 Schulz and Kelly particularly influenced Watterson's outlook on comics during his formative years.Notable elements of Watterson's artistic style are his characters' diverse and often exaggerated expressions (particularly those of Calvin), elaborate and bizarre backgrounds for Calvin's flights of imagination, expressions of motion and frequent visual jokes and metaphors.In the later years of the strip, with more panel space available for his use, Watterson experimented more freely with different panel layouts, art styles, stories without dialogue and greater use of white space.