I often see people itch but it does not cause me to need to itch just like I can watch someone yawn but it does not cause me to yawn.
I know that if you itch it causes you to itch more then you scratch more and it is never ending cycle. I will ignore a itch until it goes away usually.
Itching is such a mysterious thing. I usually don't itch if I see that someone else is. I'll just get a random itch. My ankle for example will start itching uncontrollably. I'll scratch it and it gets worse. Then a few minutes later I realize something distracted me from it and it doesn't itch at all now *smile*.
Yeah, itching is one of the mysteries of the human condition. It's kind of like a yawn. When you scratch you only spread your itch and when you yawn you only spread your yawn. Have you ever been in a crowded place, yawned or seen someone yawn and then watched as it spread?
An itch you can't scratch: Researchers find 'itch receptors' in the throats of mice. Working with mice, researchers report they have found previously known skin itch receptors in the airways that appear to contribute to bronchoconstriction and airway hypersensitivity, hallmarks of asthma and other respiratory disorders. The investigators' experiments in mice suggest that the receptors' activation directly aggravates airway constriction and -- if the same process is active in people -- may be a promising new target for the development of drug therapies. Source 5u.