Do your neighbors have a "no to advertising" sign on their mailboxes? Then there is a greater chance that you will also get one.

In a meta-study, researchers in environmental psychology at the University of Gothenburg went through 91 experiments from large parts of the world where social norms were used to stimulate environmentally friendly behavior. The conclusion: When we see others act environmentally friendly, our tendency to do so also increases.

The experiments are conducted in a natural environment and show that social norms can influence a wide range of behaviors, such as water and electricity savings, choice of vegetarian food, sustainable consumption and choice of environmentally friendly transport.

The clearest example is the research that shows that people are less likely to debris in clean environments compared to environments where it is already degraded.

- In these studies, the participants get something they can junk down with, for example a flyer on the car. Researchers then observe how the participants behave in a place that is clean and degraded, respectively, says Magnus Bergquist, a researcher in environmental psychology.

We want to feel free

The researchers have tested two different techniques to influence people. The first technology is to give people explicit information. For example, the test subject will know how others have done to save electricity and water, or how many who have chosen vegetarian for lunch.

The second technique is that people can come to the conclusion of what others have done. An example of this is turning off a public toilet, which makes people more likely to extinguish the light themselves when they leave.

- There we find a very big difference. The technologies that use more implicit agents are much more effective, says Magnus Bergquist, and continues:

- It is in line with the social psychology literature on social impact. When we humans feel that someone is trying to influence us, we are less likely to change our behavior.

Why do we work like this?

- It may have to do with our desire for autonomy. It is a built-in paradox with social influence, on the one hand we want to feel free, on the other we are very much affected by what other people do.