system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can people "sense" when they are being watched?

I'm a skeptical person by nature and disregard the paranormal, by and large. However, there seems to be good evidence that people can (sometimes) tell when they're being watched, without any discernible mechanism for being able to do so. What's up with that?
gpt
What evidence?  
   
People think they can do this for various reasons.  The primary one is that people rarely remember the times they thought someone was there but there wasn't.  They only remember the times they were correct.  This is known as "confirmation bias".   
   
But there are also a variety of ways that one might notice someone nearby without ESP.  Soft, subtle sounds.  Vibrations. Air currents.    
 
Having someone enter a room can even change the sound of the room in very subtle ways. The ambient noise that is present will take on a slightly different character.  
  
These things might not be something that is consciously noted, but the brain is still picking up the information.