GUI Wars: Window switching: OS X vs. Vista

Most computer users have a lot of windows open at once - web browser, e-mail, Word, Excel, etc. etc. Switching between them could always be accomplished through a variety of methods, but the latest operating systems have tried to jazz that up. Since a year or two ago, Apple’s OS X has had a feature called Expose. You press a mouse button or function key, and all the windows shrink to give you a live preview of each one. Then, you click on the one you want:

This works nicely because it gives you a bird’s eye view of all your windows. You can navigate this screen with your mouse or with arrow keys, so you can stay mouse- or keyboard-consistent.

Doing this in Windows Vista, the newest version of Microsoft’s dominant operating system, looks like this:

Pressing Alt-Tab brings this up, and multiple presses of Tab cycle through all the windows. This is nice because you can flip through your stack of windows until you find the one you want. In fact, the feature is called Flip3D.

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So the question is: which one is better? To answer that, we need to delve into the visual search literature. Visual search is a task used over and over again in attention research. You’re looking for a target amongst many distractors. What’s the best strategy you can employ to find it? Well, it depends on the properties of the targets and distractors. If your target is highly salient (i.e., unique compared to all the other items), search can be fast when you’re presented with all of the items at once. This is known as parallel search, and it’s fast no matter how many items are on the screen (find the green square):

However, if your target isn’t salient, then you’re slower. You generally have to examine each item individually until you find your target. This is known as serial search (find the green square again):

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So back to the window switching interfaces in both operating systems. How often is the window you want salient? Not that often - it’s not like the window that you want is bright green and everything else is gray. But you do have expectations sometimes. “I’m looking for iTunes, so I expect the window to look a certain way.” So you may be able to perform parallel search and get your search done faster. Not always, but sometimes.

Think about how both interfaces work - which interface allows you to perform parallel search? Expose! Because Flip 3D does not present you with all targets at once, there is no way you can perform quicker parallel search. You must perform serial search each and every time you switch windows. Considering how much people multitask, this can add up to a meaningful amount of time quickly.

There is the issue of clutter, though. More clutter in a display means longer searches. Expose definitely leads to more clutter than Flip3D, so a search in Expose may take longer. This primarily occurs is you have many windows open. Flip3D is not as cluttered because it only presents you with one window at a time, which underestimates how many separate objects we can handle at a time.

All in all? When it comes to switching windows, OS X’s Expose has the science behind it. By allowing users to engage in parallel search for their window, multitasking can be done much more efficiently than Vista’s Flip3D.