"It is much easier to come up with words that begin with a particular letter than to find words that have the same letter in the
third position. People tend to exaggerate the frequency of letters appearing in the first position."
It is from "Thinking, Fast and slow" by Daniel Kahneman.

Oh my gosh! You know what is so embarrassing is I actually read that book and totally forgot that part. I love Danny Kahneman and all his heuristics I'm always falling for. I still have yet to think of a single word with K as the third letter, though. Wait I got one- "like", my favorite word. Ok, touche, you win hahaha.