Monday, November 12, 2007

Common Usability Terms, pt. V: Modes

Fifth definition in the series ...

"Up until now, this series focused on rather well-known terms, but today, we will be taking on a term that many of you will not have heard of (in the context of user interface design, in any case): modes. I will start off by explaining what is meant by modes, I will give some examples, after which I will explain why some believe they are inherently evil (cue "mode errors"). I will end by explaining what can be done about solving the problems caused by modality in graphical user interfaces.

The definition of the word "mode" in a regular dictionary reveals little about its relation to graphical user interfaces. In order to get a better definition, we need to go to the man who spearheaded the campaign against the modal interface: Jef Raskin, co-creator of the Macintosh. In his well-known book, "The Humane Interface", he defines the modal interface in the following way: "A human-machine interface is modal with respect to a given gesture when (1) the current state of the interface is not the user's locus of attention and (2) the interface will execute one among several different responses to the gesture, depending on the system's current state." In other words, the same user input can produce different types of output, depending on the state ("mode") the computer is in.

There are a lot of examples of this behaviour in today's user interfaces, the most prominent of that being the infamous caps. lock key. When the caps. lock key is active, any text that gets put into the computer will be displayed with capital letters; when the key is deactivated, the computer displays the text as lower case letters - two different "modes" or "states" that the computer can be in. Another example is, as weird as it may seem, the on/off switch on that same computer: it allows you to switch between two modes: on, and (surprise) off (you did not see that one coming, did you).

However, modality is much deeper entrenched in the world of computers than these fairly tactile examples seem to illustrate: consider a drawing or photo editing program. If you want to see one type of application that is filled with countless modes, load up your favourite image editor, and click on the various options in the tool window. When you have the paintbrush tool activated, you are in a different mode than when you have the pencil tool activated. Good luck counting all the different modes in your drawing application."    (Continued via OSNews)    [Usability Resources]


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