Life is unfair. Your boss underpays you. Your spouse underappreciates you. Your parents underestimate you. Your children overburden you. Your teacher overworks you. Your cell phone company overcharges you. We’ve all been there. We’ve all been dealt the short end of the stick at one time or another.But sometimes we’re actually dealt the long end of the stick. Your boss gives you a bonus that your coworkers don’t get. Your parents give you a gift that your siblings don’t get. Your teacher gives you an extension that your classmates don’t get. Your cashier gives you a discount that the customers behind you don’t get. Sometimes in life, like in Monopoly, the bank makes an error in your favor, and you get to collect a veritable $200.Both of these situations—being dealt the short end of the stick and being dealt the long end of the stick—involve inequity. A limited pool of resources has been divided unevenly among those who have claim to such resources, be it money, time, esteem, or attention. But when the inequity works in our favor, a situation known as “advantageous inequity,” we’re much less bothered than when the inequity works against us, a situation known as “disadvantageous inequity.” Behavioral scientists have looked into the psychological status of these two types of inequity and discovered that disadvantageous inequity is significantly more salient than advantageous inequity. People reliably take notice when they are worse off than their peers, but they may not take notice when they are better off. And the same has been observed for apes, monkeys, and dogs, suggesting that mammals have evolved an innate aversion to disadvantageous inequity but no corresponding aversion to advantageous inequity. The latter may be unique to humans, developed either through internalization of cultural norms (regarding fairness) or participation in a market economy (where being unfair has reputational costs).Consistent with this idea, a recent study by the psychologist Peter Blake and colleagues, forthcoming in the journal Nature, found that an aversion to disadvantageous inequity develops earlier and more universally than an aversion to advantageous inequity. Blake and his colleagues tested 866 children between the ages of 4 and 15 in a resource-allocation task. The children were recruited from Canada, India, Mexico, Peru, Senegal, Uganda, and the US—countries selected for their variation along dimensions potentially relevant to inequity aversion, namely, population size, religion, and degree of industrialization.Each child in the study was partnered with another child and given the option of either accepting or rejecting a pre-specified division of resources. The resources were small food treats—candies—and they were divided between the two children in one of three ways: an equal division (i.e., one candy per child); an unequal division in which the decision-maker was favored at the expense of her partner (i.e., four candies for the decision-maker and one candy for the partner); and an unequal division in which the partner was favored at the expense of the decision-maker (i.e., one candy for the decision-maker and four candies for the partner). If the decision-maker rejected the offer, then no one received any candy; all candies went back to the experimenter. Rejecting an offer was thus costly, even for offers in which the decision-maker was allocated fewer candies than her partner. One candy, after all, is better than none.Children played this game for 16 offers, half of which involved equal divisions and half of which involved unequal divisions. Children’s preference for equal divisions over unequal divisions was then compared for the two types of unequal divisions: those that favored the decision-maker (advantageous inequity) and those that favored the decision-maker’s partner (disadvantageous inequity). Blake and his colleagues found that children from all seven countries exhibited an aversion to disadvantageous inequity, and the strength of that aversion increased with age. Most children did not, however, exhibit an aversion to advantageous inequity. Such an aversion was evident in only three countries (Canada, Uganda, and the US), and it developed later than the corresponding aversion to disadvantageous inequity. In short, children around the globe were willing to incur a cost to keep their peers from accruing more resources than themselves, but children from only a handful societies—mainly industrialized societies—were willing to incur a cost to keep themselves from accruing more resources than their peers.As a father, I like to think that I’m teaching my children to be as vigilant towards advantageous inequity as I am towards disadvantageous inequity, but that habit of mind is difficult to engender, in oneself let alone one’s children. Advantageous inequity just seems to slip by, unnoticed and unchecked. A salient example in my own life comes from Little League baseball. My son Teddy loves baseball, and he loves playing the position of pitcher most of all. But that position turns out to be highly coveted among budding baseball players. In one recent season, Teddy let his coaches know that he wanted to pitch at the beginning of every game, but his coaches put him in as pitcher only twice the entire season—two innings out of sixteen five-inning games, or 2.5% of the total game time. Teddy was disappointed by his lack of pitching opportunities, and we, his parents, reinforced that disappointment by griping about the inequitable rotation of positions on the ride home from each gameThe following season, everything was different. Teddy was on a new team with new coaches and new teammates, and he rose to the position of pitcher immediately. By the season’s end, he had pitched almost two innings per game, or 40% of the total game time. Teddy was elated, and so were we. Finally everything seemed fair. But things weren’t fair. A child was still hogging the pitcher’s mound, and it was Teddy. This realization eluded me until the last game of the season, when two children took the mound who had never pitched before. My first thought was that the coach had pushed them to try something new, something they had never voiced an opinion about. But I learned from Teddy afterwards that those children had wanted to pitch all season. They had just been prevented from doing so by an inequitable rotation of positions.I don’t attribute any malice to the coaches for allowing some children to pitch more than others. The coaches were just trying to play to their strengths, or at least what they perceived to be their strengths. Indeed, the inequity of the situation was likely as invisible to the coaches as it was to me—in the second season, that is. Inequity has a way of smacking you in the face when it works against you but slipping by unnoticed when it works for you, as demonstrated by the findings of Blake and colleagues (among others). Thus, in light of such findings, my New Year’s resolution is to be more vigilant towards advantageous inequity. I hope not only to spot it when it occurs but also to redress it, to balance the scales of fairness when those scales are tipped in my favor. Doing so promises to have immediate, appreciable outcomes, as advantageous inequity and disadvantageous inequity are two sides of the same coin. Every time we turn a blind eye to an unfair advantage (e.g., receiving too much change from a cashier), we fail to redress a corresponding disadvantage (e.g., a later garnishment of the cashier’s wages). Evolution may not have programmed us to care about advantageous inequity, but we have developed the cognitive and moral wherewithal to do so. So here’s to a fairer and more equitable 2016!