The same technology that simplifies life by providing more functions in each device also complicates life by making the device harder to learn, harder to use. This is the paradox of technology.
(Norman, 1990, p. 31)
In his book The Design of Everyday Things, Donald Norman describes how technology enables increasing functionality which in turn increases complexity. He cites the example of a digital watch having far more functions than a traditional analog watch (stop-watch, alarm, countdown timer, etc.) and yet being far more complicated to set the time (the original function). As the number of buttons on a digital watch are limited there is a tendency to assign them different functions when operated in different orders. Norman posits that the psychological significance of this resides in there no longer being a ‘one-to-one matching’ between a button and a function. It is this lack of one-to-one matching which causes perceptions of complexity. Norman states:
We found that to make something easy to use, match the number of controls to the number of functions…. To make something look like it is easy, minimize the number of controls. How can these conflicting requirements be met simultaneously? Hide the controls not being used at the moment.
To a certain degree personal computers utilize this adage. As I write this document using a word processor, all I see is the keyboard and an (almost) blank screen—as I hit the key, the letter appears on the screen. To make the increased range of functions visible I can select from a range of shift/alt/control/function key combinations.