This is a very interesting article, but the experiment, as described, doesn't seem to back up the thesis. They show that people who have less money are more taxed by financial questions, but that could just as easily be a cause not an effect of poverty. (ie, it could back the notion that it's trying to refute.) The article did mention a similar study in India where they tested people who were seasonally poor, but it didn't mention whether their scores changed after they received their harvests. That seems like the crucial point.
It totally does mention that their scores changed after they got the harvest... they went up, presumably because the cognitive burden was gone. Similarly, the experiment with car repairs of different expenses showed that the cognitive impact is correlated to how 'bearable' an expense was: rich people weren't impacted by a thousand dollar repair, but poor people suffered an impairment that wasn't there when the repair was only $100. This is pretty clear evidence that they didn't just pick a bunch of dumb poor people: the poor people started performing worse when there was financial pressure. This could probably be extended to test the impact of financial pressure on 'rich' people: propose they're hypothetically unemployed, or disabled and see if this has a cognitive impact. The problem is that rich people don't deal with that kind of problem with any regularity, so they might be able to shrug off a hypothetical situation.
As an anecdote, I make a software developer's income, but I also farm on the side. With some new expansion this year, virtually all of my cash assets are tied up in crops that are still growing and I'm going to struggle to finish out the remainder of the season. I'm probably considered "rich" on paper, but I have been feeling these effects start to creep into my own life regardless.
