"Objetuales" does immediately suggest "arte objetual", which takes us back to Duchamp ultimately, and "arte conceptual" is a familiar enough term in modern art. But I've come to the conclusion that this can't be what the terms are referring to here.

The main stumbling block for me here is "dándole". What is that doing there? The only way I can make this mean objective/objectual/object-based and conceptual art is by just ignoring "dándole". Also, what noun do "objetuales" and "conceptuales" refer to? "Decisiones"? How does that work? It just makes no sense to me.

But I think "dándole" has to mean "dando a la pieza". So ideas come to him while he's working on a piece and he takes decisions, giving the piece "objetuales y conceptuales". Maybe this means "ideas objetuales y conceptuales". Or maybe there is an unspoken noun there, something like atributos or cualidades.

Anyway, I conclude from these reflections that actually "objetuales" doesn't refer here to "arte objetual" but that it means "physical" or "concrete": pertaining to the artwork as object. I don't think you can express this as objective, which is not the same thing as "objetual".

This illustrates the sense in which I am interpreting the adjectives:

"El proceso se da en la medida en que la información le llega al niño de su entorno socio cultural a manera de elementos conceptuales (abstractos) y elementos objetuales (físicos)"
http://fido.palermo.edu/servicios_dyc/encuentro2007/02_auspi...