To try it, you will need:

• a doorway

OK, it is really very simple. Stand in the doorway. Start with your arms hanging down by your sides. Lift them outwards until the backs of your hands are touching the doorframe on each side of you. Now press outwards with your arms, as hard as you can. Keep pressing while you count to 60, or as long as you can without it hurting. Then take one step forward and relax your arms. Your arms will seem to rise upwards all by themselves.

What is going on? Two things are working together to make this happen. The first is muscle tension. If you tense a muscle until it gets tired, it will keep some of that tension even after your brain stops sending it a signal to push. You can try that by making a fist and squeezing it as tight as you can for about a minute. Then if you slowly open your hand, you can feel the muscle tension that is still trying to keep your hand closed.

This muscle tension by itself is not enough to explain what happens to your arms. The other part of the experiment involves suggestion. An important part of this trick is telling the person that is trying it what will happen. Because they are expecting it to happen and they are prepared for it, as soon as they feel the muscle tension lifting their arms, they unconsciously help.

Try testing the experiment with several people that do not know what to expect. They may still get some arm raising from the muscle tension, but you will probably find that you get a much stronger response from someone that has been told what to expect.

We have done experiments on suggestion before. (Remember when we saw that just thinking about your nose itching could make it itch? If you have not seen that video, try to go for 5 minutes without scratching your nose.) This experiment is another example of how the mind and the body work together, sometimes in ways that we do not realize. For example, just saying the words "ice cream" over and over can cause my body to go to the freezer for a snack, all on its own.