I try to be notoriously Vulcan during interviews. The practice is not something that’s difficult for me, nor is it necessarily unnatural. Being neutral, or stoic to the outcome of an event can allow yourself to detach from the emotional pressures. It’s hard to stand up in front of a crowd of people, or go on an interview you’ve felt frightened about, but stepping back away from one’s emotions and focusing on a broader picture, irrespective of the outcome of an event, allows you look at things through a lens you can assist with.
Neutrality, at least in emotionally difficult times, is something that can be extremely helpful. Backing away, and seeing things from the distance is like withdrawing any of the “fight or flight” instinct from a situation, and it allows you to bring your best self, or at least not your most panicked self, into a given situation.