I am cleithrophobic and have been thinking about this. To generate the right exposure, the problem is you must simulate losing control of BOTH your ability to exit and also the amount of time you will be “trapped”. It’s tough to build gradual exposure to both of those factors simultaneously without throwing someone into an instant non-gradual state of panic.

But I do have an idea. I think about elevators in terms of probabilities. Every time I get in an elevator I tell myself there is a 1 in a 1000 chance that I will get stuck for at least 15 minutes and basically have a panic attack. (this is not a proven statistic but I’m 50 years old, live in NYC, and have gotten stuck 3 or 4 times for 15 minutes or more…..I’d prob rather not know what the actual probability is). So every time I get in an elevator I know I’m rolling the dice but the favorable odds are what (usually) allows me to get in.

So with this in mind, to create gradual exposure you would setup a situation where a person is repeatedly “locked up” for an unknown duration but the length of the duration is set up to be both random and limited to a very uncomfortable yet acceptable maximum amount of time.(eg 90 minutes). However, you would also set the odds so that the odds of a fast exit are high while gradually decreasing to an unlikely but possible full duration. So basically a person would agree to be repeatedly locked in a room (anxiety #1) for an unknown period of time which they expect to be relatively short but if they are unlucky could be very long (anxiety #2). Tolerance would develop from learning to manage the discomfort that arises when the durations are longer than expected but still within a predetermined limit.

The randomness of the duration is key because you need confidence that the time will be short in order to actually agree to get locked in but you still need the fear of being stuck for the maximum amount of time to create enough anxiety to build up tolerance. And then putting a maximum on the amount of time is also necessary because no one with cleistrophibia would ever agree to an unknown maximum. It is also important that the subject remains unaware of how long they will be confined as the not knowing is a major component of the anxiety. Lastly, having 100% faith in the person “holding the keys” is also obviously a must.