This came to my observation recently, i had been to the post office via my scooter. There was a big queue in front of me and hence i had to wait for a while before my turn came to post, within the next 5 mins 6-7 people were standing in line after me. I was tensed about my scooter getting towed away hence i kept looking behind every 5 seconds. At the first 2 times no one seemed to mind my frequent turning back but soon during my 3rd-4th time of turning back 2 people that were behind me started turning back just as i did, and similarly the other people followed eventually. I soon realised that none of them were aware as to why i was turning behind but all of them repeated the action atleast once. It is amazing to see how our minds ask us to repeat the action without even thinking just because you see 3 other people doing it.