The mobile phone has gone through plenty of transformation over the years from being a standard mobile phone device to the smartphones we now carry around in our pockets. The smartphone, too, has gone through varying levels of transition, becoming more and more advanced in some ways and more simplistic in others. While it might be easy to think of the "next big thing" in smartphones as newer and faster processors, better cameras, and better battery life, these are things which are just incremental improvements over previous iterations. Features like the rumored pressure-sensitive touch coming in Android N are more along the lines of an advancement. One Microsoft researcher, Ken Hinckley, thinks that Pre-Touch enabled displays may be the future of smartphone screens, which could be the next leap in advancement for smartphone hardware.
Pre-Touch isn't necessarily a new concept, as Samsung's Galaxy Note series devices have a similar function that displays the area that's being hovered over on screen by the S-Pen. Even Sony's most recent Xperia devices have a feature called "Glove Mode" which will display a large circle on-screen when your finger gets close to it, and you can even interact with the display without touching it. It's worth mentioning here, though, that your finger has to be almost touching the display before the circle appears and it wasn't designed with a Pre-Touch functionality in mind, but it does illustrate that this type of interaction is already here on some level.
Hinckley thinks Pre-Touch sensing could be big for mobile device interaction, and has started work on a project that utilizes a Windows phone that can sense when the fingers are moving up to the display to touch it. In the video below he notes that the main focus is almost always whatever is happening on the screen at the time, like a video that's playing for example, but as soon as the fingers move up towards the display the focus shifts over to Pre-Touch and brings up a series of interaction controls that could allow the user to pause, play, skip back, or skip forward on the video. The controls also fade away when the finger moves far enough away from the screen, transferring the focus back to the video.
He also demonstrates that it would be possible for the screen to display a subset of one-handed interaction controls that are more easily accessible to the person holding the phone, swapping out things like the slider bars on fast forward and rewind functions for dials that can be utilized more easily with one hand. The Pre-Touch function also recognizes multi-touch which would allow for the screen to display additional interaction controls like screen brightness and volume enhancements, or it could be used for pinch to zoom. All of these things are still a work in progress mind you, but it's an interesting project that could bring some usefulness to the way users interact with their smartphone displays in the future, and should screen technology like this hit the market, it would allow app developers to make use of it as well.