Mothers have known it for years. Give the children a hamburger, and they will love it; spend hours making a home-cooked meal, and they will leave it on the plate. Now French scientists have discovered why. According to researchers near Paris, the brain does not respond well to unfamiliar tastes. Sensations are not as strong when the mind is struggling to understand messages that come from the tongue. This provides little reason to taste new things.Human beings are naturally like rats – we are afraid of anything new. If you give rats some food that they have never had before, they will turn their backs on it out of fear. We are the same. It is possible to introduce new foods, but only in the right psychological context, like a birthday. Once the introduction has been made, the fact of having a full stomach is physically pleasing, so the next time it is easier. However, some foods are more tempting than others. Scientists are sure that we are born with a sweet tooth. This is why children have a natural desire for sugar.Another discovery is how a sense of smell affects our appetite. In one experiment, chemical substances were put on the tongues of human participants. At the same time, air was blown down the participants’ noses so they could not smell the chemical substances. As a result, no two people got the same sensation from the same food. Physical, psychological, and cultural differences shaped the response.The intensity of feelings about food depends upon knowledge of it. The average student who eats a new dish will have only a cloudy image of it, but for some people whose tongues are trained to appreciate fine differences, they’ll have an exciting experience, much like someone who has a great musical ear. This is why someone who eats hamburgers everyday likes them and becomes a hamburger expert. They can tell the difference between a Big Mac and a Burger King, just like the Japanese can tell the difference between varieties of rice that taste the same to Europeans.21. Why do children prefer a hamburger to a home-cooked meal?