"I heard that the same thing occurred in a scene in Alien, where the creature pops out of the chest of a crewman. The other actors didn't know what was to happen; the director wanted to get true surprise"

Marvin Minsky's quote is referring to a method used in filmmaking known as "surprise acting". This method is utilized to develop a more realistic and spontaneous reaction from the actors in a scene. In the example offered, the director of the film Alien wanted to capture the real surprise of the other stars when the animal pops out of the chest of a crewman. By not informing the actors of what was to occur, the director was able to record a more authentic reaction from the stars. This strategy is frequently utilized in scary movies to create a more intense and realistic environment. Surprise acting is an excellent way to create a more credible and engaging scene for the audience.