Another study of psychology is learning. Learning is relatively permanent change in behavior that arises from experience. A type of learning is classical conditioning. Classical conditioning is a "simple form of associative learning that enables organism to anticipate events." The types of classical conditioning are delayed, simultaneous, trace and backward conditioning.
Classical conditioning came to be when an experiment on dogs that went wrong. Ivan Pavlov a physiologist in 1927 decided to do a study with dogs. He wanted to identify neural receptors in the mouth that triggered a response from the salivary glands. But the problem was that the dogs would salivate at undesired times. For example every time Ivan would feed the dogs, the dogs would salivate which is normal because of the meat. But after a while the dogs would salivate when Ivan walk into the room. Answer is because Ivan would feed the dogs; the dogs knew they would get meat. That is classical conditioning when something like Ivan would mean meat and that would make the dogs salivate.
The delayed conditioning is when the conditioned stimulus comes before the unconditioned stimulus. The simultaneous conditioning is when the conditioned stimulus and the unconditioned stimulus happens at the same time. The trace conditioning is when the stimulus is turned off and the unconditioned stimulus is still hanging around. For example when you have a light on and you stare at it for awhile and then turn the light out, you will still see the light. Finally backward conditioning is when the unconditioned stimulus is presented before the conditioned stimulus.