The first advice I ever give to anyone new to mountain biking: "Look at where you want to go, never lock up (focus or elbows), and always look further ahead than what feels natural."

You don't always need to be focusing on an object for this phenomenon to occur. Your bike generally follows where you're focusing, so if you're looking towards the exit of a turn you're more likely to reach that exit. If you focus too close to the trail you also end up increasing your center of gravity, making you more unstable.