Dr. Mike Walden, North Carolina Cooperative Extension economist in the College of Agriculture and Life Sciences at N.C. State University, responds:

"Well, first, certainly both the price of something and how much income you have affect how much we buy. And in general, the higher one's income, the more that you buy of things like gasoline. But the issue here is if income trumps price. That is, if you have a lot of income, can you just ignore the price? Well, based on a new study specifically on gas prices, the answer is a big no. What this study did is look at the responses of drivers with different income levels to higher gas prices. And what the study found is that not only did the rich cut back on gas purchases just like lower-income people when gas prices rose, but they actually cut back more than folks with lower incomes. And I think there are two possible reasons for this. One is that the rich do much more discretionary driving - driving outside of going to work and shopping and school - and that's easier to cut back on. Second reason, the rich may have more cars, so it's easier for them to shift from less fuel-efficient cars to more fuel-efficient cars when the price goes up."