What is the third method of torture that the captor uses on the narrator in "The Pit and the Pendulum"? What happens in the end?

At the
beginning of "," the Spanish Inquisition sentences the unnamed narrator to death.
However, simple execution isn't enough. The Inquisitors arrange for the man to be tortured
first. Although the torture is physical in nature, it is designed to torture the prisoner's mind
even more than his body.

First, they drug their captive so he can't trust his
thoughts or his senses. When the drug wears off, he finds himself in a completely dark cell.
Utter darkness would be terrifying in such a situation and would, itself, have been a torment.
However, the man has enough survival instinct to explore his space. He discovers that the center
of the room harbors a pit. By letting a stone drop and listening for the impact, he determines
it is extremely deep. Now fear of falling builds on fear of the dark to make his punishment an
even crueler mind game.

When the captors realize that their captive hasn't
succumbed physically or mentally to the darkness or the pit, they drug...