Participants sat in a chair or their own wheelchair in front of a table whose surface height was adjusted at the midpoint between the hip and the Xiphoid process. They placed the hand that was not used for the task on their lap.

An iPad® (Apple Inc, Cupertino, California) was located on the table in portrait mode in front of the participants at a distance that ranged between 40 and 55 cm. An adjustable metal bookstand supported the iPad® to allow the participants a comfortable screen view. The size of the screen was 19.5 × 14.6 cm. Custom software was developed for the experimental task (XCode 3.2 development environment, iOS 4.2 operating system; Apple Inc, Cupertino, California).

The subjects were required to touch targets on the iPad® screen with the index finger of their preferred (less-affected) arm. The experimental task consisted of 180 targets divided in 4 blocks: 45 targets each block with a 1-minute interval between trials to avoid fatigue. Targets appeared at 1 of 9 different locations on the screen, and subjects moved their finger sequentially from one target to the next.