https://theaggie.org/2015/03/16/the-par ... endliness/
“Americans exchange numbers and Facebook and never hear back from each other. It’s puzzling but they do it to show openness,” says Moira Delgado, the Outreach Specialist for Services for International Students and Scholars. “For Americans, when they ask for your number, they are expressing a possibility of a friendship, more than a promise to be in contact.”
Many foreigners are surprised to discover how friendly Americans are when they arrive in America. Strangers talk to each other, the cashier at the supermarket asks how your day has been, and you strike up conversations with people who are standing in line with you. For Europeans, who tend to keep a certain distance from strangers, this at first is a welcome change, but when they realize that “how are you?” only means “hi,” they often see it as a lack of genuineness from Americans.
I am American-born, and have observed this behavior my whole life. People will come up to you and be over-the-top enthusiastic, and you are not sure how to respond. Then as soon as you do give them back any attention, they suddenly ignore you. It's like they just want to see if they can get you to take the bait so they can pull one over on you.According to Delgado both Americans and foreigners can learn from each other. Foreigners have to realize that they have to take the initiative. If an American says “we should go to a movie sometime,” the foreigner should follow up and be specific. The foreigner should ask which movie and which day. Otherwise, it likely will not happen.
If you don't act like a sociopath you are considered "antisocial" and "introverted", when the opposite is true.