Longer thumbs means more typos

People with long thumbs have a tougher time hitting the right keys on their smartphone, according to a new study. Computer scientists studied how the size and shape of hands and fingers influence the accuracy of the user’s touch performance on the phone. They found people with long thumbs are more likely to make errors on their touchscreens.

“Our study demonstrates that long thumbs alone can explain 12% of all the errors made (by) users that had to hit certain targets on the screen while holding the phone with one hand,” says Henning Pohl, a postdoc in the computer science department at the University of Copenhagen.

The conventional wisdom has been that big hands or thick fingers are to blame for the majority of errors. But that’s not the case, according to the researchers. “It’s the length of your thumb, not its thickness, that makes the big difference,” Pohl says.

People with long thumbs are particularly challenged when it comes to accuracy at the bottom of the screen. The experiments demonstrate that the longer your thumb, the harder it is to guide it with precision in the lower corners.

“Even though we are constantly using touch technology, no one really knows why we users make the mistakes that we do. Neither do the big phone manufacturers — who settle for identifying and correcting errors rather than finding out what causes them. We hope that our research can help change that,” says Pohl.

The findings also confirm that phone size plays a role in the quantity and nature of errors made.

“With a large phone, you have to stretch your hand more to adjust your grip and get from the top to the bottom of the screen. Therefore, on average, slightly more mistakes are made on large phones than on small ones,” Pohl says.

“The way you hold your phone also affects how many mistakes you make. And, the grip you choose is related to the size of your hand. If you have a big hand, you need to hold your phone differently than if you have a small hand.”