Barbara Rolls and Sensory Specific Satiety and Variety
BARBARA J. ROLLS, EDMUND T. ROLLS, EDWARD A. ROWE, AND KEVIN SWEENEY
Sensory specific satiety in man.
Physiology & Behavior 27: 137-142, 1981.
With an interview of Barbara Rolls by Marion Hetherington, January 2020
Dr. Barbara J Rolls, Guthrie Chair of Nutrition and Director of the Laboratory for the Study of Human Ingestive Behavior, The Pennsylvania State University, was interviewed by Marion M Hetherington, Professor of Biopsychology and Thomas Ward Endowed Chair in Psychology, University of Leeds, in September, 2019.
Barbara and I discussed her seminal papers on sensory specific satiety and variety; raising theoretical issues, the history behind the name and the practical challenges facing her team when they first began these studies 40 years ago at Oxford University. My questions are in bold type and Barbara’s answers in plain text.
Before we begin discussing your classic papers from 1981 we should talk about the earlier papers on the variety effect that were important to your thinking. Tell me about the inspiration behind the studies on sensory specific satiety?
There had been a series of studies on alliesthesia by Michel Cabanac showing that after you loaded people with glucose they did not like the taste of sucrose as much, but this had no effect on salt liking (Cabanac, 1971). He suggested that the change in liking was driven by a change in the physiologic need for the nutrient ingested. It was intriguing to try to determine if that change in liking, with its specificity for the taste ingested, would be more related to sensory aspects than nutrient needs.
Our first publication on the variety effect was a review (Rolls, 1979) that reported a series of early experiments that were quite simple because we did not then have a facility with a study kitchen. In fact, one of the studies involved 36 student nurses and was done at the local hospital! Here we tested different flavours of yogurt on the variety effect, and one of my jobs was to extract all the fruit pieces from the yogurts to minimize differences in texture. In other studies without a specialist kitchen, I cooked foods (like sausages) at home and brought them to the Oxford psychology department’s teaching lab for experiments.
These early studies in humans were conducted as undergraduate research projects and were run in parallel with studies of dietary obesity (Rolls et al., 1980) and dietary variety in rats (Rolls et al., 1983). We saw a variety effect in rats in that food intake was enhanced when chow and three high-energy dense foods (crackers, cookies, chocolate) were offered compared to consuming chow alone or chow with any one of the other foods (Rolls et al., 1983). Furthermore, the variety effect was maintained through the seven week study and was associated with increased body weight.
The two seminal papers in humans on sensory specific satiety (Rolls et al., 1981a) and variety (Rolls et al., 1981b) came out simultaneously. Both demonstrated robust effects with relatively small sample sizes. For example, in our first study of sensory specific satiety we asked 32 participants (15 females) to taste and rate the pleasantness of eight foods that varied in food type, macronutrient content, energy density and taste (savoury/sweet). Then four participants were assigned to eat one of these foods to satiety. The pleasantness of the taste of the original 8 foods was re-rated 2 min and 20 min after the meal. Across all foods, the changes in pleasantness were greatest for the eaten foods compared to the aggregated changes for the uneaten foods. This demonstrated sensory specific satiety, since the change was specific to the eaten food (Rolls et al., 1981a).
In the second study, 24 participants took part in a 2X2 between-subjects design where they were allocated to have cheese and crackers or sausages for the first course and then the same food again or the other food. This study not only tracked changes in pleasantness of the eaten food relative to seven other uneaten foods, but also examined whether these changes in pleasantness predicted intake of a second, unexpected course. The results showed both sensory specific satiety (a greater change in pleasantness of the eaten food relative to the uneaten foods) and variety effects (more was eaten when a different food was offered in the second course compared to the same food offered again). In addition, the amount eaten in the second course was correlated with the change in pleasantness after the first course. This demonstrated for the first time that sensory specific satiety played a role in the effect of variety on intake (Rolls et al., 1981a).
We tested both men and women, recorded body-mass index, measured their liking for the foods used, ensured they were similarly food restricted before each test, selected foods to taste based on nutrient and sensory properties, and matched the test foods for energy density. All elements of good experimental practice that we would apply today (Hetherington and Rolls, 2018)!
How did the name sensory specific satiety emerge?
Le Magnen coined the phrase in 1967 when describing an earlier study by P. T. Young (1946) where pre-feeding rats with one food reduced preference for it relative to other foods using paired presentations. Le Magnen described this as “a sensory specific satiety” (Le Magnen, 1967, page 25). These days, we recognise that this phenomenon is more correctly named sensory specific satiation since it is involved in terminating the meal; however, for historical purposes and by convention most researchers still use the term sensory specific satiety or SSS.
What do we need to understand about SSS?
Sensory specific satiety and effects of variety are such well-known phenomena that everyone can understand. Most people can articulate their experience of the first bite of food tasting good but that this declines over the course of the meal and that there is still room for dessert (see: https://www.youtube.com/watch?v=lTtfqECMEb8 ).
Over the years, we have demonstrated that there is a weak effect of macronutrient type, but a strong impact of shared sensory characteristics of the eaten and uneaten foods on SSS (Rolls et al 1988a). Thus, if a savoury food is eaten, other savoury foods also decline in appeal relative to uneaten sweet foods. In addition, SSS generalises to other similar foods; thus if soup has been consumed then other soups are rated as less pleasant. SSS is observed after consumption of no or low energy foods (Rolls et al 1988b) and is greatest at 2 minutes after the food has been eaten (Hetherington et al., 1989). These studies provide support for SSS as a short term, early stage sensory and hedonic phenomenon rather than one that is dependent on changes in energy state or nutrient needs.
We have also shown that there is a cognitive component of SSS. This was illustrated by our research in patients with eating disorders. The magnitude of change was greatest in patients with anorexia nervosa despite eating small amounts of food and was blunted in bulimia nervosa although intakes were similar to controls (Hetherington and Rolls, 1989).
Sensory specific satiety is not just sensory and not simply habituation, it is a complex response to foods that includes not only immediate responses, but also a lifetime of learning about foods (Hetherington and Havermans, 2003).
Sensory specific satiety is likely to be adaptive since it drives consumption of a varied diet, which is useful to achieve a balanced diet. However, in the current obesogenic environment, the downside is that the availability of a wide variety of energy dense foods can facilitate excess intake and potentially lead to obesity. The concepts of sensory specific satiety and variety remain as important today as they were when we first discussed them 40 years ago in the very first issue of Appetite (Rolls et al., 1980; Rowe and Rolls, 1980). Our investigations continue and we have new studies of SSS underway (watch this space!).
Thank you Barbara, this has been a pleasure. I look forward to hearing more about the next steps in your long and very successful career.
Cabanac, M. (1971). Physiological role of pleasure. Science 173, 1103-1107.
Hetherington, M.M. & Havermans, R. (2013). Sensory-specific satiation and satiety. In: Satiation, satiety and the control of food intake, edited by J.E. Blundell & F. Bellisle. Pages 253-269, Woodhead Publishing.
Hetherington, M., Rolls, B.J. & Burley, V.J. (1989). The time course of sensory-specific satiety. Appetite 12, 57-68.
Hetherington, M.M. & Rolls, B.J. (2018). Favouring more rigour when investigating human eating behaviour is like supporting motherhood and apple pie: A response to Robinson, Bevelander, Field, and Jones (2018). Appetite 130, 330-333.
Le Magnen, J. (1967). Food habits. In: Handbook of Physiology. Alimentary Canal, Vol. 1: 11-30. American Physiological Society. Washington, D.C.
Rolls, B.J. (1979). How variety and palatability can stimulate appetite. Nutrition Bulletin 5, 78-86. Rolls, B.J., Rolls, E.T. & Rowe, E.A. (1980). Specific satiety and its influence on feeding. Appetite 1, p85.
Rolls, B.J., Hetherington, M. & Burley, V.J. (1988a). The specificity of satiety: the influence of foods of different macronutrient content on the development of satiety. Physiology & Behavior 43,145-153.
Rolls, B.J., Hetherington, M. & Burley, V.J. (1988b). Sensory stimulation and energy density in the development of satiety. Physiology & Behavior 44,727-733.
Rolls, B.J., Rolls, E.T., Rowe, E.A. & Sweeney, K. (1981a). Sensory specific satiety in man. Physiology & Behavior 27 137-142.
Rolls, B.J., Rowe, E.A., Rolls, E.T., Kingston, B., Megson, A. & Gunary R. (1981b). Variety in a meal enhances food intake in man. Physiology & Behavior 26, 215-221.
Rolls, B.J., Rowe, E.A. & Turner, R.C. (1980). Persistent obesity in rats following a period of consumption of a mixed, high energy diet. Journal of Physiology 298, 415-427.
Rolls, B.J., van Duijvenvoorde, P. & Rowe, E.A. (1883). Variety in the diet enhances intake in a meal and contributes to the development of obesity in the rat. Physiology & Behavior 31, 21-27.
Rowe, E.A. & Rolls, B.J. (1980). Persistent dietary obesity and regulatory challenges. Appetite 1, p86. Young, P.T. (1946). Studies of food preference, appetite and dietary habit. VI. Habit, palatability and diet as factors regulating the selection of food by the rat. Journal of Comparative Psychology 39, 139–176.