The Biasing Effect of Word Length in Font Size Encodings

From word clouds to cartographic labels to word trees, many visualizations encode data within the sizes of fonts. While font size can be an intuitive dimension for the viewer, it may also bias the perception of the underlying values. Viewers might conflate the size of a word’s font with a word’s width, with the number of letters it contains, or with the larger or smaller heights of particular characters (‘o’ vs. ‘p’ vs. ‘b’). In an ongoing set of experiments, we have found that such factors—which are irrelevant to the encoded values—can indeed influence comparative judgements of font size. For this poster, we present one such experiment showing the biasing effect of word length.