Existing substitutes for the handheld mouse include eye trackers, sip-and-puff devices and head-tracking systems. Each technology has drawbacks. Eye-tracking devices are expensive and require that the eye simultaneously take in information and control the cursor, which can cause confusion.
Sip-and-puff joysticks held in the mouth must be spit out if the user wants to speak, and can be tiring. Head-tracking devices require neck movement and expensive hardware.
