Monkey inequality


Jason Collins


November 12, 2011

Over at Wired, Jonah Lehrer has written a post in which he looks at a couple of lines of evidence about the innate response of humans to inequality. The first line, based on brain scans, is nicely discussed by Jeff at Cheap Talk.

The second involves an experiment with capuchin monkeys:

A similar lesson emerges from a classic experiment conducted by Franz de Waals and Sarah Brosnan. The primatologists trained brown capuchin monkeys to give them pebbles in exchange for cucumbers. Almost overnight, a capuchin economy developed, with hungry monkeys harvesting small stones. But the marketplace was disrupted when the scientists got mischievous: instead of giving every monkey a cucumber in exchange for pebbles, they started giving some monkeys a tasty grape instead. (Monkeys prefer grapes to cucumbers.) After witnessing this injustice, the monkeys earning cucumbers went on strike. Some started throwing their cucumbers at the scientists; the vast majority just stopped collecting pebbles. The capuchin economy ground to a halt. The monkeys were willing to forfeit cheap food simply to register their anger at the arbitrary pay scale. > >

This labor unrest among monkeys illuminates our innate sense of fairness. It’s not that the primates demanded equality — some capuchins collected many more pebbles than others, and that never created a problem — it’s that they couldn’t stand when the inequality was a result of injustice.

While this experiment shows that problems emerge following arbitrary outcomes, I would not describe the reaction as demonstrating an “innate sense of fairness”. The revolt was one-sided, and the monkeys who received grapes were not handing them back. It is more like an innate dislike of being on the bottom.

More importantly, I am not convinced that the experiment fully tested whether fair outcomes could generate unrest. As the stone gathering ability of monkeys is not likely to vary much, particularly when compared to the variation in human ability across different professions, the variation in opportunity for the monkeys was negligible. The variation in outcomes was also relatively small.

As a result, if a monkey was hungry, it is an easy task to get some stones. However, if a human needs money, the range of possibly courses of action are large, with the returns widely variable. A cleaner and a brain surgeon earn significantly different rates of return for an hour of effort.

What if the monkeys were paid on the basis that whoever collects the most stones gets the vast majority of the cucumbers or grapes? Or what if effort started to pay compound dividends, meaning that long-term focussed stone gathering delivered much higher returns. The rules might be clear and the victory fair, but I am not sure that the reaction to the significantly different outcomes would be benign.

Lehrer uses this experiment to draw the following conclusion:

When the rich do something to deserve their riches, nobody complains; that’s just the meritocracy at work. But when those at the bottom don’t understand the unequal distribution of wealth — when it seems as if the winners are getting rewarded for no reason — they get furious. They doubt the integrity of the system and become more sensitive to perceived inequities. They start camping out in parks. They reject the very premise of the game.

Even if the belief that nobody complains when the rich deserve their riches was true, do the majority of people understand the basis of the distribution of wealth in today’s economy? Has the economy reached a level of complexity that will always generate a certain level of distrust by those at the bottom?