Poverty Exacts a High Cognitive Toll

Megan Brooks

September 05, 2013

For people struggling to live paycheck to paycheck, money is not the only thing in short supply.

New research suggests that poverty directly impedes cognitive function, and this "cognitive deficit" caused by poverty translates into as many as 10 IQ points.

"Previous views of poverty have attributed low mental functioning to personal failings of the poor individuals, or a lack of education or nutrition," Jiaying Zhao, PhD, from the Department of Psychology, University of British Columbia, Vancouver, Canada, who worked on the study, told Medscape Medical News.

On the contrary, the new study suggests a "causal, not merely correlational" relationship between poverty and mental function, Dr. Zhao said. "We find that the lack of financial resources itself can lead to impaired cognitive function."

The study is published in the August 30 issue of Science.

"Eye-Opening" Study

Kathleen D. Vohs, PhD, of the University of Minnesota, in Minneapolis, calls the study "eye-opening" in a linked Perspective article in the same issue.

"It's fascinating," she added in an interview with Medscape Medical News, "and fits extremely well with a model we've been working with for decades on the impact of limited resources on cognitive abilities. It can overwhelm your whole system."

To explore the cognitive load that comes from financial pressures, Dr. Zhao and colleagues studied 2 dramatically different groups ― shoppers at a mall in New Jersey and sugar cane farmers in rural India.

In the mall study, they gave low- and middle-income shoppers (defined by household income) hypothetical financial decisions, followed by tasks that measured mental abilities.

The low-income shoppers who earlier had to contemplate a difficult financial decision (spending $1500 on a car repair) showed worse mental performance than the more well-off shoppers.

In the study of farmers, they found that the mental acuities of the same farmer varied with swings in income. These rural farmers typically are paid once per year, after the harvest, meaning they are under significant financial pressure before the harvest.

The researchers gave the farmers challenging cognitive tests before and after the harvest. They saw clear and demonstrable improvement in cognitive capacity after the harvest, as well as after payday. This outcome held after accounting for the stress of preharvest periods, they say.

Policy Implications?

Taken together, the findings suggest that poverty itself reduces cognitive capacity, Dr. Zhao and colleagues say.

The investigators conclude that this study suggests a different perspective on poverty: being poor means coping not just with a shortfall of money but also with a concurrent shortfall of cognitive resources. "The poor, in this view, are less capable not because of inherent traits, but because the very context of poverty imposes load and impedes cognitive capacity. The findings, in other words, are not about poor people, but about any people who find themselves poor," they write.

Professor Simon de Lusignan, MD(Res), from the Department of Health Care Management and Policy, University of Surrey, Guildford, United Kingdom, who was not involved in the study but who reviewed it for Medscape Medical News, called it "very thought provoking."

Dr. Zhao thinks policymakers "must beware of imposing cognitive taxes on the poor just as they avoid monetary taxes on the poor. They should try to reduce the cognitive taxes, such as simplifying forms, shortening procedures of benefit programs, and setting up smart defaults and reminders. Policymakers should also recognize the natural variation in the person's cognitive capacity and synchronize programs and services to periods when resources are abundant," Dr. Zhao said.

Current estimates are that roughly 20% of the world's population is in poverty, Dr. Vohs notes in her article. Although that is half of what it was 20 years ago, it is nonetheless a "huge number."

"Economists," she points out, "are fond of the theory that the more people on Earth, the better, because people create ideas. With more people come greater odds of discovering the cure for cancer, renewable energy sources, or how to cultivate world peace. That premise rests on the notion that all people have adequate mental capacity, a premise now called into question by this study for a fifth of the world’s population," Dr. Vohs concludes.

Science. 2013;341:969-970, 976-980. Abstract, Perspective


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