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The Anti Pinch To Zoom

At times when you don’t have two fingers to apply to your smartphone, Fat Thumb and GripSense allow you to interact with your phone using just one hand and an occasional digit.
December 24, 2012

In a preliminary hearing last week, a US court invalidated an Apple patent related to the famous ‘pinch to zoom’ maneuver. Pinch-to-zoom is one of the most easily recognizable of touch-screen commands, and in the days of the first smartphones, immediately demonstrated how useful a multi-touch screen could be.

Two-fingered gestures like pinch to zoom are put to brilliantly intuitive use on smartphone apps like maps but we sometimes encounter situations where we simply don’t have two fingers to spare. If you’re carrying an armful of bags, and fished out your smartphone to locate a nearby subway stop or cafe, there’s a chance you’d find yourself wishing zoomability could be condensed to single-finger gesture.

The “Fat Thumb” is one such alternative. Researchers at the University of Calgary propose that the position of the thumb on the screen can translate to various commands on a smartphone that would otherwise need two–one hand to hold your phone while two fingers of the other zoomed in or swiped between open windows.

In a paper presented at MobileHCI 2012 conference earlier this year, they explain that thumb contact areas are different enough to be translated to different commands. With just the tip of your thumb touching the phone, you could pan through a map. If you placed your thumb flat on the surface of the screen, the extra contact area would zoom in to map you were navigating.

A team from the Human-Computer Interaction Design labs at the University of Washinton is working on a slightly different approach that requires even less digit work.

It’s called GripSense. As the name suggests, the setup detects how a smartphone is being held, and how tightly it’s being squeezed. It does so using inbuilt accelerometers, gyroscopes, and vibration motors. In a presentation at the ACM UIST 2012 conference in Cambridge this year, developer Mayank Goel explained that the technique can differentiate between three different grip intensities and can tell which hand is holding the phone.

As an example, someone holding the phone could zoom in or out on a map by squeezing the phone with varying intensities, the authors explain in their paper. Similarly, a phone buzzing in your pocket at a meeting or movie theater could be silenced with one decisive squeeze. They tested their algorithms on a Samsung Nexus S smartphone and found that they could reliably (with 95 percent accuracy) differentiate between three intensities of pressure on the smartphone. Held in one hand, different holding positions were identified with 84 percent accuracy.

Sure, GripSense and the Fat Thumb don’t quite have the same aesthetic appeal as the pinch to zoom move. Also, depending on what commands the grip or thumb was assigned, I might have trouble remembering what they were set to do. Would a quick squeeze snooze my alarm or turn it off completely? Would a hard squeeze silence my ringing cell phone or answer it? 

But I do see how the Fat Thumb and GripSense and other gestures like them could be useful.  Existing applications like Google Maps do register single finger commands—I’m frequently double-tapping on Google Maps views to zoom in, for example, or tap-tapping to enlarge text in a mobile Safari window. When I try to zoom out, however, and I find it’s a little more complicated

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Illustration by Rose Wong

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