Monotony

The Perl motto: There's more than one way to do it. The Python motto: There's exactly one way to do it.

Monotony is a quality that an interface has if it provides only one way to perform any given command.

Contrast this to a a typical GUI interface that has a "Print" toolbar button, a "Print" menu item, a "Print" keyboard shortcut, etc.

Rationale

Despite the negative casual meaning of the word 'monotony', it is considered a good thing in interfaces. The principle that monotony is good sounds counterintiutive when you first learn about it. Doesn't having multiple ways of accessing the same command make the system more usable? Well, yes and no. The drawbacks of multiple gestures to access the same command are:

1. The total complexity of the interface is higher (It doesn't have UsabilityDesignPatterns/NothingLeftToTakeAway). 2. The user has to look in more places and look through more unwanted choices to find the command they want. 3. The user has to choose between multiple methods of doing the same thing, which imposes a cognitive burden without any benefit 4. Once the user has chosen a method that works for them, they tend to stick to it, meaning that they have no use for all those other methods that are still cluttering up their interface.

Pitfalls

If you put all your eggs in one basket, you'd better make sure it's a really good basket. Similarly, if there's only one input gesture for a certain command, you need to make sure it's a really good gesture. (Corollary: designers choose non-monotony because they don't know which gesture is really good, so they throw them all in and hope).