What binds farmers in rural India to the working class in New Jersey?

Scarcity.

Poverty has become a convergence point for many disciplines, including the behavioral sciences.

Harvard behavioral scientists, Sendhil Mullainathan and Eldar Shafir have written a new book on poverty and how it affects those who suffer under its enormous stress: Scarcity: Why Having Too Little Means So Much.

Being poor, we know, is a stressful state of being and poverty is correlated to stress-induced diseases and shorter life spans; Mullainathan and Shafir attribute to poverty something more than just stress. They claim that poverty shrinks the human brain's "bandwidth."

Simply put, if a person is poor and has to worry about where money for rent or a monthly mortgage will come from, the person's brain gets inside a hermetic "tunnel" and stays locked up there. A large chunk of the brain's bandwidth gets used up in a single task and other tasks remain unattended to. So a poor person loses the capacity to make other life-decisions effectively.

Worrying about money when it is tight captures our brains. It reduces our cognitive capacity — especially our abstract intelligence, which we use for problem-solving. It also reduces our executive control, which governs planning, impulses and willpower. The bad decisions of the poor, say the authors, are not a product of bad character or low native intelligence. They are a product of poverty itself. Your natural capability doesn’t decrease when you experience scarcity. But less of that capacity is available for use. If you put a middle-class person into a situation of scarcity, she will behave like a poor person.

Here is Eldar Shafir giving a TedEx talk on why the poor make bad decisions and choices: