The function f(x) appears to be selective for both concrete and abstract concepts. It assigns higher values closer to 1 for words that are associated with these concepts. It is not limited to a specific category of words but rather evaluates the association of any word with a concept. The function may have a preference for certain concepts as indicated by the varying values assigned to different words, but further testing with a larger variety of words would be necessary to determine the exact nature of those preferences.