David Krathwohl was an American educational psychologist who co-authored Bloom's Taxonomy, a critical publication on education. He proposed a taxonomy for the affective domain of learning focusing on how students receive and respond to phenomena, the values and attitudes they develop, and how their character is shaped by their value systems. The taxonomy ranges from receiving or being aware of phenomena, to actively responding to it, internalizing values and attitudes, comparing and relating values to build a value system, and having a value system that controls behavior and forms a consistent lifestyle. Krathwohl made significant contributions to the field of educational psychology.