The Mouse Trap

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Screen based infra-red eye-tracking technology is becoming more commonplace but is still far from mainstream in home or mobile computing. In the interim to move that pesky cursor from pixel A to pixel B we remain stuck in 'the mouse trap'. Sit back, smile and say 'cheese' as Jason provides a snapshot of the humble computer mouse.

Murine Musings

Lost among this year's US Independence Day celebrations was the passing of Douglas Engelbart? Who? Indeed, you might wonder. As you'll see if you click on the link Engelbart was the inventor of perhaps the most ubiquitously used computer media, the mouse, without which it would be impossible to navigate any software screen or activate the embedded functionality. The computer mouse's use is so commonplace that its presence and basic role as a PC peripheral device is rarely questioned. The answer however should go hand-in-hand (or rather hand on mouse) to customer selection of an appropriate device among the myriad shapes and sizes available on the market.

To Infinity and Beyond!

Until such time (if at all) that human beings merge with technology as some futurologists suggest, then we're stuck with a barrier or 'design interface' between ourselves and those bits and bytes or 1s and 0s of data in cyberspace; and here we find our answer for using a mouse. The mouse is quite literally a media, or bridge, between the electrically based software/hardware contained in our heads and that which is found on the hard-drive of your computing device. Whenever we use a computer we're attempting to change the information on the hard drive to either perform a function at that time, or else store data for future reference that's beyond our own capacity to retain and retrieve.

In an ideal world function and/or retention would be achieved by our simply thinking about them, and the changes taking place immediately on the computing device without the necessity of time-consuming data input through a media such as a keyboard or mouse. If we can't achieve this ideal then we require those media to provide as seamless an experience as possible between our brains and computers, in order to at least give the impression of 'man and machine in perfect harmony'.

There are a range of factors to take into account when trying to negotiate and reduce the 'interface friction' between ourselves and a computer, and particularly when a user is transiently injured or has a permanent musculoskeletal disability. All of these will be involved in a complex DSE ergonomic assessment, the type of which Lakeside Physiotherapy and Ergonomics specialises. In the next section I'm going to simply focus on two different type of mice which LP&E commonly prescribes to try and assist in this process.

Vertical Mice

Often imitated, never bettered, is the Evoluent Mouse. The Evoluent turns the conventional design of mouse supplied with most PC bundles on its side at a ninety degree angle, thus placing the buttons in a vertical orientation. Not only does this reduce the grip and static muscle load required between thumb and fingers to hold the casing, it also places the forearm in a neutral ‘hand-shake’ plane which reduces the tension in the wrist and finger extensor muscles found in the rear of the forearm. It therefore makes the device an excellent choice for those with either golfer’s or tennis elbow.

In terms of functionality the Evoluent has a separate dedicated button on the outside of the device to alter the cursor speed, thereby negating the need to access Windows menus/sub-menus to do so. Cursor speed setting is of vital importance in reducing interface friction especially during graphical tasks and particularly if working across a dual screen solution. If the speed is set too low the user has to use a wider arc of motion using their wrist and/or shoulder to move the cursor across the screens, and given sufficient exposure this can lead to the development of soft tissue overuse problems.

Rollerbar Mice

There are several different designs of rollerbar mice but my favourite is the Emotion Trackbar, since its size and compact nature makes it excellent for assisting in space optimisation of small desk systems, and also a candidate for inclusion in mobile productivity bundles.

Rollerbar mice require no grip and both hands can be used to roll the bar up/down/side-to-side to move the cursor. They are therefore an excellent choice for those with diminished grip strength in either hand, and in particular for those with osteoarthritic fingers since rolling the bar back and forth mobilises stiff digits.

The major advantage however is the central positioning of the device. When using a conventional length keyboard a regular design mouse is accessed some point distant to the shoulder, and this distance can be particularly large if the user has a body width less than the width of the keyboard. Holding the mouse in this position entails significant outward rotation of the shoulder and static use of the rotator cuff muscles. These can become fatigued and aching in the neck, shoulder blade and arm is not uncommon given repeat exposure. Using a rollerbar mouse however the hand accesses the mouse with arm in a much more amenable neutral orientation of approximately forty-five degrees across the body.

Just a Whisker Away…

Clearly there are far more factors to consider in mouse selection than those given here, since a mouse is simply one aspect of a DSE workstation which itself is embedded in a wider productivity process. For further advice, information, and DSE Assessment contact us here, but for now thanks for visiting and reading, Jason


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