Our experimental features are available via the user profile page. You may opt-in or -out of these features at any time.
To access your profile, log in, and simply click on your name, near the upper right-hand corner of your home page.
On your profile page, Click the "Check out our experimental features" link.
Click the Enable link to toggle an experimental feature on or off for your account. When you are finished, click Save at the bottom of the page.