Cash or Credit? The Psychoeconomics of Childhood Obesity

It seems that debit card purchases promote the same type of frivolity in children as in adults, but when cards are swiped to pay for school lunches, the impact goes deeper than just free spending. Kids’ food choices also become foolish, according to a study that appeared in the January issue of Obesity (2014; 22 [1], 24–26).

Cornell behavioral economists David Just, PhD, and Brian Wansink, PhD, studied more than 2,300 students in grades 1–12 at 287 schools across the country and discovered a surprising trend among kids who used a debit card instead of cash to buy their lunches. The debit card sample routinely made less healthful food selections than their cash-wielding counterparts.

“Across 1,036 students, the average purchase incidence for healthy food items was greater for schools with debit/cash systems versus debit-only (42% vs. 31%,),” the study authors said. “Specifically, debit/cash schools—as compared to debit-only schools—purchased more fresh fruits (47% vs. 31%); fresh
vegetables (31% vs. 11%); all fruits (62% vs. 51%); and all vegetables (53% vs. 35%). Furthermore, students from debit/cash schools consumed marginally fewer total calories (752 vs. 721) than those from debit-only schools. These results are independent of gender, age, BMI, height, race, and income.”

Importantly, said Just and Wansink, these results suggest that payment systems may be a potentially overlooked means of guiding food selection in schools. “If the use of cash versus credit or debit cards can nudge a student into making slightly healthier choices, there may be a wide range of interventions—such as a “cash for cookies” policy—that encourages students to think twice before making their selection,” concluded the researchers. “More work, including experimental studies, is needed to examine the long-term impacts of various debit systems on student purchases and determine whether this association is causal in nature.”