The human brain's decisions don't always make sense. If you ask a person to pick a green door or a blue door, they might pick a green door because they were thinking about green grapes 5 minutes earlier and how they really wanted some green grapes, or they might pick the blue door because the walls of their childhood bedroom were blue and they associate blue rooms with good memories.

And it's human nature to not pick the same thing twice; to try the alternative just to see what happens.