The study of motivation based around physiological drives is particularly influential in the study of behavior which satisfies physical drives such as eating and drinking. It may seem reasonably obvious why people eat (because they are hungry), but it is perhaps not so clear what it is that makes us feel hungry; what we feel hungry for; why we eat when we do, and what it is that makes us stop eating once we start.
It is not enough to simply claim that we eat because we are hungry or that we stop eating because we are 'fill'. There are a variety of ways that our bodies respond to our need for food. In the same way as a car will respond to its needs in a variety of ways, so the body will respond to its need for food with more than just a rumble.
A car will show a number of signs that it is not getting enough petrol, it is not getting the right kind of oil or it is running low on other necessary fluids. Some of these signs will be obvious and easy to recognize (the car stops running); others will be subtler (such as rust). In relation to the human body, this might be equivalent to the obvious signs of lethargy, or the subtler appearance of white dots under our fingernails.
The identification of hunger will often involve a subjective experience of the 'feeling' of hunger, just as much as it will involve the objective/physical symptoms. Most people will feel hungry, even if they are not experiencing any significant physical effects. Most often these subjective feelings will involve a 'feeling' of emptiness or the feeling that it is time to eat..............
