The Influence of Decorations and Word Appearances on the Relative Size Judgment in Viewers of Tag Clouds

A tag cloud is a representation of the word content of a source document where the importance of the words is represented by visual characteristics such as color and size. Tag clouds can be used for several purposes such as providing a high-level understanding of a document. Although previous research has indicated that the relative size of tags is a strong factor in communicating the importance of the words in the underlying text, there are still many unanswered questions. Examples of these questions are as follows: How do viewers perceive the relative size of the words in a tag cloud? How is the judgment of the relative size is influenced by other characteristics of the words in a tag cloud? Do viewers make their judgments based on the area, the height, or the length of the words? In this chapter, we investigate viewers’ estimation of the tag word relative sizes given while varying the size, types of letters, and the surrounding text box decorations around the target word pairs. The results indicate a range of relative sizes where relative size judgments may be approximately correct, but also a large region of relative sizes where the relative size judgments are increasingly underestimated as the true size ratio increases. This underestimation bias was only modestly influenced by appearance characteristics. The results have implications for tag cloud design, and for reliance on relative size judgment of words as a visualization technique.