Using cursor measures to investigate the effects of impairment severity on cursor control for youths with cerebral palsy

Individuals with upper limb impairments due to cerebral palsy encounter difficulties when using pointing devices and can be limited in communicating and accessing education tools through computers. Analysis of cursor trajectories can identify some of the factors limiting cursor movement, and provide a better understanding of human movement to assist in designing accessible computer interfaces. This study evaluated cursor trajectories from 29 individuals with bilateral cerebral palsy (CP) and different levels of function. The functional level was classified based on the MACS (Manual Ability Classification System). Results show that the contributors to a model that assesses different MACS levels are the movement time, acceleration-deceleration cycles and average speed. The model appears unaffected by accuracy measures. For both typically-developed youth and participants with CP, a good model of index of difficulty must include the following predictors: rapidity - movement time, average speed, zero acceleration crossings and accuracy, trajectory distance, linearity index, and indices of vertical and horizontal components. Models for those who are typically-developed should also include an index of diagonal component and curvature index.