Have you ever noticed that you have a coupon for an item in your Amazon shopping cart, but you have to click the little box to “cut” the coupon and use it? Turns out there’s a reason those little money savers don’t apply automatically — and it is a big moneymaker for the world’s largest retailer.

Forcing consumers to take that extra step to click the box helps reduce so-called “cart abandonment” — when shoppers add something to their cart, but then think twice about their purchase.

Making consumers put in just a bit of effort leads to a greater feeling of reward, Tamara Masters, an assistant professor of Marketing at the Eccles School, told CNN. Read the full story here.