Based on the results, it seems that f(x) is selective for the concept of water transportation and water-related activities. The words "boats", "ships", "kayaks", and "sailing" have strong associations with this concept. 

[DESCRIPTION]: The function f(x) is selective for the concept of water transportation and water-related activities. It assigns higher values to words related to boats, ships, kayaks, and sailing, indicating a strong association with these concepts.