Should preferred control come first on mobile device?

Question

I've got a check for pass, and an x for fail. Both controls are positioned next to each other on the right side of the screen. The preferred action is pass so it should be the most natural gesture. My question it come before or after the less favorable control (x/fail)? (if it occurs after it will be very close to the edge of the screen).

This issue becomes more apparent on mobile devices. For shorter thumbs the furthest right position feels most natural, however when tested with a larger thumb it seems more comfortable to have it in the left position.

My question then becomes is there a syntactically correct way to display the controls: and should the preferred control be displayed before or after the less-favorable control?

Answer 1

They buttons are so close that people could easily click the opposite of what they want. I think it would be beneficial to consider a different paradigm of marking a "pass"?

As to your question, apparently 70-95% of people in the world are right handed (source), which makes me think it would be better to have the preferred action near the right side edge of the screen. There is less room for accidentally pressing the fail action because extra skin would just hit the edge of the device and not inadvertently hit the wrong button.

This article by Luke Wroblewski might also be useful to look at how people tend to use navigate on mobile devices with only one thumb.