The Effect of Style and Weight on the Readability of Japanese Fonts :

A Study of Reading Evaluations with Standard Off-the-shelf Fonts

Abstract

This study aims to explain as quantitatively as possible the readability of Japanese characters in terms of certain elements in the multi-dimensional, and rather qualitative, space of font design. Based on a review of previous studies, two main dimensions have been selected as the most influential on readability ; the relative character size in the bounding box, which we call style, and the stroke width, which we call weight (when discussed in a categorical way). The Gothic fonts were chosen as the target because they are well known to be the most legible. Behavioral evaluations of readability were conducted instead of subjective judgments. In accordance with the reading acuity measurement MNREAD-J, short and easy-to-read sentences were presented to participants, and the time required to read them aloud was recorded along with any reading errors ; this provided three readability indices. Sentences were rendered in one of 12 different fonts consisting of four kinds of style-Old, Standard, Modern, and UD-times three weight levels-Light, Regular, and Bold. Findings for the style suggest that the enlargement of relative size represents a tradeoff with narrowed inter-letter spacing. This means that good legibility of single letter design may not result in good readability of letters in sentences. However, the weight had a notable effect especially in small sizes. Two readability indices were predicted relatively well by participants’ acuity and stroke width. The effect of stroke width had a ceiling between 10 and 15 ％ of the letter size.