[ 5] Rivadeneira, A. W., D. M. Gruen, M. J. Muller, and D. R. Millen.”Getting Our Heads in the Clouds: Toward Evaluation Studies of Tagclouds.” In Proceedings of CHI 2006.

tive text analysis, suggests that experts in information design might want to rethink the purpose and goals of their creations. In this moment when nonacademic designers are adopting academic visualization techniques, theorists can return the favor and take inspiration from the current burst of creativity in vernacular visualization.

[ 6] Hearst, Marti A., and Daniela Rosner. “Tag Clouds: Data Analysis Tool or Social Signaller?” In Proceedings of HICSS 41, 2008.

Acknowledgements The authors would like to thank Marti Hearst for insightful comments on an early draft of this article, and Jonathan Grudin for the invitation to contribute to the Timelines forum.

July + August 2008

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search for specific items in the display. Yet another study has determined that some users are oblivious to the fact that words are alphabetically organized [ 6]. So there’s a puzzle: If tag clouds don’t provide quantifiable benefits and if people are unaware of how items are organized in the visualizations, how and why are tag clouds being used?

Hearst and Rosner suggested one possible answer when they noted that tag clouds seem to serve another purpose, as social signifiers that imply a friendly atmosphere and provide a point of entry into a complex site [ 6]. Web 2.0 sites tend to attract thousands, sometimes millions, of users who contribute content—grasping the scale and diversity of these contributions is a challenge. Therefore, having tag clouds that summarize some of this activity in a simple manner can be a valuable asset for the community of users. In a sense, these clouds may act as individual and group mirrors which are fun rather than serious and businesslike. Indeed, this all-word visualization is a diagram that even a matho-phobe can love.

But what about tag clouds that appear outside the realm of social tagging? Our experience on Many Eyes suggests a few other uses. In some cases, tag clouds function as portraits of individuals rather than groups. One person uploaded the text from 20 blogs he read ( 10 from men, 10 from women) to create a gallery of verbal snapshots. Each cloud was accompanied by commentary on what it revealed about the blogger’s personality. While this certainly was a form of analysis, the engaging nature

of tag clouds made the technique a natural fit.

In other cases, however, tag clouds seem to be used for more traditional analytical purposes. Numerous bloggers have written about the tag clouds of political speeches and have painstakingly examined the differences among politicians. Here users actively find, analyze, and communicate patterns in text, rather than merely obtaining a glimpse of the “gist” of a piece of work. Despite the theoretical concerns, tag clouds have become a tool of choice for analysis.

A tag cloud is truly a “ vernacular” technique—one that does not come from the visualization community, and that violates some of the golden rules of traditional visualization design. Nevertheless, the tag cloud’s widespread popularity and flexibility—playing a starring role in situations ranging from psychological experiments to fiction writing to political analysis— suggest that it passes the test of applicability. One might say that tag clouds work in practice, but not in theory.

This failure of conventional wisdom deserves attention because it points to new possibilities. The increasing demand for tag clouds indicates that there is an important class of data that users want to visualize: unstructured text. In addition, the value users draw from such visualizations, as social signalers or as tools for collec-

ABOUT ThE AUThOrS Fernanda B. Viégas and Martin Wattenberg are research scientists at IBM’s Visual Communication Lab. Viégas is known for her pioneering work on depicting chat histories and email. Wattenberg’s visualizations of the stock market and baby names are considered Internet classics. Both Viégas and Wattenberg are also known for their visualization-based artwork, which has been exhibited in venues such as the Museum of Modern Art in New York, the London Institute of Contemporary Arts, and the Whitney Museum of American Art. The two became a team in 2003 when they decided to visualize Wikipedia, leading to the “history flow” project that revealed the self-healing nature of the online encyclopedia. Their current project, Many Eyes, explores the power of Web-based visualization and the social forms of data analysis it enables.

Further reading:

Many Eyes: http://many-eyes.com