The (over)consumption of calories is one of the most important determinants of the obesity problem in Europe and the United States. Governments promote the consumption of healthy alternatives and try to support consumers in making healthy choices, for instance by the introduction of the Nutritional Labeling and Education Act (NLEA) in the United States. The NLEA requires manufacturers to provide nutrition information on the packaging of food products. In a similar vein, the European Commission is working on an updated version of its regulation on food labeling, issued in December 2006. This regulation defines specific nutritional profiles which the food industry must comply with in order to bear nutrition or health claims. Hence, governments want to make sure that consumers get reliable information on food and eventually make more healthy choices. Despite these efforts, the obesity problem continues to increase in the United States and Europe.

Jonathan Wilson is a business student at Tilburg University. He has been interested in the overconsumption of food ever since he has read Brian Wansink’s famous study with the “bottomless bowls.” For this study, Wansink brought in 60 people for a free lunch and gave 22 ounce bowls of soup to half, while the other half unknowingly got 22 ounce bowls that automatically refilled as they ate (by an unseen tube under the table). The result: those eating from the bottomless bowls thought they’d eaten the same amount as people with regular bowls. They actually consumed 73% more soup. “The lesson is, don’t rely on your stomach to tell you when you’re full. It can lie,” Wansink reacted to the results of this study.

Together with his thesis supervisor, Donald Driver, Jonathan has developed a series of studies on the effects of Nutrition Labels on people’s attitudes toward the product, buying intentions, and the perceived healthiness of food products. The purpose of his latest study was to determine how the provision of objective calorie information on healthy food items influences people’s experience of hunger.

Jonathan has developed a first draft of the method section of this study, which is detailed next. The method section of a paper provides the methods and procedures used in a research study.

The experiment: predictions

We compared hunger ratings between participants who sampled a healthy food item with calorie information versus participants who sampled a healthy food item without calorie information versus a “no sample” condition. We predicted that those who eat a healthy food item in the calorie information condition will subsequently report that they feel hungrier compared to those who eat a healthy food item in the no calorie information condition or those who do not eat the sample.

Method

Participants and design . 90 undergraduate students (38 women) from Tilburg University were randomly assigned to the conditions of a 3 (food sample: healthy with calorie information vs. healthy without calorie information vs. no-sample) between-subjects design. The participants ranged in age from 18 to 37, with a median age of 22. The students received financial compensation (7 €) for their participation.

Procedure and Materials. Participants in the sampling conditions were recruited to participate in a taste test of a Muesli/granola bar that was unwrapped and contained no identifying information. Participants in the no-sample condition were invited to participate in a marketing study rating the appearance of the bar. We asked all the participants in the sampling conditions to taste a sample of the same bar. In the healthy food item with calorie information condition, participants read that they were about to taste “a new health bar containing 78 calories, high levels of vitamins and fiber, and no artificial sweeteners.” In the healthy food item

without calorie information condition, participants read that they were about to taste “a new health bar containing high levels

of vitamins and fiber, and no artificial sweeteners.” Participants in these conditions then had a 10 gram sample of the bar. Those in the no-sample condition did not complete the taste test.

Next, in order to assess the strength of the motive to fulfill their appetite, all participants rated how hungry they were at the present moment (7-point scale; 1 = not at all hungry, 7 = very hungry). Those in the no-sample condition rated their hunger but did not complete the taste test beforehand. After providing their hunger rating, they continued to rate how appealing they thought the bar was

Questions

1. Is the purpose of Jonathan’s study exploratory in nature, descriptive, or is it to test hypotheses? Explain.

2a. What is the difference between a causal and a correlational study?

2b. Is Jonathan’s study causal or correlational in nature?

3. There are various degrees of interference in research – minimal, moderate, and excessive interference. To what extent does Jonathan interfere with the normal flow of events in his study?

4a. Discuss the differences between a field study, a field experiment, and a lab experiment.

4b. What type of study is Jonathan’s study? Is it a field study, a field experiment, or a lab experiment? Explain.

4c. What is the ‘unit of analysis’ of Jonathan’s study?

5. Is Jonathan’s study cross-sectional or longitudinal in nature?