Children who have the inability to control movements often have difficulties positioning the mouse cursor. Students may also have the inability to double-click within the time necessary, or click and drag. As a result, assistive technology for children with disabilities includes several options to control the mouse cursor.
A common alternative to the mouse is a trackball. Best described as a mouse upside down with the ball exposed, trackballs remain stationary so that only movement of the ball moves the cursor. Buttons on the trackball can perform single click, double click, and drag-lock functions. The size of ball on the trackball varies from as large as a cue ball to as small as a marble.
A joystick is another input device that can control the cursor. Joysticks offer three types of control: digital, glide, and direct.
- Digital control allows movement in a limited number of directions.
- Glide and direct control allow movements in all directions.
- Direct-control joysticks have the added ability of responding to the distance and speed with which the user moves the stick.
Joysticks have the benefit of activating the computer with different parts of the body, such as the head or chin, without the use of hands. Different joysticks require more force than others. In addition, some joysticks have up to three programmable control buttons that perform various functions. Some, however, only work with software written specifically for use with them.