"All of this should lead us to worry that our hypothetical research subjects are being primed less by the grammar of their languages, and more by the cultural associations of their languages."

There is just no way to separate these, none. Take close dialects of the same language, one with the grammar variant, one without; those dialects will be associated with cultural variants in their native-spoken space. (The culture of Greek' would be altered by the mere fact of its being spoken by self-aware experiments.) Take the same language, over a span of time in which it's dropped or added the variant; shockingly enough the culture of the people who speak it will also have changed over time. Take contemporaneous families bilingual in the same two languages? Well, you said it all above.

Whorfian hypotheses are to race and nationality as evolutionary psychology is to gender; the very few legitimate inquiries are all but drowned out by the endless studies searching for some pseudo-scientific confirmation of a broadly-held and often harmful political stereotype.

Women can't do math? Must be their birthright as women. Better get cracking on a study about estrogen and left-brain function. Greeks don't save money? Must be their language as Greeks. Let's see if we can prove that Greek causes financial irresponsibility. That'll be an easy and convenient way to explain the Euro crisis that doesn't blame or prosecute anyone! (Except the Greeks, as a whole. Screw them, right?) Bonus: the study will boil down to a nice eight-word headline that'll justify a lot of racism and therefore get a lot of press.

Yes, Whorfian hypotheses are tempting. Let's just say it: they would make the entire field of linguistics more important and relevant than all the other How People Think humanities fields combined. We would all get a lot of funding and everyone would have to listen to us.

It's vitally important to recognize this temptation for what it is.

I doubt Chen's research was intended to apply to mostly monolingual families. On p. 12 of the paper he explicitly states that the seven countries that provided significant data were those for which there was significant intra-country variation in FTR, which means countries like Greece are ruled out. For at least two out of seven of the countries he used for his data (Malaysia and Singapore), monolingual families who speak Mandarin, Tamil or English (three out of the four languages studied in those two countries) are quite rare. Thus it seems likely that multilingual families were a significant proportion of the families studied.

b) Will the Greeks have to learn a different language before they can get their act together?

@Levi Montogmery: Chen is arguing, I believe, that habits such as saving are statistically correlated with the way the future is talked about in people's language. He doesn't say that not having a future tense makes everybody a saver. In my post above, I oversimplified Chen's position drastically, and I apologize if that led you astray.

This excerpt assumes that families have a choice in what language to speak. This may be true in places with large numbers of bilinguals – as in Québec or some regions of the US – but not in places like Greece where the vast majority speaks only one language, the one they have always heard around them, and any acquaintance with a second language taught in school but not significantly used in the community is minimal. I understood Chen's research to apply to mostly monolingual families.

In other words, surely there poor future-planners and good future-planners among the speakers of any single language. Rather than try to determine the relative merit of the theory's claims across two or more languages, why not examine its merit in one language?

It also seems to me that this would test Chen's thesis directly, even though we would actually be looking at how specific instances of tense marking affect behavior rather than looking at how the obligatoriness of tense marking affects behavior. I haven't read the Chen paper in full, but assuming that Sedivy's explanation is accurate, then the mechanism by which obligatory tense marking affects behavior is through "mental nudges" induced by particular instances of the tense marking. Such nudges would presumably occur when future tense marking appears but is not obligatory.

Assuming some validity, hypothetically, wouldn't a search for languages that foreground the same sorts of information linguistically help to balance out the perspective?

(I hope the sarcasm is obvious).