OPINION8 September 2015

Bias in the spotlight: social norms – part 2


We have a common tendency to adopt the opinions and follow the behaviours of the majority to feel safer and to avoid conflict, or simply to be more cognitively efficient in our decision-making.


To recap on our previous Bias in the Spotlight column, social scientists have identified two types of social norms:

  • Descriptive social norms – doing what everyone else is doing, e.g. buying the latest iPhone that everyone seems to be getting, saving energy in the home because you’ve heard all your neighbours are.
  • Injunctive social norms – what others believe, or approve of, and therefore what we know we should be doing e.g. tipping a waiter is a cultural norm, as is adhering to the speed limit on the highway.

In our previous article we looked at how injunctive and descriptive social norms could be used to nudge people to wear sunscreen. In this article, we look at how they can be leveraged to encourage people to pay their overdue taxes.

Governments all around the world lose substantial amounts of revenue from delayed or unpaid tax payments. While a handful of people may be dishonestly dodging the tax man or simply short of cash, it’s more often the case that we simply forget or procrastinate and just don’t get around to paying on time. Those who don’t pay on time may think there are many others just like them but in fact this is not the case; in most countries they are the odd ones out.

The UK is no exception to this problem with an estimated £4.55 billion of taxes owed in 2010 due to non-payment. So in 2012, a team of behavioural scientists partnered with the HMRC and the UK Behavioural Insights Team to run a large scale field experiment across more than 100,000 UK taxpayers. They tested a series of interventions to see if different social norms messages included in reminder letters about taxes owed might influence the timely payment of taxes.

In their experiment, they tested 11 variations of both descriptive and injunctive social norms messages about paying taxes.

So which of those 11 messages worked?

Those which had the biggest, statistically significant effect were mainly descriptive social norms – that is the ones that make us want to conform to what everyone else is doing:

“The great majority of people in your local area pay their tax on time. Most people with a debt like yours have paid it by now.”

 A double-hitting message reminding people not only that most people in their area had already paid their tax but also making salient that they were in the minority right now raised response rates by 5 percentage points:

“Nine out of ten people in the UK pay their tax on time. You are currently in the very small minority of people who have not paid us yet.”

 A frame highlighting that most UK taxpayers pay their taxes and making clear that the negligent taxpayer was in the minority who had not done so, increased response rates by 4.2%.

 “You are currently in the very small minority of people who have not paid us yet.”

 Similarly, stating only the last part of the message above increased response rates by 4.7%.

 Although the injunctive norms messages stating majority opinions about tax paying generally had smaller effects than the descriptive norm statements, all had a positive uplift. A message which highlighted the majority opinion as a percentage had the largest impact of all injunctive norms messages though, increasing response rates by 3.4%:“88% of people agree that everyone in the UK should pay their tax on time.”

If the most effective message – the first in the list above – had been applied to all the letters in the intervention, the researchers estimate that this would have generated an additional £15.4 million in revenue. Given that this intervention was virtually cost-free – simply a subtle change in the language used in a letter – this is an astounding result and illustrates the potential effectiveness of simple ways of using social norms statements to steer behaviour.

By Crawford Hollingworth, at The Behavioural Architects