In an experimentation, everyone is a number and all the characters; the victims and the patients are merely a data.
This experimentation has happened, may not happen or has yet to happen. The action might have taken place 50 years ago, last year or in 5 years' time.
The premise of the E.S.T. (Est) experiment is: keeping someone in the dark for as long as it is possible -one month in theory-, filming and recording everything and subject the contestant to a series of interviews in order to define the person but also to treat this person from any possible mental problems.
There is no time limit: the experimentation can go on for as long as the number is still alive.
Exhibit 6. Titan. Complete Annihilation.