Study: Kids Eat More Healthy Foods When They Pay With Cash

When people use plastic to pay for food, they make more impulse-based purchases, like ice cream, donuts and chips, compared to those who pay with cash, as I wrote here a few years ago. But the research on this effect has been done with adults. Now, this paper, to be published in the journal Obesity, has found the same effect in schoolchildren. Schools and parents may like the convenience of "no cash" card-based systems for children to pay for their lunches, it says, but those cashless systems are associated with less-healthy eating.


Authors David R. Just and Brian Wansink used data from a fine-grained Department of Agriculture study to compare lunchtime purchases of 2,314 public school children (in grades 1-12) in the United States. Of these, 725 attended schools whose lunchrooms were completely cash-free, while another 1,257 ate in cash-only lunchrooms. The remaining 311 went to schools where kids could pay either with cash or with a debit card. As the USDA study included information on the kids' recollection of what they had eaten, Just and Wansink could correlate food choices with method of payment.

They found that kids in the cash or debit-or-cash systems bought more healthy items like fruits and vegetables, and took in more calories from such items. On the other hand, kids at debit-only schools bought more total calories, and got fewer of their calories from healthy foods. The effect is not entirely consistent for each food category (for instance the 311 kids in the cash-or-debit category took in more calories from cheeseburgers than did kids in the cash-only group), but the overall pattern was that the children, like adults, eat more healthily when they have to pay cash.

In the study I wrote about in 2010, Manoj Thomas and his co-authors speculated that there's a "pain of payment" aspect to cash that hinders junk-food purchases. There is a physical hassle of digging around for coins and counting them out, which slows down the purchase and maybe lends itself to second thoughts. And there's also the emotional impact of watching your hard-earned pennies disappear. There's no such pain involved in showing a plastic card, and that makes it easier to go from impulse to purchase.

Just and Wansink don't speculate about these psychological possibilities, instead pointing to the mechanics of debit payment as a possible explanation for the contrast they found. Very few parents would give an 8-year-old $100 in twenties to spend on lunch between now and Thanksgiving. But in most debit systems, they write, parents pay up front for weeks, or even months, of meals. The familiar childhood constraints of cash (what I can buy depends on what is in my pocket) are removed. And if the money is spent more quickly than expected, it's not easy for parents to figure out that their child could have spent less if she'd stuck to the standard lunch and not the (usually junkier) a la carte food.

So the practical bottom line of the study is that school districts (who like the speediness and accounting efficiency of the cards) should make some effort to measure their effect on kids' diets. Moreover, the cash/debit contrast suggests some possible "nudges" that would help children make healthier food choices (and incidentally save parents money)—a debit-for-fruit-but-cash-for-cookies setup, for instance; or a debit system that lets parents set weekly limits on junk-food spending.

I think, though, there's also a more general take-away for those of us who are interested in how people influence each others' behavior. The questions about possible policies are often posed at a high level of abstraction. (Are debit-card payments for school lunches a Good Thing? Or a Bad Thing?) But the answers usually depend on slight variations in detail. In this case, for example, one kind of debit payment plan (monthly, no review) might encourage kids to eat more candy, while another (weekly, with reports to parents on spending) might do the opposite.

The old Rational Economic Man model taught that people make their choices consciously, with reference to coherent, never-changing preferences. It lacked something in realism but it made up for that with coherence and simplicity. There is no equivalent Post-Rational Economic Man model to predict with certainty what effect a given policy will have on people. So, as Michelle N. Meyer and Christopher Chabris point out in this smart look at "nudge" policies, the only way to find out which behavioral nudges actually work is to test them. School lunchrooms seem like a natural venue for comparing different approaches.

Just DR, & Wansink B (2013). School lunch debit cards are associated with lower nutrition and higher calories. Obesity (Silver Spring, Md.) PMID: 23929600

Thomas, M., Desai, K., & Seenivasan, S. (2010). How Credit Card Payments Increase Unhealthy Food Purchases: Visceral Regulation of Vices Journal of Consumer Research DOI: 10.1086/657331

Follow me on Twitter: @davidberreby

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Researchers hope the technology will further our understanding of the brain, but lawmakers may not be ready for the ethical challenges.

Still from John Stephenson's 1999 rendition of Animal Farm.
Surprising Science
  • Researchers at the Yale School of Medicine successfully restored some functions to pig brains that had been dead for hours.
  • They hope the technology will advance our understanding of the brain, potentially developing new treatments for debilitating diseases and disorders.
  • The research raises many ethical questions and puts to the test our current understanding of death.

The image of an undead brain coming back to live again is the stuff of science fiction. Not just any science fiction, specifically B-grade sci fi. What instantly springs to mind is the black-and-white horrors of films like Fiend Without a Face. Bad acting. Plastic monstrosities. Visible strings. And a spinal cord that, for some reason, is also a tentacle?

But like any good science fiction, it's only a matter of time before some manner of it seeps into our reality. This week's Nature published the findings of researchers who managed to restore function to pigs' brains that were clinically dead. At least, what we once thought of as dead.

What's dead may never die, it seems

The researchers did not hail from House Greyjoy — "What is dead may never die" — but came largely from the Yale School of Medicine. They connected 32 pig brains to a system called BrainEx. BrainEx is an artificial perfusion system — that is, a system that takes over the functions normally regulated by the organ. The pigs had been killed four hours earlier at a U.S. Department of Agriculture slaughterhouse; their brains completely removed from the skulls.

BrainEx pumped an experiment solution into the brain that essentially mimic blood flow. It brought oxygen and nutrients to the tissues, giving brain cells the resources to begin many normal functions. The cells began consuming and metabolizing sugars. The brains' immune systems kicked in. Neuron samples could carry an electrical signal. Some brain cells even responded to drugs.

The researchers have managed to keep some brains alive for up to 36 hours, and currently do not know if BrainEx can have sustained the brains longer. "It is conceivable we are just preventing the inevitable, and the brain won't be able to recover," said Nenad Sestan, Yale neuroscientist and the lead researcher.

As a control, other brains received either a fake solution or no solution at all. None revived brain activity and deteriorated as normal.

The researchers hope the technology can enhance our ability to study the brain and its cellular functions. One of the main avenues of such studies would be brain disorders and diseases. This could point the way to developing new of treatments for the likes of brain injuries, Alzheimer's, Huntington's, and neurodegenerative conditions.

"This is an extraordinary and very promising breakthrough for neuroscience. It immediately offers a much better model for studying the human brain, which is extraordinarily important, given the vast amount of human suffering from diseases of the mind [and] brain," Nita Farahany, the bioethicists at the Duke University School of Law who wrote the study's commentary, told National Geographic.

An ethical gray matter

Before anyone gets an Island of Dr. Moreau vibe, it's worth noting that the brains did not approach neural activity anywhere near consciousness.

The BrainEx solution contained chemicals that prevented neurons from firing. To be extra cautious, the researchers also monitored the brains for any such activity and were prepared to administer an anesthetic should they have seen signs of consciousness.

Even so, the research signals a massive debate to come regarding medical ethics and our definition of death.

Most countries define death, clinically speaking, as the irreversible loss of brain or circulatory function. This definition was already at odds with some folk- and value-centric understandings, but where do we go if it becomes possible to reverse clinical death with artificial perfusion?

"This is wild," Jonathan Moreno, a bioethicist at the University of Pennsylvania, told the New York Times. "If ever there was an issue that merited big public deliberation on the ethics of science and medicine, this is one."

One possible consequence involves organ donations. Some European countries require emergency responders to use a process that preserves organs when they cannot resuscitate a person. They continue to pump blood throughout the body, but use a "thoracic aortic occlusion balloon" to prevent that blood from reaching the brain.

The system is already controversial because it raises concerns about what caused the patient's death. But what happens when brain death becomes readily reversible? Stuart Younger, a bioethicist at Case Western Reserve University, told Nature that if BrainEx were to become widely available, it could shrink the pool of eligible donors.

"There's a potential conflict here between the interests of potential donors — who might not even be donors — and people who are waiting for organs," he said.

It will be a while before such experiments go anywhere near human subjects. A more immediate ethical question relates to how such experiments harm animal subjects.

Ethical review boards evaluate research protocols and can reject any that causes undue pain, suffering, or distress. Since dead animals feel no pain, suffer no trauma, they are typically approved as subjects. But how do such boards make a judgement regarding the suffering of a "cellularly active" brain? The distress of a partially alive brain?

The dilemma is unprecedented.

Setting new boundaries

Another science fiction story that comes to mind when discussing this story is, of course, Frankenstein. As Farahany told National Geographic: "It is definitely has [sic] a good science-fiction element to it, and it is restoring cellular function where we previously thought impossible. But to have Frankenstein, you need some degree of consciousness, some 'there' there. [The researchers] did not recover any form of consciousness in this study, and it is still unclear if we ever could. But we are one step closer to that possibility."

She's right. The researchers undertook their research for the betterment of humanity, and we may one day reap some unimaginable medical benefits from it. The ethical questions, however, remain as unsettling as the stories they remind us of.

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