Design is really an act of communication, which means having a deep understanding of the person with whom the designer is communicating. Three topics in usability design have come to stand as critical:
1. It is not your fault:
If there is anything that has caught the popular fancy, it is this simple idea: when people have trouble with something, it is not their fault, it is the fault of the design.
2. Design principles
Here is a short list of the most important design principles in usability design:
- Conceptual models. The human mind is a wonderful organ of understanding; we are always trying to find meaning in the events around us. One of the greatest frustrations of all is trying to learn how to do something that seems completely arbitrary and capricious. Worse, when we lack understanding, we are apt to err. Consider the thermostat. When some people enter a cold house, they turn the thermostat to a very high temperature, in order to reach the desired level more quickly. They do this because of their internal mental model of how the furnace works. The model is sensible and coherent, even if not well though out. It is also wrong. But how would they know? Although this behavior is wrong for the house, it works for most automobiles: turn the heat or air conditioning up all the way, and when the interior is at the correct temperature, adjust the temperature control again. The conceptual model of the house is one of two levels of operation: full power or off. Therefore in these cases setting the thermostat too high does nothing but waste energy when the temperature overshoots the target. In the automobile the conceptual model is quite different. The heater and air conditioning also have two settings, full power of off, but the desired temperature is achieved by mixing cold and hot air. So in this case faster results come by turning off the mixing until the desired temperature is reached, then adjusting the mixture to maintain the desired temperature.
- Feedback. In design, it is important to show the effect of an action. Without feedback, one is always wondering whether anything has happened. Maybe the button was not put hard enough, maybe the machine has stopped working, maybe it is doing the wrong thing. Without feedback we turn equipment off at improper times or restart unnecessarily, losing all our recent work.
- Constraints. The surest way to make something easy to use, with few errors, it so make it impossible to do otherwise: to constrain the choices. Want to prevent people from inserting batteries or memory cards into their cameras the wrong way, thus possibly harming the electronics? Design them so that they will only fit one way, or make it so that they will work perfectly regardless of how they were inserted.
- Affordances. A good designer makes sure that appropriate actions are perceptible and inappropriate ones invisible.
3. The power of observation.
In fact, if there is one single most important issue in usability design it is this: learn to watch, learn to observe. Observe yourself, observe others, and observe people and objects and how they interact. You will find yourself not longer blaming the user, but the designer. Better yet, you will find yourself explaining how to fix the problem.
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