n 1953 the celebrated Harvard behavioural psychologist BF Skinner published a paper about the gambling habits of rats. Testing his theory of 'operant conditioning' he had noticed a strange compulsive tendency among his laboratory rodents.
When one of Skinner's rats pressed a lever, it was given a food pellet. By experiment Skinner then established that if a pellet was delivered only on the 10th press of the lever, the rat would quickly learn to press the lever 10 times. If, however, a random element was introduced to the lever-pressing, whereby a pellet was still introduced on average one in 10 times, but sometimes delivered twice or three times in a row and sometimes not for 20 or more presses, the rat apparently became obsessed with the lever-operation itself.
