How does American method acting differ from the Stanislavski system?

The American method evolved from the Stanislavski system. Two actors who had studied with Stanislavski came to the US with the Moscow Arts Theatre's tour in the 1920s and stayed to teach their techniques to a group of actors at the American Laboratory Theatre in New York City. Because they had studied with Stanislavski at an early point in his career, these actors passed along the notion of affective memory as part of his system, even though Stanislavski had since abandoned it. Affective memory requires the actor to focus on the sensory stimuli surrounding an event in his/her personal life that was similar to the situation in the character's life in order to evoke an emotional response. Lee Strasberg was a student at the American Laboratory Theatre, and when he formed Group Theatre along with a number of other artists, he emphasized this aspect of the Stanislavski system. Despite learning that Stanislavski was now focusing on emotions as a by-product, rather than a goal, Strasberg, then director of the Actor's Studio, continued to develop his influential method of actor training around this technique.