We tend to think of the canoodling couple on a park bench as a decidedly “Western” phenomenon, in that is more culturally acceptable to showcase affection publicly. And while Hollywood movies have perhaps made some other cultures increasingly comfortable with public displays of affection, a new study points to a completely different explanation: competition for romantic partners.

A new study seeking to explain the different levels of passion in Eastern and Western romantic relationships challenges the conventional explanation that cultural collectivism and interdependence in the East leads to fewer overt displays of passion (both private and public), while Western values of individualism and independence foster more. Instead, the Japanese researchers say passion is likely driven by how much freedom people have to choose and replace their partners.

Long-term, monogamous romantic relationships are faced with a commitment problem, researchers explained: the conflict between maintaining a relationship with a certain partner and looking for an attractive alternative.

The team, led by PhD student Junko Yamada and Professor Masaki Yuki of Hokkaido University, hypothesized that Americans living in a society with high relational mobility (that is, greater freedom to choose and replace their partners) are constantly exposed to the risk and anxiety of being cheated on or losing their partner to a rival. It also assumed that passion will induce strategic behavior to lavish attention and affection on their partner, while proactively ignoring potential partners to reassure their current partner.

On the other hand, in Japan, where relationships tend to be more stable and hard to change (low relational mobility), people have less competition — less risk and anxiety of being cheated on or being rejected, making passionate behavior less relevant.

The findings from a survey of 154 heterosexual Americans (78 men and 76 women) and 103 heterosexual Japanese people (65 men and 38 women) recruited through online crowdsourcing marketplaces, bear out such a hypothesis, the team said. The questionnaire measured participants’ perceptions of the level of romantic relational mobility of people around them and the intensity of passion they felt toward their current partner. All participants were asked how likely they would be to adopt various commitment behaviors when forming a relationship with a specific mate. A statistically significant pattern emerged, showing Americans are more passionate toward their partners than the Japanese are, explained by the relational mobility of the society they live in, researchers say. The study also found that the more passionate a person was, the more likely they were to approach a partner and lavish affection on nobody but the partner while voluntarily abandoning relationships with other members of the opposite sex.

While the team did note more research is needed to confirm their hypothesis, their findings are at least food for thought. In India, as young people are increasingly transient, moving to new cities and living outside the family home, their social environments and thus, their relational mobility, changes, increasing both opportunity, competition, and chances of dating and love-marriage. If the researchers’ insights are correct, a large-scale increase in passionate love and displays of affection follows naturally. While Western media may have led a generation to expect this lifestyle, that they live it may simply be the result of an economic imperative, as young people seek out education and higher earning jobs in new places.