Obesity and overweight have become a global epidemic. As a result, a wide variety of preventive measures have been implemented around the world. However, effecting changes toward healthier eating and lifestyle habits is known to be extremely difficult, especially in adulthood (Hill, 2009). For this reason, and because health status acquired during childhood has a major influence on the patterns of adult life, preventing obesity and overweight among children is a critical task.
Most interventions directed to children examine the impact of educational programs and obtain mixed results. Recent evidence indicates that results may depend on how the educational message is framed. Most of the prevention programs in health have a fear-based approach (focusing on health risks if the subject does not adopt the recommended behavior). But it is not clear whether this is the most effective approach, especially when dealing with children. Therefore, it is important to examine the influence of positive versus negative messages on children's snack choices. In this paper, we design a randomized control trial experiment that allows us to identify the impact of visual information (positive and negative) about snack quality on children's immediate snack-choices.
The experiment was carried out in October 2018 at seven elementary schools in Pamplona (Spain), involving 258 students in 4th grade (8-9 years old). Selected schools captured a wide range of the socioeconomic diversity of elementary-age children in Pamplona. Randomization was performed at the individual level. We included two treatment groups (in the positive treatment, kids were exposed to photos of a smiling emoticon surrounded by fruits; in the negative, kids were exposed to photos of an angry emoticon surrounded by unhealthy snacks), and one control group (without any visual message). Along with the visual information, kids had to choose, in private, between two snack boxes: one healthy (with fresh fruit) and another unhealthy (with cookies and similar), both of them providing the same amount of calories intake.
Data analysis shows that the average treatment effect of visual messages (either negative or positive) is not significantly different from the lack of messages (control group). However, when gender is considered, the average treatment effect of positive visual messages is significantly different from the control group, encouraging the choice of the healthy snack for girls (p<0.05), but not for boys. Negative visual information about unhealthy snacks has no effect neither on boys nor girls. Our results are robust to school characteristics, nature of snacks brought the previous day of the experiment and estimation method.
Our results suggest that fear-based messages do not work to promote healthy choices among children. We also show that girls are more receptive to positive educational messages than boys. Public health interventions directed to children in the area of nutrition should take these results into account.