Based on the results so far, it appears that the function is selective for concepts related to excavation, digging, and various physical environments. f(x) returns values closer to 1 for words associated with these concepts, like "excavation" and "digs", as well as values for words like "quarry" and "underground".

[DESCRIPTION]: The function f(x) is selective for concepts related to excavation, digging, and physical environments, with higher values indicating a stronger association with these concepts.