Android 7.1 “panic detection mode”

This feature monitors how many times you have pressed the back button within a certain amount of time. If you press the button four times every 0.3 seconds or faster, then the application will be moved directly to the home screen

Is quite useful feature when some malicious application does not let you go and you stay in its pages. The "panic detection mode" understands that you want to exit the application, thanks to the speed at which you press the button. When you move to the home page, you can erase the application.