Video component of Total Internal Recall.

Please see print component in Flickr

Ivan Pavlov noticed that the dogs tended to salivate before food was actually delivered to their mouths, and set out to investigate this "psychic secretion", as he called it.

He decided that this was more interesting than the chemistry of saliva, and changed the focus of his research, carrying out a long series of experiments in which he manipulated the stimuli occurring before the presentation of food. He thereby established the basic laws for the establishment and extinction of what he called "conditional reflexes" — i.e., reflex responses, like salivation, that only occurred conditionally upon specific previous experiences of the animal.