During the 19th century a group of thinkers called the British Associationists believed in the idea that we can attribute practically all of our knowledge to conditioning, by connecting one stimulus with another, such as associating a mother's voice with her face. In the early 1900s Pavlov demonstrated classic conditioning by triggering his dog to salivate to the sound of a metronome. He paired the sound of the metronome, an unconditioned stimulus (UCS), with giving the dog meat powder which normally caused the dog to produce saliva, an unconditioned response (UCR). After repeatedly having the metronome tick and then giving the dog the meat powder, the dog came to expect the meat power when he heard the ticking of the metronome through this conditioning. After being conditioned in this way when the dog merely heard the conditioned stimulus (CS) of the metronome ticking he would begin to salivate which is considered the conditioned response (CR). I found all of this information regarding conditioning and creating a conditioned response from an arbitrary conditioned stimulus to be very interesting within chapter 6.