Yet Mr. Mansfield and Ms. Mutz reject this theory of voter attitude. If people were just looking out for themselves, their view of globalization would be determined by the industry in which they worked. Those in industries with a high concentration of exports should be favorable to an open economy, while those in industries that have to compete with imports should be opposed. In actuality, however, people’s attitudes about free trade and offshore outsourcing are unrelated to the characteristics of the industry in which they are employed.

After analyzing their survey data on individuals’ attitudes and attributes, these political scientists conclude that voters embrace policies based on the broader national interest. This theory is called sociotropic voting. There are several reasons people may look beyond narrow self-interest.

One is simply that people are more altruistic than economists usually think they are. But it’s also possible that it is just hard for people to determine with much precision how national policies affect their personal circumstances, and in light of this uncertainty, it is reasonable to presume that any policy good for the overall economy is probably good for you, too.

The issue then becomes why people think that globalization is bad for the economy in the first place. In other words, why do they doubt what so many economists teach about the gains from trade? The data analysis of Mr. Mansfield and Ms. Mutz suggests that skepticism about trade and outsourcing is closely related to three other sets of beliefs.

The first is isolationism more broadly. Trade skeptics tend to think, for example, that the United States should stay out of world affairs and avoid getting involved in foreign conflicts. They are not eager for the United States to work with other nations to solve global problems like hunger and pollution.

The second is nationalism. Trade skeptics tend to think that the United States is culturally superior to other nations. They say the world would be better if people elsewhere were more like Americans.

The third is ethnocentrism. Trade skeptics tend to divide the world into racial and ethnic groups and think that the one they belong to is better than the others. They say their own group is harder-working, less wasteful and more trustworthy.