Feedback & Responsiveness

Overview

Oftentimes, a computer's perceived speed is more important to the end user than its actual speed. A slow computer that responds to user input immediately will feel much faster than a fast computer that doesn't provide any sort of feedback until it's done with an operation. Thus, feedback and responsiveness - which are both determined by the computer's operating system - can affect the user experience greatly.

Real-time Feedback During Pauses

According to Ask Tog's First Principles of Design (Latency section), button clicks should have some kind of feedback "within 50 milliseconds." If the wait will be longer than 2 seconds, the system should display some sort of message approximating the duration of the wait.

Both Mac OS X and Windows XP have room for improvement in this area. For instance, though both display feedback at various points during system startup, neither makes it clear how long the startup sequence will take. The same is true of launching applications - both will show you that a launch is in progress (OS X's dock icons bounce, while XP's cursor sprouts an hourglass), but neither tells you how long the launch will take.

Mac OS X

Mac OS X does a fairly good job at keeping you appraised of the computer's status. For instance, application icons in the dock bounce while launching (or, if you prefer, you can set the black arrow under the dock icon to pulsate). OS X makes liberal use of a status pinwheel to show you that items are in progress:

Spotlight searches, Safari tabs, software updates, etc. all display a status pinwheel when necessary.

For intensive operations, OS X's mouse cursor will turn into a colored spinning pinwheel, showing you that you'll need to wait for the computer to finish before you continue working.

If any of these features get "stuck" (i.e., animations pause or interface elements stop reacting to your mouse), you can assume that the application or operating system has become unresponsive, and needs to be restarted.

Windows XP

Windows XP also provides a fair amount of feedback to the user. When you launch an application or perform another common operation, XP's mouse cursor sprouts a rotating hourglass; this shows you that although the computer is working in the background, you can continue using it like normal. When loading a CD or DVD, the hourglass is appropriately replaced with an animated spinning disc icon to show that the disc is spinning up. For intensive operations, the entire mouse cursor turns into the hourglass, letting you know that you'll need to wait for the computer to finish before you continue working.

Windows Explorer and Internet Explorer sport a Windows logo "flag" in the upper right-hand corner of their windows. The flag will animate whenever either of these applications is performing an extended operation (such as loading a webpage or listing many files).

Responsiveness

Thanks to GribUser for these great illustrations.

It's important to note that responsiveness is distinctly different from raw speed. While speed is a measure of how quickly an operating system or application is able to compute a task, responsiveness is more a matter of how quickly the interface responds to basic user inputs: scrolling, window dragging and resizing, selecting menus, etc.

The following are illustrations of interface responsiveness with OS X and XP. Note that these are not actual videos, but simulations.

Scrolling

Window resizing

Notice how in both illustrations, XP's interface keeps up very well with the cursor, while OS X's interface lags. This can be attributed to the difference in "approach" over how each operating system handles redrawing items on the screen. XP tends towards faster interface redraws, while OS X tends towards cleaner ones. For example, try resizing a content-heavy webpage in both OS X and XP. On OS X, the window size will lag behind the cursor, but each element on the page will be drawn in full. On XP, the window size will keep up with the cursor, but elements on the page may "flicker" while the resize is in progress.

Context-sensitive Cursors

Both operating systems have a handful of common cursors:

Arrow
Finger ("click here")
Arrow with a plus sign ("release the mouse to add the dragged item here")
Curly arrow ("release the mouse to create a shortcut here")
Circle with a diagonal line through it ("that item cannot be dropped here")
Spinning ball/hourglass ("system is busy")
I-Bar (insertion bar for entering text)
Crosshair cursor for precision selection
Question mark

Mac OS X

OS X has additional cursors:

Arrow with a menu symbol ("clicking now will reveal a contextual menu")
Magnifying glass/picker (for selecting colors; invoked from the Colors palette)

Windows XP

Windows XP has additional cursors:

Resize/move left-right
Resize/move up-down
Resize/move diagonal
Move/size arrows pointing up, down, left, and right
"Small" hourglass (attached to your pointer, this shows that the computer is working in the background)
Disc is busy (this icon of a CD next to your pointer lets you know that a disc has been insterted and is spinning up)

Conclusion

Both operating systems provide adequate feedback during pauses. Windows XP makes more extensive use of its mouse cursor to provide feedback than OS X does, with three different cursors (hourglass attached to mouse pointer, hourglass only, disc icon attached to mouse pointer) compared to OS X's one (colored spinning pinwheel). Within individual applications, OS X uses its status pinwheel while XP uses the Windows flag (though OS X's pinwheel can be found in more applications than XP's flag).

OS X and XP take different approaches to window resizing. While XP's "fast" resize may result in "flicker," this is a minor visual defect that has no effect on usability. In contrast, OS X's "clean" resize can make it somewhat difficult to resize a window to a specific size, since the window and mouse cursor will not always be in sync. This can be a minor annoyance.

XP's cursors are on the whole a bit more informative than OS X's. XP has two variations of its hourglass cursor depending on how busy the system is, as well as a "disc is busy" cursor to show that an inserted disc is spinning up.

Mac OS X: 8
Windows XP: 9

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