For their child’s safety, a parent may have to verbally constrain and prohibit him/her from exploration.
Spitz provides insights into the child’s formation of the concept of negation as constraint:
Parents first physically constrain their children verbally then do it from a distance by language and gesture.
Within a month of physical constraints, the children show signs of understanding “no” and the headshake in that type of situation.
Another sign they understand is when they intentionally disobey.