[Jonty30]

I think they know something is of value by our behaviour. The more we spend time with it and checking it, it tells them what we value.

[nickcarraway]

So I could trick them into stealing something worthless? Another victory for Homo Sapiens!

[Jamestown1630]

They probably know the value that something has for us by the effort - or tribute - we will put forth to get it back.

They aren’t stupid - like most animals, they adapt and learn from their environments. (I think we share over 90% of our DNA with monkeys and other NHPs.)