Ivan pavlov introduced the concept of CONDITIONING when he taught a dog to salivate at the sound of tuning fork
The same condition happen to human. Our brain response to our exact habitual conditioning that's why sometimes it's very hard to lose/change a habit.
For example, if you condition yourself that you need to hold some sort of doll before you went to sleep, it will be hard for you to sleep if somehow that doll is not in your possession<span />
Ivan Pavlov, the famous Russian physiologist, introduced the concept of conditioning when he taught the dog to salivate at the sound of a tuning fork - c.
The reason why the dog was salivating was because previously he gave the dog an immediate reward such as food together with the tuning fork. He then gradually changed this and gave him food on more rare occassions while stile preserving the frequency of the tuning fork.
