Autism

Yep. You can find some research about it in sociology/psychology. I think sociology calls these unspoken rules mores, if you want to look it up. The most famous example is when an entire group of people is in a new setting, like the first class of the first day as freshmen in high school, 6th graders in middle school (or whenever your local school board decides middle school starts), and college freshmen. The entire group usually sits quietly and nervously until they start taking cues from the teacher. Once they learn the basics expectations and test the boundaries, behavior falls somewhere between how they used to act and what they think is expected from the entire group. We are hugely social animals, and there's a reason that exile used to be a major punishment.

People don't seem to really grasp how much of our behavior is 'scripted' like a movie or play, and, amusingly enough, how much we follow the scripts of said movies/plays/other-observed-scenes when we're in a new or stressful situation. Remember your first time in an amorous situation with a date, say in a car or closet or back yard at a party? If you hadn't been listening to your friends and what they did (or told you they did / what to do), you might find yourself awkwardly stumbling through the actions of some movie's clip, whether that's casablanca, sixteen candles, or easy a. Hopefully it won't be anything from when harry met sally.