November 25, 2013

Are Lefties Getting the Shaft Again?

Lately I’ve been thinking a lot about the ergonomics of touch interfaces on phones. Since roughly 80% of the world is right handed, many apps and websites are optimized for right-handed use. That means the most frequently used controls are placed within easy reach of the right thumb, while options like delete or cancel are usually tucked into the top left corner where they are less likely to be tapped accidentally.

But what about lefties? How are they dealing with all these right-handed interfaces? To me, responsive design is about more than just adapting to different screen sizes, it’s about adapting to human factors too. So shouldn’t our interfaces adapt to handedness?

This led me to what I thought was a revolutionary idea: A JavaScript library that could detect handedness by analyzing how the user touches the screen. In theory a simple swipe gesture can reveal which hand is being used by observing the start and end geometry. With this information, one could design a flexible interface that not only adapts to the device’s screen size but also to the user’s handedness. In theory, ergonomics could be improved by moving certain controls from one side of the screen to the other. I thought I was really on to something but then I discovered a flaw in my thinking.

It turns out that handedness is not really the issue. Studies have shown that people will often switch between their left and right hand depending on the task, their posture and environment. I actually caught myself doing this while laying in bed this morning. I was laying on my right side and this made it easier to hold my phone with my left hand (I’m right-handed). The interface was reversed but somehow I was managing to get by.

This got me thinking. Have we all developed a degree of touch screen ambidexterity? Perhaps our environment forces us to use the opposite hand so often that we’ve naturally gained practice over time. Think of all the situations where your dominant hand is occupied with another task (holding bags of groceries or the handrail on a bus) and you’re forced to hold your phone with the other hand. Maybe lefties have already adapted themselves to right-handed interfaces.

That said, I think there is still potential to optimize phone interfaces based on which hand is being used at any given time but it gets complicated when you consider that the user could be switching back and forth throughout the day. Constantly changing the interface might only confuse people. Perhaps until we find an elegant way to handle this, important controls should be placed in a neutral position that doesn’t favour the left or right.