Design of Eye-Typing Interface Using Saccadic Latency of Eye Movement

The objective of this study was to construct and empirically evaluate an improved, online eye-typing interface with respect to its practical usability. The system used the concept of saccadic latency, a silent period of 200 to 250 msec precedes the initiation of a saccade, for identifying the user's intentional text entry. Ten individuals participated in the experiment that was conducted on 2 consecutive days, with three blocks of trials conducted on each day. A block included five trials, each of which involved completing the text entry of a short sentence using this eye-typing interface. The proposed interface was evaluated by the user's performance based on indices including typing speed and an error index. For defining the error index, the overproduction rates (ORs) were used. The results showed an average OR of 0.032 and average typing speed of 27.1 characters typed per minute. The result revealed that the typing speed changed as an effect of participant, day, and block. The characteristics of the proposed interface with the related characteristics of an eye-typing interface were summarized to discuss a further study for the eye-typing interface.