Stay committed, and change will come!

26 July 2018

Portrait of Dr Cecilia Larrosa

by Dr Cecilia Larrosa
Postdoctoral researcher

Cecilia is a postdoctoral fellow working on the Oxford Martin School-TNC Climate Partnership project 'Building resilience to climate change in the Amazon' - a project that aims to understand the interactions between climate change mitigation interven...

The Tipping point
© Tom Toles

Long-term change in undesirable human behaviour is the holy grail of conservation. Sustainability, and the preservation of biodiversity, require drastic changes in the way we do things, from consumption patterns to improved governance. However, directed sustainable behavioural change is no easy task, as people, social and ecological systems are always changing, share non-linear interactions, and present emerging behaviour.

Social conventions play a key role in determining human behaviour. By definition, a social convention is a set of agreed, stipulated, or generally accepted standards, norms, or criteria, often taking the form of a custom. Social conventions determine which behaviours are acceptable and which are not, and can ultimately become laws (Barber, 2010). Conversely, laws that don’t reflect social conventions can be ineffective. Most importantly, social conventions can change over time, such as American attitudes towards same-sex marriage or attitudes towards plastic waste in the UK. Twenty-five years after a brittish charity called the Marine Conservation Society started campaigning and lobbying against plastic pollution in shores and oceans, attitudes and behaviour towards plastic waste have changed drastically. In the last 5 years, the UK Government has introduced measures for reducing single-use plastics, such as charges for plastic bags and banning microbeads, and is evaluating a ban on plastic cutlery, plates, straws and plastic-stem cotton buds. But how do social conventions change?

There are many pathways to change social convention, such as innovation in technology and social movements. The theory of critical mass argues that when a committed minority reaches a critical group size, the social system crosses a tipping point, which triggers changes in behaviour that rapidly increase the acceptance of the minority view (Granovetter, 1978). The theory sustains that small groups of individuals can change social convention, not because they have authority or wealth, but because of their commitment to the cause. This is an enticing concept, however, evidence for critical group size in changing social conventions has been limited to theoretical models and qualitative observations.

In June, Centola et al. (2018) published a paper in Science providing experimental evidence on tipping points in social convention. To do this they first modelled a theoretical tipping point based on existing theoretical and observational evidence, finding a smallest successful minority at 25% of a population. Based on this value they run 10 trials, each with 20 to 30 participants and a committed minority whose size varied across trials (17%- 31%). Each trial consisted of an online game in which participants were matched at random into pairs for an interaction within the trial. In this interaction participants simultaneously assigned a name to a face, if their answers matched they were rewarded with a payment, and if they didn't they were penalised. After each interaction participants could see the choices their partner had made. These randomly paired interactions were repeated until a convention was established for all participants within the trial. Once a convention regarding the name was established, a "committed minority" was introduced to the trial, who attempted to change the established convention with a novel alternative name. Random interactions continued until the game finished after players had between 30 and 55 interactions. Amongst other findings, their results show that when the size of the committed minority reached ~25% of the population a tipping point was triggered, and the minority group succeeded in changing the established social convention.

There are limitations to the study, and the authors identify some of these, such as the lack of emotional and psychological attachment to the tested convention, or lack of variety in the social setting. However, results can be applied to similar settings such as the ability of organisations to introduce “minority groups” within online spaces to influence conventional behaviour.

So what does this mean for conservation and behaviour change? This new evidence strengthens the critical mass theory explaining social change. To me, this is both scary and exciting. It is scary to think how easily governments or private interests can infiltrate social media to try to change what we think is acceptable and unacceptable. However, as a conservationist, the possibility that a small group of regular individuals that are committed to a cause can shift social convention feels extremely optimistic. It makes me reconsider the value of advocacy, and appreciate the role of public engagement activities, often undervalued by the scientific community. Hopefully, our commitment to sustainability will spread and reach critical mass, resulting in new social conventions that may one day become laws. Above all, this evidence helps disperse the doom-and-gloom so common in conservation: yes, we are a minority and yes, change is slow… but if we stay committed and spread hope, we will reach those tipping points!


Barber, N. W. (2010). Laws and Conventions. In The Constitutional State. Oxford: Oxford University Press.

Centola, D., Becker, J., Brackbill, D., & Baronchelli, A. (2018). Tipping points in social convention. Science, 360(6393), 1116–1119.

Granovetter, M. (1978). Threshold Models of Collective Behavior. American Journal of Sociology, 83(6), 1420–1443.


Tipping point, acknowledgement: illustration by Tom Toles

This opinion piece reflects the views of the author, and does not necessarily reflect the position of the Oxford Martin School or the University of Oxford. Any errors or omissions are those of the author.