Computer Mice, Trackballs, Aids
Ergonomic Computer Accessories Include Joysticks, Hands-Free Devices
Jul 23, 2008
Many people, especially in home offices, place their mice on their desk tops. This causes them to reach to operate them. The shoulder muscles tense to keep the arm extended, and this can cause the chronic pain of a repetitive strain injury.
Best Place for a Mouse
The best position for a mouse for right-handed people is over the pad of number keys to he right of the keyboard, which itself should be lower than the writing surface and at an angle (see Further Reading below).
Many keyboard trays are available that have mouse trays that swivel over the number keys. Many also can place the tray on the left, or slide side to side.
Software is available that can interchange the operation of the two mouse buttons, so that the right-hand button can assume the function of the more commonly-used left-handed button, allowing left-handed people to use the index finger for the most common operations. An advantage of the Apple computers is that the mouse uses only one button.
Keyboard Instead of Mouse
Software is available that can convert the number keys to cursor control keys, so that the user does not need to move a hand away from the keyboard.
Trackballs
An alternative to the mouse is a trackball, which was invented and in use for decades before the mouse appeared. Radar operators, for example, will regard the mouse simply as an upside-down trackball.
The trackball consists of a ball in a holder fitted with buttons. The user moves the pointer around on the computer screen by rolling the ball with the fingertips. Buttons on each side or one side of the holder are the mouse buttons.
An advantage of the trackball for some people is that it remains in one position and takes up little room. It can be operated just with fingertips and with the arm at rest, and can be tucked in either side of a keyboard tray.
The software that comes with the trackball can set the buttons for left or right. However, depending on the model, experience has shown that a trackball can be used in either hand where a computer is shared by more than one person -- right-handed people can use the thumb for the left button and left-handed people can use a finger.
Large-size trackballs are available for people who lack fine motor control of their fingers.
Joysticks
Another alternative is the joystick, which can be operated just with the fingers and does not require the user to move the hand. The hand and arm can rest while the joystick lever and buttons are operated with small finger movements. It is also suitable for people with limited ability.
Hands-free devices
Developed primarily also for people who do not have full use of their hands are foot-operated pointing devices. These can also useful for all computer users. One supplier claims that by eliminating the need for people to move their hands from the keyboard, the foot-control can increase efficiency by 30%.
Touch control
Plug-in touch pads are available, similar to the touch pads of many notebook computers. They require good fine-motor control. An advantage is that a pad can be placed anywhere the user finds comfortable and convenient.
Touch-sensitive transparent overlays can be placed over a screen so that the user simply has to touch the screen to move the cursor and select commands.
Ergonomics
The mouse is the best-known type of cursor pointing device. It is also the most ill-used. It has to be placed in an ergonomic position, to avoid strain on arm and shoulder. Alternatives are available that can provide comfort, speed people at computers, and fit the needs of people who lack dexterity.
Further Reading: Desks for Comfortable Computer Use; Notebook Computers Cause Pain
Sources: AbilityHub; Cornell University, Human Factors and Ergonomics Research Group
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