The Trials was a series of three tests that the Creators, members of WICKED, created for a group of teenagers, called subjects, who are Immune to the Flare, or extremely rarely, not. They had been testing the "subjects" when they were very young, before the Maze Trials, to see if they're capable and strong enough to be sent up to the Maze. They consisted of Variables designed to provoke certain Killzone patterns which WICKED would then use to attempt to create a Cure for the Flare. After the subjects had passed all the Trials, WICKED would choose a final candidate to provide the final information needed to create the cure. This information was the physical composition of the Killzone or the brain itself. To acquire this information, however, the Final candidate would be operated on. This operation is fatal.
There were three Trials: the Maze, the Scorch, and a third test, different and various for each individual. Thomas' third trial was to be alone in complete isolation in a white room for 26 days or roughly 4 weeks, while Minho's third trial was answering 3 separate questions with one word for each answer.