Effect of letter spacing on eye movements and reading performance

Abstract

Previous studies have shown that, when presented in rapid stream (i.e., RSVP paradigm), word recognition speed for strings of three-letter words increases approximately 10% with large letter spacing, both in the fovea and the periphery (up to 10° eccentricity). A possible explanation is that small spacing may cause features of individual characters to overlap with one another, thus reducing text legibility, impeding letter and word recognition, and slowing down the reading process. In contrast, increasing letter spacing reduced the crowding effect until it was so wide that the word shape information is disrupted, or extends beyond the visual span, and thus slows down the reading.