The term user psychology was originally introduced by Tom Moran (1981). It was rarely used since. However, in early 2000 it came obvious to me that the metascientific foundations of human technology research and the way psychology is applied should be improved. Therefore, it made sense to introduce the idea of explanatory design to the use of psychological knowledge to support design decisions. This approach has been developed with Antti Oulasvirta and my other students. To emphasize the meaning of psychological explaining it was termed user psychology.