First come, first served. Does pouring sequence matter for consumption?

First come, first served. Does pouring sequence matter for consumption?

Appetite 105 (2016) 731e736 Contents lists available at ScienceDirect Appetite journal homepage: First come, first ser...

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Appetite 105 (2016) 731e736

Contents lists available at ScienceDirect

Appetite journal homepage:

First come, first served. Does pouring sequence matter for consumption? Nanette Stroebele-Benschop*, Anastasia Dieze, Carolin Hilzendegen Institute of Nutritional Medicine, Department of Nutritional Psychology, University of Hohenheim, Fruwirthstr. 12, 70593 Stuttgart, Germany

a r t i c l e i n f o

a b s t r a c t

Article history: Received 30 March 2016 Received in revised form 6 July 2016 Accepted 7 July 2016 Available online 11 July 2016

Various environmental factors associated with eating and drinking affect people’s food choice and food intake. Lately, the role of tableware has been studied in more detail. The aim of this study was to determine whether pouring sequence of food components affects portion size. Study 1 invited participants to pour a beverage containing both apple juice and sparkling water. Pouring apple juice first increased juice by almost 25% compared to pouring water first. Pouring water first increased water by almost 19% compared to pouring juice first confirming our hypothesis that pouring sequence affects the ratio poured. Study 2 asked participants to prepare themselves a snack containing cereals with milk. Within-subject comparisons revealed that pouring milk before cereals significantly increased both milk and cereal amounts resulting in larger overall portion size compared to pouring cereals before adding milk. Habitual tendencies for preparing foods causing a perception bias or a perception bias itself could be possible explanations for the divergent study findings. These findings show for the first time the influence of pouring and preparation sequence on portion size. © 2016 Elsevier Ltd. All rights reserved.

Keywords: Pouring sequence Eating behavior Snack Food preparation

1. Introduction Many environmental variables have been shown to influence our daily eating behavior (Stroebele & de Castro, 2004; Wansink, 2004a). Over the last two decades, research both in the real world as well as in experimental settings have found various ambient factors such as: plate shapes, package size, ambient cor coloring or convenience that appear to influence lighting, de people’s food choices and consumption (Wansink, 2004a, 2006). The impact of these factors seems to be mainly attributed to mindless eating (Wansink, 2006). Mindless eating describes the impact of environmental cues on people’s daily eating behavior; which is often unknown to the consumer (Wansink, 2004b). Wansink and his colleagues revealed an array of normative factors that impact our daily eating behavior in a rather subtle and unconscious matter. Besides the well-known portion size effect studied by many researchers (for a review see Hollands et al., 2015), research has also shown that the larger the plate, spoon, cup or bowl size, the more food or fluid is consumed irrespective of hunger

* Corresponding author. E-mail addresses: [email protected] (N. Stroebele-Benschop), [email protected] (A. Dieze), [email protected] (C. Hilzendegen). 0195-6663/© 2016 Elsevier Ltd. All rights reserved.

(Wansink & van Ittersum, 2013; Wansink, van Ittersum, & Painter, 2006) or even taste (Wansink & Kim, 2005). Furthermore, short and wide glasses promote more drinking than high and narrow glasses (Wansink, van Ittersum, & Payne, 2014). Even the opening size of a beer bottle seems to influence how much a person drinks (Wansink, 1996). Differences in spoon material, for instance using either plastic or metal, influences taste perception and perception of food quality (Piqueras-Fiszman, Laughlin, Miodownik, & Spence, 2012). Moreover, spoons varying in weight also affect both taste and food quality perception (Harrar & Spence, 2012). In general, dishware and food color (Harrar, Piqueras-Fiszman, & Spence, 2011; Piqueras-Fiszman, Alcaide, Roura, & Spence, 2012; Spence, Levitan, Shankar, & Zampini, 2010), dishware material (Ariely, 2008; Piqueras-Fiszman & Spence, 2011; Spence, Harrar, & Piqueras-Fiszman, 2012) or plate rim widths and coloring (McClain et al., 2014) can affect food choice, palatability and intake. Mindless consumption of food is affected by sensory cues such as hunger, palatability or scent; by emotional drivers including affect valence or stress; and by normative cues (Wansink & Chandon, 2014). Consumption norms often determine how much one should eat. People tend to rely on packages, portions and dinnerware as consumption norms without being aware of its influence. Even when made aware of it, people still served themselves more from larger packages and plates (Vartanian, Herman, & Wansink, 2008).


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Making changes to tableware that is associated with consumption norms and exposing people to convenient, attractive and new norms has already revealed promising results in regards to the consumption of healthier food choices (Wansink & Chandon, 2014; Wansink, 2015). These normative cues are starting to be of interest to public health professionals given that they are fairly easy to change in every day eating environments such as home, work or school (Wansink & Hanks, 2013; Wansink, Hanks, & Kaipainen, 2015). However, a recent meta-analysis showed only marginal increases in food intake using large versus small dishware (Robinson et al., 2014) and the authors cautioned to make recommendations regarding dishware or plate size before its influence on food intake is better understood. So far, to our knowledge, one aspect of the handling of food that has not yet been studied is the pouring sequence of different food components. Mindless eating starts with people’s habits. One of those habits includes meal preparation and, more general, food and fluid preparation. In other words, how we prepare food is often habitual and unconscious, e.g. in which order we mix drinks or how we add fluids to solid foods. The aim of these two small-scale studies therefore was to examine whether changing the habitual pouring sequence of a beverage and the pouring sequence of a solid food with fluids would impact the amount poured. In a study by Wansink and Hanks (2013), the influence of two different food order arrangements in a buffet line was examined. The results showed that the order that food was presented to people influenced what foods were selected. The first foods a person encountered in the buffet line were significantly more likely to be selected than the foods encountered at the end of the buffet line. Thus, in our study it was hypothesized that the component poured first would be larger than the following component. 2. Materials and methods 2.1. Study 1 For the first study, conducted in the fall of 2015, participants were asked to pour themselves a popular German beverage containing both apple juice and sparkling water before taking part in an experimental feeding study not reported here. The participants were invited to consume the beverage during the experimental study but the main aim of this procedure was to examine and record their pouring behavior. When diluting juice, most people tend to start with the juice which is considered the main component of the mixed beverage. The tested hypothesis therefore was that participants would pour more juice when asked to pour juice first compared to pouring juice after pouring sparkling water. 2.1.1. Subjects The participants were university students recruited via posted advertisements, flyers, a social networking site (Facebook) and the online newsletter of the University of Hohenheim, Germany. Criteria for inclusion in the study were being a student (either at the University of Hohenheim or at the University of Stuttgart), being 18e30 years old and speaking German. Students were not recruited if they had food allergies (i.e., intolerances towards foods offered in the feeding study) or studied nutritional sciences in order to avoid bias caused by their potential knowledge regarding mindful eating behavior. Before starting the experiment, participants signed an informed consent and were entered in a raffle to win a semester train ticket as an incentive for their participation. The study protocol was approved by the University of Hohenheim ethical committee and agreed with the Helsinki Declaration.

2.1.2. Procedures Before the beginning of the actual study, students were seated in a medium sized room set at a constant average temperature of 23  C in one of six comfortable lounge chairs with an adjacent small table and asked to complete a demographic questionnaire including age, gender, self-reported height and weight. Afterwards, participants were instructed to pour themselves a popular German non-alcoholic beverage called “apple juice schorle” in a 250 ml glass out of carafes positioned on the small tables. The beverage was offered to be consumed during a video show (which was part of the other study) in the event they would become thirsty. The beverage consisted of a mixture of apple juice and sparkling water. Participants were randomized into either starting with sparkling water or with juice which were made available in two separate carafes (500 ml) containing 430 ml apple juice and 430 ml sparkling water. No information in regards to pouring order was provided. Participants were told that due to “study procedures” they should pour the component already positioned on the coffee table first. After pouring the first component, research personnel replaced the first carafe with the second carafe (depending on randomization group) and carried the carafe with the remaining liquid out of the room. Both carafes were weighted before and after pouring and the amount poured was recorded. 2.1.3. Statistical analyses Main outcomes of the study were the ratio and amount of poured apple juice and sparkling water. The grams of the consumed drinks where determined by subtracting pre- and postconsumption weight of the carafes. The comparison of single components for the different pouring orders was made using independent t-tests. Due to the left-skewed distribution for analyzing the total amount of “schorle” in the two groups, a Mann-Whitney-U-Tests was conducted. Pearson’s chi2 and independent t-tests were used to compare the baseline characteristics of both groups. Means ± SD are presented in the text and tables. Statistical significance level was set at p < 0.05. Statistical tests were carried out using IBM Statistic SPSS for Windows, version 22.0. 2.1.4. Results A total of 155 students (64.8% women and 35.2% men) participated in the study. Mean age was 22.03 ± 2.80 (range: 18e36 years) and mean BMI was 22.53 ± 3.31 (range: 16.85e37.50). Participants’ characteristics did not differ between the two randomization groups. There was no significant difference between the two groups in regard to the total amount of prepared “schorle” (264.32 g ± 24.20 vs. 260.83 g ± 24.90, U ¼ 5649.5, p ¼ 0.319). The overall mean ratio of apple juice and sparkling water for the group that poured apple juice first was 1:0.91 while the group pouring sparkling water first had a ratio of 1:1.35 which shows that pouring water first slightly increased total water amount. Table 1 presents amount poured under the two pouring sequence conditions. A significant pouring effect was revealed. Those pouring apple juice first poured significantly more apple juice (138.2 ± 36.3 g; 24.54% more) compared to subjects pouring apple juice as the second beverage component (111 ± 37.2 g, t ¼ 4.613, p < 0.001). Similarly, subjects that poured sparkling water first poured 18.83% more sparkling water (149.9 ± 38.8 g) compared to subjects pouring sparkling water as the second beverage component (126.1 g ± 35.7 g, t ¼ 3.963, p < 0.001). 2.2. Study 2 The second study, also conducted during the fall of 2015,

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Table 1 Beverage components poured under the two pouring sequence conditions.


Apple juice e Sparkling water 79

Sparkling water e Apple juice 76



Apple juice grams % Sparkling water grams %

138.20 ± 36.29 52.28 ± 12.60

110.97 ± 37.20 42.49 ± 13.91

4.613 4.596

<0.001 <0.001

126.11 ± 35.73 47.72 ± 12.60

149.86 ± 38.84 57.51 ± 13.91

3.963 4.596

<0.001 <0.001

Total amount of “schorle” grams

263.32 ± 24.20

260.83 ± 24.90

U 2735.50

p 0.315

examined whether pouring sequence of a combination of fluid and solid foods would influence the amount poured (and ultimately consumed) using a within-subject design. Participants were invited to prepare themselves a snack with either corn flakes or muesli with milk before filling out a paper-pencil concentration test which was used as the pretense of the experiment. The official aim of the study was to examine the influence of two different types of cereals with milk (muesli vs. corn flakes) on concentration in a student sample. To reduce the influence of larger individual differences in snack size preference between participants, a within-subject design was chosen. It was assumed that based on the results of study 1, participants would add less of the second component compared to the first component. Since people usually start with the solid food such as muesli or corn flakes when preparing cereals with milk, it was hypothesized that starting with milk would result in less cereals poured (and subsequently consumed). 2.2.1. Subjects Again, the participants were university students recruited via the same channels mentioned above. This time, students were asked to participate in a study looking at the influence of snack consumption on concentration. In addition to the above mentioned inclusion criteria in study 1, participants in this study were asked not to eat anything 2 h prior to the beginning of the experiment to avoid being full. Before the scheduled appointment, students could pick their snack type which was either a muesli containing 78,9% of whole grain oats, 15% of raisins, and 6.1% of nuts (384 kcal per 100 g) or regular corn flakes (371 kcal per 100 g) with milk (3.5% fat, 69 kcal per 100 g). Participants signed an informed consent before the beginning of the experiment and were entered in a raffle to win a semester train ticket as an incentive for their participation. The study was also approved by the ethical committee of the University of Hohenheim and agreed with the Helsinki Declaration. 2.2.2. Procedures Once seated in a medium sized room (room temperature was set at 23  C) in one of six cubicles that shielded the participants from each other, students were asked to complete the demographic questionnaire. Afterwards, participants were informed that after snack consumption, they would be asked to fill out a series of five brief concentration exercises (e.g. mental arithmetic, letter/number identification out of rows of letters/numbers) that would last approximately 10 min. Students were asked to return to the laboratory for another series of five concentration exercises following the same procedures within seven to ten days. Depending on randomization order, students either poured milk or cereals into a bowl (volume of 400 ml) first before adding the second component during their first visit and for the second visit, the pouring sequence was reversed accordingly.

The food and liquid components were offered separately and taken away before instructing to pour the other component. Milk was served in a 500 ml carafe (containing 400 g of milk) while muesli and corn flakes were offered in a 5 L container (containing 400 g of muesli or 250 g of corn flakes). Research personnel recorded the amount poured for each component and calculated the amount consumed by adding both components and considering left-overs where applicable. After having poured both components into the bowl, students were asked to eat their snack. Once finished, they were allowed to start with the concentration test. 2.2.3. Statistical analysis Main outcome of the study was the amount of cereals and milk prepared by the participants, depending on the pouring order. Energy per grams of the cereals was determined using manufacturers’ information. Since the dependent variable was right-skewed, comparisons between the two pouring orders were made using Wilcoxon Signed-Rank-Tests. Baseline characteristics were analysed with independent t-Tests and Pearson’s chi2. Means ± SD are presented in the text and tables. Statistical significance level was set at p < 0.05. Statistical tests were carried out using IBM Statistic SPSS for Windows, version 22.0. 2.2.4. Results A total of 77 students (26 men and 51 women) participated in the study with a mean age of 23.77 ± 2.66 years (range: 18e31 years) and a mean BMI of 22.71 ± 3.40 (range: 16.81e37.11). The majority of participants chose muesli over corn flakes (67.5% vs. 32.5%). Regarding the characteristics of the two study groups, no significant differences were found. Sample characteristics are reported in Table 2. Results showed that, contrary to our hypothesis that pouring milk first would lead to less cereals poured, participants poured not only more milk (Z ¼ 1.814, p ¼ 0.070) but also over 10% more cereals (Z ¼ 2.037, p ¼ 0.042) when asked to pour milk first (see Fig. 1). The overall amount of the prepared snack was almost 9% larger when milk was poured first compared to the usual pouring sequence of cereals followed by milk (Z ¼ 2.115, p ¼ 0.034). Results differed for snack type. For muesli, the amount of cereals and milk and consequently the total amount where higher when milk was poured first (Fig. 2). The difference was significant only for milk (Z ¼ 2.500, p ¼ 0.012) and total amount (Z ¼ 2.614, p ¼ 0.009). Given the small number of participants choosing corn flakes as cereal component, no significant differences were found. Generally, participants used more gram of cereals when they prepared their snack with muesli (67.83 g ± 28.43) compared to the participant who prepared cornflakes (27.82 g ± 12.99) which is attributable to the weight and volume differences of the two types of cereals. The same results were found for caloric consumption which was


N. Stroebele-Benschop et al. / Appetite 105 (2016) 731e736 Table 2 Study sample characteristics.

N Gender Male Female Body measurements in males Weight (kg) Height (cm) BMI Body measurements in females Weight (kg) Height (cm) BMI Age (in years) Snack type Muesli Corn flakes

Cereal-milk/Milk-cereal condition 39

Milk-cereal/Cereal-milk condition 38

12 27

14 24

81.88 ± 11.73 184.00 ± 7.08 24.12 ± 2.71

76.68 ± 9.25 179.21 ± 4.28 23.90 ± 3.02

62.35 ± 10.54 167.04 ± 6.48 22.34 ± 3.70 24.13 ± 2.47

62.71 ± 12.94 169.42 ± 5.85 21.73 ± 3.31 23.39 ± 2.81

30 9

22 16

3. Discussion

Fig. 1. Amount in gram (with SEM) by pouring order for the entire sample (n ¼ 77).

Study 1 confirmed our hypothesis that pouring sequence affects the ratio poured. As already proposed by Wansink and Hanks (2013), food order appears to influence food intake. Thus, whichever component was offered first, was poured more in amount than the following component. In the case of juice and sparkling water, pouring sparkling water first increased its volume and reduced the juice volume significantly. The liquid calories of the beverage reduced from around 64 calories to around 52 calories which equals a reduction in calories of about 20%. For overall daily intake, a reduction of 12 calories might seem insignificant. However, since many adults gradually gain weight due to only small daily differences between energy intake and energy expenditure (Hill, 2009; Hill, Peters, & Wyatt, 2009; Hills,

Fig. 2. Amount in gram (with SEM) by pouring order comparing the two types of cereals.

calculated by using the nutrition information provided by the manufacturer. Pouring sequence also revealed a significant difference of 9% with more calories consumed when pouring milk before cereals (291.96 ± 132.22 versus 319.60 ± 157.22 calories, Z ¼ 2.125, p ¼ 0.034).

Byrne, Lindstrom, & Hill, 2013), even small calorie savings appear to determine whether body weight stays stable or increases slightly but continuously over the years. Therefore, changing the pouring sequence of mixed beverages by pouring the non-caloric liquid first could become another ‘small-changes’ strategy to maintain daily

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energy balance. However, whether this effect is affected by habituation has not been determined and needs to be examined further. When looking at the relationship between pouring sequence of cereals with milk in study 2 using a within-subject design, the results seem to indicate a more complex process. Pouring milk first significantly increased both milk and cereal amounts compared to the usual pouring sequence of cereals before milk. This pouring sequence effect also led to larger portion size and higher consumption. Various conclusions are probable. First, it is possible that the order effect of study 1 only applies to liquids or food components with similar consistency. To the authors’ knowledge, no studies looking at order sequence of food components with similar consistency are available yet to strengthen this conclusion. Other explanations might also be possible for the divergent study findings. For instance, pouring the uncustomary snack component first, in this case milk, might have disturbed the perception of preferred consumption ratio. These proportion preferences appear to affect amount poured and consequently intake. The basic process of perception is influenced by people’s habits (Segall, Campbell, & Herskovit, 1968,chap. 14; Commins et al., 2013) and people tend to pour their cereals first before adding milk (a fact that was confirmed by a brief online survey of over 100 students of three different German universities). Individual consumption preferences also exist in regards to many other food components, such as the amount of butter on bread, the amount of milk in coffee or the amount of gravy over meat. Thus, the participants might have overestimated the amount of milk that they usually pour and, as a result, also added more cereals. Besides habitual tendencies for preparing foods, the type and size of dinnerware (e.g. transparent to better determine ratios) to avoid perception bias or the type of food used (solid with liquids, solids with solids) can all be partly responsible or the only reason for the found effect of pouring sequence on consumption. 3.1. Study limitations First, it needs to be pointed out that this was a convenience sample of students from two local German universities and therefore the results cannot be generalized to the general population. Secondly, the results of both studies were obtained under experimental conditions and results might be different when applied to real world settings. In addition, study 2 might have yielded stronger results with more enrolled participants, especially since the standard deviations found revealed large between subject variations. However, the conducted sample size calculation assuming a difference of 10% (50 vs. 55 g) with a standard deviation of 15 g (based on study 1 and previous research (Kaiser, Silberberger, Hilzendegen, & Stroebele-Benschop, 2016)), a power of 0.8 and a significance level of 0.05, revealed a necessary sample size of 77 participants. Nevertheless, power was reduced considerably since the standard deviation was higher than expected with over 50% of the mean. Certainly, conclusions in regards to other types of food and liquid components need to be made with caution. Different types of beverage combinations, including e.g. alcoholic beverages, or different food structures (e.g. corn flakes versus oats) should be tested. Further research in determining underlying mechanisms for these findings is needed. It would be interesting to find out whether the combination and pouring sequence of two solid food components such as fruit or cereals with yogurt might led to different study results. 4. Conclusions To our knowledge, this is the first study to look into the influence of pouring sequence on consumption. Given the abundance of


possible explanations for the findings, more research in this area is needed. More research might reveal that order is mainly the key contributor to differences when pouring liquids such as water and juice or coffee with milk, potentially regardless of one’s habits. Whereas for food components varying in texture, biased perception in combination with habituation or alone might be more likely explanations for the found differences in pouring sequence. Nevertheless, various studies indicate that promoting small and rather unconscious changes to the environment or individuals’ behavior by making healthy foods appear more convenient, attractive and normative to choose might lead to healthier food choice habits in the long term (Just & Wansink, 2009; Hanks, Just, & Wansink, 2013; van Kleef, Otten, & van Trijp, 2012; Hanks, Just, Smith, & Wansink, 2012; Wansink & Hanks, 2013; Wansink, Just, Payne, & Klinger, 2012; Wansink, Payne, & Shimizu, 2011). Given our results, pouring sequence could become another consumption norm such as package or serving size, visual salience, labeling or sequence of exposure (Wansink & Chandon, 2014; Wansink & van Ittersum, 2013; Wansink, 2015) that has the potential to affect and change consumer behavior. However, more research in this unexplored area is necessary, e.g. by exploring different food and fluid components and combinations and by applying the experimental findings to public health approaches. References Ariely, D. (2008). Predictably irrational: The hidden forces that shape our decisions. London: Harper Collins Publishers. Commins, S., McCormack, K., Callinan, E., Fitzgerald, H., Molloy, E., & Young, K. (2013). Manipulation of visual information does not change the accuracy of distance estimation during a blindfolded walking task. Human Movement Science, 32, 794e807. Hanks, A. S., Just, D. R., Smith, L. E., & Wansink, B. (2012). Healthy convenience: Nudging students toward healthier choices in the lunchroom. Journal of Public Health, 34(3), 370e376. Hanks, A. S., Just, D. R., & Wansink, B. (2013). Smarter lunchrooms can address new school lunchroom guidelines and childhood obesity. Journal of Pediatrics, 162(4), 867e869. Harrar, V., Piqueras-Fiszman, B., & Spence, C. (2011). There’s s more to taste in a coloured bowl. Perception, 40(7), 880e882. Harrar, V., & Spence, C. (2012). A weighty matter: The effect of spoon size and weight on food perception. Seeing and Perceiving, 25(0), 199. Hill, J. O. (2009). Can a small-changes approach help address the obesity epidemic? a report of the joint task force of the american society for nutrition, institute of food technologies, and international food information council. The American Journal of Clinical Nutrition, 89(2), 477e484. Hill, J. O., Peters, J. C., & Wyatt, H. R. (2009). Using the energy gap to address obesity: A commentary. Journal of the American Dietetic Association, 109(11), 1848e1853. Hills, A. P., Byrne, N. M., Lindstrom, R., & Hill, J. O. (2013). ’Small changes’ to diet and physical activity behaviors for weight management. Obesity facts, 6(3), 228e238. Hollands, G. J., Shemilt, I., Marteau, T. M., Jebb, S. A., Lewis, H. B., Wei, Y., et al. (2015). Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco. The Cochrane Database of Systematic Reviews, 9, 1e387. Just, D. R., & Wansink, B. (2009). Better school meals on a budget: Using behavioral economics and food psychology to improve meal selection. Choices, 24(3), 1e6. Kaiser, D., Silberberger, S., Hilzendegen, C., & Stroebele-Benschop, N. (2016). The influence of music type and transmission mode on food intake and meal duration: An experimental study. Psychology of Music, 1e12. van Kleef, E., Otten, K., & van Trijp, H. C. (2012). Healthy snacks at the checkout counter: A lab and field study on the impact of shelf arrangement and assortment structure on consumer choices. BMC Public Health, 12, 1072. McClain, A., van den Bos, W., Matheson, D., Desai, M., McClure, S. M., & Robinson, T. N. (2014). Visual illusions and plate design: The effects of plate rim widths and rim coloring on perceived food portion size. International Journal of Obesity (London), 38(5), 657e662. Piqueras-Fiszman, B., Alcaide, J., Roura, E., & Spence, C. (2012). Is it the plate or is it the food? Assessing the influence of the color (black or white) and shape of the plate on the perception of the food placed on it. Food Quality and Preference, 24(1), 205e208. Piqueras-Fiszman, B., Laughlin, Z., Miodownik, M., & Spence, C. (2012). Tasting spoons: Assessing the impact of the material of the spoon on the taste of the food. Food Quality and Preference, 24(1), 24e29. Piqueras-Fiszman, B., & Spence, C. (2011). Crossmodal correspondences in product packaging. Assessing coloreflavor correspondences for potato chips (crisps). Appetite, 57(3), 753e737.


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