Increasing vegetables purchase with a descriptive-norm message: A cluster randomized controlled intervention in two...

Area of Science:

• Behavioral Economics
• Public Health Nutrition
• Social Psychology

Background:

• Social norms are frequently utilized to encourage healthier food choices.
• Previous research suggests descriptive norm messages can influence behavior, but their robustness requires further investigation.

Purpose of the Study:

• To assess the impact of a vegetable-focused descriptive norm message on vegetable purchasing behavior in a real-world setting.
• To examine whether such messages influence not only the choice but also the quantity of vegetables consumed.

Main Methods:

• A cluster randomized crossover design was employed across two university canteens.
• A vegetable-related descriptive norm message was compared against a neutral-behavior message.
• Data on vegetable portion selection and quantity purchased were collected from 12,994 lunch servings.

Main Results:

• The vegetable-related norm message significantly increased the probability of selecting vegetables, unlike the control message which saw a decrease.
• Individuals exposed to the vegetable norm message purchased a greater quantity of vegetables compared to the baseline.
• Conversely, vegetable quantity purchased declined in the control condition.

Conclusions:

• Descriptive norm messages are effective in promoting sustained healthy food choices, specifically increasing vegetable consumption.
• These findings support the use of social norm interventions to enhance healthier eating behaviors in food service environments.