Using text wisely in a graphical user interface can make the difference between an interface that flows well, and one that resembles a game show riddle. The first rule to remember is that the more text you put on the display, the less the user will read. Always assume your user is busy. If you put a paragraph of text in front of them, they will likely decide that they do not have time and continue using the interface without reading it. They usually figure that they can come back and read it later if their actions do not work out.
Short blunt messages like “Check Tyre Pressure” will work far better than “Tyre pressure is approaching the low threshold, and confirming pressure in all four tyres against recommended levels is recommended”.
The first message does appear to be ruder and it is not good to be rude to the user, but in this case it is the lesser of two evils.
Text as a Band-Aid
The second rule is that text should not be used as a BandAid. In some cases a design leads users to make a specific mistake. When this is seen in trials, the navigation of the interface should be fixed to make the mistake less likely. The less pleasant alternative is to add a text message that says “Warning: do not press red button while attached to patient”.
In my home town they built a roundabout with 5 entrances and exits. Each had multiple lanes. It did not work very well and led to traffic chaos. Instead of simplifying the junction, the planners added more complexity by installing traffic lights at some (but not all) of the entrances, and two sets of traffic lights halting traffic that was already in the roundabout.
Because drivers were not used to lights in a roundabout, many, many cars simply sailed through the lights oblivious to the fact that they were running a red – there were also so many sets of lights visible that you could sometimes see multiple red and multiple green lights and it was hard to be certain which ones applied to your lane.
The next step should again have been to consider simplifying the junction to something that drivers could use effectively. That of course was an expensive option. Instead the Band-Aid was to put up a sign telling the drivers what they should have already known: “Stop when Red”. This sign fails, partly because drivers (and users) read almost nothing and secondly any driver that has already been confused to the point where they ignore a red light, will likely ignore this sign also.
The lesson here is that if your interface is so difficult to use that you have to add text telling the user things that they already know then the interface is causing counter-intuitive behaviour, and the interface should be fixed rather than expecting the user to read instructions.
There are lots more rules for effective text use in my article “Wordsmith” available at http://www.panelsoft.com/articles.htm.