Uber's surge pricing can be annoying. Why pay more if you can wait 15 minutes and pay less? And that's exactly the point — surge pricing is meant to apply downward pressure to demand through an increase in pricing.

But, it turns out, riders are more likely to accept surge pricing if their phone is about to die, according to Keith Chen, Uber's head of economic research. Chen appeared on a recent episode of NPR's Hidden Brain podcast and shared some curious notes on the human behavior that Uber has noticed.

The company didn't say it was acting on these data points, just that it was making a note of human behavior. It makes sense — if your battery is low, you might not want to risk waiting 10 or 15 minutes to see if surge goes away because if your phone is dead, you aren't getting a ride at all.

"And we absolutely don’t use that to kind of like push you a higher surge price, but it’s an interesting kind of psychological fact of human behavior," said Chen.

People also are more willing to pay surge pricing if it isn't a round number. With surge pricing like 2.1x or 2.3x, Chen theorizes, people think "there must be some smart algorithm in the background" and "it doesn't seem quite as unfair."

The full conversation with Chen is available at NPR.org.