems[END_REF] looked at interaction with household lighting. They found that access to controls had a strong influence on willingness to interact: users were more likely to interact when controls were easily accessible. They noted that mobile devices -remote controls and smartphones -often required too much effort and had inconsistent availability. We think in-air gestures could be a convenient alternative, allowing direct interaction when desired. Users could gesture from across the room for instant control of basic functionality, like switching lights off or setting the air conditioning to a cooler temperature.

In-air gestures are also available when other interaction modes are inconvenient or unavailable; for example, touch is less appropriate when cooking. Kinect in the Kitchen [START_REF] Panger | Kinect in the Kitchen: Testing Depth Camera Interactions in Practical Home Environments[END_REF] explored this scenario further, allowing users to browse recipes and set cooking timers using in-air gestures. They found that gestures were effective but users required more feedback. Others have used in-air gestures for interacting with lighting controls, [START_REF] Djajadiningrat | Grace: A gesture-controlled wake-up light[END_REF] and [START_REF] Sørensen | Tangible Lights": In-Air Gestural Control of Home Lighting[END_REF]. Both used the lighting itself as functional feedback: users saw immediate feedback from how the lights changed in response to gestures. Functional feedback is often unavailable and gives limited insight into interaction, however. Users receive little feedback during gestures and if movements are unrecognised, they receive none at all.

Gesture Thermostat

Gestures give users another way to interact with household devices, although they need sufficient feedback to help them interact. Many household appliances have limited display capabilities, which limits their ability to give feedback. Functional feedback is often unavailable and does not give users enough information to help them gesture. We are exploring other ways of giving users feedback during gesture interaction with household devices. We focus on interaction with thermostats as these are common devices with limited displays and no immediately noticeable effects; such devices benefit most from extra feedback.

Our Gesture Thermostat prototype (see Figure 1) has three types of output which can be used for gesture feedback: interactive light, sound and vibration.

Lights embedded in the thermostat dial (46 LEDs, approx 7 mm apart) illuminate the surrounding wall, giving visual feedback over a large area which users can easily see from across the room. An internal speaker provides audio feedback. Wearable devices, like smart-watches, could also be used as tactile displays for feedback. We use a simple actuator as a prototype smart-watch. In the rest of this paper and in our poster, we describe the Gesture Thermostat, its gestures and feedback designs, and initial findings from a user evaluation.

Gesture and Feedback Design

We use gestures for basic functionality -adjusting temperature -as this allows instant control [START_REF] Koskela | Evolution towards smart home environments: Empirical evaluation of three user interfaces[END_REF]. More complex interactions, like programming the thermostat schedule, are less suited for in-air gestures. We give users two ways of adjusting temperature: (1) imprecise "punch" gestures, which increase or decrease temperature by a few degrees; and (2) precise "dial" gestures, which allow finer-grained temperature control.

Users initiate interaction by raising their hand with a closed fist. Upon detecting this gesture, the thermostat plays a short tone, emits a short vibration if a smart-watch is available, and reads the current temperature setting aloud; for example "twenty-two degrees". All lights turn on with a low brightness and pulse slowly to show continued responsiveness. A single area of coloured light shows the temperature setting; blue light for cooler temperatures on the left (Figure 1, left), red light for warmer temperatures on the right (Figure 1, right).

From this position, users can quickly move their hand up-then-down or downthen-up to raise or lower the temperature, respectively. Audio and tactile feedback are given to confirm a recognised gesture and lights update to show the new thermostat setting. Alternatively, users can open their hand, as though about to grasp the dial, and turn it left or right to lower or raise the temperature. We use rate-based rather than position-based control due to hand instability and sensing inaccuracy. As users perform the dial gestures, white lights stop pulsing and the coloured area of light pulses instead; this helps users identify between interaction modes. Users are given feedback about their gestures, as before.

Initial Evaluation Results

Our initial evaluation asked eight users to complete tasks using the thermostat. Our findings suggest that our feedback designs support users effectively. Evaluation participants generally understood how feedback related to their hand movements and felt it made the device seem responsive; however, some wanted more information, especially about gesture sensing. When users encountered tracking issues, they were aware that something was wrong, but did not know why. More feedback about sensing could help users overcome these issues.

Although light feedback was effective on its own, users found it most salient and useful when paired with audio and tactile feedback. Light feedback was continuous which helped show responsiveness, while discrete audio and tactile feedback were easily noticed. Participants suggested that non-visual cues made visual changes more noticeable and made the thermostat seem more responsive.

Summary

In-air gestures allow users to interact with small household devices quickly and from a distance. Users need feedback to gesture effectively, although many household devices have limited feedback capabilities. Our Gesture Thermostat exemplifies how embedded lights, sound and vibration from wearables can be used to give gesture feedback. Our initial findings are positive: these outputs help users gesture effectively and make devices fun and responsive.

Fig. 1 .

 1 Fig. 1. The Gesture Thermostat illuminates surrounding areas for visual feedback.

Acknowledgements

This research was part-funded by Nokia Technologies, Finland.


Masood Masoodian
email: masood@waikato.ac.nz

Elisabeth André
email: andre@hcm-lab.de

Thomas Rist
email: thomas.rist@hs-augsburg.de

Fostering Smart Energy Applications

Keywords: Energy usage management, energy usage monitoring, visualizations, visual interfaces, persuasive technologies, user evaluation

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

Introduction

As our reliance on energy is increasing rapidly, and worldwide non-renewable energy resources are depleting, it has become necessary to develop more advanced technologies to better manage and reduce our energy consumption. Many such technologies now exist for both domestic and commercial use. These include tools and services for public displays, dashboards, mobile apps, web-portals, simulation tools, computer games, etc. There is, however, a lack of coordinated effort in terms of research, design, development, and deployment of smart energyrelated applications. It is therefore becoming important to foster and coordinate these activities through more targeted gatherings and publications focusing on smart applications for energy systems. This workshop aims to fill this existing gap by bringing together researchers and practitioners from energy-related domains, as a follow up to a very successful workshop held last year (FSEA 2014, http://it4se.informatik.fh-augsburg.de/FSEA14/).

Theme and topics of interest

The theme of this workshop is interaction techniques, interfaces, and visualizations for energy-related applications, tools, games, and services. The topics of interest include design and evaluation of visual interfaces for: monitoring and managing energy generation and consumption, analysis of energy generation and consumption data, identifying consumption patterns and behaviour, relating energy consumption to other information, sharing and comparing energy-use data with others, influencing choices and stimulating sustainable behavior changes.

Target audience

The target audience of this workshop are researchers and practitioners from a range of backgrounds, including interaction design, human-computer interaction, visualization, computer games, media technology, and domain experts from energy-related application areas.

Workshop plan

This one-day workshop will include short presentations of accepted position papers, discussion sessions, and a hands-on design exercise session, during which the workshop participants will be divided into small groups and invited to design an interactive application for energy usage management and visualization.

Expected outcome and dissemination

The accepted workshop position papers will be included in the official adjunct conference proceedings published by the University of Bamberg Press. The position papers will also be made available through the workshop website (FSEA 2015, http://it4se.informatik.fh-augsburg.de/FSEA15/). The workshop participants will be invited to submit an extended version of their position papers for a special issue of a journal (currently being organized).

Key organizers

Masood Masoodian is an associate professor in Computer Science at the University of Waikato. His research interests include visualization of temporal data and interaction design. He has participated in numerous projects on design, development, and evaluation of energy-related interactive visualizations.

Elisabeth André is a professor in Computer Science, and the Chair of Human-Centered Multimedia at Augsburg University. She has been involved in organization of numerous conferences. She is an Associate Editor of IEEE Transactions on Affective Computing, and ACM Transactions on Intelligent Interactive Systems. She is also on the editorial board of several international journals.

Thomas Rist is a professor in Computer Science at the University of Applied Sciences Augsburg. He has a long track-record in the field of intelligent user interfaces, and interactive media systems. His current research activities comprise work at the intersection of HCI and energy-related applications. He has served as a PC or OC member of various workshops, symposia, and conferences. He has also coordinated a number of EU and German funded projects, including the IT4SE network for energy-related ICT research (http://www.it4se.net).


Youngsun Kim

Jaedong Lee
email: jdlee@korea.ac.kr

Gerard J Kim
email: gjkim@korea.ac.kr

Designing of 2D Illusory Tactile Feedback for Hand-held Tablets

Keywords: Funneling, Illusory feedback, Vibro-tactile feedback, User experience, Mobile/Hand-held interaction

In this paper, we investigate whether the "out of body" tactile illusion can be extended or applied to a relatively large hand-held device such as a tablet for which the hands/fingers would not be in direct contact with the vibration motors. We derived guidelines for applying tactile illusion techniques in 2D space with regards to operational conditions such as the size of the device, holding position, minimally required vibration amplitudes, and the effects of matching visual feedback. For this purpose, a series of exploratory pilot experiments were first conducted in 1D space. Based on the results, a 2D illusory tactile rendering method was devised and tested for its effectiveness. We have found that for a tablet sized device (e.g. iPad mini and iPad), the illusory perception was possible with a rectilinear grid resolution of 5×7 (with a grid size of 2.5 cm) with matching visual feedback.

Introduction

Smart hand-held devices nowadays come in many different sizes: from smart phones (10 -15 cm in diagonal length) to larger tablet devices and hand-held computers (18 -25 cm). There have been increasing interests in improving the user experience on hand-held devices by providing richer and more dynamic feedback through vibrotactile actuators [START_REF] Kim | Out of the Body" Saltation to 2D Mobile Tactile Interaction[END_REF][START_REF] Yatani | SemFeel: a user interface with semantic tactile feedback for mobile touch-screen devices[END_REF][START_REF] Nokia | Bouncing ball on Nokia N900[END_REF]. To avoid resorting to vibro-tactile arrays which would require a sizable and continuous contact area with the hand or body parts, researchers have proposed to apply tactile illusion techniques so that similar effects can be realized with only a few number of vibration motors [START_REF] Kim | Out of the Body" Saltation to 2D Mobile Tactile Interaction[END_REF][START_REF] Yatani | SemFeel: a user interface with semantic tactile feedback for mobile touch-screen devices[END_REF]. In addition, Miyazaki has demonstrated that tactile illusory feedback could be elicited at the "out of the body" space [START_REF] Miyazaki | Cutaneous Rabbit" hopping out of the body[END_REF]. Kim has applied the "out of the body" tactile illusory feedback for a small-sized smartphone (9.4 cm in diagonal length), and demonstrated the illusory feedback was indeed applicable and extendable for interaction in 2D screen space using only four vibrators [START_REF] Kim | Out of the Body" Saltation to 2D Mobile Tactile Interaction[END_REF].

In this paper, we investigate whether the "out of body" tactile illusion can be extended or applied also to larger hand-held devices such as tablet devices. The extension is not expected to be straightforward for few reasons. First the original "out of body" tactile illusion was only validated when the body parts (e.g. fingertips) were stimulated directly and set apart by 7-8 cm span [START_REF] Kim | Out of the Body" Saltation to 2D Mobile Tactile Interaction[END_REF], similar to when the phenomenon was originally discovered [START_REF] Miyazaki | Cutaneous Rabbit" hopping out of the body[END_REF]. With tablet devices, the operating conditions are quite different (see Figures 1(c) and (d)). For one, the vibratory stimulations are indirect, and the hands/fingers may not be in equidistance from the actuators. No relevant study has been reported for when the size of the hand-held object goes larger than the "8cm" span, not to mention for the 2D extension. Thus, to find out how to apply the "out of body" tactile illusion to tablet devices, we ran a series of pilot exploratory experiments to first observe the effects of the tactile illusion e.g. with regards to various operational conditions such as the size of the device, holding position, minimal vibration amplitudes and effects of accompanying visual feedback for a fair perception of the illusion. The findings and observations would form the basis for designing a proper 2D tactile illusory rendering method for the tablet device. We shortly describe these experiments, report the newly derived guidelines, propose for a 2D tactile illusory rendering method for a tablet, and empirically validate its effectiveness.

Related Work

Funneling is one of the major perceptual illusion techniques specifically for vibrotactile feedback (along with saltation which we do not consider in this work for now). It refers to stimulating the skin at two different locations simultaneously with different amplitudes and eliciting phantom sensations in between the two (i.e. 1D phenomenon) [START_REF] Alles | Information transmission by phantom sensations[END_REF][START_REF] Bekesy | Funneling in the nervous system and its role in loudness and sensation intensity on the skin[END_REF]. The intended location of the phantom sensation (ITL) can be changed by modulating the stimulation intensity.

Several researchers have applied this phenomenon to human interfaces, experimenting with different ways of modulating the vibration amplitudes for detailed controlling of the target phantom sensation locations [START_REF] Alles | Information transmission by phantom sensations[END_REF][START_REF] Barghout | Spatial resolution of vibrotactile perception on the human forearm when exploiting funneling illusion[END_REF][START_REF] Israr | Control space of apparent haptic motion[END_REF][START_REF] Mizukami | Tactile information transmission by apparent movement phenomenon using shape-memory alloy device[END_REF][START_REF] Seo | Initial study for creating linearly moving vibrotactile sensation on mobile device[END_REF]. For example, the SemFeel was a vibro-tactile feedback system for a mobile touch screen device [START_REF] Yatani | SemFeel: a user interface with semantic tactile feedback for mobile touch-screen devices[END_REF] using five vibrators attached to the backside of the device (4 corners and 1 center). It was capable of producing 10 different perceptible vibration patterns for expressing richer semantic information compared to the usual single vibrator scheme.

Recently, researchers have discovered such phantom sensations can be extended to the "out of body" [START_REF] Miyazaki | Cutaneous Rabbit" hopping out of the body[END_REF] (see Figure 1(a)), thus making it possible to generate phantom tactile sensations as if coming from an external object. This result is appealing in its application possibility to mobile devices. That is, there now is a potential method to make a user feel (phantom) sensations indirectly emanating from the hand-held device (e.g. middle of the display), but supplying actual vibrations only to the "natural" holding finger/hand locations (Figure 1). Kim demonstrated that the aforementioned phenomenon could be extended to 2D by employing vibrators both horizontally and vertically on a small sized (3.5 inch screen) smart phone [START_REF] Kim | Out of the Body" Saltation to 2D Mobile Tactile Interaction[END_REF]. But no general guidelines have been reported for further applications to a variety of today's hand-held media devices.

Finally, many human computer interfaces also rely on cross modal illusions to enrich user experience by fusing feedbacks of different modalities. For instance, a mere single vibrator based tactile feedback (as adopted by most current smart phones), when combined with other modalities, can induce phantom directional haptic feedback and rich user experience [START_REF] Nokia | Bouncing ball on Nokia N900[END_REF]. We posit that the tactile illusion feedback, when combined with other usual modalities such as the visual and aural, can similarly improve the interaction experience even further.

Thus, to summarize, the distinguishing point of our work is that we seek to newly extend funneling to an enlarged 2D space, and identify important design guidelines. This would open doors for a more flexible design of vibro-tactile feedback techniques for a wide variety of hand-held devices.

Pilot Experiments: "Out of body" Funneling Effects along Longer 1D Separation Span

Due to lack of space, we only provide a very short description of how the exploratory pilot experiments were run. Funneling stimulations were given through vibrators attached to an iPad mini and iPad, along three horizontal (along the top/middle/bottom row) or vertical directions (along the left/middle/right column) using two vibrators attached at the respective ends (i.e. six vibrators used for each case). Sixteen participants were asked to report the existence of any illusory tactile perception and indicate where they came from, if any (along the respective row or column). Various rendering parameters were changed and results observed.

Perception resolution and extent

Our data showed the smallest perceptible linear interval size to be comparable to that of the smart phone case (~1.6 cm) [START_REF] Kim | Out of the Body" Saltation to 2D Mobile Tactile Interaction[END_REF], "regardless of the size of the device (or distance between the vibration motors)," but only so in the middle part (40-60% of the bands). The perception resolution was notably lower (or discernable grid size "stretched", e.g. to as long as 7 cm depending on where the device was held) near the horizontal or vertical ends (see Figure 2). This was more evident in the vertical direction, because the hands were holding the device along the horizontal direction.

It seems the increased size of the devices and the fact that the hands/fingers are not in direct contact with the vibration motors somehow affect the "out of body" illusory perception near the holding positions. Based on this finding, we conjectured that for 2D situation, the perception resolution pattern and extent would look like what are depicted in Figure 2 (dotted lines).

Tactile rendering function and interpolated stimulation strength

In the pilot experiment described in Section 3.1, we initially tested the three most popular and arguably reliable (in terms of eliciting the phantom sensation from the intended location) stimulation rendering methods for funneling, namely, interpolating the two vibration amplitudes using linear, logarithmic, and tangent functions [START_REF] Alles | Information transmission by phantom sensations[END_REF]. Among the three, the tangent based interpolation showed the widest perception band (e.g. 6 intervals vertically and 9 horizontally on an iPad as shown in Figure 2). However, in the later main experiment, this finding did not carry over to the 2D case. The responses were inaccurate and irregular. This was due to the fact that when tangent-based interpolation was applied in 2D, the interpolated amplitudes at the middle region became relatively too low (compare the two interpolating functions in Figure 3). Thus, the logarithmic interpolation was chosen to render the tactile vibration amplitude with slightly less effective perception resolution (5×7) but with higher accuracy and response regularity.

Hand location

Finally, the finger/hand grabbing positions were varied between the middle and lower part on the sides of the tablets. When the users held the lower part of the tablets, the middle effective perception region also shifted in the lower direction and toward the user (see Figure 2). In the main experiment, we asked the participants to hold the middle part of the device.

4

Main Experiment: Extending "Out of Body" Funneling to Tablets

Experimental Design and Set up

In the main experiment, we used four single vibrators attached in the four rear corners of the iPad (see Figure 1). We used the same rendering algorithm as in Kim's study for the smart phone [START_REF] Kim | Out of the Body" Saltation to 2D Mobile Tactile Interaction[END_REF] but with the few parameters adjusted according to our pilot experiment findings described in the previous section. The main purpose of the experiment was (1) to assess the illusory tactile perception behavior and effectiveness of the newly adjusted rendering algorithm with the larger tablet device and (2) how combining the illusory tactile feedback with the visual would further improve the accuracy and user experience. Two cases of 2D illusory tactile renderings were compared: without any visual feedback (NV), and with visual feedback (VF).

For NV, users were given 2D illusory tactile stimulations on an iPad held in the middle part (e.g. as shown in Figure 1(d)) at the resolution of 5×7 (conservatively chosen based on the results of the pilot experiment). Participants were asked to pinpoint (using a stylus pen) where they felt the tactile feedback to be coming from.

For VF, when the stimulation was given, 5 visual icons (matching feedback), only one of them corresponding to the true intended target location (ITL), were shown and the user had to choose the correct one.

Vibrators were controlled by a voltage input using a PWM signal with an amplitude between 0 to 5V, which in turn produced vibrations with frequency between 0 and 250 Hz and associated amplitudes between 0 to 2G (measured in acceleration, or 0 to 18μm in position) respectively.

Detailed Procedure

Seven paid participants (4 men and 3 women) participated in the experiment with the mean age of 24.7. After collecting one's basic background information, the partici-pant was briefed about the purpose of the experiment and instructions for the experimental task. A short training was given for the participant to get familiarized to the experimental process. The participants wore ear muffs to prevent any bias from the sounds of the vibration. For both NV and VF conditions, the funneling stimulation was given by activating 4 vibrators simultaneously with logarithmically interpolated amplitudes according to the intended target location of phantom sensation (Figure 4).

Results

NV Experiment

ANOVA was applied for analyzing the perception resolution illustrated in the horizontal and vertical directions separately for simplicity. Figure 5 shows the cases for the first row and column where 5 and 3 distinct intervals were perceived respectively. Other rows and columns showed similar statistics. This lead us to project that the 2D perception resolution to be about only 3×5, lower than the expected (Figure 2). The graphs in Figure 5 show a similar pattern of lowered resolution at the periphery of the screen, i.e. elongated/enlarged grid size (e.g. ITLs at 1, 2 and 6, 7 in Figure 5(a) and 1, 2 and 4, 5 in 5(b)). Also note that the user response was not linear as desired, an artifact of resorting back to using the logarithmic interpolation and a possible interaction among the stimulations in 2D. Thus, we believe that better and linear responses can be obtained by employing vibration motors with larger amplitude capabilities and a "mixed" interpolation technique (e.g. logarithmic + tangent-based). Although the main purpose of NV experiment was observing user behavior for 2D response in 2D tactile feedback, correct responses for each ITL grid were recorded (Figure 6).

VF Experiment

As for the case of VF, Figure 6 shows the percentages of correct response for each ITL grid with an average of 78.6% (right part of Figure 6). Note that with the user having to select from five possible responses, the pure chance performance was only 20%. Thus the average of near 80% is considered a psychophysically meaningful response [START_REF] Geshelder | Psychophysics: The Fundamentals[END_REF][START_REF] Kingdom | Psychophysics: A Practical Introduction[END_REF]. While the performance is relatively lower in the middle upper and middle lower region (denoted darker), we claim that with the accompanying matching visual feedback, the non-regular and distorted perception pattern was much rectified and resolution improved as well (compare the left and right parts of Figure 6). In both NV and VF treatments, participants were surveyed about the localizability of the feedback, its clarity, task difficulty, and one's confidences in their responses on a 7-Likert scale. In all cases, the VF condition exhibited much more positive responses.

Conclusion and Future Work

In this paper, we carried out pilot experiments to explore how to extend 2D illusory tactile rendering to tablet devices. Tablet devices exceed in length for which "out of body" tactile illusion is known to work, and the stimulations become more indirect and their interactions in 2D more complex. Based on the experimental findings, we have devised a 2D illusory tactile rendering algorithm and have found that for an iPad sized device, approximately 5×7 regular resolution (grid size = ~2.5 cm) of illusory perception was achievable, when a matching visual feedback was provided.

For future work, we will apply our findings to real world examples such as interactive videos and mobile games, and assess whether the UX can be improved by the proposed vibro-tactile rendering method. At the same time, we plan to investigate additional ways to improve the 2D sensation localization accuracy by adjusting various rendering parameters, combining with the aural modality and employing other vibro-tactile illusion techniques such as the saltation and apparent motion.

Fig. 1 .

 1 Fig. 1. The concept of "out of body" tactile experience from a hand-held object. (a) When vibratory stimulations are given to the fingertips properly, phantom tactile sensations can be felt as if occurring from the middle of the hand-held object [7]. The 1D tactile illusion is extended to 2D for (b) a small smart phone where fingers are in direct contact with the vibration motors [6], (c) a small tablet (e.g. iPad mini), and (d) a larger tablet (e.g. iPad).

Fig. 2 .

 2 Perceptible grid sizes in horizontal and vertical directions (a) smart phone: ~1.6cm [6] (b) iPad mini: 2-3.7 cm, (c) iPad (held in the middle): 1.5-4.5 cm, (d) iPad (held in the lower part): 1.3-7 cm. The grids and the dotted area on the iPad mini and iPad show the "projected" effective perception area in 2D. Shaded regions represent the "stretched" grids.

Fig. 3 .

 3 Fig. 3. The logarithmic (dotted) and tangent based (full) stimulation interpolation functions (left) and the user's responses (right). The tangent-based interpolation stimulation produces a nearlinear user response (black).

Fig. 4 .

 4 Fig. 4. Funneling stimulations for the 5×7 grid on an iPad. Amplitudes of four vibrators in the corners are logarithmically interpolated to produce an illusory sensation in the 2D screen space.

Fig. 5 .

 5 Average percentage of correct responses in the horizontal (left) and vertical directions (right). The graphs show the same pattern of lowered resolution at the periphery of the screen (horizontal ITLs at 1, 2 and 6, 7 and vertical ITLs at 1, 2 and 4, 5).

Fig. 6 .

 6 Fig. 6. Overall performance of the NV (left) and VF (right) experiments. The percentages of the correct response are indicated in the grid.

Acknowledgements

. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (No. 2011-0030079) and funded by the Forensic Research Program of the National Forensic Service (NFS), Ministry of Government Administration and Home Affairs, Korea (NFS-2015-DIGITAL-04).


Daniel Burnett
email: d.burnett@lancaster.ac.uk

Adrian Gradinar
email: a.gradinar@lancaster.ac.uk

Joel Porter
email: j.porter@lancaster.ac.uk

Mike Stead
email: m.stead@lancaster.ac.uk

Paul Coulton
email: p.coulton@lancaster.ac.uk

Ian Forrester
email: ian.forrester1@bbc.co.uk

Physical Playlist: Bringing Back the Mix-Tape

Keywords: Tangible, Embodied, NFC, Customizable, Jewellery 1

To those of a certain age the concept of the mix-tape holds fond memories, and generally not of the musical content they contained, but rather the emotional and physical connection they represented with either its creator or recipient. They provided an embodiment of the time and effort it its creation and thus presented the same qualities of other handmade gifts. The advent of digital content, and particularly the mp3, for storage and streaming meant that audio content could be shared more quickly and easily than ever before. However, the creation of a digital playlist does not embody the same qualities present in a mix-tape and thus has not gained the same cultural significance. This research re-imagines the mix-tape for digital content as physical customizable jewellery that can once again embody values not generally attributed to digital content. Through a discussion of the design process and the results of preliminary evaluation, the potential benefits on the user experience of sharing digital content through physical objects have been highlighted.

Introduction

The shared mix-tape had an emotional and physical connection for people that digitally shared content often lacks. This connection comes from the fact that objects or artefacts often symbolize something more than their intrinsic value, and this is often preserved over the years. Our personal associations with objects often gain subjective meaning based on the memories that we have about them, although such memories are generally hidden and intangible [START_REF] Csikszentmihalyi | The Meaning of Things Domestic Symbols and the Self[END_REF]. Where once time was spent deco-rating the cover of the mix-tape 1 and carefully cultivating the tracks and possibly taking upwards of an hour to make, it now takes mere seconds with digital services such as Spotify, where on average nine playlists are created each second 2 . Between the mix-tape and Spotify was the writeable CD but they came too late, or too close, to the emergence of the mp3 to become a shareable treasured object akin to the mix-tape. The project presented in this research and developed in conjunction with BBC R&D at Media City UK resulted in the creation of a system, The Physical Playlist, that can be used to explore users experience of a physical shareable personalized object that has digital content embedded within it. Thus the project differs from those that have used objects as a means of storing memories, such as Memory Boxes [START_REF] Frohlich | The Memory Box[END_REF] or Stevens et al's Living Memory Box [START_REF] Stevens | Getting into the Living Memory Box: Family archives & holistic design[END_REF], as the object itself primarily represents the embodiment of the time and effort the creator took to personalize the gift thus making it more meaningful than a purely digital playlist.

Design Process

This research is part of a larger AHRC 3 project The Creative Exchange 4 whose aim is to bring together academics and businesses to improve the way they work together through a series of workshops exploring different themes around the concept of The Digital Public Space [START_REF]Digital public spaces[END_REF]. The theme of the workshop from which this project emerged was "Making the Digital Physical" and the Physical Playlist was one of the ideas generated by the group who went on to develop the project. The core idea was to recreate the concept of the mix-tape using digital content associated with physical objects. The physical objects could take almost any form imaginable although the original idea was for customizable jewellery and its format chosen for the initial prototype presented in this paper.

As the design was to be created collaboratively it was felt a 'research through design' [START_REF] Frayling | Research in Art and Design[END_REF] approach would be adopted, as it would allow all parties to reflect upon the design in an agile and emergent manner. One of the earliest considerations was how to embed digital content within an object that could be used easily by a user. The obvious solution to this was Near Field Communications (NFC) tags as they are relatively cheap, come in a variety of form factors, and now can be easily programmed via a mobile phone [START_REF] Coulton | Experiencing 'touch' in mobile mixed reality games[END_REF].

After deciding upon NFC tags as the bearer of the playlist, a method of personalizing the tags and then reading them back to play the associated media would have to be created. The tags chosen needed to be relatively small and robust, in the end a 14mm laundry tag was settled upon. Given its resilient nature and small footprint it was ideal for the application as the jewellery it is attached to may be worn out and about in diverse environments.

While different ideas for embedding the tag emerged a design was settled on that would allow easy programming of the tag and individual customization when incorporated within a piece of jewellery, which in this case was a bracelet. This resulted in the definition of a widget to hold the required tag and after a number of design iterations, shown in Fig. 1, a widget was produced that fulfilled this purpose. With the NFC tags suitably housed the next step was to create a means to turn this individual item into a playlist. A simple bracelet was chosen as shown in Fig. 2 below, as each widget could then be customized to produce something akin to a charm bracelet. With the playlist form factor created a method for embedding content and then reading and playing the tracks was required.

Embedding Content within Tags

An elegant solution was required for the process of storing the track data within the tag, as the chosen tags were only capable of storing 48 bytes. A simplified protocol was created where the first part of the data would be the type of track i.e. s for Spotify, y for YouTube and i for iPlayer, followed by a comma and finished with the URI (Unique Resource Identifier) for that track. The whole string was then enclosed within chevrons to give an indication of the start and end of the tag. For example:

<s,6JEK0CvvjDjjMUBFoXShNZ>

The most viable option was to create a mobile app for the Android platform due to its open nature and the prevalence of NFC technology already contained within a large number of the phones running the operating system.

With the player capable of playing a multitude of different media types from different services, in this project the media to be embedded came from YouTube5 , Spotify 6 , and BBC iPlayer 7 and the developed app had to accommodate all of these in one simple interface. The most effective way to do this was to provide a single text entry space with the option to then search any of the three services; the interface is shown in Fig. 3. Of course the utility of the App is not limited only to the initial writing of the data to the tag, it can also be used to re-write the tag so playlists can be edited on the fly to personalize them even further.

Once a playlist has been created the next step would be to play it back, for this a working device that can read the NFC tags and create a playlist and ultimately play the tracks was required.

Playing the Tracks

For the design team maintaining the order of the playlist was crucial and so it was decided that any player developed would have to respect the creators' order of the playlist. Working from a position of slow technology [START_REF] Hallnas | Slow Technology -Designing for Reflection[END_REF][START_REF] Hallnas | Expressions: Towards a Design Practice of Slow Technology[END_REF] the process of building the playlist and the act of placing the tags into the bracelet then fixing them in place, creates a time for self reflection and allows the creator to contemplate how best to actually curate the playlist.

From this standpoint a player design was formed that read the bracelet from top to bottom through the use of a rotating rod that moves a platform which can be seen in the left most image in Fig. 4 below. This image also shows the subsequent refined design showcased at MozFest 2014 8 in the middle and the 3D model that has become the finalised design. As for the actual playback of the playlist itself, the player, is in fact an Arduino9 connected to a RaspberryPi10 and transmits the data read from the tag via serial connection where it is then decoded and added to the playlist stored on the RaspberryPi. The playlist begins to play when the first tag is scanned and the arm continues to move down the playlist scanning until it encounters the next unread tag, this is then added to the playlist and the player ceases its movement until the previous track is completed. This is slow technology as was originally coined but also represents its more recent consideration as a way of slowing down the consumption of media [START_REF] Odom | Slow Technology: Critical Reflection and Future Directions[END_REF]. The playback screen on the monitor is shown in Fig. 5.

Initial Prototype Evaluation

The customizable physical shareable and a bespoke media content player were taken to MozFest 2014 for preliminary evaluation where participants were invited to create and play their own bracelets. At the end of the exercise 24 of the participants completed a simple visual tool to indicate how they currently share data and how likely they are to share that data in the future with different peer groups. The tool was designed to encourage comment and debate and enabled the researchers not only to ascertain that the users were able to create and play the produced objects easily it also drew information from the users which suggested that in the future they would be more likely to share a larger amount of personal information with friends and family if it were embedded in a physical object compared to current social network platforms. In terms of the acceptance of slow technology perhaps surprisingly the younger participants enjoyed that they couldn't skip a track and had to listen in order whereas the older participants wanted to rush through and get to the next part faster. These initial insights allowed us to move forward in the design process towards the forthcoming iterations discussed in the following section.

Future Work

The forthcoming stage of the project the 3D modelled version of the reader, shown in Fig. 4, will be created along with some custom made and designed bracelets to give the whole project a cleaner aesthetic and allow users to see the potential of the objects created. Further, plans are also underway to run a series of more in depth workshops with a range of potential user demographics through which a detailed analysis can be produced of how physical embodiment of digital content may affect users relationship with that content.

Conclusions

Whilst the original mix tapes offered elements of personalization, the flexibility of the potential objects that can be combined to form a physical playlist is considerably greater as they can take almost any form. Further, as the playlist is digitally enabled they can also be made to use other information, for instance they could be made so that they could only be played on a specific day, such as a birthday, or at a specific time, or when the weather is warm and sunny, thus allowing the creator to produce a very unique personalized experience.

Overall it is believed that the advent of 3D printing coupled with readily available means of embedding digital content in physical objects has enormous potential in creating new ways of sharing and this project offers a glimpse of the potential of this.

Fig. 1 .

 1 Fig. 1. Prototypes of widget from left (initial) to right (final).

Fig. 2 .

 2 Fig. 2. Original prototype bracelet with an NFC tag embedded in a widget

Fig. 3 .

 3 Fig. 3. The Android Application, Buttons can be seen for the three services.

Fig. 4 .

 4 Fig. 4. Initial prototype to Proposed Final Player (Left to Right)

Fig. 5 .

 5 Fig. 5. Playback screen of the Physical Playlist.

A mix-tape is the name given to any compilation of songs recorded onto any audio format although it is primarily associated with the compact audiocassette.

https://press.spotify.com/uk/information/

Arts and Humanities Research Council

http://www.thecreativeexchange.org/

http://www.youtube.com/

https://www.spotify.com/

http://www.bbc.co.uk/iplayer/

http://2014.mozillafestival.org

http://www.arduino.cc/

http://www.raspberrypi.org

Acknowledgments

The research presented in this paper has been made possible through the support of a number of organizations most notably the Arts and Humanities Research Council (AHRC) project The Creative Exchange at Lancaster University and BBC Research and Development at Media City UK.


Antje Heinicke

Christina Bröhl

Ioannis Dokas

Katrin Walbaum

Jennifer Bützler

Christopher Schlick

Development of Usability-Criteria for the Selection Process of Document Management Systems

Keywords: document management, DMS, usability, software ergonomics, selection criteria

As the overload of digital information in the SMEs requires an adequate management, document management systems (DMS) increasingly gain significance since they enhance the automation of processes within documents' registration, classification, processing, archiving and forwarding. However, in current selection processes of DMS the usability aspect seems to be unconsidered. For this purpose criteria are developed that measure the usability of existing DMS and allow the selection of a DMS according to usability aspects.

Introduction

The current scientific methods for software selection are not capable of representing the differences in the usability of the DMSs. The methods largely consider functional system requirements [START_REF] Naß | 3-Phasen-Modell zur DMS-Auswahl, Unternehmen der Zukunft[END_REF]. Objective criteria concerning the usability of DMS do not exist. Consequently, usability problems usually become visible only after the implementation. This study introduces an approach to determine objectively measurable usability criteria which can be applied by non-usability-experts for the evaluation and selection of DMS with regard to usability.

The evaluation of whether a system has a good or bad usability depends largely on the product itself and as well on the user and the context of use [START_REF] Herczeg | Software-Ergonomie[END_REF]. Accordingly, the identification of usability weaknesses of the existing DMSs, as well as the characterization of the users and their requirements was carried out in a first step [START_REF] Heinicke | Usability of Document Management Systems Considering Users' Level of Experience: A Survey[END_REF]. Based on the analysis of requirements, a user test was performed to detect the relevant usability criteria.

Method

The study included 22 subjects aged 27 to 60 years (M=43.41, SD=10.9). All Participants had experience in document management, yet little or no experience in dealing with document management systems. Only novices where included in the analysis in order to find as many aspects as possible for the formulation of the criteria which 2 may not be important for experienced DMS users and DMS experts. To make valid statements, two commercial DMS were exemplarily used for the tasks: A system with a graphic layout very similar to Microsoft Office and a system with an individual user interface design were used.

The requirement-analysis indicated that the invoice receipt, a frequently used process in many companies, is often supported by a DMS. Consequently, specific test tasks, which are associated with this process, have been developed and tested.

Procedure

A training video was presented at the beginning of the test, providing an introduction to the field of document-management and a description of DMS' aim. This ensured that also novice users of DMS gain a certain degree of knowledge about the features as well as the spectrum of uses and that all subjects had a similar knowledge about DMS. The training video was followed by the processing of the three tasks: Task type 1 included the searching and displaying of a filed document; task type 2 included the filing of a document in the DMS, while in task type 3 the participants were asked to share and comment on a document. To minimize sequence effects, both the sequence of task performance, as well as the sequence of the systems was permuted. While working on the tasks, the participants were encouraged to think aloud (Concurrent Thinking Aloud). After completing each task participants were asked to reflect their experience with the DMS in form of a structured interview.

Formulation of Criteria

With the aid of the comments made during the task execution and during the interviews, the formulation of the usability criteria took place. For this purpose the comments regarding the participants' subjective experience, were systematically analyzed, indexed and categorized with an expert evaluation. The first step hereto was the transcription of the comments into a list, sorted by subject, system and task type. In every comment, the key messages were highlighted and the comments were multiplied according to the number of key messages. Additionally, the key messages were compressed and assigned to the categories function, layout, wording, user guidance, system feedback, to the characteristics positive or negative system feature, and to the keywords depending on the type of task. Using the compressed key messages, the formulation of criteria was carried out starting with the first key message. If the further key messages could not be assigned to already existing criteria, a new criterion was formulated. Regarding the formulation of criteria it was ensured that the criteria can be evaluated with yes/no or available/not available.

Results

More than seventy usability criteria were formulated based on which the usability of a DMS can be evaluated. The usability criteria are to be considered as DMS-specific operating requirements that are related to the design of the entire user interface or to individual elements of the user interface and to the interaction with the system. The criteria show different characteristics, enabling various methods of evaluation and application.

Criteria Classification

For the specific use of the usability criteria in the DMS selection process, the criteria were separated in two categories. Criteria related to characteristics of the entire DMS user interface are of cross-functional nature (suitable for the specification sheet). Criteria, concerning specific controls or properties of the main functions "search", "import", "workflow" were correspondingly assigned as function related characteristics. In the following four examples of the most frequently mentioned criteria are listed (for the number of mentions, subjects were counted, whose comments a criterion could be assigned to at least once): ─ Cross-functional: Is a graphical representation of the filing structure available (e.g. in form of a tree structure)? ─ Functional reference to "Search": Do document details (nature/ type of the document) are displayed in a search results? ─ Functional reference to "Import": Does the user receive a visual feedback on the successful filing of a document into the DMS? ─ Functional reference to "Workflow": Are high priority tasks graphically highlighted in the task list (e.g. by a special symbol or colored highlighting)?

In case of the comparison between an already reduced number of possible DMS solutions, the usability of the main functions can be considered separately based on the functional classifications. This allows, for example, the usability evaluation of the search function separately from the usability of the workflow function. Thus, at the DMS-selection it can be focused on the usability of the particularly relevant functions for the user enterprise. Furthermore, the criteria could be characterized regarding their affiliation to norm-based dialogue principles [START_REF]Ergonomics of human-system interaction[END_REF]. This allows a standardized evaluation of a system's operating requirements.

Criteria list

The developed criteria were listed in a catalog. A weighting of the criteria based on the number of mentions was not made. The relevance of a criterion cannot be inferred from the number of mentions. Moreover, frequent mentions could be caused by the obviousness of a deficiency or a positive feature. The identified criteria primary concern general system properties as well as the three main features search, import and workflow. This fact is due to the type of tasks that were carried out. Therefore, the catalog of criteria does not claim to be complete. With the help of project partners, both DMS users and DMS provider companies, the set of criteria could be validated in terms of relevance, practical application and comprehensibility. For this purpose, 4 the categorized catalogue of criteria was given to the users, expanded by an evaluation option according to the specification sheet. Users should evaluate each criterion as to whether it is critical for them, required, optional, or not required. A note below each category intended to provide information on whether the review decision was easy to make or not. If not, the users could name the criteria which were difficult to evaluate. Furthermore, optional comments could be included. Providers also received an expanded catalogue including the evaluation of whether a criterion is met, not met or partially met by their own system. Furthermore, they were able to insert comments when understanding problems occurred. On the basis of the comments made by both the users and the providers, criteria were reformulated and redundancies as well as irrelevant criteria were removed from the catalogue.

Summary and Outlook

In the DMS selection process, established procedures are applied that often neglect usability aspects. With the aid of user tests, over seventy objectively measurable usability criteria were formulated, which can add the factor of usability to the future selection process. Due to the classification in cross-functional and function-related criteria, these can be used in different phases of the DMS selection process.