Sperry's research with "split-brain" cats helped lead to the discovery that cutting the corpus callosum is a very effective treatment for patients who suffer from epilepsy. Initially after the patients recovered from surgery there were no signs that the surgery caused any changes to their behavior or functioning. This observation rendered the question: if the surgery had absolutely no effect on any part of the patients' normal functioning then what is the purpose of the corpus callosum? Was it simply there to keep the two sides of the brain from collapsing, as Karl Lashley jokingly put it? Sperry was asked to develop a series of tests to perform on the "split-brain" patients to determine if the surgery caused changes in the patients' functioning or not.