When form criticism questioned the historical reliability of the Gospels, scholars began looking for other criteria. Taken from other areas of study such as source criticism, the "criteria of authenticity" emerged gradually, becoming a distinct branch of methodology associated with life of Jesus research. The "criteria" are a variety of rules used to determine if some event or person is more or less likely to be historical. These criteria are primarily, though not exclusively, used to assess the sayings and actions of Jesus.