MARY LOUISE KELLY, HOST:
Poor families who rely on food stamps often find themselves caught in a familiar cycle. In the days after they receive the benefit each month, there's plenty of food on the table. But as the weeks tick away, food becomes scarce. Here with some new research on the consequences of this monthly cycle is NPR's social science correspondent Shankar Vedantam. Good morning.
SHANKAR VEDANTAM, BYLINE: Hi, Mary Louise.
KELLY: Hi. This new research, I gather, it focuses on the link between food stamps and academic performance. How so?
VEDANTAM: That's right. This work comes from Orgul Ozturk, she's an economist at the University of South Carolina, along with her colleagues, Chad Cotti, and John Gordanier. They find that children who come from families that are several weeks removed from receiving their food-stamp benefits perform worse on an important math exam.
ORGUL OZTURK: We find that when the test date happens to be very far away from the receipt date, students score much lower, significantly lower on the mathematics test.
KELLY: It seems like it kind of makes sense, that if you're hungry you can't concentrate so you might test lower. How do they know, though, that this is the food-stamp cycle, that that's what's responsible?
VEDANTAM: Well, it has to do with two quirks in the way the food-stamp program is administered in South Carolina. Recipients receive benefits on the first 10 days of the month. Some families get it on the first, some on the second and so on. Simultaneously, children in grades three through eight also have to take an annual math exam on the second Wednesday of May. Now, the second Wednesday of May falls on different dates each year. So if your family received food stamps on the 10th of April, for example, and the exam falls on the 8th of May, you're likely to have gone hungry for several days before you took the test.
KELLY: And to be clear, people don't all get their food stamps on the same day. It's...
KELLY: ...Scattered around the month.
VEDANTAM: Exactly. Now, on the other hand, if your family received food stamps on the 2nd of May and the test is on the 8th of May, you've probably eaten well in the days before the test. The researchers not only compared kids who've eaten well to kids who are hungry, they also compare the math performance of kids who've eaten poorly to their own math performance in another year when they've eaten well. Ozturk told me that while her study measures the effect of being hungry on one math test, this is a monthly cycle, meaning that the real effects are likely to be much larger.
OZTURK: This is happening to these kids every month over the course of nine months. It adds up. What we are measuring is a reduction in performance that month. But they are hungry every single month. The cumulative effect is very significant.
KELLY: Shankar, can researchers control whether this is in fact food? It seems like they're clear on the link to food stamps, but if food stamps are running out maybe the parents are stressed, there's stress in the household and that's what kids are reacting to?
VEDANTAM: That's a fair point, Mary Louise. We know that there's a relationship between food stamps and math performance. We don't know specifically if it's about food or just because the family as a whole is stressed and the kids in some ways are reacting to that stress.
KELLY: So what's the implication here? Might it be better to, say, distribute food stamps more frequently?
VEDANTAM: So that's an idea that some people are thinking about, and it's an intriguing idea. If you can distribute the benefit twice a month, perhaps you can smooth-out the cycle. But it's the kind of thing that needs to be tested because you could have unintended consequences, and now instead of students being hungry once a month they're going to end up being hungry twice a month.
KELLY: Which is clearly not the direction that you would want to go.
KELLY: That's NPR's Shankar Vedantam. Shankar, thank you.
VEDANTAM: Thank you, Mary Louise.
KELLY: He joins us regularly to talk about social science research. You can follow him on Twitter at @hiddenbrain. You can follow me at @nprkelly, and you can follow this program at @morningedition. Transcript provided by NPR, Copyright NPR.