An imaginary thing in the mind of the infant. An imaginary thing in the mind of the mother. Infant and mother are in unconscious confluence. No individual mind can exist without a framework consisting of cultural components. There is no such thing in reality.
Cultures change over time and across space.
It is probably helpful to our understanding to say that, at some point in time, one culture has evolved into a different culture. It is a current cultural convention, a rule, that we think of action as originated from individual minds located in individual bodies. Some current commentators say that the present typical state of consciousness is a trance state. And each of you for helping me. At least for me they are unthought until I think them.