Relationship of mother and child food purchases as a function of price: a pilot study.

To our knowledge, there are no data on parental influences on child purchasing behavior of healthy or unhealthy foods. Mothers and children in ten families were given 5.00 US dollars to purchase portions of preferred fruits/vegetables and high energy-dense snack foods for each of ten trials of price manipulations. For five of the trials the price of the fruit/vegetable increased in price from 0.50 US dollars to 2.50 US dollars (in 0.50 US dollar increments), while the price of the energy-dense snack food remained constant at 1.00 US dollar. For the remaining five trials, the commodity that previously rose in price remained constant at 1.00 US dollars and the other commodity varied from 0.50 US dollars to 2.50 US dollars. Same-price elasticity was shown for both the child and parent purchases, and parent purchases were significantly related to child purchases of both healthy (regression estimate = 0.46, p < 0.001) and unhealthy (regression estimate = 0.12, p = 0.036) foods. Children's purchases of unhealthy snack food items were positively related to family socioeconomic status, and negatively related to child age. These results indicate that parental food choice and purchasing behaviors may play a role in the development of children's purchasing of both healthy and unhealthy foods.

Purchases of food in youth. Influence of price and income.

One way to increase choice of healthy over unhealthy behaviors is to increase the cost of less healthy alternatives or reduce the cost of healthier alternatives. The influence of price on purchases of healthy and unhealthy foods was evaluated in two laboratory experiments. In Experiment 1, thirty-two 10- to 12-year-old youth were given $5.00 and allowed to purchase multiple portions of a healthy food (fruit or vegetable) and a less healthy food (higher-fat snack). The price of one type of food varied from $0.50 to $2.50, while the price of the other type was held at $1.00. Increasing the price of a type of food reduced purchases of that type of food, but did not lead to substitution with the alternative type of food. In Experiment 2, twenty 10- to 14-year-old youth were given $1.00, $3.00, and $5.00 to purchase healthy and unhealthy foods. The price of each food was raised and lowered by 25% and 50%. Raising the price of healthy or unhealthy foods resulted in decreased purchases of those foods, and income available interacted with price to predict the pattern of substitution of alternative foods. These results show the potential for controlled laboratory studies of price and food purchases, and show that the substitution of healthier for unhealthy food is related to available money.

The value of sedentary alternatives influences child physical activity choice.

The choice to be physically active or sedentary depends in part on the value of the alternatives that are available. The shift from sedentary to active alternatives may be a function of the value of the sedentary alternatives. To evaluate the influence of the value of the sedentary alternatives on the choice to be physically active or sedentary, 30 nonobese 8-12-year-old youth were randomized in groups that provided a choice between 4 active alternatives or 4 sedentary alternatives (Group 1), their least valued sedentary activity (Group 2), or their most valued sedentary activity (Group 3), on computerized and questionnaire versions of a behavioral choice task. The computer task required participants to work for access to the alternatives. The work required to obtain access to the active alternatives remained constant for all choices, while the work required to gain access to the sedentary alternatives progressively increased. Compared to Groups 1 and 3, participants in Group 2 chose to be sedentary less often as they had to make a choice between being physically active or sedentary on the computerized (p < .005) and the questionnaire version (p < .05) of the behavioral choice task, which correlated r = .54, p < .01. These results suggest interventions designed to increase physical activity by reducing access to sedentary behaviors may need to consider the value of the targeted sedentary behavior and the extent to which the sedentary behaviors compete with physical activity.

Habituation of salivation and motivated responding for food in children.

Repeated presentation of food cues results in habituation in adults, as demonstrated by a decrement in salivary responding that is reversed by presenting a new food cue in adults. Food reinforced behavior in animals shows the same pattern of responding, with a decrease in responding to obtain the food, followed by a recovery of responding when a new food is presented. The present study assessed whether children would show the same pattern of a decrement of food reinforced responding followed by recovery of responding when a new food is presented for both salivation and food reinforcement tasks. Subjects were assigned to one of two groups that differed in the trial that the new food stimulus was presented to ensure recovery was specific to the introduction of the new food stimulus. In the salivation task, subjects were provided repeated olfactory presentations of a cheeseburger with apple pie as the new food stimulus, while in the food reinforcement task subjects worked for the opportunity to consume a cheeseburger, followed by the opportunity to work for consumption of apple pie. Subjects in both groups showed a decrement in salivary and food reinforced responding to repeated food cues followed by immediate recovery of responding on the trial when a new food was presented. Subjects increased their energy intake by over 30% in the food reinforcement task when a new food was presented. These results are consistent with the general process theory of motivation that suggests that changes in food reinforced responding may be due in part to habituation.