The paper takes a long time to get to an illustration of its thesis, but the very first example is stunning:

There are cultures in the world that are completely unaffected by this illusion - http://goldmark.org/jeff/papers/ridley/html/img1.gif

If something as basic as visual perception is so hugely affected by culture, the paper asks, is there any aspect of psychology that is not? How, then, can we trust the conclusions of studies whose subjects are all drawn from the same, highly unusual cultural group?

I'm glad I stuck with it until I got to this point. Now I have to read the rest of it.