A reciprocal exercise in hygiene habit formation


Cristina Parilli

Shortlisted for the LSE Sir Julian Le Grand Essay Prize 2020

Masters Student in Behavioral Sciences, University of Pennsylvania


A reciprocal exercise in hygiene habit formation: Lessons to inform post-pandemic life?

The COVID-19 pandemic of 2020 has made citizens around the world update their behaviour. Regular hand washing, surface cleaning, and the avoidance of handshakes have been widely promoted and adopted as protective behaviours. An important question is whether these “new” habits will be sustained over time. Will past behaviours return once the crisis is over? How can policymakers incentivise habit formation in good sanitary practices, particularly in shared public spaces?

My focus here is a specific behavioural intervention that appeared effective in incentivising gym users to keep equipment clean, particularly exercise mats. Although the motivation of this is not based on relevant behaviours to stop the spreading of viruses such as COVID-19, it could serve as an example on how to incentivise people to shift from unhygienic  behaviours to hygienic ones.  The intervention included changing the choice architecture and using reciprocity messaging. It was implemented at Bloomsbury’s Fitness, the official gym of the University College London (UCL) Student’s Union. It is worth noting that this intervention was carried out in 2019, well before the COVID-19 pandemic, and thus prior to the physical distancing requirements of 2020.

Maintaining gym equipment in an optimal state might represent an important challenge for fitness centres. Dirty equipment, such as exercise mats, can carry bacteria and can also Image 1decrease the enjoyment of its users; one could assume that people prefer to train with clean equipment. Mats can get dirty through contact with the user’s skin, from their sweat or from external sources such as shoes. In this case, it was especially noticeable that Bloomsbury Fitness’ users did not usually take their shoes off when exercising with mats, thus transferring dirt from their shoes to the mats, making them visibly dirty, and fostering an unpleasant environment for exercise. This became the main targeted behaviour.

What could have been motivating this behaviour? There are several possible factors: Firstly, there were no formal rules to prevent people from leaving their shoes on when using mats, as the default. Secondly, there was no normative information promoting the desirable behaviour. Thirdly, as mats get dirty easily and were not constantly replaced, users could have been demotivated to take their shoes off. Lastly a social norm appeared to be in place, in which people did not take off their shoes, as almost no one else did so.

The intervention

A behaviourally-informed poster was displayed to incentivise people to take off their shoes while training with mats. This intervention alluded to reciprocity (Fehr et al, 1997) and was inspired by the EAST framework (BIT, 2014). Additionally, and motivated Image 2by the ‘broken windows’ theory (Wilson and Kelling, 1982; Kelling and Coles, 1997), a complementary intervention was included in which dirty mats were replaced with new ones. This was expected to potentially boost the effect of the poster by providing a cleaner environment that could motivate people to dedicate more effort to maintain it.

As people tend to determine their own routine when training at the gym, one could argue that an intervention focused on the choice architecture is appropriate; to promote hygiene whilst still allowing people the freedom to choose how to behave. Additionally, if it is assumed that people do prefer to train with clean mats, a small encouragement in the form of information could increase their willingness to voluntarily take their shoes off to achieve that goal.

Let’s reciprocate

Reciprocity seems a strong element in human behaviour; a “golden rule”. Maus (1954) argued that people tend to act according to the expression: ‘I give in order that you may give’. Therefore, people are not always likely to merely take or give, but are rather more inclined to give if others give and thus, tend to reciprocate (Kahneman et al, 1986). Reciprocity also appears to be an important driver of co-operation within groups (Oliver, 2017).

Considering this behavioural finding, the poster clearly highlighted, with an intense purple colour at the bottom, the phrase ‘Let’s help each other!’. This reciprocity phrase was meant to help people to understand that, if they all behave properly, they can all benefit. This behaviour might be particularly relevant for the current COVID-19 crisis, in which effective collective collaboration can be beneficial to all.

…and maintain a clear environment

The ‘broken windows’ theory (Wilson and Kelling, 1982; Kelling and Coles, 1997) outlined that an urban environment with signs of deterioration (i.e: dirty streets and broken windows) saw an increased crime rate. This theory was used in New York City under Mayor Rudy Giulani administration when minor crimes, such as vandalism and public drinking, were heavily penalised in order to maintain cleaner streets.

This theory was adapted so as to think of dirty mats as a sign of environmental deterioration. By replacing the old mats with new ones, we were changing the environment (or choice architecture). This would encourage people to improve sanitary practices as they would  feel that their effort was contributing to the maintenance of an already clean environment.

Did it work?

In order to assess the impact of the intervention in its real-life setting, a non-experimental evaluation was carried out in Bloomsbury’s Fitness on the 29th and 30th of April 2019. Given that, for logistical reasons, it was not possible to randomly select people to read the poster or not, field observations were used. The primary subject of the study was to observe how many of those who used mats chose to take off their shoes.

Figure 1 - Evaluation groups
The Evaluation Groups

According to our observations, there was no significant difference between only displaying the poster and its respective control, although people who were exposed to the poster did take their shoes off more than their control (difference of 26 pp). However, when people were exposed to the poster and new mats, they reacted even better, with 74% of them taking their shoes off versus only 10% of people in the control. This represents an important difference of 64pp, and it is statistically significant at 1% of significance level, which means that a major behaviour change was evidenced when adding the new mats to the choice architecture. This can also be seen in Images 4 and 5.

Table 1
Evaluation Results

Image 3 and 4

What can we learn from this intervention?

This intervention seemed to help shed light on the relevance of reciprocity for people to behave in a way that achieves a collective goal, and how this effect can be greatly boosted if the choice architecture is more heavily altered, such as keeping a clean environment (in this case, keeping the mats clean).

When thinking about approaches to help sustain current hygiene practices due to the COVID-19 crisis of 2020, it could be relevant to think about messages that include reciprocity content, that can be delivered to the audience in a timely manner (such as placing them in key locations as was done with the gym poster), and that are easy to digest (only one or two phrases).

These results might also tell us that it is important not only to motivate people with messages, but also to arrange their environment to prompt the desired behaviour. In this case, it seems that continuously promoting a clean space can further boost our sanitary practices. Hence, this finding might encourage policies to ensure that public spaces, such as toilets, gyms, and even supermarkets, are kept visibly clean.

Overall, this intervention highlights the potential value of a focus on choice architecture,  for cost-effective and simple solutions to problems that negatively affect daily life. It also offers some hope that policymakers can pre-emptively address one of the many lasting challenges from the current viral pandemic; that society can be prompted to act reciprocally for the benefit of all.

Hopes for the Future

The current pandemic has made citizens around the world update their hygiene practices, such as regular hand washing, avoiding handshakes and cleaning high-touch surfaces. Will these habits be sustained over time? Although it is not yet possible to answer such a question, we can start thinking about potential ways to incentivise people to maintain their new hygiene habits, to help limit future disease outbreaks.

The result of this small intervention in a London gym suggests that reciprocity can be an important motivator for hygiene, but also that environmental factors play an important part in turning this motivation into action.


[1] Previous authorisation was granted to conduct this intervention.