If you're using the light bar: 'you are going to see several lights several lights going from (direction), almost like looking at a train going by, what I want you to do is look in the middle (point at the light thats there) and count out loud the lights as the go by, i'll let you know when they switch directions'
9 out 10 times this works, if it doesn't tell them to pick up the light on 1 end track to the other end and repeat.
For the projector depending on the program, if there are no red dots on the screen tell the person to find a red dot as the dots go by. Haven't had an issue with this yet.