Modes, Quasimodes and the iPhone

A mode is a user-changeable state that influences how a computer reacts to user input. For example, if the Caps Lock key is active, all letters typed by the user appear in upper case. If it is not active, letters appear in lower case. Whether Caps Lock is active or not is not immediately obvious to the user, which often causes people to accidentally activate Caps Lock. This, in turn, causes unexpected results when users start to type.

Since modes can cause computers to behave in unexpected ways, they are typically frowned upon.

When Apple started to work on the original Macintosh, one of the team's most important goals was to avoid modes. Famously, the original Mac did not even have a "rename file" mode. Instead, when a file was selected, typing anything on the keyboard would instantly change the file's name. This caused a few problems, and Apple eventually recanted. On, Bruce Horn writes:

In the Finder, the startup disk would appear on the desktop, in the top-right corner, ready to be opened. The Finder would initially select it; once selected, typing would replace the current name, following the modeless interaction model that I had learned in the Smalltalk group from Larry Tesler. This meant that whatever anyone typed when they first came up to the Macintosh would end up renaming the disk.

This particular problem was solved by introducing a mode, but as a general rule, the Mac remained mostly mode-free. Following Apple's lead, avoiding modes has been an important design goal in all modern computer systems.


In some cases, modes are unavoidable. On desktop computer systems, quasimodes are often used when modes are not avoidable. Quasimodes are modes that are temporary and only exist as long as the user explicitly activates them. The aforementioned Caps Lock key introduces a mode. Its quasimodal counterpart is the Shift key, which introduces a transient mode that only exists as long as the user holds down said key. Since the user has to keep the quasimode alive explicitly, there is no chance that he or she will be confused by the mode.

A quasimode is thus a benign, harmless version of a mode.

Copy and Paste on the iPhone

We are so used to avoiding modes and using quasimodes instead that it often becomes hard to think outside of this box. When Apple famously claimed that the iPhone did not have copy and paste because it was difficult to find the perfect interaction model, a lot of mockups of how copy and paste might use popped up. Most of them used quasimodes to select text,1 often activated by touching the iPhone's screen with a second finger. Even the Palm Pre uses a quasimode to select text: the "select" quasimode is activated by holding down the shift key on the keyboard.

Apple went a different way. Instead of using a quasimode, they introduced an actual, real mode. To select text, the user taps and holds the screen until the loupe appears. After releasing the finger, the iPhone either goes into a text selection mode, or displays a menu which allows the user to go into a text selection mode. This mode allows the user to move the start and end of the selection, and to cut, copy or paste using a popup menu.

But aren't modes evil?

Not necessarily. Modes are not always bad. Modes cause issues if they make computers behave in unexpected ways. However, if the modes themselves are obvious to the user, if it is always clear how to exit the current mode, and if the modes interfere with as few of the user's actions as possible, these issues disappear. In some cases, modes may even be preferable to quasimodes or to a non-modal interface.

Quasimodes require the user to do several things at the same time, such as holding down the Shift key while typing. Modes, on the other hand, allow users to do things sequentially - hit Caps Lock, type, hit Caps Lock again. Sequential actions, especially if guided well, are often easier to execute than parallel actions.

Additionally, the iPhone has very limited input mechanisms. Basically, the user interacts with most applications by touching the screen. While the iPhone can accept multiple touches at the same time, requiring multitouch interaction is often a poor idea. It makes it impossible to use the app with only one hand, it forces the user to obstruct larger parts of the screen, and it requires precise, coordinated user input.

Instead of overwhelming your users with a quasimodal or non-modal multitouch interface, it may often be a good idea to explore a guided modal interface which allows users to make choices sequentially. But keep a few things in mind:

  • The modes should be obvious
  • The modes should interfere with as few user actions as possible
  • If the user does something outside of the parameters of the active mode (such as tapping text outside the current selection in the iPhone's selection mode), you should exit the mode immediately

If you use them carefully and with consideration, modes can be a useful and powerful interface design concept.

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