Everybody knows the eerie feeling when we are on the street and suddenly people around us look up as if they see something. We feel compelled to follow their gaze and "look up" as well. If they act as if they see something we will struggle mightily to try as see "it" as well. We feel certain that there must be something there that has caught their attention.
There is a classic psychology experiment that builds on this. Here's a video of Asch's conformity experiment with some analysis of why people feel compelled to bend to group pressure:
This "conformity" was tested further by Stanley Milgram in an obedience to authority experiment. This was his attempt to understand how Germans so easily gave into the murderous Nazi regime in Germany:
A variant of conformity was the infamous Philip Zimbardo prison study experiment at Stanford: