I recently setup the Starbucks app on my phone and I was furious to find out that it supports Apple/Android Pay only to reload a digital giftcard stored in the app instead of just paying for the purchase directly. This is an insidious way of trapping your customers because the minimum reload amount is always a round number, and a purchase is almost never a round number, which means you’ll have money left on your ridiculous digital giftcard. That means the next time you want to buy a cup of coffee you’re going to think “Well I do have a couple of bucks left on my Starbucks giftcard…” and once you get to the point where the amount remaining isn’t enough for your purchase, you’ll have to reload it and the cycle starts all over again.

Mobile games are the most notorious example of this design choice, and they add in the additional manipulative elements of theming and big numbers. “I need 1500 gems to unlock the next level, but I only have 500! Good thing I can buy 2000 gems for just $0.99! Oh wait… it’s 2500 to unlock the level after that… good thing 2000 gems are just $0.99!”

The worst part of psychological trickery like this is that knowing what’s happening doesn’t automatically free you from it’s effects. I totally bought that cup of coffee using the app because God damn it I want those stars.