Andrew Huberman· PhD
The first babies are the a babies. So these were kids that would get upset when their caretaker would leave. But when their caretaker would return, the infant would respond with happiness, with what looked like delight. They would go to the caretaker. They seemed happy. If they had been fussy before or sad, they felt relieved. These are referred to as secure attached kids. So they have a healthy response to separation, and they have a healthy response to re-engaging with the caretaker.