Some people are impulsive and impatient; they prefer a dollar or a donut today far more than a dollar or a donut tomorrow, so much so that they’re willing to give up shocking amounts of dollars and donuts tomorrow for just one today. This is one reason, some say, that we see such high interest rates for short-term borrowing, from New York to Calcutta.
Some people are not only impulsive and impatient, but inconsistently so. they care a lot about a dollar today versus tomorrow, but could care less between getting a dollar either 10 or 11 days from now. Economists call this ‘hyperbolic discounting’.
Both behaviors–impatience and time inconsistency–could be a source of persistent poverty.
Or not. Abhijit Banerjee presented a new paper here yesterday, written with MIT colleague Sendhil Mullainathan. They look at a number of seemingly unusual behaviors by the very poor–from exorbitant rates of short-term borrowing to the low take-up of small, high-return investments. Impatience cannot explain the patterns, they say. The impatience approach also requires the poor think differently than the rest of the population.
Another view: we’re all impulsive and impatient in the same way, but over a narrow range of goods that are quickly and cheaply satisfied. If you’re poor, these temptations are a big fraction of your income. If you’re even somewhat wealthy, they are not. Temptations are declining in income.
The paper runs through half a dozen perplexing patterns of behavior, and shows that these simple assumptions can explain a great deal.
This approach has a great deal in common with hyperbolic discounting, but is empirically distinct (and has very different policy implications). Parsing out and testing these subtleties strikes me as one of the most important frontiers in the study of poverty. Declining temptation, if true, could explain all sorts of odd behaviors. With more than a few Uganda and Liberia surveys on the horizon, I’m now scheming ways to test whether it’s true.
It’s a difficult paper, especially for those uninitiated in micro-economic theory. Even if that sounds like you: the subtle points are worth the slog.
For an intro to the subfield, see Senthil’s essay, Development economics through the lens of psychology. Another great resource is Stefano Dellavigna’s recent JEL article on evidence from the field. Both are ungated.