In 2016, 17,250 people were killed in the United States. How does thinking about that make you feel—on a scale of 1 to 100, with 1 being “not at all upset” and 100 being “as upset as I could imagine getting”?

Now think about this: In 2016, 76,000 people were killed in Syria. Using the same 100 point scale, and trying to be honest with yourself, does hearing that make you feel more or less upset than hearing about the murdered Americans?

Source: This is Kteily's official public photo

Nour Kteily is an associate professor in Northwestern’s department. He obtained his Ph.D. five years ago at Harvard, where he worked with Jim Sidanius on social dominance orientation—which is the extent to which a person wants his or her own group to dominate and be superior to other groups (Kteily, Sidanius, & Levin, 2011; Sidanius & Pratto, 1999). People who score high on social dominance orientation prefer social systems in which groups are ordered hierarchically, and believe that groups that come out on top of the hierarchy (very often their own) have every right to be wealthier and more powerful. Compared to those low in social dominance orientation, high scorers are also more in favor of military spending, international conflict, and retaliatory torture against one’s enemies.

In one of the most thought-provoking findings in this area, Kteily and his colleagues have also found that people high in social dominance tend to view other groups as less human than their own (Bruneau & Kteily, 2017; Kteily, et al., 2015). To make this determination, Kteily and his colleagues developed a very interesting measure of dehumanization. If you were a subject in one of their studies, you would be asked to rate the members of different groups in the following way:

Source: Based on Kteily et al. paper in JPSP, journal permits use of up to 3 figures per article.

When the researchers asked Israelis to rate Palestinians on this scale, they found shocking results—Palestinians were rated 40 points lower on the humanity scale—closer to a four-legged human ancestor than to the “fully evolved” upright modern human. And consistent with this judgment, the average Israeli would be willing to kill 575 Palestinian civilians to save the life of one soldier wounded by a Palestinian militant.

When the researchers asked Palestinians to make the same ratings, they found a similar pattern, only in reverse. The average Palestinian rated Israelis 37 points lower than themselves on the humanity scale, again closer the quadruped ancestors than to the “fully evolved” modern human. And they valued Palestinian lives far higher than those of Israelis (Bruneau & Kteily, 2017).

Why do we dehumanize members of other groups? Haslam and Stratemeyer (2016) found that part of the explanation is that we presume that other groups do not experience emotions in the same way we do. In fact, when Melissa McDonald and her colleagues (2017) informed Jewish Israelis that Palestinians had shared their emotional response to an -inducing news story, dehumanization dropped.