Hitchcock On The Kuleshov Effect

The "Kuleshov Effect" was a 1918 film editing experiment conducted by Lev Kuleshov:  

During this time I created a montage experiment which became known abroad as the 'Kuleshov Effect'. I alternated the same shot of Mozzhukhin [a Tsarist matinee idol] with various other shots (a plate of soup, a girl, a child's coffin), and these shots acquired a different meaning. The discovery stunned me - so convinced was I of the enormous power of montage.

Alfred Hitchcock demonstrates in this excerpt from A Talk With Hitchcock.  You can find other excerpts of this video scattered across the Internet or cough up $8.50 for the complete 52 minute DVD.