Menu-engineering in restaurants - adapting portion sizes on plates to enhance vegetable consumption: a real-life experiment.

BACKGROUND: The aim of this research was to investigate whether increased portion sizes of vegetables and decreased portion sizes of meat on main dishes increased the amount of vegetables consumed in a real-life restaurant setting without affecting customer satisfaction. The participants were unaware of the experiment. METHODS: A cross-over design was used in which three restaurants were randomly assigned to a sequence of an intervention and control condition. In the intervention period, the vegetable portion sizes on the plates of main dishes were doubled (150 g of vegetables instead of 75 g) and the portion sizes of meat on the plates were reduced by an average of 12.5%. In the control period, the portion sizes of the main dishes were maintained as usual. In total, 1006 observations and questionnaires were included. RESULTS: Vegetable consumption from plates was significantly higher during the intervention period (M = 115.5 g) than during the control period (M = 61.7 g). Similarly, total vegetable consumption (including side dishes) was significantly higher during the intervention period (M = 178.0 g) than during the control period (M = 137.0 g). Conversely, meat consumption was significantly lower during the intervention period (M = 183.1 g) than during the control period (M = 211.1 g). Satisfaction with the restaurant visit did not differ between the intervention period (M = 1.27) and control period (M = 1.35). Satisfaction with the main dish was significantly lower during the intervention period (M = 1.25) than during the control period (M = 1.38), although in both cases, the scores indicated that participants remained (very) satisfied with their main dish. CONCLUSIONS: This study showed that increasing vegetable portions in combination with decreasing meat portions (unknowingly to the consumer) increased the amount of vegetables consumed and decreased the amount of meat consumed. Furthermore, despite the changes in portion sizes, participants remained satisfied with their restaurant visit and main dish. The findings of this study suggest that modifying portion size in restaurants is an effective tool for stimulating vegetable consumption and consequently healthy and sustainable diets.

An In-Store Experiment on the Effect of Accessibility on Sales of Wholegrain and White Bread in Supermarkets.

Even though whole grain foods have various health benefits, consumers have been found not to eat enough of them. Nudging interventions are built on the premise that food purchases and consumption are strongly influenced by the environment in which decisions are made. Little research has been conducted to examine the influence of a small and inexpensive nudging intervention on bread choices in a real-life supermarket context. An in-store experiment was conducted in two six-week periods in two supermarkets to investigate the effects of accessibility on consumers' purchase of healthier whole grain and other types of bread. In the high accessibility condition, healthier bread was placed in a more convenient location for the shopper on the left side of the shelves where it was encountered first. In the low accessibility condition, it was placed on the right side. There were consistent significant differences in sales between supermarkets, types of bread, day of the week, but not between low and high accessibility. Additional research is needed to better understand the effects of convenience and accessibility on bread choices.

Prosocial consequences of imitation.

Research has shown that helping behavior can be primed easily. However, helping decreases significantly in the presence of inhibition cues, signaling high costs for the executor. On the other hand, multiple studies demonstrated that helping behavior increases after being mimicked. The present study investigated whether imitation still increases helping when more substantial costs are involved. Helping behavior was operationalized as the willingness to accompany the confederate on a 15-20 minute walk to the train station. Results show that even in the face of these high costs, participants who were mimicked agreed more often to help the confederate than participants who were anti-mimicked. These findings suggest that mimicry not only makes people more helpful when it comes to small favors, but also allows them to ignore the substantial costs possibly involved in helping others.