The study found that as of the middle class often have an incentive to focus on the reason. And think about the future than those in the lower classes. Which takes into account the present and the past.
Like the study found that middle-class people, often with incentives focused on why more and more people think of the future in low-floor, which take into consideration the current and past but only.
such as from the study found that middle-class people tend to have an incentive to focus on the reasons why more and more people are thinking about the future more than the low level, having regard to the current and past.