When the test proctor, Tori, tells Beatrice that her test results are inconclusive because her scores indicate aptitude in three factions (Abnegation, Dauntless, and Erudite), Beatrice realizes that she is Divergent.
Beatrice belongs to an Abnegation family and is torn between choosing a new faction or staying with her loved ones. To be factionless is to live the life of an outcast in an impoverished section of the city, always hungry and destitute, performing work that no one else wants to do. Poised on the cusp of adulthood, Beatrice knows that tradition will eventually force her to make a choice.
At the Choosing Ceremony, Beatrice chooses to join the Dauntless faction. Her initiation into the Dauntless faction will be divided into three stages. Eric, one of five Dauntless leaders, tells the initiates that they will be ranked and that only the top ten initiates will be allowed into the Dauntless faction. The rest will be cut from the group and left factionless.
The first stage primarily tests physical strength, the second tests emotional strength, and the third, mental strength. Stage Two tests the ability of the initiates to overcome their fears in frightening situations.
In Stage Two, all initiates are strapped into metal chairs and injected with a serum which contains a transmitter. The serum stimulates the amygdala (which processes emotions) and induces the initiates to hallucinate. Each initiate has to encounter a personally designed hallucination which tests their abilities to stay calm (and control the rate of their breathing and heartbeat) during a simulated disturbing experience.
The transmitter in the serum sends information about the brain's electrical activity to the computer during the simulations. The computer then processes the electrical activity into images the test proctor can monitor on the screen. A recording of all initiate brain activity during the simulations is reportedly sent to Dauntless administrators. The initiates stay in hallucinatory mode until they exhibit control over their breathing and heart rates during the frightening simulations.