Investigation of the angle and age effect using Fitts' Law for mouse input

In human-computer interaction Fitts’ Law has proven to be a highly accurate model for predicting movement times of pointing tasks. The original Fitts' Law only considers one-dimensional movements. In the field of human-computer interaction however one has to deal with at least two dimensions. Due to inconsistency in previous research concerning the integration of the motion angle into the Fitts' formulation, we investigated the influence of this factor on movement times and total fixation time on target object. 93 subjects, separated in three age groups were tested in executing a pointing task with a computer mouse. The results reveal that horizontal and vertical pointing movements result in significantly shorter movement times than diagonal pointing movements. Regarding the total fixation time on target object we found significantly longer fixation times for pointings in upper areas than for pointings in lower areas. Moreover, movement time as well as total fixation time on target object was significantly higher with increasing age. Practitioner Summary: We investigated which angle leads to lowest movement times when carrying out goal directed pointing movements with a computer mouse. For different age groups horizontal and vertical pointing movements were beneficial as they led to lower movement times than diagonal pointing movements.