We only have so much cognitive capacity to spread around. It's a scarce resource.

This understanding of the brain’s bandwidth could fundamentally change the way we think about poverty. Researchers publishing some groundbreaking findings today in the journal Science have concluded that poverty imposes such a massive cognitive load on the poor that they have little bandwidth left over to do many of the things that might lift them out of poverty – like go to night school, or search for a new job, or even remember to pay bills on time.

In a series of experiments run by researchers at Princeton, Harvard, and the University of Warwick, low-income people who were primed to think about financial problems performed poorly on a series of cognition tests, saddled with a mental load that was the equivalent of losing an entire night’s sleep. Put another way, the condition of poverty imposed a mental burden akin to losing 13 IQ points, or comparable to the cognitive difference that’s been observed between chronic alcoholics and normal adults.