What are the psychological effects of line design?

Different lines invoke different feelings depending on your mental background. Though they differ in the minds of others, horizontal lines usually leave a sense of tranquility, imagine a sunset cast upon the ocean. Vertical lines give a feeling of stability, for example, pillars that hold a building, or a tall man, one would consider him more "stable" or confident if he was vertical and upright rather than slouching. While curved, and zig zag lines offer a more lively sensation. I hope this has helped.

Alex - Student of art and psychology.