Sensory-Specific Satiety, the Variety Effect and Physical Context: Does Change of Context During a Meal Enhance Food Intake?

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An extensively studied aspect of eating behaviour is sensory-specific satiety (SSS). SSS refers to a decline 1986; Rolls, Rolls, Rowe, & Sweeney, 1981). According to this concept, a specific food item becomes less liked during its consumption, whereas there is little change in liking for other unconsumed foods. As 49 the established satiety is food specific, SSS promotes the selection of a variety of foods (Rolls, 1986; 50 Rolls, Rolls, Rowe, & Sweeney, 1981;Hetherington & Havermans, 2013). An important function of SSS 51 then is to promote meal variety (Hetherington & Rolls, 1996). Conversely, meal variety itself is thought to foods was introduced. In their experiment, participants were served fries and brownies with or without 61 condiments (ketchup and whipped cream, respectively). The results of this experiment showed that 62 participants ate more of the fries and brownies with (as opposed to without) condiments, and that this 63 effect was associated with attenuated SSS for the fries and brownies. Reviewing 10 within-subjects design 64 studies, McCrory, Burke, and Roberts (2012) found an average increase in food intake (energy or amount) of 22% when a meal was varied as opposed to the availability of just one food item. A recent meta-66 analysis corroborated these findings, reporting a small to medium effect of variety on intake (Embling, referred to as the 'variety effect' (Rolls, Rowe, et al., 1981).   showed a lower overall magnitude of olfactory SSS in the cafeteria setting, suggesting that contextual 93 variables can affect SSS.

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The literature described above indicates that contextual factors can influence food intake, food whether altering the physical context during a meal, by changing (elements of) the context in which a 97 meal is served (e.g., temperature, lighting, odour, sound), acts as a dishabituating stimulus that can 98 consequently lead to an increase in meal intake. This expected context-switch effect is based on the widely 99 held assumption that SSS is a form of habituation (in fact, the terms are often even used interchangeably,  In order to test for a potential contextual effect as described above, a study design consisting of

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Therefore, we considered a medium effect size for the context main effect and an interaction between food 136 variety and a context switch to be relevant and reasonable. To be able to find such an effect, the power 137 calculation indicated a total sample size of 128 participants.

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The participants of this study were adult men and women (aged between 18 and 50 years), who 139 were recruited via convenience sampling (e.g., posters and flyers, internet, advertisements, and other 140 related sources). Participants aged above 50 years were excluded due to prior study results suggesting that 141 the variety effect is different for older and younger adults (Remick et al., 2009). Participants were also 142 excluded when they reported adhering to an energy restricting diet. Exclusion criteria further comprised 143 medical or psychological disorders that affected eating (e.g., a history of cancer, gastrointestinal illness, 144 celiac disease, dental surgery within the last three months, COPD, diabetes, or eating disorders) as well as who were hypersensitive or allergic to the food products used in the study or disliked the food items, who were vegan, or pregnant/breastfeeding were also excluded from the study. expected to taste and evaluate. In case a participant had a cold (which influenced his/her ability to taste 151 and smell), the scheduled appointment was rescheduled. When included in the study, participants were 152 given the necessary information about participation. The exact nature (i.e., the aim and hypotheses) of the 153 study was not disclosed until after the participant completed his/her participation in the study. Upon 154 completion of the participation, participants were compensated with a €5 gift voucher.

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The participants in the study were tested individually. Each participant took part in an eating 175 session at the laboratory, scheduled between 1 p.m. and 5 p.m. Participants were asked to eat a standard 176 breakfast and/or lunch on the day of the laboratory session and not to eat or drink during the two hours prior to the session (except water, coffee or tea) to ensure that they experienced a certain degree of hunger.
Variety, Context, or Var & Con (see table 2 for the procedure of the experiment). Test foods and 180 laboratory rooms (i.e., contexts) were completely counterbalanced within each of the four conditions. Participants in all conditions had free access to tap water during consumption, and were instructed not to 182 use their phone, read a book, or engage in any other activities that could distract them from the instructed tasks.
On arrival at the laboratory, the participants were led to one of two laboratory rooms. These rooms which the food was placed, the decoration (e.g., plants or paintings), the scent in the room (different     Open Science Framework (https://osf.io/54gaf/). The data of two participants were removed for the SSS 259 and 'desire to eat' analyses due to missing values for one of the control foods.

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To test the potential effects of food variety and a context switch on consumption, the amount of food eaten in the second course was calculated by averaging the volume (weight) and amount (energy in 262 kcal) of the foods consumed for each condition. Differences between the experimental conditions were 263 then analysed using a 2 (Context: same or different) x 2 (Food: same or different) ANOVA. This ANOVA 264 was the key test for examining the three hypotheses outlined in the Introduction section.

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Note that for the analyses to assess SSS (given course 1) and a potential effect on intake due to a 266 context or food switch (given course 2), the relevant data were first screened for error outliers (e.g., due to 267 incorrect data entry), interesting outliers (e.g., unexpected extreme values not due to error), and influential

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Next to assessing SSS in terms of change in pleasantness, we also tested whether there was a significant ratings for consumed food items (in course 1) dropped significantly more after consumption than these 317 ratings for control foods, thereby replicating SSS. Furthermore, we replicated the variety effect as our 318 results showed that introducing a different food increased consumption in the second course. We did not 319 find any evidence that a context switch enhances consumption, which implies that SSS is not context-320 specific. The results indicate that SSS develops specifically for the food that is consumed, and not for the 321 situation in which this food is consumed (i.e., it is a truly sensory 'specific' satiation; see also Higgs, implying it is possible to dishabituate SSS, the context switch should have resulted in a recovery of 324 consumption when the same food was presented in a different context. The absence of a dishabituating 325 contextual effect in our study suggests either that SSS is not a form of habituation (see also Hetherington

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The absence of a contextual effect might be due to the relatively subtle context manipulation. The

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context manipulation in this study was mainly produced by altering certain details in two fairly similar 330 laboratory rooms (e.g., a rug on the floor versus no rug on the floor, or a cushion on the chair versus no 331 cushion on the chair), in order to create equally 'distracting' contexts, without one of these being more or 332 less associated with food consumption (e.g., a dining room). One might argue that these differences may have been too subtle to have been noted by participants, and therefore they did not experience a contextual

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The authors would like to thank Imke van der Velden for her assistance with the data collection and The authors' contributions were as follows: AEMH, CN, AB and RCH designed the research; AEMH, 360 IMJL, and BB conducted the experiment; AEMH analyzed the data and wrote the manuscript in 361 consultation with CN and RCH; all authors read and approved the submitted revised manuscript.