Day care drop-offs and work deadlines may combine with financial woes to put a literal strain on your ability to think.
New work by a team of psychologists and economists supports the notion that humans have limited bandwidth for decision-making. And the capacity to make choices can take a hit once that cognitive load becomes too heavy. The research, based on experimental data collected on people with varying levels of self-reported income in rural India and a New Jersey shopping mall, concludes simply that at least short-term financial stress can max out our mental reserves on par with the level of impairment that results from pulling an all-nighter.
These results are “very convincing,” says Bruce McEwen, a neuroscientist specializing in stress studies at The Rockefeller University in New York City, not involved with the work. The findings are detailed in the August 30 issue of Science.
The researchers took their hypothesis on finite brainpower to a mall in New Jersey, where they asked several hundred people to participate in questioning designed to sometimes remind them of their own finances while considering hypothetical budgetary decisions. Respondents were then asked to perform standardized tasks that measured logical thinking and cognitive control, such as choosing which shapes fit into a missing sequence and their ability to click in certain parts of a screen after seeing certain figures. Subjects who were less well off in real life (as defined by household income) performed worse than those who reported higher real-life incomes. The researchers also took into account several variables, such as math anxiety and low incentives for correct answers, to establish a causal link between household income and cognitive performance.
Notably, when low-income and more affluent individuals were asked to make easier financial decisions in an exercise about smaller sums of money—meant to reproduce conditions in which participants would be less likely to think of their own financial hardships—both groups performed at similar rates on the cognitive tests. Household income among the sampled population ranged from a median of about $70,000 to as low as $20,000 adjusted by family size, roughly approximating a cross-section of the U.S.
The authors also wanted to test their hypothesis on people dealing with their real-world budget decisions before performing cognitive tests. So they studied sugarcane farmers living in India before and after harvest time, gauging how resulting swings in income had an impact on subjects’ ability to solve standardized psychological problems similar to those posed to the New Jersey subjects. As with the U.S. results, higher household incomes were tied to better performance on the cognitive tests. Following the harvest, when the farmers’ finances were more assured, these same individuals performed better than before the harvest at cognitive tasks. Better performance did not result from familiarity with the cognitive tests though—to dismiss that possibility, the researchers ran the experiment separately on farmers who did not participate in the preharvest experiments and came up with similar findings.
The Indian farmers’ better scores when they had more cash could not be explained away by season (harvest times varied across the sample) nor by changes in physical exhaustion (the farmers were typically managerial and did not perform physical labor). No significant nutritional differences were observed among subjects preharvest and postharvest either. Periods of stress during harvest time, as measured through heart rates and blood pressure in separate work, also could not account for the changes.
So what’s at the root of the income–brain work problem? The scientists suggest that it is a matter of “attentional capture,” meaning that poverty triggers intrusive thoughts that draw on the brain’s limited reserves. That distraction goes beyond the myriad, random thoughts that can pop up in our daily lives, says study author Eldar Shafir, a behavioral scientist at Princeton University. “If I am driving and someone is riding past on a unicycle, I get distracted, and then I’m back in a few moments,” he says. “Here it is ‘capture’—I spend an enormous amount of time on [financial concerns] and I keep coming back.” Shafir and one of his co-authors has a forthcoming book on the topic.