It’s been hard not to miss the steady stream of news suggesting that some time soon the U.S. will catch up with the rest of the world when it comes to using mobile phones and other devices as digital wallets. If you don’t know what we’re talking about, the idea of mobile payments is pretty simple: You go to a store, and rather than whipping out cash or plastic, you offer up your cell phone, which pays for your purchase and charges a credit card that you’ve used to open your mobile phone bank (as it were)… What some refer to as “contactless payment” makes spending remarkably easy, which is why the two of us, progress lovers both, are at least a little nervous about the implications of this technology. Our concern is based on an ur-principle of behavioral economics — mental accounting.

Broadly, this is the idea that we treat money differently depending on where we get it (say, salary vs. bonus vs. gift), where we keep it (college fund vs. checking account vs. retirement nest egg) or how we use it (large buys vs. small purchases or lump sums vs. installment). Mental accounting can be useful if it keeps you from touching your kid’s college account, less useful if it causes you to pony up for an optional sun roof simply because you’re already spending a lot of dough to buy the car it will make that much cooler. The relevance to mobile-payment systems is that there is considerable evidence to suggest that the farther away we get from spending money that’s actual money, the more likely we are to spend it more easily.

Rread more, via TIME.com.