Y&B #47 Should we use mirrors in yoga classes?

Whether or not to use mirrors in yoga classes is a popular topic of discussion among teachers. This is the first episode in my new yoga and movement research series. I talk to Jules Mitchell about the efficacy of using mirrors when learning yoga asana. We discuss a study entitled, "Effect on performance of learning a pilates skill with or without a mirror."  The study examines a pilates move called the STAR movement,  but what we learn from it can also be applied to yoga. The STAR move is similar to Vasistasana (side plank) while raising and lowering the top leg. The stated goal of this study was to "use an objective measure of performance to look at the effect of mirrors when learning Pilates star movement that must then be done without the mirrors." What do you think? Is it best to learn a motor skill with or without mirrors?