Why is it so difficult to teach young children to share their toys instead of hogging their playthings all to themselves? Similarly, why does your neighbor’s dog bark so aggressively whenever you approach, chasing you off the edge of their lawn? Why do lions stand guard over freshly-killed prey to deter any other predators from getting at it? The answer to these questions is in the zero-sum bias.

Here’s Why

Every animal (including humans) is wired with the belief that all the resources in their environment come in limited supply. Thus, whenever another creature takes a unit of that limited supply for themselves – whether it’s a toy, a patch of land, or a piece of prey – that means there is one less unit of that resource available to you, making the odds more difficult for you to survive. Due to this instinctive belief that there is constant competition for resources, babies, pet dogs, and lions alike are quite aggressive when it comes to claiming possessions for themselves.

Definition of Zero-Sum Bias

Zero-sum bias is the false belief that when a group of creatures interact, one creature can only benefit or “gain” if another one “loses.” In other words, imagine a forest ecosystem where all the creatures living there have to split one pie between them. If one creature takes a bigger slice of the pie, that means all the other creatures have to settle for a smaller slice. Thus, one creature “gaining” from the situation, or having more pie, can only come at the cost of all the other creatures suffering a loss, or getting less pie. 

The History

There is no specific experiment associated with the zero-sum bias. Many researchers suggest that the zero-sum bias is a product of evolution: the early humans who believed that all resources were scarce and could only be obtained through fierce competition were the ones that survived within their species. Since the zero-sum bias was so helpful to the survival of early humans, natural selection has ensured that it remains an instinctive way of thinking in modern humans.

Applying it 

Although the United States is a country formed from diverse peoples, Americans still have an irrational fear and prejudice towards immigrants. Even before the 1882 Chinese Exclusion Act, which explicitly prohibited the immigration of Chinese laborers to the U.S., many working-class Americans already believed that jobs were a scarce “resource” in society and opposed opening their country’s borders to immigrants and refugees out of fear that these newcomers would snatch all of the limited supply. Unfortunately, this belief – which stems from the zero-sum bias – is still prevalent among some Americans today. In actuality, the zero-sum bias oversimplifies the consequences of immigration, exaggerates the scarcity of jobs, and causes people to view immigrants as their rivals when there are enough resources in most developed countries for everyone to coexist peacefully. 

The zero-sum bias not only hinders our thinking in socio-political matters, but also in economic matters. As human society grew more civilized and technologically advanced, people realized that cooperating with others to reach mutually beneficial outcomes is more productive than competing with others and trying to snatch their resources. For instance, the idea of trading goods between nations is only possible because humans resisted their zero-sum bias. In the modern day, each country has skills that are best suited to making certain products and focuses all its efforts on making those products. Then, various countries can come together and trade their goods so that everyone gets the supplies they need in an efficient manner. In situations of trade, both parties are typically satisfied because they each get a product that they wouldn’t be able to easily make on their own – no one suffers a “loss.” Thus, although the zero-sum bias undoubtedly helped primitive humans survive, cooperation and mutual gain are much more useful for succeeding in the modern world.

    Learn More

    1. Friedman, Stewart D., et al. Work and Life: The End of the Zero-Sum Game. p. 14.
    2. Meegan, Daniel V. “Zero-Sum Bias: Perceived Competition Despite Unlimited Resources.” Frontiers in Psychology, vol. 1, 2010. Frontiers, doi:10.3389/fpsyg.2010.00191.
    3. Norton, Michael I., and Samuel R. Sommers. “Whites See Racism as a Zero-Sum Game That They Are Now Losing.” Perspectives on Psychological Science, vol. 6, no. 3, May 2011, pp. 215–18. SAGE Journals, doi:10.1177/1745691611406922.

    Think Further

    1. Can you think of some examples where you’ve noticed yourself relying on the zero-sum bias?
    2. Should modern people still rely on the zero-sum bias? Explain your reasoning for why or why not.
    3. Should other animals still rely on the zero-sum bias? Explain your reasoning for why or why not.

    Teacher Resources

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