In stuffing knowledge into heads, we mischaracterise everything. Here is a nice illustration. This is one of the first moving pictures every shown, having among the suite of 10 films commercially screened by the Lumiere brothers in Paris in 1895.
Given the novelty of the technology, and the age of the child, we would confidently assert that the child does not know or understand that it is being filmed, and so we might attribute its motions or behaviour to itself alone.
But the child is embedded in a social situation that includes two caregivers, and it is responding sensitively to each and every thing they do. They know about the filming, and they are greatly affected by it. So the child’s behaviour is equally affected. Knowledge lies between us, not in heads.
It takes little effort to extrapolate from this to the laboratory of the behavioural psychologist.