In my opinion cognitive development and language have different ways to be perceived as "natural". It just all depends on what form of "natural" you are referring to. There is the natural process of socially learning things and words or there are the genetic/psychologically common or "natural" things that you somehow gain knowledge of on your own. I personally am stuck in the middle of each, as said in 'Vygotsky on Language and Thought', "At that stage, word meaning denotes nothing more to the child than a vague syncretic conglomeration of individual objects that have somehow or other coalesced into an image in his mind … Many words … have in part the same meaning to the child and the adult, especially words referring to concrete objects in the child’s habitual surroundings." which I perceived as both. The child has the individual mental state that they will bring random objects together and learn how to express it on their own, but because of their specific expressions and surroundings the adult is able to make a connection with the social education they have developed or expressed which helps. them to make a connection as to what the child want and or needs. With this example i believe that it can also explain a strength and weakness in neurosciences approach to understand learning. It can be a weakness because not all learning developments can be tracked and followed through the brain, such as the social learning I previously referred to, but the strength is that there are many ways to track the brain as someone is studying or trying to use the knowledge they gain and see if their is a mental effect as to why they are having trouble or developing knowledge faster than others.

Lev Vygotsky

http://newlearningonline.com/new-learning/chapter-6/vygotsky-on-language-and-thought