Hartmut Obendorf

Web page revisitation revisited: implications of a long-term click-stream study of browser usage

This paper presents results of an extensive long-term click-stream study of Web browser usage. Focusing on character and challenges of page revisitation, previous findings from seven to thirteen years ago are updated. The term page re-visit had to be differentiated, since the recurrence rate--the key measure for the share of page revisits--turns out to strongly depend on interpretation. We identify different types of revisitation that allow assessing the quality of current user support and developing concepts for new tools. Individual navigation strategies differ dramatically and are strongly influenced by personal habits and type of site visited. Based on user action logs and interviews, we distinguished short-term revisits (backtrack or undo) from medium-term (re-utilize or observe) and long-term revisits (rediscover). We analyze current problems and provide suggestions for improving support for different revisitation types.

Not quite the average: An empirical study of Web use

In the past decade, the World Wide Web has been subject to dramatic changes. Web sites have evolved from static information resources to dynamic and interactive applications that are used for a broad scope of activities on a daily basis. To examine the consequences of these changes on user behavior, we conducted a long-term client-side Web usage study with twenty-five participants. This report presents results of this study and compares the user behavior with previous long-term browser usage studies, which range in age from seven to thirteen years. Based on the empirical data and the interview results, various implications for the interface design of browsers and Web sites are discussed. A major finding is the decreasing prominence of backtracking in Web navigation. This can largely be attributed to the increasing importance of dynamic, service-oriented Web sites. Users do not navigate on these sites searching for information, but rather interact with an online application to complete certain tasks. Furthermore, the usage of multiple windows and tabs has partly replaced back button usage, posing new challenges for user orientation and backtracking. We found that Web browsing is a rapid activity even for pages with substantial content, which calls for page designs that allow for cursory reading. Click maps provide additional information on how users interact with the Web on page level. Finally, substantial differences were observed between users, and characteristic usage patterns for different types of Web sites emphasize the need for more adaptive and customizable Web browsers.

The look of the link - concepts for the user interface of extended hyperlinks

The design of hypertext systems has been subject to intense research. Apparently, one topic was mostly neglected: how to visualize and interact with link markers. This paper presents an overview of pragmatic historical approaches, and discusses problems evolving from sophisticated hypertext linking features. Blending the potential of an XLink-enhanced Web with old ideas and recent GUI techniques, a vision for browser link interfaces of the future is being developed. We hope to stimulate the development of a standard for hyperlink marker interfaces, which is easy-to-use, feasible for extended linking features, and more consistent than current approaches.

Automatic support for web user studies with SCONE and TEA

This paper describes the concepts of TEA, a flexible tool that supports user tests by automating repetitive tasks and collecting data of user inputs and actions. TEA was specifically designed for user studies in the World Wide Web and is able to interact with a web browser. Building on a web intermediary (WBI) and a framework for web enhancement tools (SCONE), TEA can be applied in a range of test settings - providing either a controlled laboratory environment or a quick tool for collecting informal data.

Comparing link marker visualization techniques: changes in reading behavior

Links are one of the most important means for navigation in the World Wide Web. However, the visualization of and the interaction with Web links have been scarcely explored, although Links have severe implications on the appearance and usability of Web pages and the World Wide Web as such.This paper presents two studies giving first insights of the effects of link visualization techniques on reading habits and performance. The first user study compares different highlighting techniques for link markers and evaluates their effect on reading performance and user acceptance. The second study examines links-on-demand, links that appear when pressing a dedicated key, and discusses their possible effects on reading and browsing habits.The findings of the conducted studies imply that the standard appearance of link markers has seriously underestimated effects on the usability of Web pages. They can significantly reduce the readability of the text, and alternatives should be carefully considered for the design of future Web browsers.

Simplifying annotation support for real-world-settings: a comparative study of active reading

Despite the multitude of existing interfaces for annotation, little is known about their influence on the created annotations. In this paper, first findings of a comparative video-supported study of active reading are presented. The support for active reading offered by traditional paper-and-pencil vs. two existing annotation tools for the World Wide Web is examined and possible implications for annotation systems are drawn.An immediate conclusion is the existence of a strong need for simplicity and the importance of generic tools that can be adapted to the users task at hand.

Much to know about history

Users often revisit pages while browsing the Web, yet little is known on the character of these revisits. In this paper we present an analysis of various revisit activities, based on results from a long-term click-through study. We separate backtracking activities from recurrent behavior, discuss the impact of the use of multiple windows, and show that in particular infrequently reoccurring activities are poorly supported by current history support mechanisms. We conclude with a discussion on design implications for more personalized history support.

HyperScout: Darstellung erweiterter Typinformationen im World Wide Web -- Konzepte und Auswirkungen

Die Benutzung eines Web-Browsers ist einfach zu erlernen, dennoch stellt die Navigation im Web selbst fur erfahrene Benutzer immer wieder Herausforderungen bereit. Einer der Grunde liegt in der Vielfalt von Links und Linkzielen, die fur den Benutzer oft nicht transparent sind und ihn so vor Uberraschungen stellen, nachdem er einen Link angeklickt hat. Das Projekt HyperScout beschaftigt sich mit Moglichkeiten, die Navigation zu vereinfachen, indem man Typinformationen von HTML-Links und referenzierten Objekten fur den Benutzer sichtbar macht. Dieser Bericht stellt die entwickelten Konzepte und die Ergebnisse einer Evaluation des daraus abgeleiteten Prototyps vor. Die Ergebnisse geben Aufschlusse daruber, welche Informationen Benutzern vor der Anwahl eines Links hilfreich sind und wie sie dargestellt werden konnten.

Teaching balance and respect: HCI Group & Software Technology Group at the University of Hamburg

research by applying theoretical models and methodologies from different research fields? The doctoral program follows a “back to school” principle itself by coming from different backgrounds, bringing all the specific knowledge, and dedicated language. “Back to school” is also implemented for the HCI part of this program through a very advanced course on HCI fundamentals, theories, and approaches which helps make students capable of solving problems in the field. In addition, an advanced course on contextual interfaces teaches the innovative application of HCI to design innovative approaches in different contexts. Getting the Right Problems. No one can solve problems without the right problems. There is a need to take the real world problems to schools for students to work on them. This is a call for all the companies with problems to solve (there are always enough things to do). Schools are waiting to include real, complex world problems into the different levels of education. If done properly, this could be an ideal vehicle to merge two often separated worlds. It gives one answer to what is the better education: schools or training on the job? Both.

Einsatz elektronischer Medien zur Unterstützung der universitären Lehre: Ein Erfahrungsbericht

Erfahrungen mit dem Einsatz verschiedener Systeme zur Unterstutzung von Lehrveranstaltungen werden gegenubergestellt und Konsequenzen des Einsatzkontextes fur den Entwurf von Informationsplattformen, die die Lehre unterstutzen sollen, und die Auswahl der Plattformen aufgezeigt.