Expressionism was actually a reaction to
modernism
medievalism
impressionism
serialism
primitivism

Expressionism was actually a reaction to IMPRESSIONISM.

Expressionism in art works is when artists paint based on what they are feeling. They express their emotions through artwork. The standard of assessing the quality of an artwork is now based on how the artist portrayed his or her feelings and how the audience perceive it and not on what the composition of the art work is like techniques, etc.