That sounds like you have experience with one outlier. As a whole, this is generally true.
A few tens or hundreds of thousands of years ago, that outlier that didn't get quiet would have been selected right out of the gene pool of that family group, leaving behind the quiet babies to go on and have more quiet babies.
Actually it is from the moving objects just out of their peripheral vision along with bright colors and music.
At birth, a baby's vision is pretty fuzzy, though it could make out light, shapes, and movement. Newborns can see only about 8 to 15 inches away — just far enough to clearly make out the face of the person holding them. Which is just a few inches below where most baby mobiles are.
The bird thing is a myth.
They scream.
They fucking shriek.
This is a lie.
A few tens or hundreds of thousands of years ago, that outlier that didn't get quiet would have been selected right out of the gene pool of that family group, leaving behind the quiet babies to go on and have more quiet babies.
It's how evolutionary selective pressure works.
At birth, a baby's vision is pretty fuzzy, though it could make out light, shapes, and movement. Newborns can see only about 8 to 15 inches away — just far enough to clearly make out the face of the person holding them. Which is just a few inches below where most baby mobiles are.
The bird thing is a myth.