I'm guessing that the study was conducted with readers of a left-to-right language. I wonder what the results of a study on right-to-left or top-to-bottom readers would be.
Yes, the article says so explicitly. I'd expect right-to-left readers to essentially mirror left-to-right readers' movements, and a quick look at the design of e.g. www.al-jazeera.net supports this. (Amusingly, the only thing in the top left is labeled "English".)