title: Effects of Word Width and Word Length on Optimal Character Size for Reading of Horizontally Scrolling Japanese Words.
abstract: The present study investigated, whether word width and length affect the optimal character size for reading of horizontally scrolling Japanese words, using reading speed as a measure. In Experiment 1, three Japanese words, each consisting of four Hiragana characters, sequentially scrolled on a display screen from right to left. Participants, all Japanese native speakers, were instructed to read the words aloud as accurately as possible, irrespective of their order within the sequence. To quantitatively measure their reading performance, we used rapid serial visual presentation paradigm, where the scrolling rate was increased until the participants began to make mistakes. Thus, the highest scrolling rate at which the participants' performance exceeded 88.9% correct rate was calculated for each character size (0.3°, 0.6°, 1.0°, and 3.0°) and scroll window size (5 or 10 character spaces). Results showed that the reading performance was highest in the range of 0.6° to 1.0°, irrespective of the scroll window size. Experiment 2 investigated whether the optimal character size observed in Experiment 1 was applicable for any word width and word length (i.e., the number of characters in a word). Results showed that reading speeds were slower for longer than shorter words and the word width of 3.6° was optimal among the word lengths tested (three, four, and six character words). Considering that character size varied depending on word width and word length in the present study, this means that the optimal character size can be changed by word width and word length in scrolling Japanese words.
authors.affiliation: Division of Cognitive Psychology, Faculty of Letters, Kumamoto University Kumamoto, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Teramoto
authors.affiliation: Mitsubishi Electric Corporation Tokyo, Japan.
authors.forename: Takuyuki
authors.initials: T
authors.lastname: Nakazaki
authors.affiliation: Division of Cognitive Psychology, Faculty of Letters, Kumamoto University Kumamoto, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sekiyama
authors.affiliation: Department of Informatics, Faculty of Information Science and Electrical Engineering, Kyushu University Fukuoka, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Mori
keywords: Japanese; character size; reading; scrolling; word perception