In today's political climate, we often hear that people's behavior is driven by partisan motives rather than cognition and reason. And, of course, the claim that motives play a part in political behavior is hard to dispute. The behavior of many Democrats and Republicans seems better explained by the desire to see their group on top than by any sort of consistent ideology.

But it is also an underappreciated fact that motives can only act on beliefs that we find intuitively plausible. It seems plausible to believe, for instance, that the other party’s leaders are dishonest; many politicians are crooked. However, when a belief strains credulity, motives are often helpless. I may certainly be motivated to believe that I have a million dollars in my bank account, but I don't end up endorsing and acting on this belief.

This is a key principle: Political partisanship and bias emerge at the intersection of motive and intuition. As a result, a full understanding of political behavior must involve charting out the space of beliefs that people find intuitive.

An important, but often overlooked, source of information on what people find intuitive is developmental psychology. Although some of the beliefs we form as children are overturned with age, most survive in the form of bedrock intuitions that are overlaid with only a veneer of more sophisticated beliefs. These dormant intuitions may provide fertile ground for partisan motives, especially in circumstances that put additional pressure on our already limited cognitive resources (e.g., an economic crisis).

Recent research that Larisa Hussak conducted for her PhD thesis illustrates the usefulness of a developmental perspective in understanding a prominent phenomenon in the current sociopolitical landscape: nationalism. In the case of nationalism, the motivation to view one’s national group as superior to others must work hand in hand with a belief that members of this group are systematically, meaningfully different from members of other national groups; if we’re all the same, claims of superiority don’t make sense.

Much of what Americans learn via formal schooling goes against the idea of deep differences. We are told, for instance, that nation states have only existed for a blink in the long span of human history, and that the genetic material that differs between human groups is minuscule relative to that which is shared or to the genetic variability observed within groups.

Yet, nationalism makes sense to a lot of people. Why? One reason might be that it is intuitive to think of national groups as deeply different, perhaps in part because it’s aligned with how we viewed these phenomena as children.

A recent investigation, by Hussak and me, of young children’s concepts of national groups suggests that they view these groups as reflecting deep, meaningful, quasi-biological divisions in the social world. For example, when we asked a sample of American five- to eight-year-olds whether you can tell if someone is American by looking at their insides (such as their blood or their bones), younger children were significantly more likely to think this is possible than older children. Younger children were also more likely to think that the traits and behaviors that are associated with being an American (e.g., eating certain types of foods) are not learned but simply inherited from one’s parents. One child succinctly summarized this view: Being an American “feels like it’s in your body.”

Is it possible, though, that this is just a strange belief that American children have? They are, after all, growing up in one of the most patriotic countries in the world. This doesn’t seem to be the case. Telli Davoodi and her colleagues asked similar questions of children aged five to 10 from the U.S. and Turkey. For example, they asked children if two characters of different nationalities have different brains, and if in the future scientists could tell the characters’ nationality by looking at their blood under a microscope. Young children in the U.S. and Turkey were equally likely to think these things were possible, much like children in the studies that Hussak and I conducted.

But are these beliefs just a quirk of children’s thinking? Do they actually matter for how we view, say, people of other nationalities or immigrants? Although developmental research on this topic is just beginning, it does seem that beliefs portraying nationality as biological relate to more nationalistic, xenophobic attitudes.

In one of our studies, we measured both children’s concepts of national groups and their attitudes toward people of other nationalities. For example, we asked children whether it’s fair that Americans are wealthier than people from other countries and whether Americans deserve their greater wealth. We also asked children to assign positive (e.g., nice) and negative (e.g., mean) traits to unfamiliar American versus foreign children.

Among the older children in our sample, the belief that nationality is “deep” began to link up with proto-nationalist attitudes that portrayed children’s national in-group (in this case, Americans) as superior to other groups and as deserving of their superior status.

This link between biological views of nationality and negative attitudes toward other nations persists into adulthood. For example, Mostafa Salari Rad and Jeremy Ginges recently found that seeing nationality as biological predicted anti-immigrant sentiment among both U.S. and Indian participants. Other prior work, such as that on the distinction between ethnic and civic views of nationality, points in the same direction.

Developmental psychology is a useful tool for peeling back the layers of accumulated knowledge and uncovering the intuitive bedrock on which (motivated) political attitudes form. It may also be a tool for intervention: If we make the intuitive unintuitive by providing children with compelling alternative frameworks that they can use to make sense of the world, the hostile, xenophobic attitudes observed among adults may be less likely to take root.