Nothing to do with IQ, but with modes of thinking. According to Nisbett, Eastern thinking is more holistic and concrete vs. the Western formal and abstract approach. He says that Easterners often make fewer thinking mistakes when dealing with other people, where a more holistic approach is needed (for example, Easterners are much less prone to the Fundamental Attribution Error). But at the same time they tend to make more thinking mistakes when it comes to thinking about scientific questions, as that often requires formal, abstract thinking. Nisbett also speculates that this is why science developed only in the west even though China was way ahead of the west in (concrete-thinking-based) technological progress.

In general there's very little if any correlation between IQ and rationality. A lot of Keith Stanovich's work is on this.