Ever since Apple pushed out the 7.1 update for iOS 7, people have complained about these small circular buttons used in the Phone app. These buttons are much smaller than before, so why would Apple do this?

According to Fitts' Law, "the time required to rapidly move to a target area is a function of the distance to the target and the size of the target". Basically, it would take more time to point (or tap in our case) to our desired object when the object is smaller and further away.

Wouldn't we want to tap on larger buttons to decrease the amount of time? Well, not so fast. With smaller buttons, we slow down our reaction time and possibly give us more time to consider our decision before executing the action. This can help us with well-intended decisions, such as not answering a phone call from an ex even though you two broke up two weeks ago.

Regions of thumb reach on a smartphone. Credit: Luke Wroblewski.

In addition, well-intended actions are supported by the placement of these buttons. The placement can prevent any accidental taps. The bottom right and left areas (right and left-handed, respectively) on the phone are the easiest to reach with our thumbs and more prone to accidental taps.

Let's consider these thumb regions for receiving a call. For a person using her right thumb on iOS 7, she can accidentally tap on any of these four buttons since there is little space between each button. In iOS 7.1, she can reach all four buttons as well but there is more space between each button.

The smaller buttons and placement of the buttons help prevent accidental taps because more effort is required to execute the intended action.

References:

Fitts' Law - http://en.wikipedia.org/wiki/Fitts's_law
Responsive Navigation: Optimizing for Touch Across Devices - http://www.lukew.com/ff/entry.asp?1649

Comment

What's with those new buttons in iOS 7.1?