In an era of fidgety fingers attached to portable devices, does your app pass the banana?

People interact with smartphones and tablets differently than desktops and laptops. Our tiny, pocket sized computers have shrunk, yet we remain the same size (assuming you’ve already gone through puberty). As we try to design and adapt with all the historical baggage of large computer screens, we’ve come far from just squeezing and shrinking content to fit. Besides visual constraints of being able to read comfortably, there are other human factors that don’t seem as apparent when it’s time to design.

Touch screens are made to be touched. But you can’t control the size of someone’s finger, whether people use their long-nailed pinky finger, their knuckle, or if they are holding 50 pounds worth of groceries. They’ll hold it their own way, or else succumb to the awkwardness that your app demands. Fingers today are doing gymnastics and contortions in surprising and unintended ways, from hooked thumbs to Photoshop’s bearable Save for Web claw. The variety in finger positionings show that people discover their own ways to accomplish what they need.

How can anyone possibly anticipate every move our fingers will make in the wild, short of memorizing the logarithm for Fitts’ Law and requesting your users to upload their finger measurements?

Well, if you learned anything by now (or remember the title of this article), you might try a little reverse-biomimicry with a banana. The peel of a banana literally has the right fingery essence to work with the capacitative touchscreen (but it probably won’t crack your fingerprint authentication). See if your app design is accessible and friendly for larger hands, non-ideal fingers, and other physical scrutiny—bananas are a good stand-in for a large thumb mashing its pad on a tiny screen and covering visible screen estate, or a parallel finger that with fingernails that rival Scissorhands.

Below is a quick and dirty video I took using a real banana as the touch input on the iPad while playing Joggle Brain Training game.

Forget everything you know about human factors, ergonomics, usability, the HIG, or “Metro” design principles. Instead, slip on a banana… I’m not monkeying around.