A study was conducted on ten day-care centres in Haifa, Israel. Economists kept track of the number of parents who came late to pick up their children.
After four weeks, a fine was introduced. Any parent who picked up their children late had to pay an extra $3 on top of their monthly bill.
After the fine was put up, the number of late pickups promptly... went up.
When I read this in the introducing chapter of Freakonomics, I said - what da? Surely nobody wants to pay an extra three bucks. You can (almost) buy a burger with that! But as it turns out - by introducing such a dismal fine (on top of the $380 monthly fee), it allowed a channel for parents to feel not so guilty when they are late in picking up their children.

Last year I failed to read a single book.
Lots of magazines (with lots of pictures), but no books. Nadda.
This year, I told myself 'I should at least read one book'. Doesn't matter if it’s thin, thick or pink or gold covered (thou shall not judge a book by its cover!!) as long as I read a book. That was my new year's resolution.
I finished my second book this year and I'm glad I've gotten back to reading.
I think I was just being stubborn from all the Harry Potter attention that's why I've stayed away from books. Or maybe because I didn't make time to read books. But who was I kidding. My brain needed a work out just as much as my body did. So off to Borders I went.
Freakonomics was a non-themed book which was dry in some parts and interesting in others. I say non-themed because it was really hard to put a finger on what the authors were trying to say.
But I'm glad I read it. Now I'm walking away with some pearls of wisdom on why drug-dealers still live with their mom and why claiming to be single, tall and wanting to be in a long-term relationship will maximise my hits in Yahoo! Personals.
The message I took home from this book was that people are driven by incentives. Be it economic, social or moral. Positive or negative - rewards determine who we are.
And although that may sound trivial, it made me realise the type of people around me by looking into what their goals are. I could have figured that out. But it took a book for me to think it.