|5645||COLORFUL NOTIONS||COLORFUL NOTIONS||1984||color||47 min||vhs|| (Horizon (BBC-TV) Series) Why do humans see in color? It surely could not be for aesthetic reasons alone. Color vision must have evolved to serve some practical purpose. Illuminating breakthroughs in the study of sight, this production overturns all the old assumptions about how and why people see color. It also explores strange visual effects, such as "negative after-image," which have been known for hundreds of years but never fully explained--until now.