Limited time offer: When nudges stop working

Context is crucial

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If you remember back to last year, there was a big splash about how sending text messages could increase the rate of uptake of Covid vaccines. The research seemed to show how using simple ’nudges’ could have a potentially large impact on this critical public health issue.  

Photo by Clay Banks on Unsplash

However, a new study published in Nature now shows that this nudge stopped working pretty quickly.

Timing matters. A lot. 

When the vaccine became available, text messages seemed to increase uptake immediately. But later on in the pandemic, they stopped being effective. This was true even when using the same language and framing in the text messages that had proved so effective in getting people over the line to get vaccinated earlier in the pandemic in Jan / Feb 2021. 

Why did this nudge lose its power to influence behaviour?

The research team put forward a few ideas. One reason is that the people who may have been open to influence had already taken up the invitation to get vaccinated. Those who had still not received the vaccine more than a month after it became available were perhaps less amenable to change and held stronger anti-vaccine opinions, and were therefore less likely to respond to this text-message nudge. Polarised debate had also taken hold at this point online and in the mainstream media, further entrenching these positions and meaning that small nudges like this rapidly lost their potency as people became overwhelmed with messages about vaccination. 

“Although we cannot identify the mechanism(s) responsible for decaying efficacy of nudges, the possibilities include novelty effects early on, oversaturation effects later on, different types of hesitancy (logistical barriers versus objections to vaccines), and, especially for COVID-19, increasingly polarized discourse, divergent social norms and differential vaccine knowledge.”

This doesn’t mean that nudges are useless. But it means that timing and audience are critical. 

It’s also important to note that too many messages might also have the unintended impact of further polarising opinion and driving people away from the very behaviour you are trying to increase.

This particularly study had to be ended a day early because the Department of Health was fielding complaints from people who thought they were getting too many messages. The Department became concerned that people would block messages and end up missing critical health and emergency information. 

This is a lesson we need to learn as it is looking more likely that we may need to understand how to ask some particularly vulnerable people to get vaccinated again.

Nudges not only need to be effective, but they also need to fit into the context of all that is going on.

Miss that context, and you may end up doing more harm than good.