Movement time to edge and non-edge targets

Time to capture a target at the edge of a screen is expected to be less than when the target is slightly away from the screen edge. This is due to the effective target width, in the direction of cursor movement, being large when the target is at the screen edge, allowing a user to control the movement only in a direction perpendicular to the direction of movement. An experiment with 71 participants and a range of Fitts' Index of Difficulty (ID) showed a strong difference in the capture times of targets at the screen edge and targets placed one pixel from the screen edge. This advantage is typically 100 ms, independent of the ID of the movement. Practitioner Summary: Movement time to icons placed at the screen edge (no space between icon and screen edge) is faster than when they are placed a short distance from the edge (as in Microsoft Windows).