Learning

This chapter is without question the most important one of the book. It concerns the core, almost philosophical question of what learning really is (and what it is not). If you want to remember one thing from this book you will find it here in this chapter.

Ok, let’s start with an example. Alice has a rather strange ailment. She is not able to recognize objects by their visual appearance. At her home she is doing just fine: her mother explained Alice for every object in her house what is is and how you use it. When she is home, she recognizes these objects (if they have not been moved too much), but when she enters a new environment she is lost. For example, if she enters a new meeting room she needs a long time to infer what the chairs and the table are in the room. She has been diagnosed with a severe case of ”overfitting”. What is the matter with Alice? Nothing is wrong with her memory because she remembers the objects once she has seem them. In fact, she has a fantastic memory. She remembers every detail ofthe objects she has seen. And every time she sees a new objects she reasons that the object in front of her is surely not a chair because it doesn’t have all the features she has seen in earlier chairs. The problem is that Alice cannot_generalize_the information she has observed from one instance of a visual object category to other, yet unobserved members of the same category. The fact that Alice’s disease is so rare is understandable there must have been a strong selection pressure against this disease.Imagine our ancestors walking through the savanna one million years ago. A lion appears on the scene. Ancestral Alice has seen lions before, but not this particular one and it does not induce a fear response. Of course, she has no time to infer the possibility that this animal may be dangerous logically. Alice’s contemporaries noticed that the animal was yellow-brown, had manes etc. and immediately un-