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The generally accepted answer to the question on Left-handed persons and usability is that rather than asking users which hand they use in order to determine your layout, you should let them choose their own layout (because choice of layout may be independent of dominant hand).

In the context of a touch-screen application, I wonder if it's still true that you shouldn't give the user an option to set their preferred hand. Given that layout shouldn't be set based on hand preference, are there benefits to knowing a user's preferred hand?

For example, is there any evidence to suggest that knowing your user's dominant hand can help you to interpret certain gestures (such as swipes and pinches) more accurately?

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  • Allow them choose their own layout. The dominant hand may not be dominant in ALL activities. I know an engineer that prefers to use his left hands while handling his tools and writes with his right hand... So is he right handed or left handed?
    – Justjyde
    May 7, 2013 at 18:40
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    I can't see a technical reason why this would be the case. I could be wrong, but there's no physical movement that is lateralized. Palm detection/rejection (maybe)? Think about the variation in the physical writing process. Or in anything, really. There's no fundamental, core physical action that is adequately consistent to consider in designing an interaction. May 8, 2013 at 5:58

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I'd say the "handedness" of a user is only of limited information. Many other factors affect the way a user interacts with the touch screen of a hand held device. You could be lying on your side, or perhaps you put your smartphone down on a table. While a gesture (say a sideways swipe) might have a different curvature when performed with either hand, it will also be different depending on the user's position in relation to the device.

I would also expect the device to react the same way for both my hands. A right-handed two-finger-pinch will probably touch top right and bottom left, while left-handed would be top left and bottom right. I would not expect the device to care. And nothing stops me from doing a left-handed pinch touching top right and bottom left, if that's natural from where I'm sitting.

The goal of adding information to the gesture detection would be to wide the detection for gestures. To catch a gesture that you would otherwise miss if you did not know that the user is left-handed. Or that the device is on a table. My guess, without research, would be that the case for this is actually quite small. Detection of gestures is already quite wide when it comes to things like still detecting a curved swipe. Devices usually only ignore a gesture when it's too close to a different gesture (where that 3 or 4 fingers? was that a tap?).

Looking at this from a different angle, I would also expect the device to act machine-like when it comes to my input. To have clear boundaries for when to detect one gesture or the other, or for when a gesture fails. When a system becomes fuzzier about interpreting my input, for instance when it thinks I might be using my off hand, that also makes it less predictable and more open for errors in that interpretation. When an interface you use a lot is strict and predictable, you can learn what kind of input it understands and in what situations it will fail.

So, that's kind of a long way to say that no, I don't have evidence to support your hypothesis and I doubt it exists, but I could be wrong :)

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Not exactly related but this paper works on identifying the hand and adapting the interactions based on it.

GripSense: Using Built-In Sensors to Detect Hand Posture and Pressure on Commodity Mobile Phones

It tackles the problem the other way round, rather than looking at the accuracy of gestures based on handedness, it tries to figure out the grip and adapt the UI based on that.

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If I can use the analogy of writing, then being left or right handed doesn't really affect the way information should be presented, but it does affect the way content is created. The pain of left handed users smudging their writing as they deal with normal book/page layout has become a thing of the past with keyboard and mouse, and in general there hasn't been any changes in terms of navigation and layout of applications and web pages that are required because it is to do with the presentation of content only. So basically we need to look at the software versus the hardware issue here.

The touch screen re-introduces the interaction, but there are two aspects of this. The first is that preferences in terms of layout and position of user interface elements such as toolbars are very flexible these days and not really to do with being left or right hand but personal preferences and workflow. The second is that physical elements are still relevant (so there are left handed wacom tablets) and that's the only thing that probably needs to be taken into account. If there are cases where the software needs to know about the physical device then there might be a good reason for this, but I can't think of any.

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