text: It is true you cannot preform any mental functions when you sneeze however when something is done so much that it becomes "habitual" such as walking it is not governed neccessarly by your mind.  It is then goverend by your nerves at your spinal column.  This is why you don't have to think about removing your hand from a hot stove...it never reaches your mind it is intercepted by your spinal cord and sent back to remove your hand.  When you sneeze it inturupts what your mind sends out but not neccessarily what your nervous system sends out to your body.  So it is possible to sneeze and walk.