1. According to the structural relationship of the animal brain, when it is always rotating, it is easy to have the illusion of direction, which is what we often call "halo". However, if you cover your eyes, because you can't see the changes in the surrounding scenery, your brain won't have this illusion and your body can keep a natural balance. So generally speaking, when the donkey pulls, it will cover its eyes to prevent it from turning blindfolded.

Secondly, another important reason why the donkey is blindfolded when pulling is to prevent it from stealing food.