I have this DVD recorder that has puzzled me time and time again. Why is it that whenever I am instructed to press the Return key in the Remote Control, it takes me a while to locate it.
Here is the part of the remote control where the Return key is located.
Instinctively I find myself pressing the top-right key, even though that key is also marked to be used for "Previous Chapter".
After realizing that the screen does not respond to pressing this key I then remember, by examining the bottom of this panel, that the key title is written above the corresponding key and not below. This can easily be figured out by looking at the bottom of this panel, where the lowest keys have their titles marked above them.
However the top line keys have no title above them, their title is on each key. This is why the titles of the second line of keys (the first line of text) look as if they correspond to the first line of keys.
The mix of icons on the keys and titles above the keys is required when a key carries 2 actions (each relevant in different contexts of use). This is why the icons on the top keys are regarded as a secondary action of the keys and the titles below them are automatically regarded as belonging to the same keys. However this is not the case, all keys are used for a single action.
The following modified image would produce a much clearer panel. In this case the right key of the second line would be instinctively (and correctly) identified as the Return key.
This is an example of how the lack of consistency effects the ability of the user to remember how the interface should be operated.
In this case pressing the "Previous Chapter" key instead of the Return key results in no effect (because the "Previous Chapter" is not relevant in cases the Return key is relevant"). It would have been much more annoying if the "Previous Chapter" key would have effected the flow of operations.
It is highly important to keep the user interface consistent and to adhere to whatever layout model you choose to implement. Failing to keep interface consistency will result in increased users frustrations, loss of valuable time, and more mistakes.
