According to the TNGS, categorising occurs ‘on value’. That is, categorising neuronal systems are linked with value systems — cholinergic and aminergic — of the hedonic centres and limbic system, whose functions include homeostasis and appetites.[1] This means that categorising processes occur in the context of the current state of the organism, and the effect of this is to make categorising meaningful — to matter — to the categorising organism.
Footnote:
[1] Through this linkage, inherited value systems bias the categorising process in ways that have been of advantage to ancestors; the value systems of those who do not survive to reproduce are not passed down the generations of a biological lineage.