Alright, what about a child who sees cars everyday, but has never been told what a car is.
If a child can see cars but there's no one there to name them for the child, the child is being neglected... and perhaps even in physical danger.
And haven't you observed children name things ad hoc by the sounds they make?
So I don't buy the idea that a child "can still manipulate the car concept as easily as if he knew the word for it".
Also, yes, people with "very small vocabularies... because they have been exposed to a small number of words"
do have their cognitive skills affected, usually for the worse.
If a child can see cars but there's no one there to name them for the child, the child is being neglected... and perhaps even in physical danger.
And haven't you observed children name things ad hoc by the sounds they make?
So I don't buy the idea that a child "can still manipulate the car concept as easily as if he knew the word for it".
Also, yes, people with "very small vocabularies... because they have been exposed to a small number of words" do have their cognitive skills affected, usually for the worse.