Nudge of the Month

Challenging the Broken-Window theory

How can we prevent individuals from urinating in open areas?

In the Nudge TV show “The Power of Habit”, Sille Krukow, a behavioural expert based in Denmark, designed a nudge to help the Copenhagen Central Station. The problem they were faced with was that many men would urinate in hidden corners outside the building, despite the close location of public (and clean) toilets.


Staff has to clean the area several times a day

According to Ms. Krukow, this phenomenon can be explained by the broken-window theory of policing (Wilson and Kelling, 1982). When individuals observe others misbehaving, they tend to act in the same way, instead of doing the right thing.

The solution adopted in the show was to add a urinal to the area in question and stickers on the sidewalks signaling the direction and distance to the closest WC.

WC stickers.png

Implementation of the WC stickers


Urinal installed in the most critical zone

Around 500 people had been observed urinating in two corners of the station during the week before the experiment. After the intervention, half of the people did the right thing, i.e. they instantly used the urinal, while the other half started  to urinate on the street, but changed their behaviour once they saw the urinal. This means that the cleaning staff and station customers were saved of 5,000 liters of urine a week!

To learn more about this nudge (and other experiments), you can find the episodes online here.

Nudge of the Month

Nudges and Social Norms

When are nudges most effective? A study by Pelle Guldborg Hansen, founder of the Danish Nudging Network, a non-profit organisation in Copenhagen, suggests that nudges may work only if they are in line with social norms. They tested two potential “social nudges” in partnership with the local government, both using symbols to try to influence choices:

In one trial, green arrows pointing to stairs were put next to railway-station escalators, in the hope of encouraging people to take the healthier option. This had almost no effect.

The other experiment had a series of green footprints leading to rubbish bins. These signs reduced littering by 46% during a controlled experiment in which wrapped sweets were handed out.


“There are no social norms about taking the stairs but there are about littering,” said Mr Hansen. Hence, perhaps existing social norms must be studied before designing a nudge!

Our Work

Nudges for a healthy lifestyle – Part II

In the article Nudges for a healthy lifestyle – Part I”, we talked about the nudges created by governments around the world related to improving people´s lifestyles.

If you wonder why governments care about lifestyles of their citizens, the reason is mainly money. Unhealthy diet, frequent consumption of addictive substances (mainly alcohol or tobacco), and lack of physical movement are all widespread and may lead to “non-communicable diseases”, such as diabetes or cardiovascular diseases. The governments have two possibilities – either encourage the change in lifestyles and decrease the occurrence of such diseases or pay for the cure. Obviously, prevention is a cheaper choice and in case of lifestyle issues, also feasible.

Moreover, if governments understand human behaviour, their attempts to change it will probably be more successful. That is why Behavioural Economics can be helpful in this domain.

Part I of this article was dedicated to the nudges related to food consumption. Part II will discuss nudges concerning tobacco and alcohol consumption and physical movement.


As for physical movement, there has been a very simple nudge trial conducted in the City of Melbourne in Australia. To encourage people to take the stairs instead of elevators in a train station building, the City of Melbourne had the stairs painted in a colourful and catchy way (see Picture 1). It may not seem like  a very strong nudge; why would anyone struggle on the painted stairs if they can see them also from the elevators? But it seems that the citizens of Melbourne did not think like this – according to a report by the Behavioural Insights Team (that collaborated on this trial), the usage of the stairs increased by 25% during off-peak times and by 140% in  peak times!


Picture 1

Source: Zest Events


Moving to tobacco consumption, the nudges used around the world are quite uniform. There are two major manipulations that have been implemented.

1) The first one is plain packaging, whereby the tobacco producers cannot use the package as a marketing space and have to comply with rules for uniform font, size and colour of the text, as well as uniform package colour. The space previously used by companies is now dedicated to health warnings, both in words and in pictures (see Picture 2). The rationale behind such a policy is that it decreases the appeal of tobacco products and at the same time, gives more importance to the health warnings, which should deter people from smoking. It seems like a good idea at first glance, but when one thinks about it more, the following doubts arise. Firstly, there is a large amount of brand loyalty among smokers, so it is not probable that they will stop smoking only because of a change in design. Secondly, there is the optimism bias that goes against the effectiveness of health warnings. People usually overestimate the probability of positive things happening to them and underestimate the probability of the negative ones. Hence, when they see a health warning, they may simply think “it happens, but to the others, not me”.


Picture 2

Source: WHO

2) The second widespread anti-smoking nudge-based policy is the tobacco display ban. In the countries where it has been introduced, tobacco products have to be displayed so as not to be visible to the customers in the shops (with the exception of specialised tobacco shops, of course). Again, such policy goes against marketing possibilities of tobacco producers and the hope is that it will decrease the amount of impulse purchases, which are frequent mostly among the young.

There are several papers trying to evaluate the impact of these two anti-smoking policies, but there is no clear conclusion to be drawn. It seems that smoking is a very complex issue and is cannot be easily solved by using only nudges. Another issue is that in many countries, these policies have been implemented only recently, so it is too early to know their impact. Anyway, even if the nudges are not the solution in this case, maybe they could still complement some other policies to make a real change.

The last lifestyle issue is alcohol consumption and there is a very nice example of the use of nudges in this domain. At the Northern Illinois University, a simple marketing campaign based on social norms (i.e. informing the students about how many drinks other students have when they party) was enough to decrease students´ binge drinking.

(If you want to know more about this particular policy, see the article A Social Norms Approach to Preventing Binge Drinking at Colleges and Universities.)

To conclude both articles about the nudges related to healthy lifestyles, I would like to say one thing. Clearly, nudges do not automatically solve all problems. But as long as they are low-cost and do not harm anyone (such as removing the salt shakers from restaurant tables or painting the stairs in a train station), I think they are worth trying, because even a small positive difference is a step forward towards a healthier life.

Nudge of the Month

Increasing charitable giving

How can we nudge people to donate to charities? There are many ways to do so, but we would like to share one in particular which is very simple and surprisingly powerful.

It seems that peer effects are an effective tool to change people’s behaviour. We want to do what people like us are doing. If teenagers have friends that smoke, they are very likely to start smoking themselves (and much more likely than if their parents smoke). The same holds for donations – if our colleagues donate, we would like to donate as well.

This is what has been tested by the UK´s Behavioural Insights Team in cooperation with Her Majesty’s Revenue and Customs (HMRC). The HMRC employees in Essex were sent postcards describing the donation efforts of their colleagues and encouraging them to do the same, to see if more people would start donating. However the experiment went even further (and this is where it gets interesting). One group of employees got postcards featuring a picture of the donor in addition to the above information (see Picture 1). An insignificant change, you may think, but 6.4 % of people signed up for the donation scheme in the latter condition, compared to 2.9 % in the no-picture condition.


Picture 1: Postcard featuring a photo of the donor

Source: The Behavioural Insights Team (2013)

If you want to know more about behavioural insights applied to charitable giving, see The Behavioural Insights Team (2010) and for a further discussion of peer effects (social norms), read Institute for Government & Cabinet Office (2010).

Nudge of the Month

Attractive names of meals for healthier diets of children

Carrots or French fries? Fruit salad or a chocolate bar? These are the dilemmas that children face when choosing their meals in school lunchrooms. From convincing them that veggies will give them superpowers to ominous threats of what will happen to their bodies if they don’t eat healthy, there are few options left unexplored on how to get kids to eat right.

Unsurprisingly, when all else fails, BE swoops in and saves the day. Discarding classical solutions such as information campaigns, it offers a much simpler alternative: make the healthy options more tempting.

How? By changing their names. Several research teams in the US have tried this strategy in various school canteens and they found that making the names “seductive”, catchy or funny can induce children to eat healthier.

Decisions, decisions…

Source: Tes Global Ltd

Hence, instead of offering carrots as “vegetable of the day” or simply “carrots”, call them “X-ray vision carrots” or “twisted citrus-glazed carrots” and you will increase the probability that children will pick them!

For reference, see Wansink et al. (2012) and Turnwald et al. (2017).

Article Review

A Social Norms Approach to Preventing Binge Drinking at Colleges and Universities

Review of the paper by Michael P. Haines (1996)

It is well-known that increased alcohol consumption of young people is a persistent problem and college and university students are no exception.

The Northern Illinois University (NIU) came up with a solution that has since spread to other US universities and even high schools. It all started by conducting a survey about students´ drinking behaviour, which revealed the presence of a large knowledge gap. Most of the students thought that binge drinking was more widespread than it really was.

The Health Enhancement Services Office at NIU decided to take action – develop a campaign to correct the perceptions of the students. What is the logic behind this? It is the belief that people are sensitive to social norms and tend to behave in line with them. For example, we all know that when we ask for something, we should say “please” and “thank you”. We do it because it is a norm accepted in our society and everyone does so. There are several papers proving that perceptions about the drinking behaviour of other students are a strong predictor of the actual drinking behaviour, so norms are at work also in this case (for the reference, see Graham et al., 1991 or Prentice and Miller, 1993).

The organisers of the NIU campaign were very careful with the design, since they wanted to spread the message as much as possible. They chose the campus newspaper, widely read by the students, as their medium to publish the following very simple message: “Most NIU students (55 percent) drink five or fewer drinks when they party”. This message was repeated on flyers, posters and on any occasion the students were likely to hear it.

The NIU team also came up with incentives for students to pay attention to the message. Two students were hired to work as “Money Brothers” (inspired by the movie The Blues Brothers). They would ask students how many drinks most NIU students consume and give $1 to anyone who answered correctly.  They also created some posters and would give $5 to those students living in university dorms who were found to have it on the wall of their rooms during random checks.

It is clear that the NIU team really worked hard to make students notice the message. The result? After the first year, there was an 18 % reduction in perceived binge drinking and a 16 % reduction in real binge drinking. Obviously after such success, the campaign has been repeated in the following years and binge drinking decreased further.Graph

Source: Haines, M. P. (1996): A Social Norms Approach to Preventing Binge Drinking at Colleges and Universities

The take home message of this initiative is that social norms are powerful and capable of changing our behaviour. However, the message needs to be simple, truthful and most importantly, noticed by the target audience.

Since then, other universities and high schools applied the same technique to fight binge drinking of their students. Here are some of the campaign materials:

Sources: Social Norms Consultation & Nudge blog

How about you? Do you know how many drinks people from your university/company normally have?

Our Work

Nudges for a healthy lifestyle

Part I – Food related nudges

Nowadays, non-communicable diseases (such as cardiovascular diseases, chronic respiratory diseases or diabetes) are a serious problem, killing around 38 million people every year according to WHO. An interesting fact about them is that they are often caused by an unhealthy lifestyle – tobacco and alcohol consumption, unhealthy diet and lack of physical activity.

Obviously, governments worry about the health spending and so they try to come up with programs to solve these issues. But it seems that many times they fail to deliver the desired results. Why is that?

One of the reasons may be that the programs do not provoke the right actions. A traditional approach is to give people information, based on the assumption that they engage in unhealthy behaviours, because they do not know how harmful they are. Another traditional solution is to increase the costs related to certain behaviours, such as increasing the taxes on tobacco or alcohol. A common problem of these methods is that they may not lead people into action. They rely on the fact that people are rational, always weigh the costs and benefits and decide to do what is best for them.

But these programs fail to take into account that people may behave differently in reality. A mere information about the risks of smoking is not sufficient, since people suffer from an optimism bias – they do not believe that something bad could happen to them. There is also a present bias – the cigarette “now” is so pleasurable and the risk of cancer is “so distant”, which is why people will procrastinate their decision to join a stop smoking program.

The behavioural approach means taking these biases into account and creating nudge-like interventions that really lead to actions and consequently to a better health.

Here are some examples of nudges aiming at improving our diet:

1) A very successful and simple initiative comes from the Nordic countries – they use food labels to simplify decision-making process while grocery shopping. The Nordic Council of Ministers established a set of nutritional criteria, which have to be met in order for a product to get the Keyhole label. People know that if they see the sticker, it means the product is good for their health. Some evaluations of the Keyhole label showed that the level of awareness about it is really high (more than 90 %) and that it truly helps people to choose healthier food products.


2) However, such labelling strategies do not work everywhere. Some countries (e.g. Australia, UK) came with the idea of using the Traffic Lights label, which uses the colours of traffic lights to indicate if a product is healthy (green), unhealthy (red) or somewhere in between (amber). It may seem like a good idea, but somehow the results from the countries that are using this label are mixed. Also, the Traffic Lights label faces a lot of reluctance from food producers. For example, several countries of the European Union fought hard against its use, in order to avoid their typical products being labelled red (e.g. Italy, famous for its meat products, among other things).


3) In the US, they have the Smarter Lunchrooms Movement that uses nudges in school canteens. It is run by behavioural economists from Cornell University and it seems to be quite successful. The interventions are minimal, such as changing the names of the food or changing the ways in which the food is displayed, but it has some positive effects on children. I bet you would also prefer to eat “X-ray Vision Carrots” than “The Food of the Day”.

4) To conclude, I mention my favourite food nudge that comes from Argentina. The problem with hypertension (i.e. high blood pressure) in the city of Buenos Aires became very widespread and so the city decided to remove salt shakers from the tables in the restaurants. Now, consumers may get salt only if they ask for it. This way the liberty of choice is preserved, but the choice architecture changes in favour of breaking the automatic habit of adding salt to your meal. The only pity is that there is no study evaluating the impact of this nudge!

Do you know about some other food nudges that governments around the world used to improve their citizens’ diets? Let us know about them!

Next article: Part II – nudge interventions to deal with smoking and alcohol consumption