Can a Nudge Reliably Make People Budge?

A fascinating debate is unfolding in the Proceedings of the National Academy of Sciences (PNAS). It’s mostly about publication bias, but the bottom line question is not so esoteric. Can a nudge make meaningful behavior change happen in a wide variety of situations?

Late last year, Stephanie Mertens and colleagues published a meta-analysis of nudging strategies in a variety of domains. They concluded that “choice architecture interventions successfully promote behavior change across key behavioral domains, populations, and locations.”

But there was a catch. They found evidence for moderate publication bias. In other words, they found evidence that studies showing that nudges are ineffective might have been less likely to make it into the research literature. Though Mertens noted this bias, it was not a factor in their conclusion that nudges work.

Not So Fast

In response to Mertens et al, three different research letters recently appeared in PNAS. Each of them raised the possibility that nudging is not such a reliably robust tool for moving behavior toward diverse policy goals.

Maximilian Maier and colleagues said it bluntly. It’s perfectly reasonable and doable to adjust the meta-analysis for publication bias. They did it and concluded there’s “no evidence for nudging after adjusting for publication bias.”

Barnabas Szaszi and colleagues said it a bit more gently. There’s “no reason to expect large and consistent effects from nudge interventions.” They take issue with an “implausibly large” effect size in the Mertens paper.

Jonathan Bakdash and Laura Marusich dive a little deeper into issues with effects data that “are clearly left-truncated” and thus point to an over-statement of the general effectiveness of nudging.

In response to all of this, Mertens et al agree that these issues are important and that they point to “growing pains” for the concept of choice architecture – a fancier name for nudges.

Nudging Strategies to Prevent Obesity

Quite a few strategies to prevent obesity lean heavily of faith that nudging can move the population toward healthier behaviors to drive obesity rates down. It’s quite appealing. But it hasn’t really worked out yet.

Perhaps one of the most famous disappointments was the wildly popular concept of “mindless eating” that Brian Wansink promoted with a book and a whole series of media-savvy studies in support of nudges for changing eating behavior. His ideas lost much of their shine with retractions of many of his studies.

So folks who want to believe that nudges can add up to a really effective policy response for high obesity rates would do well to bring some objective skepticism to their work. It’s easy to see what we want in an intervention we truly believe can help. But the data must speak for itself. And costly experience tells us that preventing obesity is not so easy as people like to believe.

Click here, here, here, here, and here for the Mertens, Maier, Szaszi, and Bakdash papers, as well as the Mertens response. For further perspective, click here and here.

Prime Mover, from the ‘Stanza della Segnatura,’ fresco by Raphael / WikiArt

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August 8, 2022