 Research has also indicated opposition to immigration may be motivated by concern about a persons concern about their group's social position.Studies found that increasing Hispanic immigration to the US caused greater support for immigration restriction amongst both white Americans and non-Hispanic non-white Americans (Hispanic Americans showed no change in attitudes), suggesting that concerns about group position could motivate opposition to immigration.David Frum suggests that while mass migration has occurred historically, for societies that have undergone a demographic transition, immigration brings change faster since the native population has fewer children.