Click the iPhone’s Home button once, and (naturally enough) you’ll end up on the home screen. Double-click it, and you’ll see the iPhone’s multitasking bar appear at the bottom of the display. But what happens if you try triple-clicking the Home key?

Well, most of the time, you’ll just wind up back at the home screen—or, if you’re already on the home screen, the multitasking bar will play a brief game of peek-a-boo.

But if you flip a switch deep in the Settings menu, you’ll be able to choose between four (or five, strictly speaking) new functions that triple-clicking the Home key can activate.

Tap Settings, General, Accessibility, then scroll all the way down to a setting labeled “Triple-click Home.” Most likely, it’s set to “Off.” Feeling adventurous? Then go ahead and tap.

You can pick and choose what happens when you triple-click the iPhone’s Home key.

You’ll now see a quartet of actions that the iPhone can take when you triple-click the Home key. They include:

• Toggle VoiceOver: Pick this option, and the iPhone will switch to a mode where it reads aloud web pages, email, and navigation labels on its touchscreen, perfect for iPhone users with impaired vision.
• Toggle White on Black: In this mode, the iPhone reverses the colors on its screen, resulting in a display that shows white text on a black background for email, text messages, and most web pages. The inverted colors don’t stop there, though; wait until you get a load of the groovy white-on-black home screen.
• Toggle Zoom: Find yourself squinting at the tiny text on your iPhone’s screen? Turn on the Zoom function to magnify the display with a three-finger tap. Read more…
• Toggle AssistiveTouch: Activates a mode that lets you “pinch” or swipe the display—or even “shake” the entire phone, for that matter—without actually having to pinch, swipe, or shake, an essential feature for anyone without the full use of their fingers. Read more…

There’s also a fifth option for triple-clicking the Home key: “Ask,” which (as you’ve probably guessed) makes your iPhone ask whether you’d like to turn on VoiceOver, White on Black, or Zoom. (AssistiveTouch isn’t one of the “ask” options, oddly enough.)

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