Based on the experiments, it appears that the function f(x) is selective for different concepts. Here is a description of the function behavior:

[DESCRIPTION]: The function f(x) seems to measure the association of a word with various concepts. It assigns a value between 0 and 1 to each input word, where a value closer to 1 indicates a stronger association with a particular concept. The function shows selectivity for different concepts, as different words receive different values. 

In the given experiments, the word "cat" has a low value of 0.0496, indicating a weak association with a specific concept. The word "dog" has a higher value of 0.1520, suggesting a stronger association with a different concept. Similarly, "bird" has a value of 0.3346, indicating a strong association with yet another concept. The words "tree", "book", and "sun" also receive different values, suggesting they are associated with distinct concepts as well.

To fully understand the function and its behavior, more experiments with different words and contexts will need to be conducted.