From action icon to knowledge icon: Objective-oriented icon taxonomy in computer science
Introduction
The principle of iconic representation may be partly demonstrated from the evidence of imaged cognition [1]. “People often recognize pictures of things and understand them more quickly than they do verbal representations of the same things.” [2] Early research in Dual-coding theory [3] postulated that both visual and verbal codes for representing information are used to organize incoming information into knowledge that can be acted upon, stored, and retrieved for subsequent use. The theory showed that memorization for some verbal information is enhanced if a relevant visual is also presented or if the learner can imagine a visual image to go with the verbal information. Likewise visual information can often be enhanced when paired with relevant verbal information.
Several definitions offered by experts tried to make clear boundaries between the terms of icon and symbol [4], [5]. For example, Horton considers icons as a subset of symbols [6]. McDougall argues for an inverse subordination between these two concepts: “For the sake of simplicity, icon is the term used […] to refer to the broad range of icons, signs, or symbols used to help individuals interact with machines and their environment” [7]. Marcus argues for a distinction between an icon and a symbol in terms of the concreteness of the representation: “Icons are signs that are familiar, are easy to understand, and are often concrete representations of objects or people. Symbols are signs that are often more abstract and require specific instruction to learn” [8].
In this paper, we follow Horton’s definition of icons to consider “icon” is a general reference of visual symbol. Particularly, we define that the symbolic characters of icon imply how an icon signifies the object while the graphical characters referring to the graphical variable used in an icon, like color and shape.
Computer icon (henceforth “icon”) plays a critical role in Graphical User Interface (GUI) [9]. It is a group of icons displayed on the computer screen in conjunction with computer windows, menus and a pointing device form of computer system and enables the user to easily and intuitively navigate the system. One of the most notable icon designers, Susan Kare was quoted saying “good icons should be more like road signs than illustrations, easily comprehensible, and not cluttered with extraneous detail” [10].
Studies on icon taxonomy provided deeper theoretical explanation of iconic representation from the view of its characteristic. They illustrated what kind of icon existed and how each kind of icon signified the target through symbolic characters and graphical characters. The findings in turn served later icon design and implied why some icons were better accepted than others. However the previous studies focused more on physical appearance of icons themselves instead of considering the influence on applied environment. Moreover, the former findings were carried out based on simpler computer background where user’s perception was single and icon needs was direct. Following the diversity of users and icon applications, the static icon-character-oriented taxonomy could not satisfy completely icon research. Besides, the development of visualization and knowledge engineering creates more changes for icons. They are employed not only for user’s operation guide but also in use of knowledge representation, in order to enhance knowledge understanding and knowledge reuse under sharing environment. This is one of the reasons to form two icon sets which have a strong relationship with icon applying trends: action-oriented and knowledge-oriented.
Consequently, we are proposing an objective-oriented icon taxonomy, which highlights the use purpose of computer icons rather than their graphical characters or symbolic characters. This applied-domain-focused icon taxonomy is supposed to improve computer icon serving for information visualization. On one hand, new categorizing criterion will enrich icon taxonomy study. How one icon could represent an object is not the only analysis point of computer icon any more. Where this icon is able to be applied and why it occurs on this kind of interface design is also interesting to be emphasized. On the other hand, deeper illustration on icons that are suitable in each applied field will enhance the understanding on the potential of icon and in turn explore more possible icon-based interface design. The icon design could start from applying needs instead of seeking appropriate platform for the icons that have been created. This study is assumed to be meaningful for icon-based human computer interface both at theoretical level and practical level.
This paper will firstly review the development path of icon taxonomy, respectively from physical appearance, user perception and representation strategy, these three main criterions. In Section 3, we will explain the proposed icon taxonomy and present two icon categories produced by it: action icon and knowledge icon. Then in the next section, a test carried out to demonstrate new icon categorizing criterion will be presented and typical application domains of each icon category will be precisely illustrated. Discussion on this objective-oriented icon taxonomy will be also analyzed in details. Finally, we conclude.
Section snippets
Background – previous studies on the taxonomy of computer icons
The studies on computer icon taxonomy started in line with GUI. It was pointed out in the purpose to clarify the characters of kinds of icons applied in computer interface and tried to find the common attributes among these icons in varied appearance. The common attributes were supposed to support the creation of icon-based GUI in a diversified way. The icon taxonomy has been explored and improved for about thirty years and it formed progressively into three branches based on three different
Proposed icon taxonomy based on application purpose in computer science
The application of computer icons could trace back to visual design for computer interface. Taking use of these symbolic graphs users are able to easily master operations on the computer. Meanwhile computer interface turns to be more artistic and practical in both space and time compared with writing in text. However in fact even in ancient Chinese characters and Mayan texts, icons were used to spread information and annotate knowledge [26], [27]. These original symbols, not be called as icons,
Method and results
To assess the icon taxonomy proposed in our study, we selected 620 icons from 140 icon-concerned applications presented recently (1994–2014) online from website, conference articles and journal articles. All these applications chose icons to improve theoretically or practically computer use in a specific background. The icons displayed in the following sections do not receive any change after being selected in our study. They keep their appearance in original applications. We worked out a
Discussion
Seen from the experimental results of icon taxonomy based on applying objective, action icon and knowledge icon are two meaningful terms to describe current icon applications in computer interface. Unlike previous three classification criterions, action icon and knowledge icon have a more certain boundary from different icon categories. No matter it is concrete icon or abstract icon, it will be called action icon if the applying objective is to let users do some operations on the computer. No
Conclusions
This paper presents an objective-oriented icon taxonomy method and defines two new terms of computer icon as action icon and knowledge icon. The practice of icon classification manifested that this kind of icon taxonomy focuses less on the relation between icon and its representing object, which simplifies the problems on blur boundaries of physical-appearance-based method. The sub-categories of this icon taxonomy suggest the applied preference of each potential field and make clearer the
Acknowledgements
This research is sponsored by the National Natural Science Foundation of China (71403201), Social Sciences Foundation of Shaanxi Province of China (2014L03), the MOE Project of Scientific Research Foundation for the Returned Overseas Chinese Scholars ([2014]1685) and the Fundamental Research Funds for the Central Universities (JB140611).
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