The Usability Evaluation Of Finger Slide Direction In The Direct-touch Device

The touch technology of Human-Computer-Interaction will finish the interaction with computer by finger without any tools, so it is taken for a friendly and convenient interactive mode. Fingers slide on the touch screen, could be considered as an common operating mode in touch interaction. Due to the limitation of finger properties such as biology, physics and so on, it could lead to error with block and shake, then the positive user feedback will be hard to get. Starting with the difference of finger slide direction, this paper will do in-depth research about the availability. The main achievement is as follows:Firstly, the experiments confirmed that if the fingers slide without any direction guidance, the computed result about slide direction will be no difference between start-stop point method and loci method. The fingers have good stability, keep smaller deviation angle with initial slide direction, could reflect users’ intention very clearly; at the same time, the data of included angle between fingers slide direction and coordinate axis follow normal distribution.Secondly, the experiments about slide direction confirmed that there is a regional character about the difference of slide direction. In the same region the difference of slide direction is not significant. Otherwise, the difference will be obvious. Based on this regional difference, the selecting sequence in the UI design is the first quadrant, the third quadrant, the fourth quadrant and the second quadrant.Thirdly, in order to research the basic behavior properties of fingers during touch and move, some tunnel slide experiments in different directions were designed based on the Steering Law. The results showed that users also have directional difference during the tunnel slide. When the angle is0, it is easy to get a better feedback, and the success rate is higher than other angles. When the angle is120, the results can not be satisfied for the users, so it is inappropriate in the UI design. Meanwhile, the results also pointed out that if the width of slide is less than14px, it is also hard to get the satisfied results.This is a fundamental research about the touch technology, and it is an important guidance for touch interaction and gesture design.