Why won't you wait one more day today, but will a year from now?

Because the value we put on a reward drops steeply over the first short delays and only gently over longer ones, a pattern called hyperbolic discounting. Waiting one day from now feels expensive; waiting one day a year from now barely registers. A classic test asks: "Would you prefer a dollar today or three dollars tomorrow?" and then "Would you prefer a dollar in one year or three dollars in one year and one day?" It has been claimed that a significant fraction of people take the dollar today, but will gladly wait the extra day when it's a year off. Economists call this a time-inconsistent model of delay discounting, and it is one of the cornerstones of behavioral economics.

The same flip shows up with bigger sums. Offered $50 now or $100 in a year, many people choose the immediate $50; offered $50 in five years or $100 in six, almost everyone chooses the $100, though it's the same choice seen five years further away. In an early study, people were indifferent between $15 now, $30 in 3 months, $60 in a year or $100 in 3 years, implying annual discount rates that fell from 277% to 139% to 63% as the delay grew. The result: people make choices today that their future selves would prefer they hadn't, with the same information.

It isn't a quirk of human culture: the first preference-reversal findings were in rats and pigeons. Researcher George Ainslie found many people preferred $50 immediately to $100 in six months, but not $50 in 3 months to $100 in 9 months, the same choice moved three months away. Studies have also found that drug-dependent people discount delayed consequences more than matched controls, and some evidence suggests the same for pathological gamblers, though whether steep discounting comes before addiction or after is unknown.