Messaging, visual cues can reduce the use of plastic produce bags, says study from UBC prof

The University of British Columbia psychology professor behind a new study says using interventions such as visual cues or motivational messages in grocery stores can reduce the use of plastic produce bags.

"I think one of the insidious items that's still out there is produce bags. We now ban single-use plastic bags at grocery stores, but produce bags are still freely available," said Jiaying Zhao, an associate professor in UBC's Dept. of Psychology who studies behaviours around waste reduction and recycling.

Countries around the world are struggling with how to reduce the amount of plastic ending up in oceans. A year ago the United Nations approved an agreement to create the world's first global plastic pollution treaty, while an increasing number of jurisdictions in places like B.C. have put bans on single-use checkout bags in stores.

• Paper bags in Vancouver grocery stores now cost at least 25 cents, reusable bags $2

Zhao decided to focus on produce bags — used to pack fruits, vegetables, or bulk foods in grocery stores — in her latest study, published in the journal Resources, Conservation and Recycling, because they are rarely reused and can greatly contribute to plastic waste at landfills or in the ocean.

For the study, messages like "Join your fellow citizens to not use produce bags" or an image of a turtle with a bag in its mouth were displayed in an online grocery shopping experiment when it came time for participants to select how many produce bags they required.

All interventions resulted in a reduction of bags compared to a control group. The least successful intervention reduced produce bag use by 9.2 per cent. An incentive known as an extrinsic nudge — "If you choose not to use produce bags, we will donate to Ocean Wise, which is a globally-focused conservation organization on a mission to protect the ocean" — netted a nearly 50 per cent reduction in bag use.

The study, which was originally planned to be conducted in grocery stores in 2019 but had to be taken online due to the pandemic, builds on Zhao's other research.

Zhao says her latest study helps communicate to consumers how their behaviours are linked to plastic pollution.

"It directly links the consequence of our actions to that decision to use a produce bag in the first place," she said.

'You don't need to add any more plastic'

Since 2015, NADA, Vancouver zero-waste grocery store, has sold fruits and vegetables along with bulk items without providing packaging of any kind.

Claire Lester, the digital manager for NADA, said practices in grocery stores — such as using flimsy produce bags — have become an unnecessary habit for shoppers.

"Produce and fruit, they all have a skin to them that kind of protects them from the outside world that you don't need to add any more plastic to, so oftentimes you will see really unnecessary packaging in grocery stores like cucumber wrapped in plastic," she said.

Lester was impressed at how Zhao's interventions were able to break people's habit of using produce bags. She encourages the practice in conventional grocery stores to help customers change their ways.

"I know for myself, it just seems weird to grab a plastic bag for things that don't need it now, so it's kind of a retraining that happens and I think it's totally possible for anyone to do," she said.

Zhao hopes her studies bridge the gap between businesses and municipalities that want to reduce plastic pollution without implementing punitive measures.

"Behavioural interventions are a really powerful tool to change human behaviour," she said. "I know that changing policy is difficult so I think ... at the very least what we can do as consumers or as businesses is to implement those interventions ourselves and see the changes that result."

Zhao hopes to partner with a grocery store chain and conduct a repeat of the produce bag study in stores. 

"I think the results would be stronger," she said.