Edward Thorndike was an influential psychologist who developed the theory of operant conditioning through his experiments with animals in puzzle boxes. He found that cats would initially try random behaviors to escape the box but would eventually learn to press the lever, as this led to a reward of food. With repeated trials, the cats grew faster at pressing the lever as they associated this action with a positive outcome. Thorndike proposed the "Law of Effect" - that behaviors followed by pleasant consequences become more likely to be repeated, while those leading to unpleasant outcomes tend to stop. His work laid the foundations for B.F. Skinner's later development of operant conditioning within behaviorism.