It's commonly said that if you hold a chicken's beak to the ground and draw a straight line in front of it, it will stare at the line and not move. There's no shortage of footage on youtube to prove that it does seem to work. But have any scientific studies been done to verify and/or explain the effect? Could it just be that gently holding a chicken's head to the ground is what causes the effect, and the line is irrelevant? I've tried looking through places like Wiley with keywords like "chicken hypnosis" but I really have no idea how to find this kind of literature.