A Report on “The Psychology of Eating and Drinking” by A W Logue¹
by Aidan Moloney
Traditionally psychologists and psychotherapists adopt one particular level of analysis and examine issues from that perspective. For example some psychologists explore many different behaviours such as eating, drinking, mating, aggression, and parenting from one point of view e.g. physiology. Psychotherapists may be behavioural, cognitive, humanistic, etc. and filter all things through these lenses. By contrast, The Psychology of Eating & Drinking explores one type of behaviour – eating and drinking – using many different levels of analysis. This makes it easier to see what each level of analysis contributes to our understanding, gives a more holistic view of the topic and is a useful antidote to intellectual myopia. It describes scientific inquiries into eating and drinking behaviour. While it covers the major eating and drinking disorders, it also looks at eating and drinking in a non- pathological context.
Evolution and Eating and Drinking
Organisms behave so as to maximize the survival of their genes, their inclusive fitness (the probability that their biological relatives will survive). In this way natural selection – survival and reproduction of the fittest individuals – occurs. Because survival and eating and drinking are so intertwined, evolution has played a major role in the origins of eating and drinking behaviour.
Although there is widespread agreement that an organism’s behaviour is guided by evolutionary processes, organisms sometimes do, apparently, very non-adaptive things. For some it is the non-adaptive behaviour that is often the most fascinating – anorexia nervosa and bulimia are more intriguing than why we eat normally – but all theories of eating and drinking must accommodate adaptive and apparently non-adaptive behaviour.
Most theories of eating and drinking begin with the concept of homeostasis through negative feedback. The term homeostasis was coined by Walter B. Cannon, an American, in 1929². It can be seen at work outside as well as inside our bodies. If a thermostat is set at a certain temperature, it reacts to any deviation from that temperature (the set point), by changing the environment in ways that decrease or eliminate those deviations. If the temperature is too high, the heat will be turned off. If the temperature is too low, heat will be turned on. This process is called negative feedback.
The purpose of eating is not determined solely by the body’s attempt to return itself to an optimal physiological internal state. Jerry A. Hogan³ has argued that it is not reasonable to conceive of homeostasis as a system solely influenced by physiological factors. Animals deprived of food will not always eat even when they have the opportunity to do so. The food intake of a hen incubating eggs is 20 percent less than its usual intake. The body’s internal environment is always being affected by reactions within the body as well as by occurrences in the body’s external environment.
There are many problems with the concept of homeostasis when applied to motivational processes. It either has to be abandoned or understood in some way that incorporates not only the organism s optimal state and the mechanisms that lead to that state but also the organism’s particular motivation in the situation.
The Psycho-dynamic Approach
Psycho-dynamic theorists adopt a combined physiological and environmental approach to hunger. Hunger has a physiological basis but is immediately affected by learning. With learning, feeding can become associated in early life with experiences that usually accompany feeding, such as a mother’s attention and warmth.
Psycho-dynamic theorists believe that learning is so intimately connected to the physiological regulation of hunger that it is virtually impossible to separate the two. It is easy to see how a child might come to eat when frightened or lonely, since he or she associated feeding with security and a mother’s love.
Researchers began investigating hunger by considering peripheral cues involved in the initiation and termination of feeding bouts. The stomach traction, stomach distention, environmental temperature are examples of these theories. The variety and extent of these theories suggested that a multitude of factors are involved in hunger. For this reason many researchers searched for particular locations in the brain that might coordinate and synthesize the information from various sources. Such areas have not been found. More recent attempts to understand hunger and feeding have involved constructing elaborate behavioural or physiological models that eliminate any reference to central determinants of feeding.
Types of drinking behaviours
There are an astonishing number of different types of drinking behaviours. The overall goal of homeostatic drinking is to maintain, within fairly narrow limits, the concentration of solutes in the blood plasma, as well as the overall volume of the blood plasma. Much of the drinking that animals and humans do is non-homeostatic, and is not to replenish water deficits. For example, rats exhibit patterns of drinking behaviour dependent on the time of day. They consume 75 percent of their water during the 12 dark hours of the 24 hour day when their meals are scheduled at 2 to 4 hourly intervals. Most of the drinking that we do occurs while we are eating a meal. There are physiological reasons for drinking, to help digest food, or the food is salty and we need to replenish the water that the salt draws from our cells. Both reasons, however, are only partly correct. We need the water several hours after we consume the food but we drink liquids as we consume food. We anticipate a need for water. This is known as anticipatory drinking. Animals drink as well as eat before there is any actual need to do so.
Animal experiments have demonstrated that if an animal is deprived of food but not deprived of water, when they subsequently are provided with food again they will consume large amounts of water while replenishing their need for food. F. M. Toates (4), a motivational theorist, noted that a lot of eating and drinking behaviour is non-homeostatic and much of it is determined by the environment and by learning (rather than by physiological stimuli), so that there is little point in retaining the traditional notion of homeostasis. John L. Falk (5) has classified such behaviours, as adjunctive behaviours. These are behaviours that increase in response to reinforcers that ordinarily do not motivate these types of behaviour. The adjunctive behaviour, drinking, occurs as an adjunct to a different motivational system, in this case food consumption. According to Falk, animals will drink when they are motivated to eat but cannot do so. Their motivation to eat is displaced to another drive whose satisfaction is available, in this case thirst. Falk suggests that animals in the wild will take advantage of whatever reinforcers are available. When experiments of this type are conducted in the laboratory excessive drinking results. An interesting hypothesis here regarding over-eating and excessive drinking is that people do them to compensate for some other behaviour that is not currently satisfied.
The Importance of Taste and Smell
Given that an organism is hungry or thirsty, how does it choose what to eat or drink? The senses of taste and smell are critical to an animal’s survival, especially to animals that are omnivores. Omnivores have the difficult task of identifying food and drink and avoiding poisonous substances. Once a food or drink has entered the stomach, removing it may be difficult or impossible. Rats lack the musculature to vomit but even vomiting is not a protection against fast acting poisons.. To be able to eject poisonous food from the mouth before it has been swallowed is an advantage. The four taste primaries are sweet, sour, salt, and bitter. At least three of these help identify foods that are critical to the survival of omnivores. A sweet taste often indicates a good source of carbohydrates – good sources of energy. Poisonous foods are sometimes bitter. Salt is necessary for maintaining cellular homeostasis and an inability to taste salt could imperil an animal’s survival.
There appear to be substantial genetic contributions to many preferences. Babies make characteristic facial expressions when they experience, sweet, sour and bitter tastes. The genes also appear responsible, at least to some extent, for an acceptance response for sweet substances, the rejection response for bitter substances, the tendency of certain food preferences to be related with levels of sensation seeking, and the increased preference for different and strong tasting foods with advancing age. Even though genes do affect our food preferences, the environment also plays a strong role.
Learning to Eat and Drink
Experiments with humans and animals show that we develop preferences for those foods that we are first exposed to and exposed to more frequently. Sibylle K. Escalona (6) was one of the first to record the social transmission of food preferences and aversions Working as a psychologist in the Massachusetts Reformatory for Women during the 1940s, she was able to observe the inmates and their children. The children lived in the nursery and they were looked after by their mothers, other inmates and reformatory staff. On main occasions Escalona observed what she believed was the subconscious influence on the children’s food preferences by their caretakers.
“ ……..many of the babies under four months of age showed a consistent dislike for either orange or tomato juice. (These juices were offered on alternate days with equal frequency.) The number preferring each kind of juice was about equal…….preferences seemed to change and a baby who had refused orange juice for about three weeks occasionally would reverse his preference within two or three days, accepting orange juice and refusing tomato henceforth. A checkup revealed that where there was a sudden change in preference the baby’s feeding had been reassigned from one person to another.”
When Escalona checked the preferences of the feeder, she found it coincided with the preference of the baby but more significantly, in cases where the baby changed preference, the new preference was the same as the feeder’s preference.
Birch has shown that if an adult repeatedly gives a child a food while being very friendly to the child, the child’s preference for the food will increase. The adult does not have to provide specific praise for eating the food just a general positive social context. (7)
Many events including illness, changes in nutrition and association with other foods or experiences affect individual preferences for foods. For example, when two tastes are first paired and then one is made aversive by following it with illness, the other taste also becomes aversive. Conversely, if a taste is paired with a different, positive taste that is sweet, the preference for the first taste increases. This type of learning is responsible for the acquisition of preferences for initially aversive substances such as tea and coffee. A new coffee drinker usually adds more palatable substances such as sugar and milk to it. Gradually, as the actual taste of the coffee or tea becomes associated with the taste of the sugar or the milk, the coffee or tea can be drunk with less, and finally, no sugar or milk.
Birch has shown that making participation in a pleasurable activity contingent on consuming a particular food results in a decrease in preference for that food. She has also shown that parents who insist that children can only eat sweets if they eat their vegetables are adopting an increasingly counter-productive strategy. What happens is the children’s dislike of vegetables will actually increase. This effect is known as incentive contrast. The strategy to be adopted according to this research is to let children eat their dessert before the main course. No one has tried this experiment yet.
We also have a genetically determined preference for high calorie foods compared to low calorie foods. However if one flavours a low calorie food with a flavour associated with a high calorie foods then an individual’s preference for the low calorie food will increase. That’s why the dressing is so important to the salad.
Associating food with visual or aural stimuli affects our preferences sufficiently to initiate a change in behaviour. In the US, children view on average 22,000 commercials per year and 50 percent of these promote food of poor nutritional value. Several experiments show that children’s preference for these foods increases as a result of exposure to advertising.
The behavioural effects of being deprived of specific nutrients have been investigated. Current protein deprivation results in poorer learning in rats and monkeys. For ethical reasons such experiments have been limited to animals but field studies where deprivation has occurred for other reasons confirm that people also suffer from deprivation of nutrients.
A deficiency in iron intake is the world’s most common nutritional disorder. Investigations into the effect of iron deficiency on learning in 3 to 6 year old children show that iron deficient children learn discrimination tasks and perform other tasks requiring attention less well than do non-deficient children. When the iron deficiency is removed, some studies show the previously deprived children perform as well as other children. Unfortunately other studies have found that the mental impairments persist after the iron deficiencies are removed.
People consume a great deal of caffeine in coffee, tea, soft drinks and chocolate. The effect of small amounts of caffeine is to increase wakefulness, energy, attention, speech rate and to change mood. In some people drinking two cups of coffee produces restlessness, nervousness, excitement, insomnia, flushed face, diuresis and gastrointestinal complaints. Long term consumption of caffeine can result in physiological dependence.
Whether or not some other non-nutritive substances cause abnormal psychological behaviour remains currently unresolved. Attention-deficit hyperactivity disorder is probably the most widely known syndrome at present that has been attributed to diet, on the proposition that some children are allergic to certain substances that are part of modern food processing methods. While changing diet and drug prescription are part of the treatment of this syndrome, they must be accompanied by teaching hyperactive children new behaviour patterns as well.
Anorexia means lack of appetite. It may occur for many reasons. Some animals consume little food when behaviours other than eating have a greater value, for instance during hibernation or incubation. Other causes of anorexia include the effects of cancer and drugs, many psychological problems, depression, mania, anxiety and currently anorexia nervosa which in the popular consciousness is now almost synonymous with anorexia but is in fact a particular form of anorexia. Anorexia Nervosa has been defined as “the relentless pursuit of thinness through self-starvation even until death itself” (9). Some of the causes appear to be a desire to be thin, a need for love and attention from parents and friends, a desire to improve sports fitness and a desire to prevent sexual development,
In cancer treatment induced anorexia, people acquire an aversion to foods taken near in time to chemotherapy. As many as 40 percent of chemotherapy patients report nausea and vomiting in anticipation of chemotherapy because they associate environmental factors surrounding the chemotherapy with the treatment. It is important therefore to be aware of the possibilities of such associations developing, because a person may develop an aversion to important foods or surroundings. Certain therapies are useful in assisting people to avoid developing these aversions or reducing their effects if they develop.
Mood and food
Mood and food are related. Some people who are depressed as well people who are manic usually eat less than people of average affect. Some people who are depressed eat excessively. The relationship between depression and eating seems to be as follows, if you are a normally a dieter you will increase the amount you eat when you become depressed, if you are a non-dieter you will tend to decrease the amount of food you eat when you are depressed
Overeating and Obesity
There has been a great deal of research on the possible causes of overeating. They can be genetic, physiological and environmental. Obese parents tend to have obese children. Only 10 percent of children who have no obese parent become obese. Approximately 40 percent of children with one obese parent become obese, 70 percent of children with two obese parents become obese. Is it transmitted by nurture or nature? Well, it is possible to breed rats and mice that have a propensity to become obese just by repeatedly repeating obese animals. However significant correlations have been found between adoptive mothers and their children, but identical twins tend to have more similar weights than fraternal twins and biological parents and their children are closer in weight than adoptive parents and children.
A genetic predisposition still has to be realised. Adipose cells in our bodies store fat. When we eat and fill adipose cells there is less hunger. There is evidence that adipose cells increase when we gain weight but they never decrease, so that by becoming overweight we predispose ourselves to be permanently overweight or hungry.
Stress induced Eating
In a laboratory experiment rats that were given a tail pinch six times per day over a five day period gained over 18 percent in weight. Some tail pinched rats will even go on eating binges like humans. Such experiments lead to an hypothesis that organisms that are sensitive to external stimuli (like people) are more likely to eat given the presence of food because we have difficulty in discriminating between the external stimuli associated with anxiety and hunger signals. Injections of an opiate reducer eliminates stress-induced eating in the rats. It seems that among other things, parties are the human equivalent of tail pinching.
Burch’s theories ¹¹ postulate that food can stand for love or power, can express hate or rage and can be substitute for sex. These multiple uses of food arise from the learning that goes on in early infancy between the interaction of the care giver and the child. The child learns to use food to satisfy many drives in addition to hunger, some of which lead to eating disorders.
When we eat in the presence of others we also tend to eat in accordance with our beliefs about their expectations about eating. For example if we eat in company with someone who is dieting we will eat less than when we are eating with people who are not dieting.
All this concentration on the negative aspects of eating must be counter- pointed by cuisine – a unique human achievement. Cuisine depends on what foods are available and from those, people select foods that are inherently preferable, sweet and salty foods, but not bitter foods. There are exceptions such as chili pepper that are most interesting. Chili pepper is now one of the most widely consumed spices in the world. Most people don’t like chili pepper the first time they eat it. The effect of chili in the mouth is similar to being burned – pain and heat. (Hikers use chili people to keep their feet warm.) So why have we come to love chili? The first tasting is probably the result of social pressure. Later we come to like it because it actually has large amounts of vitamin A and C. It also engenders salivation and gastric movements that help digestion of starchy foods. Finally the pain that accompanies it is actually safe so it provides a thrill. Interestingly animals don’t like chili pepper but they can be induced to eat it if they see other animals consuming it – monkeys will eat it if they have seen humans eating it.
Cuisine also depends on the technology available. Until fermentation was discovered no cuisine could contain alcoholic beverages. Of course no culture will survive if the food is not nutritionally balanced but different cuisines achieve this is many innovative ways either by including exotic varieties or treating food to improve its nutritional value. Mexicans, in the past and occasionally in the present, ensure protein by including insects and worms in their cuisine. Native American Indians treat corn with an alkali solution to increase its nutritional value. The amount of energy required to prepare the meal, the money to purchase it, will also affect the content of the cuisine. Beliefs also have a very powerful effect – some foods arc classified as breakfast foods and others as dinner foods. A kosher Jew experiences difficulty eating a mock-turkey and cheese sandwich even where the mock-turkey meat is made out of tofu (kosher Jews cannot eat meat and milk in the same meal).
I must include a table from the book that shows the flavour principles of different cuisines around the world. I think it contains the basic principle of good cooking and I have finally found something to guide my culinary endeavours.
Figure 2. the Flavour Principles of Cuisines ¹²
My one major disagreement with the book is the narrow definition of science and mind adopted by the author.
“The orientation consistently espoused here is a natural science approach which assumes that natural laws govern human behavior and that behaviour is entirely the result of genetic and environmental influences. Further a natural science orientation holds that there is no separation, no essential difference, between mind and body, and that what some refer to as mind consists entirely of physiological reactions. Only with this orientation is it possible to conduct experiments to determine the causes of behaviour. If the mind were not a physiological entity, if it were not governed by traditional physical laws, then an experimenter could never assume that manipulation of an experimental variable was the cause of a subsequent change in behaviour.”
Fortunately the author did not restrict herself to such an narrow terrain. In practice the physiological definition of mind doesn’t detract from the presentation of experiments and their results. No matter what one’s orientation one can certainly obtain useful insights and strategies for understanding and dealing with eating disorders and cooking more exotic meals.
1. Logue, A. W., The Psychology Eating & Drinking – An Introduction. 2nd ed.. W.H. Freeman and Company, New York.
2. Cannon, W. B..“Organization for Physiological Homeostasis”, Physiological Reviews 9(1929):399-431.
3. Hogan, J. A., “Homeostasis and Behaviour” in Analysis of Motivational Processes, eds. F.M.Toates and T. R. Halliday, London: Academic Press. 1980.
4. Toates, F.M. “Homeostasis and Drinking” Behavioral and Brain Sciences 2(1979): 95-139.
5. Falk, J. L, “The Nature and Determinants of Adjunctive Behaviour”, Physiology and Behaviour 6(1971): 577-588.
6. Escalona, S. K., “Feeding Disturbances in Very Young Children”. American Journal of Orthopsychiatry 15(1945):76-80.
7. Birch, L. L., “Generalization of a Modified food”, Child Development 52(1981):755-758
8. Birch, L. L., D. Birch, D. W. Marlin and L. Kramer, “Effects of Instrumental Consumption on Children’s Food Preference”, Appetite 3(1982): 125-134
9. Burch, H., Eating Disorders, New York: Basic: Books. 1973. p.4.
10. Blundell, J. E., “Systems and Interactions: An Approach to the Pharmacology of Eating and Hunger”, in Eating and Its Disorders, eds. A.J. Stunkard and F. Stellar, New Raven Press, 1984.
11. ibid. Burch.
12 Rozin, E., Ethnic Cuisine: The Flavor-Principle Cookbook Brattleboro. VT: The Stephen Greene Press, 1983.