In one experiment from 1959, the psychologist Peter Dews trained three octopuses – which he named Albert, Bertram and Charles – to pull a lever in their tank, which lit up a bulb and released a small piece of fish. Albert and Bertram learned how to do this without a great deal of difficulty. Charles, however, was more obstinate. Dews wrote: "Charles anchored several tentacles on the side of the tank and others around the lever and applied great force. The lever was bent a number of times, and on the 11th day was broken, leading to a premature termination of the experiment."