I'm not saying such an effect doesn't exist. I'm saying the statement "The fact is people dont react when someone need help in the street/metro. " is patently false. There are many many more anecdotes where people do help. In fact, I havent read one anecdote where this device would have changed anything. It seems to me that most of the deadly delay is caused by shock and fear more than anything else.

Feel free to provide me a study where they actually conducted scientifically rigorous tests in public and not just a few guys in a test room. I'd like to see the actual percentage of failures to assist and I'd like to see evidence where this device helps at all. For all we know it could hinder matters, though I would suspect not.