There has been plenty of noise about the Heritage Foundation’s report on immigration reform, with most of that noise centered around the PhD thesis of one of the report’s co-authors, Jason Richwine (part 1 and part 2). In his thesis, Richwine proposed an IQ filter on immigration (dressed up as a skills test) to avoid the potential social and economic consequences of admitting immigrants with persistently low IQ.
The debate (or to be more accurate, the lack thereof) triggered a couple of tangential thoughts. The first is that existing immigration policy in many developed countries already has an IQ filter. Australia and Canada’s skilled immigration systems are often pointed to as being among the most successful; so successful in fact that they are the two OECD countries where second generation immigrants outperform students with native parents in the PISA tests – see here, here and here. A large part of improvements in Swiss PISA test scores was attributed to immigration changes in the 1990s.
The immigration reforms that triggered the Heritage Foundation’s report also contain a skills-based component, including a points systems like that used in Australia and Canada. The United States is effectively implementing some of Richwine’s recommendations. (Since I first drafted this post, I see that Ed Realist has pointed out how some of Richwine’s ideas were doing just fine until the storm around the Heritage report.)
Another thought is that IQ-barriers are pervasive within countries. Tests for entry into college or university (such as the SAT) are highly correlated with IQ scores. IQ test results predict success in universities and awarding of scholarships. Many jobs have IQ-testing as part of the application process, particularly in police and fire departments (which often makes them the subject of litigation about exclusion of minorities). Intelligence is also a filter for who we are friends with and who we marry. Being of low intelligence has significant costs.
We can have a high level of confidence that the difference in IQ scores within developed countries has a genetic component. Estimates of the heritability of IQ from twin and adoption studies are robust. This means that within many countries we already actively exercise discrimination based on genetic factors, on both an institutional and personal level.