Axioms

Perhaps the reader can guess; this writer is an engineer. First all the hardware description and now “axioms”?! Don’t worry; this won’t hurt. Even though Assistive Technology and user interfaces cover a lot of territory; and even though there are many details in the text that follows, and even though there is a daunting number of products to learn about at the RESNA and CSUN and Closing the Gap conferences – still there is only a small handful of super-rules, axioms that apply across the board. Learn these and you can’t go far wrong.

	Axiom 1: There’s usually something to work with. If there is anything, any motor output of any kind that a would-be AT user can produce reliably, there is almost certainly a technology for sensing that action and using it for controlling something – using it as the control interface to an AT device. Certainly ten fingers, two feet and a perfectly articulated voice are handy, but useful control can be found through the movement in one finger or two reliable sounds or the arching of an eyebrow.
	Axiom 2: It’s not just the buttons. A control interface is more than the just the sensors and hardware and buttons and mice. It’s also about logic, intuitiveness, familiarity, efficiency – in other word the rules that govern the use of the interface hardware. Sometimes this is about selection menus; for other systems it’s about how reasonably the input relates to the output. The bottom line is: don’t squander limited motor control resources on an interface that makes less sense than it could.
	Axiom 3: You may not be able to find it in a catalogue. It’s true that there is a remarkable number and diversity of interface options available off the shelf. Some of these are mass-market products that happen to be well suited to a particular AT user and application. Others are marketed as AT components. Either way, it is commonly the case that modification, adaptation, customizing, combining and generally tweaking will be needed to suit a standard interface to a particular user. Good vendors and good shops are like horse and carriage.
	Axiom 4: AT requires an interface that requires AT. A computer mouse might be an ideal control interface for an on-screen sketching system – AT for artists who lack the ability to hold a brush or a pen or pastel crayon. It is requires no grip strength, can be made more or less sensitive to movement, and allows digital processing to reduce the effects of tremors. However, a particular user who experiences weakness in her deltoid muscles may need a mobile arm support to resist gravity and keep her elbow from dangling off the edge of the lap tray. This is an example of a desirable interface for using AT itself requiring an adaptation to be useful.
	Axiom 5: The easy stuff is hard. If you’re at the point where the pieces of an interface have been identified and bought – the switches, keyboards, display panels, speakers, etc. – and now “all that’s left” is figuring out how to mount them so that the user can best access them – pay close attention. “Simple” brackets and bolts and hose clamps and goose necks meant to position everything where it belongs and keep it there in constant use and misuse – well this “simple” stuff is often hard. Hard to do well. Interfaces that gradually slip out of position or vibrate when touched or are prone to getting bumped by passersby and doorways – any of these flaws can make an otherwise well designed interface useless and frustrating. The user does not need the extra challenge of dealing with them. AT abandonment and rejection of future attempts to introduce AT becomes much more likely.