An earlier and rather different connectionism was held by Edward Thorndike, a turn of the century psychologist who studied learning, with his most famous contributions being work on how cats escaped from puzzle boxes, and his formulation of the Law of Effect. His analysis (and its descendants) are peppered with references to associations between stimuli and responses. Though the S-R aspect has today been abandoned by radical behaviorists and cognitive psychologists (including connectionists), it is easy to impose the notion of association and modification of association strength on connectionist models.