Interesting. Instead, kid enters the room, you tell them that they will be sitting there anywhere from 5 minutes to 3 hours, depending on how long the experimen

Interesting. Instead, kid enters the room, you tell them that they will be sitting there anywhere from 5 minutes to 3 hours, depending on how long the experiment should be. They get to choose a sequence of doors. At each step, the door can either contain +10 minutes or -10 minutes, representing the number of minutes which will be either added to or subtracted from their experiment duration, respectively. My guess is that the depressed/bored children will now respond a little bit better to this experiment. It's just a guess -- but I think depressed/bored kids would tend to avoid spending time being bored in a little lab room.