Marie Sklodowska seemed not to feel cold or hungry. Sometimes, during the cold winter months, in order not to buy coal, which cost money and sometimes because she didn’t want to take the time from her studies, she did not light the small fire. She continued her work without noticing that her fingers were getting stiff and her shoulders were shaking. Hot soup would have comforted her, but she did not know how to make it. Besides soup would have cost money, and above all. Soup would take time to prepare. So for days and days she had nothing but bread and butter and tea. Eating only this food, she became very thin and weak. Often her head seemed to turn round and round and sometimes she fell fainting.
For some time past it has been widely accepted that babies---and other creatures---learn to do things because certain acts lead to “rewards” and there is no reason to doubt that this is true. But it used also to be widely believed that effective rewards, at least in the early stages, had to be directly related to such basic physiological “drives” as thirst or hunger. In other words, a baby would learn if he got food or drink or some sort of physical comfort , not otherwise.
It is now clear that this is not so. Babies will learn to behave in ways that produce results in the world with no reward except the successful outcome.
Papousek began his studies by using milk in the normal way to “reward” the babies and so teach them to carry out some simple movements, such as turning the head to one side or the other. Then he noticed that a baby who had enough to drink would refuse the milk but would still go on making the learned response with clear signs of pleasure. So he began to study the children’s responses in situations where no milk was provided. He quickly found that children as young as four months would learn to turn their heads to right or left if the movement “switched on” a display of lights and indeed that they were capable of learning quite complex turns to bring about his result, for instance, two left or two right, or even to make as many as three turns to one side.
Papousek’s light display was placed directly in front of the babies and he made the interesting observation that sometimes they would not turn back to watch the lights closely although they would “smile and bubble” when the display came on. Papousek concluded that it was not primarily the sight of the lights which pleased them, it was the success they were achieving in solving the problem, in mastering the skill, and that there exists a fundamental human nature to make sense of the world and bring it under intentional control.