Click the image to see it in its full 1970s glory.
The illustration above comes from Volume 3 of Understanding Human Behavior, a 24-volume series of books published in — as you might have guessed — 1974. I love the Lex Luthor / Joker purple-green color scheme in that office!
The cover for Volume 1 was pretty surreal:
Found at 70s Sci Fi Art via Merlin Mann.