Leftists’ solidarity with Palestinians is on the rise in the United States. Over the last two decades, support for Palestinians has nearly doubled among liberal Democrats. Some have even been willing to go to extreme means. In 2003, the American Rachel Corrie was killed by a bulldozer while fighting for Palestinian rights. More recently, hundreds of western Leftists have joined the Kurds, a stateless group that has been struggling for autonomy for decades, in their fight against the Islamic State and now against NATO member Turkey. Many never returned. Just this March, Anna Campbell became the first British woman to die while fighting alongside Kurdish forces in Syria. Usually people show such extreme support only for groups they are part of. This made us wonder, what drives activists such as Campbell and Corrie to risk their lives for groups they don’t belong to?

Our research suggests that these activists may have been driven by a visceral feeling of “oneness” -- something that has been termed identity fusion in the psychological literature. Importantly, this feeling of oneness with other groups may have been fueled by their Leftist political ideology. We found that when groups are commonly perceived as being oppressed, Leftists tend to feel a deep sense of connection to them -- often even deeper than to their own group. This sense of oneness, in turn, motivates many of them to defend such groups, even if it means risking their own lives.

In our research, we conducted a series of studies in different countries in which we measured people’s political orientation and their willingness to participate in extreme or risky activism for the Palestinians and Kurds. One of our first studies focused on a conundrum. Although one may argue that the situations faced by the Kurds and Palestinians are similar in many respects, Leftists tend to show solidarity with the Palestinians while being relatively uninvolved in the Kurdish struggle. So is the case in Norway, a country that has been historically left-wing and also pro-Palestinian while being reluctant to support the Kurdish people. We wanted to test whether different levels of oneness or identity fusion to these groups could explain why Norwegians support Palestinians more than Kurds. As expected, Norwegians experienced a higher sense of oneness with the Palestinians and this explained why they were more willing to join extreme protest for this group. Crucially, it was Leftist who felt especially connected with the Palestinians but not the Kurds. This finding made us wonder, what made Leftists care more about one group of people than the other? Could it simply be that they did not know about Kurds living under oppressive occupation?

To test this, we conducted a study in the U.S. in which we experimentally framed the Kurdish struggle as being an “oppressive occupation”. The more politically Leftist people were, the greater oneness they felt with Kurds and a higher willingness to engage in risk to support their struggle. Yet, this was only the case when we presented the Kurds as being under oppressive occupation.

Finally, we surveyed foreigners who were on the verge of joining or had already joined the Kurdish forces. On average, these individuals who were mostly from Western countries experienced a stronger sense of connection with the Kurds than with their own groups back home. Importantly, amongst these aspiring foreign fighters, Leftists who believed that their political beliefs morally compelled them to support the Kurds in their struggle experienced a particularly strong sense of oneness with them. This sense of oneness was again related to higher support for the Kurds and even to a willingness to actually sacrifice one’s life for them.

Our research can help us understand why people like Anna Campbell and Rachel Corrie were willing to risk their lives for other groups. What might appear irrational to some, may actually be a deep-seated psychological feeling of being “fused” with groups whose suffering one politically condemns. For the Leftist, this feeling tends to be especially strong for groups who are perceived as being oppressed.

Jonas R. Kunst, PhD is a post-doctoral fellow in the Psychology Department at Yale University and University of Oslo. Sasha Y. Kimel, PhD is an Assistant Professor of Psychology at California State University San Marcos.