Supplier characteristics and changes in recycling behaviour

The following hypothesis was designed to test how supplier characteristics and recycling behaviour are related:

H1: System performance improves when supplier characteristics facilitate recycling behaviour.

The intervention that was designed to test this was an informational letter containing a nudge with the purpose to activate social norms that target food waste recycling behaviour. This was because motivation was the supplier characteristic that showed the most promise in its ability to affect actual recycling behaviour, and nudging appeared to be the best way to affect the motivation of end-consumer-turned-suppliers. The reasoning behind this choice was that if motivation could be increased, it would become a facilitator of recycling behaviour, as opposed to a lack of motivation, which would instead act as a barrier.

As expected, intentions to recycle food waste are higher than actual recycling behaviour. Our results show that 83% of the experimental group report that almost everything or everything of their food waste is sorted into green bags, versus 92%

in the control group, with around 60% of respondents in both groups claiming they sort all their food waste into green bags. This means that almost all respondents in both groups claim to sort ~75% or more of their food waste, if almost everything is interpreted as being in the middle of approximately half (50%) and everything (100%).

In contrast, the pick-analysis showed that actual recycling behaviour is not as high as intentions. The control group sorted 52% of total food waste in the pre-test, meaning the control group actually recycle approximately half their waste. For the experimental group however, the pre-test showed that 39% of total food waste was sorted into green bags, which is less than half. This means that there was a large gap between intention and action for both groups prior to our interventions.

Post-test results showed that the control group sorted 53% of food waste. For the experimental group, recycling behaviour improved, as 17% more food waste (56%) was sorted into green bags after the intervention. This increase in green bags was also without contamination. There is still a gap between intention and action for both groups, but the gap has become smaller for the experimental group, whereas the control group’s behaviour remained constant. It therefore appears that using an informational nudge to improve food waste recycling worked, and that we did manage to activate a norm regarding recycling. Our results are in line with other studies that have successfully used social norms to improve environmental friendly behaviour such as littering, and energy conservation (Barr 2007, 470, Goldstein, Cialdini, and Griskevicius 2008, Allcott 2011, Ayres 2012). The results also support the observational study of Schultz (1999), in which messages activating social norms were found to have an effect on participation in recycling schemes, and on amount of waste recycled. As we used a combination of descriptive and injunctive norms, our results seem to support evidence that suggests these messages are effective in changing behaviour (Schultz et al. 2007, Cialdini 2003).

However, because the intention-action gap is present in both groups, and as both groups only recycle a little over half their food waste, it is worth discussing to what degree a social norm regarding recycling has been internalised in the housing cooperative. If a social norm is internalised, it becomes a personal norm and source of internal motivation (Schultz 1999). We do not know to what degree each person actually recycles their waste due to the way the collection points are configured. We do not know if some end-consumer-turned-supplier recycle nothing, and some everything, as our numbers reveal average recycling behaviour.

If we for example assume that the questionnaire respondents who reported high intentions also recycle all their food waste, and that the people who did not respond to it recycle nothing, the overall recycling rate will still be approximately 50%, and there is likely a smaller intention action gap. This also means that our intervention may only have succeeded to re-activate a latent personal norm about recycling present in the experimental group, and not established a new norm for those who previously did not recycle.

To further explore this, we asked respondents how they perceived their neighbours’ food waste recycling behaviour, as this was what the informational nudge had targeted. We found that a higher share of the respondents in the experimental group both believed that their neighbour sorted their waste, and that their neighbours were better than themselves at sorting their waste. The questionnaire response rate of 33% means we can only use this data to support the findings from the pick-analysis. Taken together, these results indicate that the observed change in food waste recycling behaviour probably was caused by the informational nudge and an activation of a social norm.

This also controlled for the change in distribution method, as the experimental group was also provided with green bags for food waste disposal when the nudge was distributed. This change in distribution method may partially have caused the increase in food waste recycling because end-consumer-turned-suppliers simply had not recycled because they lacked the equipment to do so, and this may confound our results.

In conclusion, it appears plausible that the informational nudge did in fact activate a social norm, which successfully increased the recycling rate of food waste.