Aristotle figured out pretty early on that human beings are by their nature constantly pulled by two opposing forces: on the one hand their propensity to go after immediate rewards, even though they are often deleterious for them (akrasia, or “weakness of the will”); on the other hand the necessity to work for their long term welfare (eudaemonia, loosely translated as “happiness” but better understood as flourishing).

This is, of course, the stuff of countless novels and movies, not to mention the reason people go to therapy (sometimes successfully coupling the artistic with real life, as in the case of Woody Allen). Yet, until recently there have been very few controlled studies assessing what in technical terms is known as “future discounting,” i.e. the idea that we might prefer a smaller but immediate reward to a larger but delayed one. More interestingly, little research has been done on how flexible human future discounting is, and in response to what kinds of circumstances our eudaemonic calculus may change.

But a few years ago Margo Wilson and Martin Daly of McMaster University in Canada began to address these issues systematically with the publication of a paper published in the Proceedings of the Royal Society of London (vol. 271, S177-179). Wilson and Daly wanted to know whether men and women would change their future discounting rate in response to visual stimuli, and in particular whether seeing pictures of attractive or non-attractive individuals of the opposite sex, or of “hot” vs. normal looking cars, would affect their discounting decisions. The discounting was measured by the frequency with which subjects would pass a smaller but more immediate monetary reward for a larger one to be delivered in the more distant future.

The results were fairly clear: men are indeed, as the title of the paper puts it, “inspired to discount the future” when presented with mildly arousing pictures of attractive women, but they were not so inclined when the women in the photos were not attractive. Women also showed a mild tendency to respond in the same way, but the difference between the two treatments was actually not statistically significant, meaning that it is clearly men who do most of the future discounting (or, in lay terms, are more likely to lose their minds in the presence of an attractive member of the opposite sex).

The results with the cars, however, were reversed: a “hot” car did not have any effect on the men’s propensity for future discounting, but it did influence women, whose discounting rate was much higher when a hot car was pictured in comparison to a boring looking one. Clearly, the old idea that a good way to attract women’s attention is to drive around in an attractive (and expensive) looking car does have scientific foundation…

Wilson and Daly point out that we also know of the neural correlates of these behaviors: brain scan experiments show that when men look at pretty women their nucleus accumbens lights up. This is the area of the brain associated with the evaluation of rewards, and it is connected directly to the orbitofrontal cortex, a brain region that deals with rewards from sweet food as well as money.

All of this makes much sense, but the question remains as to why on earth we would go for immediate rewards even when we realize that long-term ones are significantly better -- let’s call it the Aristotelian paradox. The most intriguing aspect of Wilson and Daly’s study is their suggestion that our future discounting rate is phenotypically plastic: that is, how much discounting we do depends on the environmental conditions. In a previous paper, the same authors argued that “the relatively short time horizons of criminal offenders, the poor and the young may not deserve pejorative terms like ‘myopia’ and ‘impulsivity,’ but instead reflect modulated future discounting in response to social and economic cues of the relative values of present and future goods and opportunities.” In other words, the more uncertain the future reward, the better off you are betting on the immediate one. And what can be more immediate than a good looking woman smiling right at you?