Healthcare is rife with situations in which costs and benefits are separated over time. For example, staying adherent to preventive therapies (e.g., antihypertensive medications) means bearing costs today to gain future benefits.
Researchers have repeatedly demonstrated that a significant proportion of people have very high discount rates; that is, outcomes that occur in the near term loom very large relative to those that occur later. Even more interesting is the finding that a large element of this preference has nothing to do with how much later in time downstream outcomes occur; they’re simply discounted because they don’t happen now.
Much of this research has involved posing questions such as the following:
Which do you prefer?
A) $5 today
B) $6.20 in 26 days
By fiddling with the relative amounts and the delay, one can get a measure of time preference.
Three researchers at Stanford — Eran Magen, Carol S. Dweck, and James J. Gross — realized that in both options A and B above, there’s a “hidden zero.” That is, if you choose option A ($5 today), you are also implicitly choosing to get nothing later; if you choose option B ($6.20 in 26 days), you are also implicitly choosing to get nothing today.
We know that framing can have big effects in decisions such as these. It’s also been shown that people prefer increasing income over time, even if there is no economic difference between the income streams. Thus, it’s quite plausible that making the zeroes explicit might change subjects’ choices.
To investigate, the Stanford team randomized subjects to receive the implicit version (as described above) or an explicit version. An example of the explicit version is:
Which do you prefer?
A) $5 today and $0 in 26 days
B) $0 today and $6.20 in 26 days
Each subject faced 15 such decisions, and the researchers kept track of the fraction of times the subject chose the near-term option. They referred to this percentage as the “impulsivity” score.
In the first study, the researchers simply asked the subjects which they would choose. The subjects could answer however they wished but didn’t have to live with the results of their decisions. In a second study, they informed the subjects that one of their choice pairs would be selected at random, and the subjects would receive the option they’d selected. Here are the main results:

Two important points jump off this chart. First, moving from a hypothetical decision to one in which there’s a chance that you might have to live with the results makes a big difference; impulsivity scores drop by about a third. Second — and this is pretty interesting — making the zero explicit (that is, laying out both what you’re getting and giving up at the relevant points in time) has an effect of comparable magnitude. Full results of the study were published in the July issue of Psychological Science.
These findings suggest that when communicating choices to patients, we need to do our best to make the comparison of options as “apples to apples” as we can. It will be interesting to see how best to apply this insight to decisions like therapy adherence.