Poverty doesn't itself reduce IQ—but research suggests that active financial worries can impair thinking.

People who regularly face financial hardship are especially sensitive to money-related stress.

Field studies find that cognitive performance drops during periods of financial scarcity.

Timing your decisions to avoid peak financial worry can meaningfully improve the choices you make.

In a famous research article, Mani et al. (2013) concluded that those who struggle with financial problems "are less capable not because of inherent traits, but because the very context of poverty imposes load and impedes cognitive capacity." This article is often taken to imply that financial stress reduces IQ—but that is not quite correct.

How do financial worries impair your cognitive functions? And how much should we worry about whether we worry?

Financial Worries and Your Brain

In their paper, Mani et al. examined the cognitive performance of New Jersey shopping-mall visitors while financial concerns were on their minds. First, participants were asked to think about some hypothetical decisions, like this one:

"Your car is having some trouble and requires $1,500 to be fixed. You can pay in full, take a loan, or take a chance and forego the service for now. How would you go about making this decision?"

"Your car is having some trouble and requires $1,500 to be fixed. You can pay in full, take a loan, or take a chance and forego the service for now. How would you go about making this decision?"

While thinking about these decisions, participants completed two tasks used to measure cognitive capacity: Raven's progressive matrices, which are often part of IQ tests, and a spatial incompatibility task, which measures impulse control. Only after completing those tasks did they provide their answers to the hypothetical decisions.

Unbeknownst to the participants, they had been randomly allocated to two groups. For the High Worry group, the cost of car repairs in the example was indeed $1,500. For the Low Worry group, it was only $150. The participants' actual answers to the hypothetical questions were irrelevant. The point is that the questions triggered a state of financial worry in the High Worry group, but most likely not in the Low Worry group. In psychological terms, this is a manipulation, a technique used to identify the causes of an effect.

The researchers then compared results across income levels, splitting participants at the median. For people who were relatively poor (below median income), financial worries reduced performance on both cognitive tests. For people who were relatively well-off (above median income), there was no effect.

In other words: For people who regularly have to worry about money, the study suggests that having financial worries actively in mind impairs cognitive capacity, including thinking, problem solving, and impulse control.

Paychecks and Your Brain

How much should we trust those results? After all, those were hypothetical questions, not actual financial worries.

To address this concern, Mani et al. also conducted field studies with sugarcane farmers owning small plots of land in Tamil Nadu, India. Farmers there are paid once a year, at harvest time. As last year's earnings slowly run out, the months before the harvest represent a period of financial scarcity, while the months just after it represent a period of relative abundance. The researchers used this naturally occurring difference in financial pressure to replicate the study in a more realistic setting.

Farmers completed two tasks measuring cognitive capacity both before and after the harvest. One was again based on Raven's Progressive Matrices. The other was an adapted version of the Stroop task, a classic psychological measure of cognitive control. As expected, performance on both was worse before the harvest than after.

Critically, the researchers did not induce financial worries. They arose naturally from the farmers' lives—further bolstering the conclusion that when financial concerns are permanently present, cognitive capacity is reduced.

What This Means for Your Financial Worries

The conclusion of these studies is not that being poor reduces your IQ. It is not even that financial trouble leads directly to worse decisions.

The conclusion is more specific: If you regularly face financial difficulties, your mind is likely to be more sensitive to financial concerns, and when those concerns are active, your cognitive capacity is likely to be reduced.

This is not different from trying to multiply 12 by 45 while keeping the number 6,549,387 in mind. That is an example of cognitive load: when your mind is otherwise occupied, your thinking suffers.

Of course, impaired thinking can lead to poor decisions. But the distinction matters, because it means that making poor decisions is not a foregone conclusion. It means you should be deliberate about when you make important decisions.

Think back to the New Jersey shopping-mall visitors. As much as possible, avoid making important decisions while a specific financial problem is at the front of your mind. Give it time, and do not trust your gut. Talk things through with a trusted friend, and create some distance from your worries before deciding. Pour yourself a cup of tea or coffee, sit in your favorite place, and read for a while before returning to the problem.

This can help even when the decision you have to make, as will often be the case, involves the financial concern itself. The key is emotional distance: let time pass, create a stable and reassuring environment, or seek out the perspective of a friend who does not share the same pressures.

If you live paycheck to paycheck and are permanently worried about making ends meet, that is easier said than done. Even so, think back to the sugarcane farmers. When you can, avoid making important decisions at the end of the month (or whenever you're lowest on funds). Wait for your paycheck, and use the window of relative calm it creates to address serious choices.

Financial worries tax your brain. Releasing them, even temporarily, could help you think more clearly and make better decisions. Of course, you may never be able to let go of them fully. But being aware of the problem is the first step toward managing it.

Mani, A., Mullainathan, S., Shafir, E., and Zhao, J. (2013). "Poverty impedes cognitive function." Science, 341, 976–980.

Mullainathan, S. and Shafir, E. (2013). Scarcity: The True Cost of Not Having Enough. Penguin.

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