Two players get a relationship from the audience. A player leaves the room: for the other player the captain asks what their reaction is to the other player and what the trigger for this reaction is. So for example: they laugh (reaction) when the other says “I” (trigger). Then this player leaves the room and you ask the same thing for the other player.
The scene is a free improvisation from this point. The Pavlov reactions need to be consistent and believable, because this is what the audience will pay attention to!
As a captain, take the time to ask for suggestions. “Picking their nose” will result in terrible play (it will become forced and does not invite nice emotional reactions) and “singing the national anthem” as a trigger is also worthless because a player will generally not do this very often, let alone multiple times in one scene. Try to get suggestions from the audience like “Confessing something”; these kinds of Pavlov reactions can really push a scene forward.
This game is very good for people that think too much during play, because you can’t plan the scene but instead you have to continuously respond to the play of your fellow player (this can be both the trigger of the other player as well as the reaction to your trigger, e.g.: “why do you keep laughing when I talk about myself? Do you think my misery is funny? You have always been a sadist…. sniff sniff…”). It is also a good exercise to practice paying attention to your fellow player.