what makes someone tick

"The Drunkard's Walk" を読み終えたので次ぎの本として "PREDICTABLY IRRATIONAL" by Dan Ariely を読み始めました。　この本もオーストラリア人のピーターさんが推薦していた本の一つで、サブタイトルに The Hidden Forces that Shape Our Decisions とあり behavioral economics と言う私には馴染みのない、しかし興味を覚えるのジャンルの本の様です。
本文の前のintroductionに早速私のアンテナに引っ掛かる表現が出てきました。
My goal, by the end of this book, is to help you fundamentally rethink what makes you and the people around you tick.
"tick" は知らない単語ではもちろんありませんが、ここでの意味がピンと来ません。何せ私は時計でもダニでもないので。早速辞書のお世話になります。
・Dictionary.com: what makes one tick, the motive or explanation of one's behavior: The biographer failed to show what made Herbert Hoover tick.
・McGraw-Hill Dictionary of American Idioms and Phrasal Verbs: Fig. something that motivates someone; something that makes someone behave in a certain way. (Fig. on what makes something tick.) William is sort of strange. I don't know what makes him tick. When you get to know people, you find out what makes them tick.
・Macmillan Dictionary: the feelings and ideas that make someone behave the way that they do
an interviewer who is determined to find out what makes her subjects tick
なるほど、この本の目的を表すのにピッタリの表現なのですね。