Apps like PayPal, Square, Breadcrumb, Apple Pay and Facebook’s new payment feature are supposed to be making paying for things easier. Want to figure out a complicated dinner tab among five friends? Just tap a few buttons on your smartphone.

But the advent of these exciting new payment technologies is actually creating its own challenge: tipping. If you’ve purchased a ristretto in recent months, chances are you’ve experienced that awkward moment when your finger hovers above an iPad, anxiously trying to figure how much to tip.

It makes for a less-than-“seamless” experience, to borrow a favorite Silicon Valley buzzword. Part of the problem is that these devices are forcing customers to make a new and difficult choice.

“The big issue here is that this is putting a new social pressure on customers,” said Michael Lynn, a professor of consumer behavior at the Cornell University School of Hotel Administration, who studies tipping. “It’s up to me to leave the change in the tip jar, or not. Yet when you turn the screen around and I have to explicitly click ‘No Tip’ in front of you, that’s a lot harder.”