Nudge, nudge, wink, wink.

“I didn’t kill him; I only nudged him in the general direction of death.”

I am usually quite good at recalling lines I liked from films or TV series and exactly where they are from, but for this one, I really can’t. Perhaps it was just something triggered by what I was watching at one point but was eventually a product of my wandering mind.

OK, the opening might have been a bit flippant, but what I actually want in this post is to remind you – or rather myself – how powerful nudges can be. To begin with, there is a brilliant book by Richard Thaler and Cass Sunstein, Nudge (2008), which is precisely about that. I am generally not very enthusiastic about the economist’s perspective, from which this book approaches the topic, but I found the passage in the book about what a significant difference a choice between opt-in and opt-out defaults makes in terms of organ donation rates across American states or other countries fascinating.

One strategy is to alter the default rules for signup. Most states, as well as many other countries, use an “opt in” or “explicit consent” rule, meaning that people must take a concrete action, like going to a public library or requesting and mailing in a form, to declare they want to be donors. But many who are willing to donate organs never get around to such steps.

An alternative approach, used in several European countries, is an “opt out” rule, often called “presumed consent,” in which citizens are presumed to be consenting donors unless they act to register their unwillingness.

In the world of traditional economics, it shouldn’t matter whether you use an opt-in or opt-out system. So long as the costs of registering as a donor or a nondonor are low, the results should be similar. But many findings of behavioral economics show that tiny disparities in such rules can make a big difference.


Consider the difference in consent rates between two similar countries, Austria and Germany. In Germany, which uses an opt-in system, only 12 percent give their consent; in Austria, which uses opt-out, nearly everyone (99 percent) does.

No time to read the whole book? Here’s an article Thaler wrote for the New York Times (which the above quotation is also from). If you want to see reviews of the book before committing to it? Here’s one by Levitt (of Freakonomics).

And this applies to many other things, including software default settings. I myself didn’t pay enough attention to this issue until I listened to a presentation by Rajiv Shah of the University of Illinois in the 2006 AoIR conference. It was one of those presentations that I am glad that I chose over other parallel ones.

After the recent unveiling of Facebook’s new privacy policy, there has been a debate whether the change has been made for the better or the worse. What I was more interested in was how so obviously the Facebook team was gearing users towards the no-privacy option despite what they claimed about “improving privacy” (in Mr Zuckerberg’s words). Nudge, nudge, wink, wink. Say no more.

(Screenshot from here. Forgot to capture mine.)


4 thoughts on “Nudge, nudge, wink, wink.

  1. I am a project manager and part of what I do involves getting people to agree with me. So I am a big fan of the concept of presumed consent. Rather than follow-up feedback or input of stakeholders in a design proposal, I spell out the salient points agreed, say, in a meeting in an email with a line at the end stating to the effect that “non-response to this email will be interpretted as agreement to the points raised above” (of course written in a more softly-softly tone).

    Saves me a lot of time making phone calls and enables me to focus more on moving a project forward.

    It takes a while for people you work with to get used to it. But if you remain consistent, you progressively earn a reputation for no-nonsense clarity.

  2. I find this interesting from two points of view. One is that economists do seem to be moving in a more ‘social’ direction. (Probably a good thing given recent events in the financial markets.) On the other hand, in disciplines like sociology, for example, there is perhaps too much of an assumption that how and why people act is explicit, conscious, and motivated. Yet small contextual factors are important and consequential.

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