A Two Parts Model In Virtual Reality Accurately Describes The Operational Characteristics Of Eye Control To Complete The Positioning Task

Eye tracking can provide interaction for virtual reality devices and is gradually becoming an important interaction method in virtual reality applications.Studying the behavioral performance of eye tracking and establishing motion behavior models are important for providing references for interaction design.However,previous research has lacked models that accurately describe eye tracking behavior,possibly due to differences in eye tracking behavior between small-scale interactions and large-scale interactions.Therefore,the purpose of this study is to establish models that accurately describe eye tracking behavior in two ranges of interactions.This study recruited 24 college students(9 males,15 females)who used eye tracking in a virtual reality environment to quickly and accurately place a small ball into a larger,white,semi-transparent target ball of the same height and depth.The study set up 8 horizontal movement distances(distance between the center of the small ball and the center of the target ball:10°,20°,30°,35°,40°,50°,60°,70°)and 4 target tolerances(difference in diameter between the small ball and the target ball:5°,7°,9°,11°).The results showed that as the movement distance increased,the total operation time showed a two-parts change.When the movement distance increased from 10°to35°,the total operation time slowly increased.When the movement distance exceeded35°,the total operation time increased rapidly.Further analysis found that the two-part change in total time was related to head turning angle.Eye tracking did not require head turning participation before the movement distance reached 35°,but head turning increased after the movement distance exceeded 35°.We further divided the movement process into a ballistic phase(cursor moving from start to near the target)and an correcting phase(cursor slowly placed into the target ball),and found that head turning mainly occurred in the ballistic stage,and that eye tracking had two-parts performance in the ballistic stage.Therefore,we proposed two-parts functions to describe the eye tracking behavior before and after the movement distance reached 35°.After the movement distance exceeded 35°,Fitts’Law well explained the data in this study(R~2=0.899);before the movement distance reached 35°,a two-parts model well fitted the eye tracking performance(R~2=0.916).The results of this study will provide theoretical support and application guidance for eye tracking interaction design in virtual reality.