Behaviour Change

PROPAGANDA FOR CHANGE is a project created by the students of Behaviour Change (ps359) and Professor Thomas Hills @thomhills at the Psychology Department of the University of Warwick. This work was supported by funding from Warwick's Institute for Advanced Teaching and Learning.

Thursday, May 3, 2018


Whilst looking around lecture rooms, the library and even on the bus we noticed a significant number of people are using disposable single-use water bottles (pictured below).

Whats the problem with this?


Use of these types of bottles can bring a host of negative consequences for both the individual and the environment. 

In regards to individual health, 86% of teenagers tested by researchers at University of Exeter had BPA in their urine. BPA is a chemical found in plastic and can leach from the plastic into the water which is then consumed. This chemical can be harmful as it can disrupt the endocrine system and affects hormones (Golloway et al, 2018).

Furthermore, the plastic industry has produced 8.3 billion metric tons of plastic, most of which ends up in the trash. In particular, 91% of the plastic produced is NOT recycled and this is extremely wasteful (Parker, 2017). Additionally, plastic water bottles that are not recycled have become a significant problem for world wide marine pollution. Another study by Geyer (2017) suggests 79% of plastic waste ends up in landfills and oceans. When these bottles end up in the ocean, they take more than 400 years to decompose, so therefore the plastic still exists in the ocean in some form. This is problematic as the remains of the plastic can enter the marine food chain, which can cause harm to sea life (Parker, 2017). Finally, if we continue, research by the Ellen MacArthur Foundation suggests that by 2050 there will be more plastic in the ocean than fish!

In order to put the issue into further perspective for University of Warwick students, the above picture shows single use plastic bottles polluting our local area in Jephson Gardens, Leamington Spa. Additionally, use of plastic and its negative consequences is extremely topical at the moment, especially since the recent series of Blue Planet presented by Sir David Attenborough, who shed light on the damaging impact plastic pollution is having on marine life. Therefore, our aim was to promote behaviour change by encouraging people to switch from these single-use bottles to more substantial reusable water bottles for the benefit of health and our environment.

What We Did and Techniques Used

Instagram Account


We chose to utilise social media for our project (Instagram, in particular). We decided to use the power of Instagram because, interestingly, there are several behaviour change techniques involved in how influential it is. In order to gain a following of our account, we decided to use the classic ‘follow for follow’ strategy. This engages the technique of reciprocity as by following people on Instagram, they then feel obliged to return the small favour and follow back (Cialdini, 2007). The influence of reciprocity is demonstrated in the classic study by Regan (1971) where a confederate offered a subject a bottle of Coke during the break of the study and afterwards asked the subject to buy raffle tickets. The subjects who received the bottle of Coke were more likely to buy raffle tickets than those who did not. This demonstrates that small favours increase the tendency for people to return the favour through the power of reciprocity. This was a good way to gather a sizeable audience of 122 followers for our Instagram campaign on the use of plastic bottles.


Additionally, an area of Social Psychology that has received increasing attention recently is the idea of ‘Fear of Missing Out’ (FoMO). This concept describes the feeling that one is missing out on an event elsewhere (Przybylski et al., 2013). Instagram can trigger this feeling by exposing the individual to what everyone else is doing. Therefore, FoMO can encourage others to get more involved, which was an aim of our social media campaign. Therefore the influence of FoMO was used to gain followers to begin our behaviour change, as it is an influential aspect of Instagram.

How did we use this Instagram account?
We decided to start posting images of students around campus using their own reusable water bottles instead of single-use ones, as 'shout outs' (see examples below). This also created a snowball effect whereby more people started to send photos of themselves with their bottles, including from other universities, like Newcastle University.

Social Proof

One of our aims here was to engage the power of social proof, showing similar others how they can make the switch to reusable bottles too. The principle of social proof was identified by Cialdini (2001) as one of the key psychological principles relating to compliance, and describes the way in which people tend to examine the behaviour of others in a certain situation in order to determine how they should behave themselves. This is particularly influential in terms of similar others (Cialdini et al., 1999). This idea is largely based on social comparison theory (Festinger, 1954), which proposed that we judge the correctness of our actions on how others respond in the same situation. The principle of social proof has been shown to be effective for encouraging donation of money to charity (Reingen, 1982) as well as reducing littering behaviour (Cialdini, Reno & Kallgren, 1990). Therefore, we hope to engage the principle in encouraging the use of reusable water bottles.

This is relevant to our campaign as it suggests that, theoretically, we should be able to encourage behaviour change by suggesting to university students that it is correct to use reusable bottles instead of single-use plastic bottles. When it comes to environmental issues, many people think that their individual actions will have no impact and it is someone else’s job to fix. However, our posts were images of university students (relatable individuals), which would show that individual people can make a difference, and that the message is inclusive of our target audience (students). This is also important because as mentioned earlier, social proof is particularly powerful amongst similar others, so creating a relatable message coming from relatable sources would strengthen the influence of our posts.


We also used the hashtag #plasticisnotfantastic under each post and repeated this hashtag wherever possible. Repetition can be a powerful feature of propaganda, and Adolf Hitler said a successful technique for propaganda is to “confine [the message] to a few points and repeat them over and over”. Additionally, Weaver et a (2007) demonstrated ‘a repetitive voice can sound like a chorus’. The effectiveness of repetition is shown in a study by Weaver et al (2007) where a opinion repeated three times by the same person proved to be just as persuasive as the opinion stated by three different people. Therefore, our aim for the hashtag was to create a memorable ‘slogan’ to increase availability and salience of the message.


As well the instagram account, we created a poster with a direct powerful image with two facts about single use plastic bottles. The image was used to grab attention and clearly show how plastic is problematic (see image below). A QR code was used to provide a link to our instagram account. We placed these posters all around campus to reach as many people as possible.


Challenging Misconceptions

Furthermore, by talking to a few people about using sustainable reusable bottles we noticed a few recurring reasons for why people continue to use single-use bottles, and we want to challenge these misconceptions.

Reusable bottles just start to smell after a while”

Reusable bottles do not smell if washed properly, and this process takes less than one minute. 

“Reusable bottles are expensive”

The bottles are not always expensive, amazon offers great deals on BPA free, leak proof bottles

“Water that I buy in plastic bottles tastes better than tap water”

To solve this, water filtering jugs can be purchased and kept in the fridge. This way you can pour cold, filtered water that tastes nicer than tap water into reusable bottle.


In order to assess our impact on behaviour change we conducted a 'poll' on instagram at the beginning and end of our campaign.

The initial poll suggested that 70% did, while 30% did not use a sustainable and reusable bottle. Our aim was to reduce the amount of people who did not use a reusable bottle, and increase the number who do.

The second poll on the Instagram account to see how many people used a sustainable water bottle again, and how much they had been influenced by this account. 81% said they had used a sustainable bottle since following this page, and 92% stated they were more likely to use a sustainable bottle in the future. The percentage of people who did not use reusable bottles decreased from 30% to 19%.



Overall, we consider our #plasticisnotfantastic campaign to be a success as we managed to increase the percentage of people using reusable bottles. Additionally, our Instagram account received many commendable messages from likewise projects, and some also asked if we would like to collaborate with them. This also demonstrated the influence and impact of our project.


Cialdini, R. B. (2001). Influence: Science and Practice, Allyn & Bacon.

Cialdini, R. B., & Cialdini, R. B. (2007). Influence: The psychology of persuasion (pp. 173-174). New York: Collins.

Cialdini, R. B., Reno, R. R., & Kallgren, C. A. (1990). A focus theory of normative conduct: Recycling the concept of norms to reduce littering in public places. Journal of personality and social psychology, 58(6), 1015.

Cialdini, R. B., Wosinska, W., Barrett, D. W., Butner, J., & Gornik-Durose, M. (1999). Compliance with a request in two cultures: The differential influence of social proof and commitment/consistency on collectivists and individualists. Personality and Social Psychology Bulletin, 25(10), 1242-1253.

Festinger, L. (1954). A theory of social comparison processes. Human relations, 7(2), 117-140.

Galloway, T. S., Baglin, N., Lee, B. P., Kocur, A. L., Shepherd, M. H., Steele, A. M., ... & BPA Schools Study Consortium. (2018). An engaged research study to assess the effect of a ‘real-world’ dietary intervention on urinary bisphenol A (BPA) levels in teenagers. BMJ open, 8(2), e018742.

Geyer, R., Jambeck, J. R., & Law, K. L. (2017). Production, use, and fate of all plastics ever made. Science advances, 3(7), e1700782.

MacArthur, D. E., Waughray, D., & Stuchtey, M. R. (2016). The New Plastics Economy, Rethinking the Future of Plastics. In World Economic Forum.

Regan, D. T. (1971). Effects of a favor and liking on compliance. Journal of experimental social psychology, 7(6), 627-639.

Reingen, P. H. (1982). Test of a list procedure for inducing compliance with a request to donate money. Journal of Applied Psychology, 67(1), 110.

Parker, L. (2017, July 19). A whopping 91% of plastic isn’t recycled. National Geographic               
Accessed from: 

Przybylski, A. K., Murayama, K., DeHaan, C. R., & Gladwell, V. (2013). Motivational, emotional, and behavioral correlates of fear of missing out. Computers in Human Behavior, 29(4), 1841-1848.

Weaver, K., Garcia, S. M., Schwarz, N., & Miller, D. T. (2007). Inferring the popularity of an opinion from its familiarity: A repetitive voice can sound like a chorus. Journal of personality and social psychology, 92(5), 821.

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