Habit formation in Children: Evidence from Eating Fruits and Vegetables

We present findings from a field experiment conducted at 40 elementary schools, which tested whether the duration of time that an eating behavior has been modified affects the strength of habit formation.  Over a three week or five week period, students received an incentive for eating a serving of fruits or vegetables as part of their school provided lunch.  Relative to an average baseline rate of 38.7%, during the intervention the fraction of children eating at least one serving of fruits or vegetables rose to 78.2%. Two months after the end of the intervention, the consumption rate at schools 21% above baseline for the three-week treatment and 44% above baseline for the five week treatment.  These findings support the prediction that longer interventions are associated with stronger habit formation.