Poverty is like a tax on the brain, a team of researchers has reported, because it imposes a measurable burden on the mental capacity of those who must struggle with it day after day.
The result, part of a study of cognitive reasoning across income groups, may explain why low-income people seem to have a harder time with certain tasks that require focus or planning and appear to make decisions that work against their best interests. It also suggests that policies and programs designed to help the poor improve their lot may not be successful if they do not take into account how much brain power is used simply in the act of trying to get by with scarce resources.
"They're distracted, basically," said Jiaying Zhao, an assistant professor of psychology at the University of British Columbia, who conducted the study along with colleagues in the United States and Britain.
"It's not handling problems" that slows down the mental performance in the poor, Dr. Zhao added, but "the lingering preoccupation on the mind" that comes with living on the economic edge.
As part of the study, published on Thursday in the journal Science, research subjects recruited in a New Jersey mall were asked how they would cope with an unplanned expense, such as a car repair, and then their mental performance was tested with a range of cognitive tests. When the scale of the expense was relatively low – $150, for example – all subjects performed about the same level. But when the scale of the expense shifted to $1,500, people with low incomes scored lower on the cognitive tests while trying to answer the car question. Those with middle to high incomes exhibited no such change.
In another part of the study, the group found a similar effect with farmers in rural India, who were able to perform much better on standard cognitive tests after their harvest than when they were coping with higher debt loads and strained budgets before harvest.
"The amount of focused attention that people can have is a scarce resource," said Anandi Mani, an economist at the University of Warwick who oversaw the India portion of the study. "There's only so much multitasking that we are really able to do effectively."
In the case of the New Jersey mall-goers, whose incomes ranged from $20,000 to $160,000, Dr. Zhao said it was startling to see those with lower incomes perform just as well as others while handling a range of scenarios but then lag behind once the financial stakes were raised. The researchers suggest that the challenges posed by making do with less eat up mental "bandwidth" by persistently creating hurdles that cannot be put off to a more convenient time.
"If you're dealing with having to pay the rent or face eviction, you don't have the mental luxury of saying: 'I'll deal with that tomorrow,' " said team member Eldar Shafir, a behavioral economist at Princeton University.
Dr. Shafir, whose work is supported by the Canadian Institute for Advanced Research, is co-author of a new book that explores the theory of mental bandwidth called Scarcity: Why Having Too Little Means So Much.
In a separate perspective piece in Science, Kathleen Vohs, a psychologist at the University of Minnesota in Minneapolis who was not involved with the study, called the work "eye-opening." Observing that "the lives of poor people are filled with land mines of desire, trade-offs and self-control dilemmas," she said governments and organizations need to recognize the drain on mental reserves when imposing administrative tasks on low-income groups. That could mean designing better application forms, or making banking and other financial transactions more automated to help reduce mental overload.
Better informed policies and programs are key, Dr. Shafir said, because those living with scarcity must try to function while facing an ever-present demand on their attention – something akin to driving through a heavy rainstorm.
Amedeo D'Angiulli, a cognitive neuroscientist at Carleton University in Ottaw, praised the study but was cautious about its conclusions, which he said sidestep poverty's impact on brain development and other factors that may account for why different income groups perform differently in certain circumstances.