Readability of Japanese Electronic Text with Phrase-based Line Breaking

We propose a new Japanese electronic text format with phrase-based line breaking for tablet computer to improve reading speed. The new text format prohibits splitting of a phrase and breaks a line between phrases. We measured reading speeds and eye movements using both the new text format and a conventional text format. Reading speeds for the new text formats are faster compared to the conventional text formats at all line lengths tested. The enhancement of reading speed in the new text format seems to be caused by the optimization of eye movements at the beginning of a long-length line, and the increase of short-length lines that can be recognized by a single fixation without horizontal saccade.