“…The complexity of the calculation task can be used to evaluate the difficulty of the related task. To date, researchers have proposed many quantitative models for different interactive tasks and interactive devices based on Fitts' law and its existing extensions, such as the AR pointing model [8,10], scrolling interaction [19,22], touch interaction [4,17], the manipulation task [15], peephole pointing [7,20], menu selection [25], visual search [23] and head interaction [5,16].…”