The effects of sub-pixel addressing on users' performance and preferences during reading-related tasks

Abstract

Sub-pixel addressing is a font-rendering technology that triples the apparent horizontal resolution of liquid crystal displays by capitalizing on the spatial layout of the displays' colored sub-pixels. Microsoft's ClearType is an implementation of sub-pixel rendering that uses a spatial filtering method in an attempt to maximize “readability” while minimizing chromatic artifacts in the text; ClearType is available within Windows XP. Four separate experiments measured the subjective and objective effects of ClearType relative to standard (aliased) font rendering techniques during an hour-long pleasure reading task, a lexical decision task (distinguishing words from non-words in text strings presented briefly at various horizontal eccentricities), a word naming task (verbalizing briefly presented words), and a sentence comprehension task (determining whether two sentences fit together plausibly). Participants preferred, and gave higher readability ratings to, text that had been rendered using ClearType. ClearType also significantly improved the accuracy of lexical decisions as well as the speed and accuracy of sentence comprehension. ClearType did not affect reading speed during pleasure reading, and it influenced neither the speed nor the accuracy of word naming. Taken together, these findings indicate that ClearType provides substantial benefits to users while adding no cost to display hardware. ClearType may provide these benefits by facilitating reading processes such as lexical access and the use of contextual expectations.

Footnotes

 Funding was received from Microsoft Corporation.