English to Portuguese Social Sciences Psychology

Please, what does it mean "proper" at the end of this sentence?

"The definition given previously is limited to the level of human cognition proper (roughly the last three in this list)."

Broader context:

The term “subject” might already presuppose more than is required. The notion of equilibration is applied by Piaget from very broad to very specific, for example, to inorganic evolution, to organisms and physio- logical mechanisms, to nonhuman functioning, to schemes, to senso- rimotor regulations, or to thinking. The definition given previously is limited to the level of human cognition proper (roughly the last three in this list). What would be minimally presupposed for equilibration to be possible, though, is a complex system that is in a permanent exchange with its environment.

The text is in a book about Piaget (psychology). Translation from English to Portuguese.

Thank you very much!