Glad to be of (some) help :)<p>I&#x27;m not a developmental psychologist btw, just have an interest in cognitive development. The proof you&#x27;re looking for would be more the field of cognitive neuroscience.<p>There definitely are graph-like connections between concepts all over the brain, I didn&#x27;t mean to suggest that our brains work hierarchical only, to the exclusion of all other relations. As an example: if our brains were strictly hierarchical, we would be unable to see the similarity in colour between a grey table and a grey hare. I just meant to explain my thinking on how abstract thought is tied to a attribute&#x2F;property hierarchy, not proclaim that I know how the brain works.<p>(edit: snipped on-topic content, best reserved for a separate post)