You're correct about the arms, but I believe the Rift has additional sensors on its touch controllers [1], allowing it to record your thumb position and update

You're correct about the arms, but I believe the Rift has additional sensors on its touch controllers [1], allowing it to record your thumb position and update the hand model accordingly. 1: https://upload.wikimedia.org/wikipedia/commons/d/d8/Oculus-Rift-Touch-Controllers-Pair.jpg https://upload.wikimedia.org/wikipedia/commons/d/d8/Oculus-R...