Human-Centered Aspects

Abstract

Humans have remarkable perceptual capabilities. These capabilities are heavily underestimated in current visualizations [759]. Often, this is due to the lack of an in-depth user study to set the requirements for optimal visualizations. The designer does not understand what kind of information should be visualized, how it should be presented or what kind of interactions should be supported. The key elements of successful information visualization are the correct data using the best visualization technique and the best interaction techniques with respect to users. If one of these elements is ignored, people might interpret the data in the wrong way and thus might not understand the underlying information or a pattern.In order to design effective interactive visualizations, it is important to take into account the limitations of human perception, context of use, and the goals and activities that are to be performed to reach these goals. In order to obtain a usable application, developers have to pay attention to the user's working environment and tasks; this focus-on-user idea is comprised in the human-centered concept.The next section discusses usability (the property of being usable) from the human-centered point of view. Usability has application in many areas, but our focus is on the human-centered approach to design of interactive systems, also called user-centered , in order to inform the reader on how to design visualizations according to human cognitive and perceptual abilities, specific to the context of use and goals of potential users. Then, the usability concept is explained in the "Usability in Human-Centered Design" section. The next Section "User Aims and Requirements" discusses how to define a user group, establish user goals and requirements. Finally, an overview of the different evaluation methods and current evaluation practices, including the practical issues of experiment design that can help to improve the effectiveness of visualizations is presented in the "Evaluation of Visualizations Environments" and "User Studies and a Science of Visualization" sections. Stone et al. [798] describe a human-centered design giving the following definition: Human-Centered Approach

Structuring visual exploratory analysis of skill demand

“…However, an open challenge, especially where the backgrounds and technical capability of target users vary significantly, is corresponding variation in visual literacy [1,29,31]. To address this, we follow a userand task-centred approach that uses ontologies to abstract and aggregate dynamic, heterogeneous data into structured information spaces.…”

“…We extend van Wijk's visual analytics model [2] to define our methodology, illustrated in Fig. 1, that employs (interactive) visual analytics, relying on the human in the data exploration and analysis loop, to obtain an understanding, first, of data content [see also 1,26,29,31]. Working from this we iteratively build, verify and refine a model of our target users, their tasks and the resources required to work toward their end goals, as we widen the scope of our analysis to include new data.…”

“…As part of our user-centred approach we feed information from target end users into a cycle of requirements specification and verification and (re)design, to ensure usability and utility, and practical adoption of our framework and the tools coupled to it [see, e.g., 4,31,32]. At this stage in our UCD cycle -iterating between design and development -we collect user feedback through formative, heuristic evaluation [44].…”

“…Inselberg [30], Heer et al [25], among others, look at the benefits in multi-dimensional visualisation techniques such as scatterplot matrices and parallel coordinates. Kulyk et al [31] examine the use of focus+context techniques to aid delving into ROIs in large, complex data.…”

“…Developing intuitive, user-centred, and therefore also taskcentred, tools for effective visual analysis is not trivial, especially where a wide range of expertise, or lack thereof, is found in target end users [1,25,31]. Designing effective support for complex scenarios and data typically involves the exploration of the impact and use of multiple sub-components [4,12,26,27,29,32], following a process that may involve any or all of the following in an iterative cycle:…”