Abstract
Purpose: :
The eye movements for following a moving target or reading a book are well controlled by the coordination of saccadic and pursuit systems. Though it is thought that following vertically moving target is more difficult than horizontally, the reason has not yet been clarified. We compared the eye movements when reading vertically written composition to a horizontally written one in Japanese characters.
Methods: :
Ninety–nine normal volunteers with ages of 19 to 23 years old were measured. Eye movements while reading horizontally written Japanese composition, then the same, but vertically written were recorded by infrared glasses (Ober 2, Sweden). The composition consisted of 45 words in one line with each word subtending 0.6 degrees, and were written in Japanese characters which were a mixture of Kana and Kanji, easy to read. Subjects were asked to read the compositions freely without a head rest in a lighted room. Analysis of the eye movements were made using the frequency and velocity of saccadic eye movement for changing the fixation from presently reading words to next words. We also made a simple questionnaire about the subjective comparison of the ease of the two kinds of reading.
Results: :
The pattern of eye movements while reading Japanese compositions showed basically the same components of saccade and pause whether written vertically or horizontally. It was just a staircase pattern. The difference between horizontal and vertical reading was that there was a tendency for higher frequencies and slower speeds of saccades in vertical than in horizontal reading. The subjects reported that horizontally written compositions were easy to read.
Conclusions: :
There are two ways for reading Japanese compositions, horizontally and vertically. Young Japanese can read a horizontally written composition better than a vertically written one. Physiologically, vertical eye movements may be controlled by more complex systems than horizontal eye movements during reading, which requires precise functions of fusion and fixation.
Keywords: reading • eye movements • eye movements: saccades and pursuits