Hypnotic learning has not been fully explored, but a number of reported experiments show positive results. The first studies dealt primarily with conditioning during a hypnotic trance—for example, if the hypnotist snapped his fingers while his subject smelled camphor, it was found that the subject would suddenly and mysteriously smell the same odor when the experimenter snapped his fingers after he had been awakened. This occurred without posthypnotic suggestion. Sears (1955) found that subjects who studied Morse code under hypnosis made fewer errors when they were later tested in the waking state than subjects who were given the same amount of training without hypnosis. Cooper and Rodgin (1952) found that they could increase the learning ability of hypnotized subjects by altering their sense of time, suggesting that seconds would appear like minutes. These subjects were able to memorize word pairs in one quarter of the time it took them to learn equivalent material while awake.These positive results are believed to be due to the fact that hypnosis is a state of extreme concentration and freedom from distraction. The method has not been widely used for other than research purposes, although a few actors claim that they find it highly effective in helping them learn their lines.