Sight Line - Beginner
The reason babies freak out when you play peek-a-boo is they haven't figured out the concept of object permanence—basically, that if you can't see an object it's still probably there. They think when you cover your face that your face is gone forever.
But we're adults and we know better, right? Not if Sight Line has any say in the matter. Sight Line keeps track of where you're looking in the world, and when you turn away for a second everything can change. Peek-a-boo.