Puzzle Box
Early psychologist Edward Thorndike conducted his well-known cat experiments using “puzzle boxes” like the one shown above. At the start of the experiment, Thorndike’s cats pawed around haphazardly until they managed to unlatch the cage and then eat the fish treats outside the door. As the trials wore on, the felines learned to free themselves more quickly. After several trials, the amount of time needed to escape the box dropped significantly (see graph below). Thorndike attributed this phenomenon to the law of effect, which states that behaviors are more likely to reoccur if they are followed by pleasurable outcomes.

Data from Thorndike, 1898