As a child (pictured here at two) I was a woefully picky eater - hot dogs, chicken nuggets and cheese ravioli factored prominently into my diet, to the exclusion of most other foods. My aversion to new things left my family bewildered and frustrated. My uncle once forced me to eat tri-color pasta blindfolded. It was a traumatic episode in my early youth; at the time I preferred foods that were white. My mother, constantly at her whit’s end, instituted “try new food days” to no avail.
Protecting Ourselves
All human beings are born with the same basic taste preferences. We like sweet foods and avoid anything bitter or sour. These inclinations make evolutionary sense. Sweeter vegetables tend to be more nutritious and are less likely to be poisonous. Mother’s milk is sweet, as are ripe fruits - both are good sources of vitamins, minerals and calories.
As humans, we have hard-wired aversions to many types of food. Most of us recoil upon smelling rotten or decaying foods; toxic plants are often bitter. These reactions are present at birth and can be seen by examining the facial expressions of infants. Known as the gusto-facial reflex, sweet substances tend to elicit little smiles and sucking while sour tastes produce lip pursing and a wrinkling of the nose - the classic yucky face. Aversion is acted out through disgust, the human emotion like most closely linked with the rejection of food.
Not all aversion is hard-wired. Pavlov introduced the concept of associative or classical conditioning. For associative conditioning to occur, two or more objects must be paired. Once together, qualities of one element may be transferred to the other. In Pavlov’s classic experiment, a bell was paired with food, causing a dog to salivate. After repeated conditioning, the bell triggered salivation, even in the absence of food.
Social Cues
As social animals, we pick up cues from those around us. You may have witnessed your father swooning over a chocolate chip cookie. While it may not be as clear as a bell, it does enforce the notion that chocolate chip cookies lead to positive feelings.
Many children get satisfaction from eating their boogers. Kids tend to act without thinking of the health or social consequences. Did your mother ever scold you for picking your nose? Did your playmates ridicule your behavior? When nose picking becomes associated with shame, boogers are forever been tainted.
As adults, many people are averse to wonderful foods like oysters or okra. Paul Rozin, a University of Pennsylvania psychologist, describes this as “secondary disgust: - disgust for something that looks or feels similar to something disgusting in its own right. In an experiment, Rozin presented subjects with two pieces of chocolate fudge, one was shaped to look like a muffin and the other was sculpted into a realistic replica of dog poo. Guess which one subjects found more palatable.
Endorphins
While helpful, relying solely on external cues offers far too simplistic an explanation of our food preferences. We are in tune with our bodies; this internal feedback plays a critical role in shaping our eating habits.
Endorphins, a group of hormones secreted within the brain have a number of psychological functions. Principally, they activate the body’s opiate receptors, which affect the brain’s pleasure or reward center (they also play a role pain relief).
Hard sustained exercise will spur endorphin production. This generates a feeling commonly referred to as runners high. In those so disposed, it creates exercise junkies. There are many other things you can do to get the body to produce endorphins; the most popular among all walks of life is eating.
Sugar is especially good at promoting endorphin production. When the tongue’s sweet receptors are activated they trigger a release of these hormones. Experiments show that sucrose affects infant rats much like morphine. It will make them stop crying (yes, rats can cry, but you’ll need ultrasonic listening equipment to detect it).
As a species, we are predisposed to sweet, calorie-dense foods. The endorphin release associated with these foods leads to good feelings, reinforcing our preference for treats, often to the exclusion of other novel nutrient sources.
Overcoming Aversion
Kids often suffer from neophobia - a fear of new things. As omnivores, we need variety in our diet, but evolutionarily we also need to stay alive and procreate, which may have required some conservatism in our eating habits to avoid being poisoned.
According to Leann Birch, a professor of nutritional sciences at the University of Illinois, it often takes up to ten exposures to a food before a child will get over their fear of something new. Recall, if you will, your first experience with Roquefort cheese.
For picky eaters, an endorphin cue may help. A tablespoon of sugar added to vegetables not only makes the food more palatable, it activates the body’s reward center and may create a positive association. Sweetness and blandness generally protect a food from the neophobic response. Few children are scared of a new dessert - even something as threatening as a Baked Alaska.
My peculiar habits are still somewhat of a mystery. Around the time I was eleven or twelve, I began to explore foods other than hotdogs and ravioli including vegetables and fruits. In high school I happily ate anything - even foods that I didn’t enjoy at first. Surviving and procreating are arguably much easier today than they have ever been, yet picky eaters still exist. With all our knowledge, there are still countless factors that shape a child’s eating habits - it’s an inexact science.