[smallish]

You are suggesting that maybe poor people just have lower IQ, but this study doesn't support that.

It shows that cognitive performance between rich and poor is the same when they're asked questions which both groups consider easy and/or non-stressful.

[bobbinsIII]

the cognitive performance between rich and poor was the same in the sample they looked at (using their specific test). we know that is not true in general -- richer people are smarter on average.

[smallish]

Good point. What I mean to say is that the question of "who's smarter, rich or poor?" is not relevant to the study in question, and can't explain the results.