BACKGROUND: A Carnegie Mellon University doctoral student has designed a new gestural input system, called EdgeWrite, that helps people with motor skill problems work more easily with computers.
HOW IT WORKS: EdgeWrite consists of a square plastic overlay that is placed on the touch screen of a PDA device. The overlay helps guide a stylus along the edges of the template, even if the user's hand is unsteady. The EdgeWrite language is based on forming letters not by stroke, but by hitting a series of corners on the template in a particular sequence, making it very tolerant of wiggles and tremors. So if a user has a shaky hand when guiding the stylus, it won't affect recognition of the text. That's because the device doesn't identify letters based on the shape of the stroke, but on a sequence identified by the device's own alphabet, which can represent letters, numbers, punctuation, accents, and even other languages.
THE PROBLEM: Most PDAs, such as the Palm Pilot, use a language called Graffiti as a writing method, but it is difficult for people with motor impairments -- or even able-bodied users walking or riding in a vehicle -- to write clearly because letter recognition depends on the path of movement. It is also difficult for these users to use shift or caps lock modes; Edgewrite only has modes for punctuation or extended characters.
WHAT'S NEXT: In the future, the EdgeWrite system could be used with a trackball or cell phone, and entire words completed as the users enter sequences of letters.
ABOUT MOTOR FUNCTION: Even a simple motor movement involves many different regions of the body, but the primary motor cortex of the brain is one of the most important. It sends out electrical impulses through nerve cells called neurons that control the execution of movement. Every part of the body is represented in the primary motor cortex; the left side of the brain controls the right side of the body, and vice versa. Certain diseases or brain damage can disrupt these basic functions. For instance, cerebral palsy is a disorder that affects body movement and muscle coordination because of brain damage, which interferes with messages from the brain the body, and vice versa.