It's an interesting experiment, but not surprising.
I wish cognitive bias was a concept I'd been introduced to much earlier, but I did not read about such a thing until reading the book
Thinking, Fast and Slow several years ago. The examples from that book include not just judgment situations, like in the parenting study, but also ways which cognitive bias will even affect people examining inflexible results, such as mathematics, if the mathematical problem is posed in a way that triggers an emotional response.
For whatever reason, I've locked onto this idea like learning a new word, and now I see it everywhere (the parenting study is one of many examples); and I try to be cognizant of it in my own decision-making, perhaps overly so.
Here's a
link to an interview on the subject of bias with psychologist Daniel Kahneman, author of
Thinking, Fast and Slow. Please note that I posted the link to the interview, but I haven't read the interview yet. If it proves to be something worthless, I'll find a better link. EDIT: It's a good interview, though not particularly deep, but I still managed to get a new piece from the interview ? from the interviewer more than Kahneman himself.
If you're curious about
Thinking, Fast and Slow, it's not an in-depth psychology book by any means. It's an anecdotal popcorn book on many different topics. I give this book my highest recommendation, especially if you like Freakonomics or even something like Imponderables. This one is more useful, though. EDIT: I was reminded by reading the interview that while each chapter does contain different examples, the book is tied together by Kahneman's general notion of a "fast brain" and a "slow brain."
Anyway, the parenting study also reminded me of another article I'd seen within the past couple of years or so. I might have even been led to it by a link here on LGK. The choices I make are not influenced by man sources.

This other article was about the changing attitude toward parenting in general. Specifically, it was about how, as a mother, if you speak of your child in anything other than doting terms today, you will be harangued from every direction, while that wasn't always the case. I'm neither a parent, nor a woman, so I know nothing of that from experience, but it seemed to dovetail nicely with this article, too.